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Electrical engineering, Electrotechnique, Energy, Énergie, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Electrotechnique. Electroenergetique, Electrical engineering. Electrical power engineering, Matériel électrique divers, Various equipment and components, Condensateurs. Résistances. Filtres, Capacitors. Resistors. Filters, Aluminium Phosphate, Aluminium Phosphates, Aluminio Fosfato, Composé ternaire, Ternary compound, Compuesto ternario, Condensateur électrochimique, Electrolytic capacitor, Condensador electroquímico, Couche ultramince, Ultrathin films, Evaluation performance, Performance evaluation, Evaluación prestación, Forme cylindrique, Cylindrical shape, Forma cilíndrica, Gonflement, Swelling, Inflamiento, Lithium Oxyde, Lithium Oxides, Litio Óxido, Lithium Titanate, Lithium Titanates, Litio Titanato, Matériau modifié, Modified material, Material modificado, Matériau revêtu, Coated material, Material revestido, Performance, Rendimiento, Revêtement, Coatings, Revestimiento, Supercondensateur, Supercapacitor, Supercondensador, Titane Oxyde, Titanium Oxides, Titanio Óxido, Traitement surface, Surface treatment, Tratamiento superficie, Li4Ti5O12, H2Ti12O25, Hybrid supercapacitor, Surface modified, and Swollen phenomenon

Hydrogen titanium oxide, H2Ti12O25 is prepared by soft chemical method. A fabricated asymmetric hybrid supercapacitor using an AlPO4 modified H2Ti12O25 anode shows electrochemical performance superior to a Li4Ti5O12 anode, including cycling performance. The anode comprised of H2Ti12O25 coated with 3 wt.% AlPO4 shows the energy and power density of 41.1 Wh kg-1, 194.1 W kg-1, respectively, at a current rate of 0.1 A g-1 as well as the highest cycling performance, with 94.1% specific capacitance retained after 1000 cycles at a current rate of 3.0 A g-1. These excellent results are convincing evidence that H2Ti12O25 should be regarded as one of the more promising anode materials.

Electrical engineering, Electrotechnique, Energy, Énergie, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Electrotechnique. Electroenergetique, Electrical engineering. Electrical power engineering, Electroénergétique, Electrical power engineering, Conversion directe et accumulation d'énergie, Direct energy conversion and energy accumulation, Conversion électrochimique: piles et accumulateurs électrochimiques, piles à combustibles, Electrochemical conversion: primary and secondary batteries, fuel cells, Energie, Energy, Energie. Utilisation thermique des combustibles, Energy. Thermal use of fuels, Appareils de production et de conversion d'énergie: énergie thermique, énergie électrique, énergie mécanique, etc, Equipments for energy generation and conversion: thermal, electrical, mechanical energy, etc, Piles à combustible, Fuel cells, Alcool primaire, Primary alcohol, Alcohol primario, Collection courant, Current collection, Colección corriente, Gestion eau, Water management, Gestión del agua, Métal, Metal, Méthanol, Methanol, Metanol, Noyage, Flooding, Inundación, Oxydation, Oxidation, Oxidación, Pile combustible alcool, Alcohol fuel cells, Traitement par plasma, Plasma assisted processing, Traitement surface, Surface treatment, Tratamiento superficie, Collecteur de courant, Current collector, Direct methanol fuel cell, Plasma electrolytic oxidation, and Water flooding

A novel water management system for micro passive DMFC is fabricated and characterized in this paper. This system consists of both a cathode current collector made of a 316L sintered stainless fiber felt (SSFF) and an aluminum-based end plate fabricated with a perforated flow field. Besides, some water-collecting channels were fabricated on the surface of the cathode end plate and then covered by the plasma electrolytic oxidation (PEO) coating. The results show that the PEO coating plays crucial roles in the water management system. Because of the highly hydrophilic property of the coating, the channels work well in collecting the liquid water from the current collector, and water accumulation along the air-breathing holes can be well prevented, which improves the stability of the micro DMFC.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Dépôt de matériaux non métalliques, Nonmetallic coatings, Barrière thermique, Thermal barrier, Barrera térmica, Conductivité thermique, Thermal conductivity, Conductividad térmica, Waermeleitfaehigkeit, Dilatation thermique, Thermal expansion, Dilatación térmica, Thermische Ausdehnung, Dopage, Doping, Dopen, Expansion, Expansión, Oxyde d'yttrium, Yttrium oxide, Ytrio óxido, Yttriumoxid, Perovskite, Perovskita, Revêtement non métallique, Non metal coating, Revestimiento no metálico, Nichtmetallischer Ueberzug, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, TBC, perovskites, thermal conductivity, and thermal expansion

Y2O3 and Yb2O3 co-doped strontium hafnate powder with chemistry of Sr(Hf0.9Y0.05Yb0.05)O2.95 (SHYY) was synthesized by a solid-state reaction at 1450 °C. The SHYY showed good phase stability not only from 200 to 1400 °C but also at a high temperature of 1450 °C for a long period, analyzed by differential scanning calorimetry and x-ray diffraction, respectively. The coefficient of thermal expansion of the sintered bulk SHYY was recorded by a high-temperature dilatometer and revealed a positive influence on phase transitions of SrHfO3 by co-doping with Y2O3 and Yb2O3. The thermal conductivity of the bulk SHYY was approximately 16% lower in contrast to that of SrHfO3 at 1000 °C. Good chemical compatibility was observed for SHYY with 8YSZ or Al2O3 powders after a 24 h heat treatment at 1250 °C. The phase stability and the microstructure evolution of the as-sprayed SHYY coating during annealing at 1400 °C were also investigated.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Argent, Silver, Plata, Silber, Choc laser, Laser impact, Choque laser, Dépôt projection, Spray coating, Depósito proyección, Spritzbeschichten, Matériau composite, Composite material, Material compuesto, Verbundwerkstoff, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Cold spray, Composite, Laser shock, Oxide, Powder, Splat, and Tantalum

Since the major technological issues in cold spray are now controlled, the key parameter for successful coating relates to the powder. The influence of the main characteristics of the starting powder on the final coating properties remains rather unknown. This includes primarily metallurgical, morphological and physico-chemical characteristics of the particles. This article focuses on the so-called local approach to these characteristics to show that the current global approach is insufficient. The discussion is based on many examples of cold spray results, including recent work on Ag-based and Ta cold sprayed-coatings. This results in proposed specifications for powders which are claimed to be tailored for cold spray.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Métallurgie des poudres. Matériaux composites, Powder metallurgy. Composite materials, Métaux et alliages frittés. Cermets, Sintered metals and alloys. Pseudo alloys. Cermets, Traitements de surface, Surface treatment, Corrosion, Action des agents de corrosion, Corrosion environments, Propriétés mécaniques. Rhéologie. Mécanique de la rupture. Tribologie, Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology, Frottement. Usure, Contact of materials. Friction. Wear, Propriété mécanique, Mechanical properties, Propiedad mecánica, Composé intermétallique, Intermetallic compound, Compuesto intermetálico, Intermetallische Verbindung, Corrosion électrochimique, Electrochemical corrosion, Corrosión electroquímica, Elektrochemische Korrosion, Frittage, Sintering, Sinterización, Sintern, Microstructure, Microestructura, Mikrogefuege, Métallurgie poudre, Powder metallurgy, Metalurgia polvo, Pulvermetallurgie, Revêtement, Coatings, Revestimiento, Ueberzug, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Tribologie, Tribology, Tribología, Usure, Wear, Desgaste, Verschleiss, Corrosion, and Intermetallics

An erbium modified Mg17Al12 based coating was fabricated by hot press sintering on as extruded AZ61 Mg alloy. The Er modified coating was composed of Mg17Al12 and Al3Er phases. As a result of the presence of the dispersed Al3Er phase, the coating had a greater microhardness than Mg17Al12. Thermal effects of sintering at 400°C for 1 h caused no obvious deterioration in the wear resistance of the AZ61 Mg matrix. Electrochemical and wear resistance tests showed that the Er modified Mg17Al12 based coating had a lower corrosion current density and a lower friction coefficient than Mg17Al12, the AZ61 Mg matrix and a thermal diffusion coating (TDC). The superior wear resistance of the sintered coating resulted from the hard Al3Er phase. The corrosion resistance of the sintered coating was better than that of the TDC as a result of suppression of hydrogen evolution by the rare earth metal Er.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Propriétés mécaniques. Rhéologie. Mécanique de la rupture. Tribologie, Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology, Frottement. Usure, Contact of materials. Friction. Wear, Propriété mécanique, Mechanical properties, Propiedad mecánica, Contrainte résiduelle, Residual stress, Tensión residual, Eigenspannung, Dépôt projection, Spray coating, Depósito proyección, Spritzbeschichten, Projection à chaud, Hot spraying, Proyección en caliente, Spritzen, Revêtement, Coatings, Revestimiento, Ueberzug, Résistance usure, Wear resistance, Resistencia al desgaste, Verschleissfestigkeit, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Tribologie, Tribology, Tribología, Usure, Wear, Desgaste, Verschleiss, iron alloys, residual stress, robot, and wear resistance

Even though the application of thermal spray coatings on complex geometries gained a greater interest in the last decade, the effect of different geometrical features on the wear behavior is still ill-defined. In this study, the wear resistance of FTC-FeCSiMn coated 3D surfaces was investigated. The wear test was carried out by means of two innovative testing procedures. The first test is a Pin-on-Tubes test where the rotating motion is realized by a lathe chuck. The specimens in the second test were fixed on the table and a robot arm operated the pin. This wear test was applied on specimens with concave or convex surfaces. The residual stresses, which were determined by means of an incremental hole-drilling method, show a dependency on the substrate geometry. The obtained stresses were put in relation to the different radii. After the wear test, a 3D-profilometer determined the wear volume and the sections of the coatings were characterized by a scanning electron microscope. The results indicate that the wear resistance is strongly influenced by the geometry of the substrate.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Alliage base titane, Titanium base alloys, Aluminium alliage, Aluminium alloy, Aluminio aleación, Aluminiumlegierung, Dépôt projection, Spray coating, Depósito proyección, Spritzbeschichten, Formage projection, Spray forming, Formación proyección, Formage à tiède, Warm forming, Modelado en tibio, Halbwarmumformen, Microstructure, Microestructura, Mikrogefuege, Porosité, Porosity, Porosidad, Porositaet, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Vanadium alliage, Vanadium alloy, Vanadio aleación, Vanadiumlegierung, microstructure, oxygen content, porosity, and warm spraying

Warm spray (WS) is a modification of high-velocity oxy-fuel spraying, in which the temperature of the supersonic gas flow generated by the combustion of kerosene and oxygen is controlled by diluting the combustion flame with an inert gas such as nitrogen. The inert gas is injected into the mixing chamber placed between the combustion chamber and the powder feed ports, thus the temperature of the propellant gas can be controlled from ∼700 to 2,000 K. Since WS allows for higher particle temperatures in comparison to cold spray, warm sprayed particles are more softened upon impact, thus resulting in greater deformation facilitating the formation of shear instability for bonding. Recently, the combustion pressure of WS has been increased from 1 (low-pressure warm spray) to 4 MPa (high-pressure warm spray) in order to increase the velocity of sprayed particles. Effects of spray parameters on microstructure, mechanical properties, and splats formation of Ti-6Al-4V were systematically studied. Obtained coatings were examined by analyzing the coating cross-section images, microhardness as well as oxygen content. In addition, flattening ratio of splats was calculated as a function of nitrogen flow rate. It was found that the increased particle velocity caused by the increased combustion pressure had significant beneficial effects in terms of improving density and controlling the oxygen level in the sprayed Ti-6Al-4V coatings.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Dépôt de métaux et d'alliages, Metallic coatings, Corrosion, Action des agents de corrosion, Corrosion environments, Alliage base nickel, Nickel base alloys, Corrosion, Corrosión, Korrosion, Dépôt chimique, Chemical deposition, Depósito químico, Stromloses Beschichten, Irradiation, Irradiación, Bestrahlung, Revêtement métallique, Metal coating, Revestimiento metálico, Metallischer Ueberzug, Résistance corrosion, Corrosion resistance, Resistencia corrosión, Korrosionsbestaendigkeit, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Coatings, Electroless plating, Magnesium alloy, and Ultrasonic irradiation

Ultrasonic irradiation (UI) is applied to assist the electroless plating (EP) Ni―P coating on a magnesium alloy substrate. The results show that under UI, the Ni―P coating becomes smooth, compact, has refined grains and is free of cracks and pores, leading to significant improvement in the coating corrosion resistance. The crystallinity of the coating is also improved by UI, transforming from amorphous state to mixture of amorphous and nanocrystalline one.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Dépôt de métaux et d'alliages, Metallic coatings, Propriétés mécaniques. Rhéologie. Mécanique de la rupture. Tribologie, Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology, Frottement. Usure, Contact of materials. Friction. Wear, Propriété mécanique, Mechanical properties, Propiedad mecánica, Adhérence, Adhesion, Adherencia, Adhaesion, Application, Aplicación, Anwendung, Dépôt projection, Spray coating, Depósito proyección, Spritzbeschichten, Erosion, Erosión, Force adhérence, Adhesive strength, Fuerza adherencia, Haftfestigkeit, Plasma, Projection plasma, Plasma spraying, Proyección plasma, Plasmaspritzen, Projection à chaud, Hot spraying, Proyección en caliente, Spritzen, Revêtement métallique, Metal coating, Revestimiento metálico, Metallischer Ueberzug, Résistance mécanique, Strength, Resistencia mecánica, Festigkeit, Résistance usure, Wear resistance, Resistencia al desgaste, Verschleissfestigkeit, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Tribologie, Tribology, Tribología, Turbine gaz, Gas turbine, Turbina gas, Gasturbine, Usure, Wear, Desgaste, Verschleiss, MCrAlY, abradable coating, adhesive strength, atmospheric plasma spray (APS), erosion resistance, gas turbines, and rubbing wear

The processing conditions, microstructural and tribological characterizations of plasma-sprayed CoNiCrAlY-BN high temperature abradable coatings are reported in this manuscript. Plasma spray torch parameters were varied to produce a set of abradable coatings exhibiting a broad range of porosity levels (34-62%) and superficial Rockwell hardness values (0-78 HR15Y). Abradability tests have been performed using an abradable-seal test rig, capable of simulating operational wear at different rotor speeds and seal incursion rates (SIRs). These tests allowed determining the rubbing forces and quantifying the blade and seal wear characteristics for slow and fast SIRs. Erosion wear performance and ASTM C633 coating adhesion strength test results are also reported. For optimal abradability performance, it is shown that coating hardness needs to be lower than 70 and 50 HR15Y for slow and fast blade incursion rate conditions, respectively. It is shown that the erosion wear performance, as well as, the coating cohesive strength is a function of the coating hardness. The current results allow defining the coating specifications in terms of hardness and porosity for targeted applications.

Electronics, Electronique, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Domaines interdisciplinaires: science des materiaux; rheologie, Cross-disciplinary physics: materials science; rheology, Science des matériaux, Materials science, Méthodes de nanofabrication, Methods of nanofabrication, Formation de nanomotifs, Nanoscale pattern formation, Traitements de surface, Surface treatments, Sciences appliquees, Applied sciences, Electronique, Electronics, Electronique des semiconducteurs. Microélectronique. Optoélectronique. Dispositifs à l'état solide, Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices, Dispositifs à ondes acoustiques, piézoélectriques, piézorésistifs, Acoustic wave devices, piezoelectric and piezoresistive devices, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Surface treatment, Composé III-VI, III-VI compound, Compuesto III-VI, Alumine, Alumina, Alúmina, Tonerde, Aluminium, Aluminio, Angle contact, Contact angle, Angulo contacto, Kontaktwinkel, Anodisation, Anodizing, Anodización, Elektrolytisches Oxidieren, Courant intense, High strength current, Corriente intensa, Diminution coût, Cost lowering, Reducción costes, Kostensenkung, Dispositif entraînement, Driving device, Dispositivo arrastre, Durcissement, Hardening, Endurecimiento, Haerten, Electrolyte acide, Acid electrolyte, Electrólito ácido, Evaluation performance, Performance evaluation, Evaluación prestación, Formation nanomotif, Nanopatterning, Formacíon nanomotivo, Gyroscope, Giroscopio, Microscopie électronique balayage, Scanning electron microscopy, Microscopía electrónica barrido, Rasterelektronenmikroskopie, Nanocomposite, Nanocompuesto, Nanofil, Nanowires, Nanostructure, Nanoestructura, Précision élevée, High precision, Precisión elevada, Rotor, Surface rugueuse, Rough surface, Superficie rugosa, Rauhe Oberflaeche, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Traitement(durcissement), Curing, Vitesse déplacement, Speed, Velocidad desplazamiento, Geschwindigkeit, 0707D, 8107B, 8107V, 8116R, Al2O3, Matériau nanostructuré, Nanostructured material, Drag reduction, Liquid-floated rotor gyroscope, Nanostructured, and Oleophobic

Liquid-floated rotor gyroscopes can provide high accuracy at small volume and low cost. In rotor gyroscopes, the rotating speed of rotor can significantly affect the detection accuracy. This work presents a new kind of liquid-floated rotor gyroscope using super-oleophobic surface processing, which can improve the performance of driving system. In this work, an unconventional anodization in oxalic-acid electrolyte under high current was employed to fabricate diverse nanostructured alumina surfaces. The top-view SEM image shows the nanowire pyramid structure on the surface of processed sample. Modification of the rough surfaces was achieved by dipping substrates in 0.5 wt% 1H,1H,2H,2H-perfluoro-octadecyltrichlorosilane-in-hexane and then curing then at 120 °C for 1 h. The maximum contact angle (CA) of the aluminum rotor with nanowire pyramid structure was measured to be 156° in average. The oleophobicity of the rotor surface was used to reduce the resistance in the floating liquid. The test results show that, under the normal working state, the rotating speed of super-oleophobic rotor can be reached up to 3200 rpm. While a similar system without the micro-nano composite structure can only reach 2860 rpm. Thus, the nanostructured super-oleophobic alumina surface processing can greatly increase the rotating speed, thereby improving the performance of the gyro system.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Techniques de l'ingénieur appliqués à la métallurgie. Applications. Divers, Engineering techniques in metallurgy. Applications. Other aspects, Applications, Industrie automobile, Automotive engineering, Adhérence, Adhesion, Adherencia, Adhaesion, Application, Aplicación, Anwendung, Force adhérence, Adhesive strength, Fuerza adherencia, Haftfestigkeit, Industrie automobile, Automobile industry, Industria automóvil, Autoindustrie, Industrie aéronautique, Aeronautic industry, Industria aeronáutica, Luftfahrtindustrie, Morphologie, Morphology, Morfología, Plasma, Projection plasma, Plasma spraying, Proyección plasma, Plasmaspritzen, Projection à chaud, Hot spraying, Proyección en caliente, Spritzen, Revêtement conducteur, Conductive coating, Revestimiento conductor, Résistance mécanique, Strength, Resistencia mecánica, Festigkeit, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Adhesion testing, aircraft, atmospheric plasma spray (APS), automotive, copper, and electrically conductive coatings

Metallization of Carbon Fiber-Reinforced Polymer (CFRP) composites aggrandized their application to aircraft, automobile, and wind power industries. Recently, the metallization of CFRP surface using thermal spray technique, especially the cold spray, a solid state deposition technique, is a topic of research. However, a direct cold spray deposition on the CFRP substrate often imposes severe erosion on the surface owing to the high-impact energy of the sprayed particles. This urges the requirement of an interlayer on the CFRP surface. In the present study, the effect of surface treatment on the interlayer adhesion strength is evaluated. The CFRP samples were initially treated mechanically, chemically, and thermally and then an interlayer was developed by atmospheric plasma spray system. The quality of the coating is highly dependent on the splat taxonomy; therefore the present work also devoted to study the splat formation behavior using the splat-collection experiments, where the molten Cu particles impinged on the treated CFRP substrates. These results were correlated with the coating adhesion strength. The coating adhesion strength was measured by pull-out test. The results showed that the surface treatment, particularly the chemical treatment, was fairly successful in improving the adhesion strength.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Formage, Forming, Laminage, Rolling, Traitements de surface, Surface treatment, Corrosion, Action des agents de corrosion, Corrosion environments, Protection contre la corrosion, Corrosion prevention, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Application, Aplicación, Anwendung, Corrosion, Corrosión, Korrosion, Formage, Forming, Conformado, Umformen, Impédance, Impedance, Impedancia, Laminage à froid, Cold rolling, Laminado en frío, Kaltwalzen, Matériau composite, Composite material, Material compuesto, Verbundwerkstoff, Microscopie force atomique, Atomic force microscopy, Microscopía fuerza atómica, Oxyde de fer, Iron oxide, Hierro óxido, Eisenoxid, Passivation, Pasivación, Passivierung, Polarisation anodique, Anodic polarization, Polarización anódica, Anodische Polarisation, Polymère, Polymer, Polímero, Protection corrosion, Corrosion protection, Protección corrosión, Korrosionsschutz, Pyrrole polymère, Pyrrole polymer, Pirrol polímero, Revêtement composite, Composite coating, Revestimiento compuesto, Synthèse, Synthesis, Síntesis, Tôle laminée à froid, Cold rolled sheet, Chapa laminada en frío, Kaltgewalztes Blech, anodic polarization, composite coatings, conducting atomic force microscopy, conducting polymers, corrosion, electrochemical impedance spectroscopy, micaceous iron oxide, passivation, and polypyrrole

Novel hybrid composite pigments consisting of micaceous iron oxide (MIOX) and polypyrrole (PPy) were synthesized using a chemical oxidative polymerization method and water as a reaction medium. Three different particle sizes (5, 10, and 30 μm) of MIOX, namely. MIOX5, MIOX10, and MIOX30, were used for the synthesis of MIOX/PPy composite pigments. The synthesized hybrid composite pigment was characterized by scanning electron microscopy (SEM) for morphology, energy-dispersive spectroscopy (EDS) for elemental analysis, four-point probe conductivity, and conductive-atomic force microscopy (C-AFM) for conductivity studies. Density tests were also performed for the adhesion between MIOX and PPy. MIOX30/ PPy composite pigment-based coatings were formulated at 15, 25, and 35% pigment volume concentration (PVC) on cold-rolled steel and were exposed to salt spray test conditions according to ASTM B117. Corrosion performance was analyzed by electrochemical impedance spectroscopy (EIS) and anodic polarization. Equivalent circuit modeling of the EIS data was performed for the understanding of the corrosion processes on the coated substrate. A smaller drop in impedance was observed for MIOX30/PPy composite pigment-based coating at 100 days of salt spray exposure than MIOX30 pigment coating for the same duration of exposure.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Corrosion, Action des agents de corrosion, Corrosion environments, Corrosion, Corrosión, Korrosion, Dépôt projection, Spray coating, Depósito proyección, Spritzbeschichten, Projection à chaud, Hot spraying, Proyección en caliente, Spritzen, Revêtement, Coatings, Revestimiento, Ueberzug, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Coating, Properties, Resistance, Spraying, and Structure

Coating technology is growing because of its important role in improving, e.g. corrosion resistance, thermal and electrical conductivities, and other properties of material in order to decrease costs and increase service life and safety. Cold spraying is the technique to produce coatings from powder feedstock by spraying solid particles on the substrate, forming the coating. Cold spraying is a relatively new spraying method, which has many advantages over other forms of thermal spraying. The advantages are dense and pure structures, high deposition efficiency, low residual stresses, minimal heat input to substrate, phase and compositional stability, and little need for masking. Furthermore, cold spraying is a cost effective and environmentally friendly alternative to, e.g. soldering, electroplating, and painting. One potential application field of cold sprayed coatings is corrosion protection due to the possibility to produce fully dense and impermeable coatings. From this aspect, this review is focused on corrosion properties of cold sprayed coatings and structural details behind these coatings.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Propriétés mécaniques. Rhéologie. Mécanique de la rupture. Tribologie, Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology, Adhérence, Adhesion, Adherencia, Adhaesion, Alumine, Alumina, Alúmina, Tonerde, Dépôt projection, Spray coating, Depósito proyección, Spritzbeschichten, Haute résolution, High resolution, Alta resolucion, Microscopie électronique transmission, Transmission electron microscopy, Microscopía electrónica transmisión, Transmissionselektronenmikroskopie, Mécanisme formation, Formation mechanism, Mecanismo formacion, Projection à chaud, Hot spraying, Proyección en caliente, Spritzen, Propriété mécanique, Mechanical properties, Propiedad mecánica, Propriété traction, Tensile property, Propiedad tracción, Zugeigenschaft, Revêtement, Coatings, Revestimiento, Ueberzug, Résistance mécanique, Strength, Resistencia mecánica, Festigkeit, Résistance traction, Tensile strength, Resistencia tracción, Zugfestigkeit, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, HRTEM, adhesion, alumina, aluminum, cold gas spraying (CGS), and tensile strength

The metallization of ceramics by means of cold gas spraying (CGS) has been in the focus of numerous publications in the recent past. However, the bonding mechanism of metallic coatings on non-ductile substrates is still not fully understood. Former investigations of titanium coatings deposited on corundum revealed that a combination of recrystallization induced by adiabatic shear processes and hetero-epitaxial growth might be responsible for the high adhesion strengths of coatings applied on smooth ceramic surfaces. In the present work, the interface formation between CGS aluminum and alumina substrates is examined for different particle sizes and substrate temperatures. Furthermore, the influence of subsequent heat treatment on tensile strength and hardness is investigated. The splat formation of single particles is examined by means of scanning electron microscopy, while a high resolution transmission electron microscope is used to study the Al/Al2O3 interface. First results suggest that mechanical interlocking is the primary adhesion mechanism on polycrystalline substrates having the roughness in sub-micrometer range, while the heteroepitaxy between Al and Al2O3 can be considered as the main bonding mechanism for single-crystalline sapphire (α-Al2O3) substrates with the surface roughness in nanometer range. The heteroepitaxial growth is facilitated by deformation-induced recrystallisation of CGS aluminum.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Carbure de tungstène, Tungsten carbide, Wolframio carburo, Wolframcarbid, Carbure fritté, Cemented carbides, Carburo sinterizado, Hartmetall, Cobalt, Cobalto, Dépôt projection, Spray coating, Depósito proyección, Spritzbeschichten, Ecaillage, Scaling, Escamadura, Nanostructure, Nanoestructura, Poudre fine, Fine powder, Polvo fino, Projection HVOF, HVOF spraying, Proyeccion HVOF, Projection à chaud, Hot spraying, Proyección en caliente, Spritzen, Revêtement, Coatings, Revestimiento, Ueberzug, Résistance usure, Wear resistance, Resistencia al desgaste, Verschleissfestigkeit, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Tribologie, Tribology, Tribología, Usure glissement, Sliding wear, Desgaste deslizamiento, Gleitverschleiss, Usure roulement, Rolling wear, Desgaste rodadura, Waelzverschleiss, Fine structured coatings, HVOF, Nanostructured coatings, Scaling effects, WC-Co, Wear effects, Wear resistant coatings, and Wear testing

Fine structured and nanostructured materials represent a promising class of feedstock for future applications, which has also attracted increasing interest in the thermal spray technology. Within the field of wear protection, the application of fine structured or nanostructured WC-Co powders in the High Velocity Oxy-Fuel flame spraying technique (HVOF) provides novel possibilities for the manufacturing of cermet coatings with improved mechanical and tribological characteristics. In this study the tribological behavior of HVOF sprayed coatings derived from conventional, fine and nanostructured WC-12Co powders under sliding and rolling wear are investigated and the results are compared to C45 steel (Mat.-No. 1.0503). In addition, sliding and rolling wear effects on a microscopic level are scrutinized. It has been shown that under optimized spray conditions the corresponding fine and nanostructured WC-12Co coatings are able to obtain higher wear resistances and lower friction coefficients than the conventional coatings. This can be attributed to several scaling effects of the microstructure and to the phase evolution of the coating, which are discussed.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, A froid, Cold process, En frío, Dynamique fluide, Fluid dynamics, Dinámica fluido, Dépôt projection, Spray coating, Depósito proyección, Spritzbeschichten, Formage à froid, Cold forming, Modelado en frio, Kaltformgeben, Préchauffage, Preheating, Precalentamiento, Vorwaermen, Revêtement, Coatings, Revestimiento, Ueberzug, Simulation numérique, Numerical simulation, Simulación numérica, Température, Temperature, Temperatura, Temperatur, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Carrier gas, Coating, Cold spray, and Computational fluid dynamics

Carrier gas is known as the medium to inject the cold sprayed powders into the main driving flow inside the nozzle. Hence, the properties and conditions of carrier gas should be of great importance to the particle motion behaviour and then particle deposition process. In this study, the effect of carrier gas temperature on the particle acceleration and deposition in cold spray process was investigated by both numerical and experimental methods. It is found that the supersonic driving gas flow and the consequent particle acceleration behaviour are significantly influenced by the carrier gas temperature, more specifically, higher carrier gas temperature results in higher particle impact velocity. In addition, because the carrier gas has additional heating effect on the powder particles before injection, the final impact temperature also increases with the carrier gas temperature, which leads to the reduction in the critical velocity. The increase in particle impact velocity and reduction in critical velocity enable the deposition efficiency and coating bonding strength to significantly improve as the carrier gas temperature increases. The particle impact velocity is found to be more influential than critical velocity reduction.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Dépôt de matériaux non métalliques, Nonmetallic coatings, Corrosion, Action des agents de corrosion, Corrosion environments, Protection contre la corrosion, Corrosion prevention, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Composé organique, Organic compounds, Compuesto orgánico, Organische Verbindung, Corrosion, Corrosión, Korrosion, Couche protectrice, Protective layer, Capa protectora, Schutzschicht, Protection corrosion, Corrosion protection, Protección corrosión, Korrosionsschutz, Revêtement non métallique, Non metal coating, Revestimiento no metálico, Nichtmetallischer Ueberzug, Revêtement protecteur, Protective coatings, Revestimiento protector, Schutzueberzug, Système intelligent, Intelligent system, Sistema inteligente, coatings, corrosion, multifunctional, nanoscale materials, self-healing, and smart materials

Development of materials possessing the ability to recover their main function(s) in response to destructive impacts is, today, one of most rapidly growing fields in material science. In particular, protective organic coatings with the features to heal or restore their protective function autonomously are of great interest infighting surface deterioration processes like corrosion, biofouling, and other affecting metallic structures. Embedding of micro- and nanocontainers in protective coatings is a frequently used technique nowadays to provide them one or several feedback-active functionalities. Depending on the container's morphology and active agent(s) filled, coatings with specifically aimed self-recovering functionalities (anticorrosive, water-repelling, antifouling, etc.) or multifunctional coatings can be created. In the present paper, different types of containers for self-recovering functional coatings synthesized by use of mesoporous nano- and microparticles or on the emulsion basis are presented. L-b-L polyelectrolyte deposition, interfacial polymerization, surface precipitation, Pickering emulsions, and in situ emulsion polymerization were utilized for the preparation of nano- or micro-scaled containers. Morphology of containers, efficiency of encapsulation, and kinetics of active agents release were investigated using modem techniques such as transmission mode in the scanning electron microscopy (T-SEM), cryo scanning electron microscopy (Cryo-SEM), etc. Incorporation of containers in the coating matrix was followed by the experimental modeling of external impacts, leading to simultaneous container damage. Subsequent release of the active agent at the affected site caused the active feedback of the coating and self-recovery of its specific protective function. The advantages of novel container-based protective coatings as compared to conventional ones are illustrated by corrosion tests results according to ASTM Standard B117.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Cémentation caisse, Pack carburizing, Cementación en paquete, Pulveraufkohlen, Dépôt chimique phase vapeur, Chemical vapor deposition, Depósito químico fase vapor, Chemisches Aufdampfen, Dépôt chimique, Chemical deposition, Depósito químico, Stromloses Beschichten, Microscopie électronique balayage, Scanning electron microscopy, Microscopía electrónica barrido, Rasterelektronenmikroskopie, Oxydation, Oxidation, Oxidación, Protection, Protección, Revêtement, Coatings, Revestimiento, Ueberzug, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Chemical vapour deposition, SEM, TG, and XRD

The growth of Mg and Al coatings on copper by pack cementation is examined in this work by investigating the mechanism of the process, the effect of temperature and heating time on the coating structure. The experiments were undertaken at temperatures ranging from 550 to 600°C, while the duration of the process varied from 30 min to 3 h. It was found that the magnesium coatings consist of two phases corresponding to MgCu2 and CuMg2. These phases appeared as distinguished layers or mixed with each other, depending on the deposition temperature and duration. On the other hand, the aluminium coatings consist of a single Al4Cu9 phase whose thickness increases with deposition time and temperature. Finally, the oxidation resistance was also evaluated by thermogravimetric measurements, which revealed that the coated samples have superior resistance to bare copper, while Al coated coupons had the best performance when exposed in high temperature environment.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Propriétés mécaniques. Rhéologie. Mécanique de la rupture. Tribologie, Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology, Matériau composite, Composite material, Material compuesto, Verbundwerkstoff, Condition opératoire, Operating conditions, Condición operatoria, Dépôt projection, Spray coating, Depósito proyección, Spritzbeschichten, Grosseur grain, Grain size, Grosor grano, Korngroesse, Microstructure, Microestructura, Mikrogefuege, Nanocomposite, Nanocompuesto, Propriété mécanique, Mechanical properties, Propiedad mecánica, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, cold spray, mechanical properties, microstructural behavior, nanocomposites, and processing parameters

Cold spray is a coating technology based on aerodynamics and high-speed impact dynamics. In this process, spray particles (usually 1-50 μm in diameter) are accelerated to a high velocity (typically 300-1200 m/s) by a high-speed gas (pre-heated air, nitrogen, or helium) flow that is generated through a convergent-divergent de Laval-type nozzle. A coating is formed through the intensive plastic deformation of particles impacting on a substrate at a temperature below the melting point of the spray material. In the present paper the main processing parameters affecting the microstructural and mechanical behavior of metal-metal cold spray deposits are described. The effect of process parameters on grain refinement and mechanical properties were analyzed for composite particles of Al-Al2O3, Ni-BN, Cu-Al2O3, and Co-SiC. The properties of the formed nanocomposites were compared with those of the parent materials sprayed under the same conditions. The process conditions, leading to a strong grain refinement with an acceptable level of the deposit mechanical properties such as porosity and adhesion strength, are discussed.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Alliage base aluminium, Aluminium base alloys, Alliage base magnésium, Magnesium base alloys, Dépôt projection, Spray coating, Depósito proyección, Spritzbeschichten, Projection à chaud, Hot spraying, Proyección en caliente, Spritzen, Revêtement, Coatings, Revestimiento, Ueberzug, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Aluminium, Coating, Magnesium, Optimisation, and Spray

Cold spray technology continues to attract increasing attention in surface modification of light metals due to its low temperature operation. A method for selecting optimum process parameters is presented for cold spraying of aluminium coatings upon magnesium alloy AZ91. In the present study, particle deposition behaviour is investigated via modifying spraying parameters. Subsequently, based on the relationship between bonding ratio and particle velocity, the critical particle velocity for successful adhesion is determined. Finally, the influence of particle velocity on key coating characteristics is examined, including coating porosity, hardness, deposition efficiency and bond strength.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Dépôt projection, Spray coating, Depósito proyección, Spritzbeschichten, Modélisation, Modeling, Modelización, Prédiction, Prediction, Predicción, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Transfert chaleur, Heat transfer, Transferencia térmica, Waermeuebertragung, Vitesse, Velocity, Velocidad, cold spray, heat transfer, numerical model, and particle velocity

In cold spraying (CS), critical velocity of particles is one of the most important parameters. The impacting particle and substrate inevitably undergo a strong thermomechanical coupling process at the contacting interface and serious plastic deformation in a very short time. In this paper, a coupled thermomechanical Eulerian (CTM-Eulerian) model was, for the first time, developed for CS particles to investigate plastic deformation and heat conduction within the bulk, and to predict the critical velocity. Results show that heat conduction has a significant effect on the temperature distribution within the particle which will influence the atom diffusion at the impacting interface, while a little influence on plastic deformation. Moreover, based on the deformed particle shapes and plastic strain analysis, a calculated critical velocity of about 300 m/s for copper is obtained. Finally, this CTM-Eulerian model is extended to other commonly sprayed materials and the predicted critical velocities of Fe, Ni, SS304, Al, In718, and TC4 are about 350, 380, 395, 410, 490, and 500 m/s, respectively.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Domaines interdisciplinaires: science des materiaux; rheologie, Cross-disciplinary physics: materials science; rheology, Science des matériaux, Materials science, Méthodes de dépôt de films et de revêtements; croissance de films et épitaxie, Methods of deposition of films and coatings; film growth and epitaxy, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Couche mince, Thin film, Capa fina, Duennschicht, Dépôt phase vapeur, Vapor deposition, Depósito fase vapor, Aufdampfen, Dépôt physique phase vapeur, Physical vapor deposition, Deposición física fase vapor, Physikalisches Aufdampfen, Dépôt projection, Spray coating, Depósito proyección, Spritzbeschichten, Membrane, Membrana, Membran, Perovskite, Perovskita, Plasma, Projection plasma, Plasma spraying, Proyección plasma, Plasmaspritzen, Projection à chaud, Hot spraying, Proyección en caliente, Spritzen, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, oxygen transport membrane, perovskite La1-xSrxCoyFe1-yO3-δ, plasma spray physical vapor deposition, porous metallic support, and thin films

Plasma spray physical vapor deposition (PS-PVD) is a very promising route to manufacture ceramic coatings, combining the efficiency of thermal spray processes and characteristic features of thin PVD coatings. Recently, this technique has been investigated to effectively deposit dense thin films of perovskites particularly with the composition of La0.58Sr0.4Co0.2Fe0.8O3-δ (LSCF) for application in gas separation membranes. Furthermore, asymmetric type of membranes with porous metallic supports has also attracted research attention due to the advantage of good mechanical properties suitable for use at high temperatures and high permeation rates. In this work, both approaches are combined to manufacture oxygen transport membranes made of gastight LSCF thin film by PS-PVD on porous NiCoCrAlY metallic supports. The deposition of homogenous dense thin film is challenged by the tendency of LSCF to decompose during thermal spray processes, irregular surface profile of the porous metallic substrate and crack and pore-formation in typical ceramic thermal spray coatings. Microstructure formation and coating build-up during PS-PVD as well as the annealing behavior at different temperatures of LSCF thin films were investigated. Finally, measurements of leak rates and oxygen permeation rates at elevated temperatures show promising results for the optimized membranes.

Electronics, Electronique, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Etat condense: structure, proprietes mecaniques et thermiques, Condensed matter: structure, mechanical and thermal properties, Surfaces et interfaces; couches minces et trichites (structure et propriétés non électroniques), Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties), Interfaces solide-fluide, Solid-fluid interfaces, Mouillage, Wetting, Domaines interdisciplinaires: science des materiaux; rheologie, Cross-disciplinary physics: materials science; rheology, Science des matériaux, Materials science, Traitements de surface, Surface treatments, Sciences appliquees, Applied sciences, Electronique, Electronics, Electronique des semiconducteurs. Microélectronique. Optoélectronique. Dispositifs à l'état solide, Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices, Fabrication microélectronique (technologie des matériaux et des surfaces), Microelectronic fabrication (materials and surfaces technology), Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Surface treatment, Mécanique fluide, Fluid mechanics, Mecánica flúido, Hydromechanik, Circuit intégré, Integrated circuit, Circuito integrado, Integrierte Schaltung, Dépôt plasma, Plasma deposition, Depósito plasma, Empilement, Stacking, Apilamiento, Encrassement, Fouling, Enmugrecimiento, Epaisseur, Thickness, Espesor, Dicke, Etherethercétone polymère, Polyetheretherketone, Eter éter cetona polímero, Fabrication microélectronique, Microelectronic fabrication, Fabricación microeléctrica, Formation motif, Patterning, Formacíon motivo, Gravure plasma, Plasma etching, Grabado plasma, Haute résolution, High resolution, Alta resolucion, Hydrocarbure fluoré, Fluorocarbon, Hidrocarburo fluorado, Hydrophilie, Hydrophily, Hidrofilia, Hydrophobicité, Hydrophobicity, Hidrofobicidad, Lithographie, Lithography, Litografía, Microfluidique, Microfluidics, Microfluidic, Mode empilement, Stacking sequence, Modo apilamiento, Mouillage, Wetting, Remojo, Méthacrylate de méthyle polymère, Methyl methacrylate polymer, Metacrilato de metilo polímero, Oxygène, Oxygen, Oxígeno, Sauerstoff, Photolithographie, Photolithography, Fotolitografía, Photorésist, Photoresist, Fotorresistencia, Propriété surface, Surface properties, Propiedad superficie, Oberflaecheneigenschaft, Réseau (arrangement), Array, Red, Résist, Resist, Resistencia, Silicium, Silicon, Silicio, Système sur puce, System on a chip, Sistema sobre pastilla, Technologie planaire, Planar technology, Tecnología planar, Traitement par plasma, Plasma assisted processing, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, 4785N, 8116N, 8116R, 8540H, Cancer cell patterning, Fibrosarcoma cancer cell line HT1080, Plasma nanotexturing, Selective cell attachment, cell repelling, Superhydrophobic, antifouling surfaces, and Thick resist patterning

We propose a planar technology for fabrication and surface modification of disposable, polymeric, microfluidic devices, and show applications in cell patterning. By planar technology we mean lithography directly on a polymeric plate followed by plasma etching of the plate. In this context, we developed lithographic processes directly on the polymeric substrate, employing easily strippable photoresists, for which stripping is performed without attacking the polymeric substrate. We then applied oxygen plasma etching to transfer the pattern and chemically modify the polymeric substrates, followed by optional fluorocarbon plasma deposition through stencil masks, producing microfluidic channels with desired geometrical and wetting characteristics. We tested various organic photoresists such as AZ 15nXT, AZ 9260, maP-1275, a silicon containing resist Ormocomp® on an organic strippable underlayer (LOR@), as well as metal masks in order achieve high resolution (1-4 μm), plasma etch resistance, and stripability for photoresists with thickness of ~5-20 μm (for details see Supporting information). We selected the Ormocomp® stack as the best candidate to define microfluidics with plasma etching onto PMMA, PEEK and COP substrates containing hydrophilic and superhydrophobic areas. We demonstrate significantly increased cell attachment on the plasma treated PMMA areas compared to untreated ones, and highly selective cell attachment (on-off) onto hydrophilic versus the superhydrophobic areas using a particular cell line. Such control of cell attachment and growth on plasma nanotextured surfaces can be applied to creation of microdevices aiming to cell patterning, cell isolation, as well as cell arrays.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Activité catalytique, Catalyst activity, Actividad catalítica, Anatase, Anatasa, Dépôt projection, Spray coating, Depósito proyección, Spritzbeschichten, Eau usée, Waste water, Agua residual, Abwasser, Nanostructure, Nanoestructura, Oxyde de titane, Titanium oxide, Titanio óxido, Titanoxid, Revêtement, Coatings, Revestimiento, Ueberzug, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, cold gas spray, nanostructured TiO2 powder, photocatalysis, and wastewater

This article describes a photocatalytic nanostructured anatase coating deposited by cold gas spray (CGS) supported on titanium sub-oxide (TiO2-x) coatings obtained by atmospheric plasma spray (APS) onto stainless steel cylinders. The photocatalytic coating was homogeneous and preserved the composition and nanostructure of the starting powder. The inner titanium sub-oxide coating favored the deposition of anatase particles in the solid state. Agglomerated nano-TiO2 particles fragmented when impacting onto the hard surface of the APS TiO2-x bond coat. The rough surface provided by APS provided an ideal scenario for entrapping the nanostructured particles, which may be adhered onto the bond coat due to chemical bonding; a possible bonding mechanism is described. Photocatalytic experiments showed that CGS nano-TiO2 coating was active for photodegrading phenol and formic acid under aqueous conditions. The results were similar to the performance obtained by competitor technologies and materials such as dip-coating P25® photocatalysts. Disparity in the final performance of the photoactive materials may have been caused by differences in grain size and the crystalline composition of titanium dioxide.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Corrosion, Action des agents de corrosion, Corrosion environments, Application, Aplicación, Anwendung, Corrosion, Corrosión, Korrosion, Déchet industriel, Industrial waste, Desperdicio industrial, Industrieabfall, Dépôt projection, Spray coating, Depósito proyección, Spritzbeschichten, Incinérateur, Incinerator, Incinerador, Projection à chaud, Hot spraying, Proyección en caliente, Spritzen, Revêtement, Coatings, Revestimiento, Ueberzug, Traitement déchet, Waste treatment, Tratamiento desperdicios, Abfallbehandlung, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Coating, and NiCrAIY

NiCrAIY coating was deposited on Ni based Superni 76 superalloy using cold spray process to enhance the life of superalloy. The present investigation is an attempt to evaluate comparative behaviour of hot corrosion of the bare and coated superalloy in actual industrial medical waste incinerator. The study was conducted in the secondary chamber of medical waste incinerator for 1000 h under cyclic conditions at 900°C. The life of bare and coated superalloy has been evaluated based on thickness lost due to erosion-corrosion. The cold sprayed NiCrAlY coating successfully provided protection to the superalloy against hot corrosion. Based upon thickness loss data, the corrosion rate of exposed coated specimen calculated as 35·87 mpy.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Matériau composite, Composite material, Material compuesto, Verbundwerkstoff, Activité catalytique, Catalyst activity, Actividad catalítica, Dépôt projection, Spray coating, Depósito proyección, Spritzbeschichten, Nanocomposite, Nanocompuesto, Oxyde de titane, Titanium oxide, Titanio óxido, Titanoxid, Projection HVOF, HVOF spraying, Proyeccion HVOF, Projection à chaud, Hot spraying, Proyección en caliente, Spritzen, Revêtement, Coatings, Revestimiento, Ueberzug, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, HVOF, TiO2, nanocomposite structure, photocatalysis, photocatalytic activity, rhodamine B, and suspension

Photocatalytic properties of titania have been studied very intensively for a variety of applications, including air and water purification. In order to clarify the influence of the phase composition and other parameters, thermal spraying with suspensions was applied to produce photocatalytically active titania coatings starting from two commercially available anatase and rutile submicron powders. Aqueous suspensions containing 40% solids by weight were sprayed with an HVOF process using ethylene as the fuel gas. The spray parameters were chosen in order to produce mechanically stable coatings and to preserve a high content of the initial crystalline phases of the powders. The coating microstructures, phase compositions, and surface properties were characterized. The photocatalytic performance was evaluated by degradation of the pink dye Rhodamine B (RB) using two techniques: degradation of an aqueous solution of RB and discoloration of impregnated RB. All the coatings exhibited photocatalytic activity to varying degrees, depending on the phase composition as well as other factors, namely, the coating microstructure, surface morphology, surface hydroxylation, light absorption, and interaction with the pollutant.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Corrosion, Action des agents de corrosion, Corrosion environments, Corrosion, Corrosión, Korrosion, Dépôt projection, Spray coating, Depósito proyección, Spritzbeschichten, Oxydation, Oxidation, Oxidación, Projection HVOF, HVOF spraying, Proyeccion HVOF, Projection à chaud, Hot spraying, Proyección en caliente, Spritzen, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Vitesse, Velocity, Velocidad, Bond coat, Cold gas dynamic spray, and High velocity oxygen fuel

CoNiCrAlY coating for protection against oxidation at elevated temperature was prepared on the surface of the 316L by high velocity oxygen fuel (HVOF) and cold gas dynamic spray (CGDS) techniques. The phase composition, microstructure and oxidation resistance of the coating were investigated at 900°C in air. According to the results, the CGDS coating shows low oxide growth rate as a result of low porosity, oxide content and high hardness. CGDS coating provided excellent oxidation protective ability at 900°C in air, whereas HVOF coating showed high levels of visible defects, oxide content, spinel type oxide and high oxide growth rate. Electrochemical study shows that the HVOF process provided better corrosion resistance as compared to CGDS process.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Dépôt projection, Spray coating, Depósito proyección, Spritzbeschichten, Microstructure, Microestructura, Mikrogefuege, Revêtement, Coatings, Revestimiento, Ueberzug, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Coating microstructure, Kinetiks, MRO, Nickel alloys, PCS-1000, and Waspaloy

The deposition of pore free and highly adhered Ni and Co superalloy coatings is of great interest for engine design and gas turbine applications, both in case of maintenance repair and overhaul operations as well for mechanical and chemical protection purposes in aeronautics and energy applications. This study would like to give a wide overview about the capability of cold spray technology on this topic: two different commercially available deposition systems, Sulzer-CGT Kinetiks 4000 and Plasma Giken PCS-1000, were compared, and deposition processes with both nitrogen and helium as carrier gas have been explored. Microstructural investigation, microhardness and adhesion results are reported to depict a preliminary scenario of coating properties. Fully dense coatings with thickness >1 mm and adhesion >50 MPa are obtained using helium, while quite porous, 20 MPa adhered coatings are obtained using nitrogen. Finally, general considerations about the potential applicability of those coatings for repair purpose in aerospace applications are pointed out.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Dépôt projection, Spray coating, Depósito proyección, Spritzbeschichten, Fabrication, Manufacturing, Fabricación, Fertigung, Matériau composite, Composite material, Material compuesto, Verbundwerkstoff, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, cold spray, diagnostic, energetic materials, and nano composites

It has been shown that the cold-gas dynamic spraying process, or simply cold spray, is a suitable technique to manufacture nanoscale energetic materials with high reactivity and low porosity. The current study focuses on the Ni-Al system, for which the reactivity has been increased by an initial mechanical activation achieved by the ball-milling technique, leading to lamellar nanostructured composite particles. The consolidation of this nanoscale energetic material using the cold-gas dynamic spray technique permits to retain the feedstock powder nanoscale structure in the coatings, which in turn retain the high reactivity features of the powder. However, it has been noticed that the stagnation temperature during the spray can lead to partial reaction of the highly reactive feedstock powder, which directly influences the reactivity of the coatings. In this study, different stages of the spray process were investigated: (i) the in-flight behavior of the nanoscale energetic material (powder) at different stagnation temperatures (from 300 to 800 °C); (ii) the substrate-temperature evolution as the function of gas temperature; and (iii) the impact of the powder on the substrate, related to particle's velocity and its influence on the nanostructure of the particles.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Dépôt de matériaux non métalliques, Nonmetallic coatings, Matériau composite, Composite material, Material compuesto, Verbundwerkstoff, Apatite hydroxylée, Hydroxyapatite, Hidroxiapatito, Application médicale, Medical application, Aplicación medical, Medizinische Technik, Biomatériau, Biomaterial, Dépôt projection, Spray coating, Depósito proyección, Spritzbeschichten, Microstructure, Microestructura, Mikrogefuege, Nanocomposite, Nanocompuesto, Nanostructure, Nanoestructura, Projection à chaud, Hot spraying, Proyección en caliente, Spritzen, Revêtement composite, Composite coating, Revestimiento compuesto, Revêtement non métallique, Non metal coating, Revestimiento no metálico, Nichtmetallischer Ueberzug, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, graphene-nanosheet, hydroxyapatite, microstructure, nanocomposite coatings, and vacuum cold spray

Development of novel biocompatible nanomaterials has provided insights into their potential biomedical applications. Bulk fabrication of the nanomaterials in the form of coatings remains challenging. Here, we report hydroxyapatite (HA)/graphene-nanosheet (GN) composite coatings deposited by vacuum cold spray (VCS). Significant shape changes of HA nanograins during the coating deposition were revealed. The nanostructural features of HA together with curvature alternation of GN gave rise to dense structures. Based on the microstructural characterization, a structure model was proposed to elucidate the nanostructural characteristics of the HA-GN nanocomposites. Results also showed that addition of GN significantly enhanced fracture toughness and elastic modulus of the HA-based coatings, which is presumably accounted for by crack bridging offered by GN in the composites. The VCS HA-GN coatings show potential for biomedical applications for the repair or replacement of hard tissues.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Corrosion, Action des agents de corrosion, Corrosion environments, Propriétés mécaniques. Rhéologie. Mécanique de la rupture. Tribologie, Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology, Corrosion, Corrosión, Korrosion, Elasticité, Elasticity, Elasticidad, Elastizitaet, Indentation, Indentación, Microstructure, Microestructura, Mikrogefuege, Module Young, Young modulus, Módulo Young, Module élasticité, Elastic modulus, Módulo elasticidad, Elastizitaetsmodul, Propriété mécanique, Mechanical properties, Propiedad mecánica, Revêtement, Coatings, Revestimiento, Ueberzug, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, MAO, Magnesium, Nanohardness, Nanoindentation, and Young's modulus

The micro arc oxidation (MAO) process is one of the most industrially accepted, prospective methods to design and develop microstruturally integrated, intrinsically generated oxide/ceramic coating over Mg alloys. Here we report, the surface engineering of AZ31 Mg alloy to form MAO coatings by silicate and phosphate based electrolytes. The microstructural examinations of the MAO coatings were carried out by scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis. Further, the nanoindentation studies revealed that the MAO coatings had nanohardness (H) and Young's modulus (E) values as high as about 3―7 times and 1·5―2·5 times those of the as received AZ31 Mg alloy respectively. Both H and E values gradually increased from virgin Mg substrate end to the surface coating end. Further, sealing by hot water did not affect the H and E values of the MAO coatings.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Dépôt de matériaux non métalliques, Nonmetallic coatings, Matériau composite, Composite material, Material compuesto, Verbundwerkstoff, Barrière thermique, Thermal barrier, Barrera térmica, Lanthanide, Lantánido, Nanocomposite, Nanocompuesto, Plasma, Projection plasma, Plasma spraying, Proyección plasma, Plasmaspritzen, Projection à chaud, Hot spraying, Proyección en caliente, Spritzen, Revêtement composite, Composite coating, Revestimiento compuesto, Revêtement non métallique, Non metal coating, Revestimiento no metálico, Nichtmetallischer Ueberzug, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Zirconate, Zirconates, Zirconato, lanthanum zirconate, suspension plasma spray, and thermal barrier coating

This work seeks to develop an innovative nanocomposite thermal barrier coating (TBC) exhibiting low thermal conductivity and high durability compared with that of current TBCs. To achieve this objective, nanosized lanthanum zirconate particles were selected for the topcoat of the TBC system, and a new process—suspension plasma spray—was employed to produce desirable microstructural features: the nanocomposite lanthanum zirconate TBC contains ultrafine splats and high volume porosity, for lower thermal conductivity, and better durability. The parameters of plasma spray experiment included two main variables: (i) spray distance varying from 40 to 80 mm and (ii) the concentration of suspension 20, 25, and 30 wt.%, respectively. The microstructure of obtained coatings was characterized with scanning electron microscope and x-ray diffraction. The porosity of coatings is in the range of 6-10%, and the single phase in the as-sprayed coatings was pyrochlore lanthanum zirconate.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Matériau composite, Composite material, Material compuesto, Verbundwerkstoff, Composé intermétallique, Intermetallic compound, Compuesto intermetálico, Intermetallische Verbindung, Nanocomposite, Nanocompuesto, Nanocristal, Nanocrystal, Projection détonation, Detonation spraying, Proyección detonación, Flammschockspritzen, Revêtement composite, Composite coating, Revestimiento compuesto, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Gas detonation spraying, multiphase nanocomposite coating (based on FeAl), and nanocrystalline self-decomposing powder

The nanocomposite structure of Fe-Al intermetallic coating, created in situ during gas detonation spraying (GDS) of as-milled self-decomposing powder and containing disordered 8 nm FeAl nanocrystals, was analyzed using scanning electron microscopy (SEM) with energy-dispersive x-ray (EDX) spectroscopy, transmission electron microscopy (TEM), selected-area electron diffraction (SAED), and x-ray diffraction methods. It is found that the Fe-Al coating is characterized by a sublayer morphology consisting of flattened and partially melted splats containing a wide Al range from about 26 to 52 at.%, as well as Al2O3 oxides, created in situ at the internal interfaces of splats during the GDS process. The complex oxide films, identified as amorphous Al2O3, which are formed in the nanocrystalline Fe-Al matrix of the GDS coating behave like a composite reinforcement in the intermetallic Fe-Al coating. The combined presence of nanosized subgrains in the Fe-Al matrix and the Al2O3 nanoceramic dispersoids significantly increases the microhardness of the coating.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Métallurgie des poudres. Matériaux composites, Powder metallurgy. Composite materials, Métaux renforcés par dispersion, Dispersion hardening metals, Traitements de surface, Surface treatment, Acier inoxydable 304, Stainless steel-304, Acier inoxydable austénitique, Austenitic stainless steel, Acero inoxidable austenítico, Austenitischer nichtrostender Stahl, Acier inoxydable, Stainless steel, Acero inoxidable, Nichtrostender Stahl, Borure, Borides, Boruro, Borid, Dépôt laser, Laser deposition, Depósito laser, Dépôt projection, Spray coating, Depósito proyección, Spritzbeschichten, Fusion laser, Laser fusion, Fusión láser, Laser, Láser, Matériau composite, Composite material, Material compuesto, Verbundwerkstoff, Microdureté, Microhardness, Microdureza, Mikrohaerte, Microstructure, Microestructura, Mikrogefuege, Métal renforcé dispersion, Dispersion strengthened metal, Metal reforzado dispersión, Dispersionsgehaertetes Metall, Projection HVOF, HVOF spraying, Proyeccion HVOF, Projection à chaud, Hot spraying, Proyección en caliente, Spritzen, Revêtement composite, Composite coating, Revestimiento compuesto, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, laser melting, microhardness, microstructure, nano-boride, and nano-silicide

The study concerned a detailed microstructural investigation of nano-borides (Cr2B and Ni3B) and nano-silicide (Ni2Si) dispersed γ-nickel composite coating on AISI 304 stainless steel by HVOF spray deposition of the NiCrBSi precursor powder and subsequent laser surface melting. A continuous wave diode laser with an applied power of 3 kW and scan speed of 20 mm/s in argon shroud was employed. The characterization of the surface in terms of microstructure, microtexture, phases, and composition were carried out and compared with the as-coated (high-velocity oxy-fuel sprayed) surface. Laser surface melting led to homogenization and refinement of microstructures with the formation of few nanosilicides of nickel along with nano-borides of nickel and chromium (Ni3B, Cr2B, and Cr2B3). A detailed microtexture analysis showed the presence of no specific texture in the as-sprayed and laser-melted surface of Cr2B and Ni3B phases. The average microhardness was improved to 750-900 VHN as compared to 250 VHN of the as-received substrate. Laser surface melting improved the microhardness further to as high as 1400 VHN due to refinement of microstructure and the presence of silicides.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, A froid, Cold process, En frío, Basse pression, Low pressure, Baja presión, Niederdruck, Dépôt projection, Spray coating, Depósito proyección, Spritzbeschichten, Epaisseur, Thickness, Espesor, Dicke, Formage à froid, Cold forming, Modelado en frio, Kaltformgeben, Procédé dépôt, Deposition process, Procedimiento revestimiento, Beschichtungsverfahren, Projection à chaud, Hot spraying, Proyección en caliente, Spritzen, Revêtement conducteur, Conductive coating, Revestimiento conductor, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, cold spray, copper, electrically conductive coatings, and thickness

Most of the existing multi-response optimization approaches focus on the subjective and practical know-how of the process. As a result, some confusion and uncertainty are introduced in the overall decision-making process. In this work, an approach based on a Utility theory and Taguchi quality loss function has been applied to the process parameters for low-pressure cold spray process deposition of copper coatings, for simultaneous optimization of more than one response characteristics. In the present paper, two potential response parameters, i.e., coating thickness and coating density, have been selected. Utility values based on these response parameters have been analyzed for optimization using the Taguchi approach. The selected input parameters of powder feeding arrangement, substrate material, air stagnation pressure, air stagnation temperature, and stand-off distance significantly improve the Utility function (raw data) comprising quality characteristics (coating thickness and coating density). The percentage contribution of the parameters to achieve a higher value of Utility function is substrate material (50.03%), stand-off distance (28.87%), air stagnation pressure (6.41%), powder feeding arrangement (4.68%), and air stagnation temperature (2.64%).

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Propriétés mécaniques. Rhéologie. Mécanique de la rupture. Tribologie, Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology, Rupture, Fractures, Dépôt projection, Spray coating, Depósito proyección, Spritzbeschichten, Modélisation, Modeling, Modelización, Propriété mécanique, Mechanical properties, Propiedad mecánica, Rupture, Ruptura, Bruch, Simulation numérique, Numerical simulation, Simulación numérica, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Vitesse, Velocity, Velocidad, Cold spraying, Critical velocity, and Impact behaviour

Cold spraying (CS) is a coating technique, which has developed rapidly in the last two decades and shows great potential in the industrial community due to its advantages of low temperature deposition as well as no oxides forming in the coating. This review's focus is on the behaviour of particles impacting and the prediction of critical velocity for particle deposition during CS as calculated by numerical simulations according to the open literature. The first part presents an introduction of CS and its particle bonding mechanism. The second part briefly introduces the typically employed numerical computation methods and compares these methods. The third part discusses the effect of particle parameters on particle deformation behaviour. Finally, the current problems and prospects existing in numerical simulations of the impact of CS particles are explored.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Basse température, Low temperature, Baja temperatura, Tieftemperatur, Ecoulement, Flow(fluid), Flujo, Fluide Stroemung, Modélisation, Modeling, Modelización, Simulation, Simulación, Température, Temperature, Temperatura, Temperatur, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Transfert chaleur, Heat transfer, Transferencia térmica, Waermeuebertragung, fluid flow and heat transfer, low-temperature oxygen-fuel spray, particles behavior, and simulation

The low-temperature oxygen-fuel (LTOF) spray is a modification of high velocity oxygen fuel spray. In this process, the high-temperature gas is accelerated to supersonic speed through a Laval nozzle followed by a straight barrel. By injecting room temperature gas into the mixing chamber, the temperature of the gas can be controlled in a range of about 1000-2500 K, so that some oxygen and temperature-sensitive materials, such as titanium and copper, can avoid oxidation or decomposition during the spraying process. The purpose of this paper is to establish a 2-D mathematical model to simulate the supersonic gas dynamics and particles behavior in LTOF process. The temperature and velocity of the flow fields, and the trajectory and heating of in-flight particles are predicted for different operating parameters. The model is validated by experimental data in the literature. Effects of the mixing gas flow rates, particle sizes, and injection conditions on this process were investigated as well.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Propriétés mécaniques. Rhéologie. Mécanique de la rupture. Tribologie, Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology, Matériau composite, Composite material, Material compuesto, Verbundwerkstoff, Abrasif, Abrasives, Abrasivo, Schleifmittel, Alliage base nickel, Nickel base alloys, Dépôt projection, Spray coating, Depósito proyección, Spritzbeschichten, Microstructure, Microestructura, Mikrogefuege, Nanocomposite, Nanocompuesto, Propriété mécanique, Mechanical properties, Propiedad mecánica, Revêtement composite, Composite coating, Revestimiento compuesto, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Tribologie, Tribology, Tribología, Usure abrasive, Abrasive wear, Desgaste abrasivo, Abrasivverschleiss, abrasive wear behavior, cBN-NiCrAl, cold spray, mechanical properties, microstructure, and nanocomposite

20 vol.% cubic boron nitride (cBN) dispersoid reinforced NiCrAl matrix nanocomposite coating was prepared by cold spray using mechanically alloyed nanostructured composite powders. The as-sprayed nanocomposite coating was annealed at a temperature of 750 °C to enhance the inter-particle bonding. Microstructure of spray powders and coatings was characterized. Vickers microhardness of the coatings was measured. Two-body abrasive wear behavior of the coatings was examined on a pin-on-disk test. It was found that, in mechanically alloyed composite powders, nano-sized and submicro-sized cBN particles are uniformly distributed in nanocrystalline NiCrAl matrix. Dense coating was deposited by cold spray at a gas temperature of 650 °C with the same phases and grain size as those of the starting powder. Vickers hardness test yielded a hardness of 1063 HV for the as-sprayed 20 vol.% cBN-NiCrAl coating. After annealed at 750 °C for 5 h, unbonded inter-particle boundaries were partially healed and evident grain growth of nanocrystalline NiCrAl was avoided. Wear resistance of the as-sprayed 20 vol.% cBN-NiCrAl nanocomposite coating was comparable to the HVOF-sprayed WC-12Co coating. Annealing of the nanocomposite coating resulted in the improvement of wear resistance by a factor of ∼33% owing to the enhanced inter-particle bonding. Main material removal mechanisms during the abrasive wear are also discussed.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Matériau composite, Composite material, Material compuesto, Verbundwerkstoff, Dopage, Doping, Dopen, Dépôt projection, Spray coating, Depósito proyección, Spritzbeschichten, Microstructure, Microestructura, Mikrogefuege, Nanocomposite, Nanocompuesto, Nanostructure, Nanoestructura, Plasma, Projection plasma, Plasma spraying, Proyección plasma, Plasmaspritzen, Projection à chaud, Hot spraying, Proyección en caliente, Spritzen, Revêtement composite, Composite coating, Revestimiento compuesto, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Zircone stabilisée, Stabilized zirconia, Zircona estabilizada, La2Ce2O7, nanocomposite coating, nanozones, phonon scattering, and plasma spraying

Nanostructured La2Ce2O7-doped YSZ coatings were developed using atmospheric plasma-spraying technique by optimizing various process parameters. To ensure the retention of nanostructure, the molten state of nanoagglomerates was monitored using plasma and particle diagnostic tools. It was observed that the morphology of the coating exhibits a bimodal microstructure consisting of nanozones reinforced in a matrix of fully-molten particles. The thermal diffusivity of nano-LaCeYSZ coatings is lower than that of nano and bulk YSZ. The reason for this change in thermal diffusivity may be attributed to scattering of phonons at grain boundaries, point defect scattering and higher inter-splat porosity. Also, the thermal conductivity of the nanocomposite coatings was lower than those of nanostructured and bulk YSZ coatings. XRD results show cubic zirconia with a small amount of tetragonal zirconia. The average grain size of the as-sprayed La2Ce2O7-YSZ nanocomposite coatings is -150-200 nm. The improved thermal behavior is mainly due to a dense, packed, and more compact structure of the coatings.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Propriétés mécaniques. Rhéologie. Mécanique de la rupture. Tribologie, Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology, Microstructure, Microestructura, Mikrogefuege, Propriété mécanique, Mechanical properties, Propiedad mecánica, Revêtement, Coatings, Revestimiento, Ueberzug, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Biodegradable Mg, Coating, Mechanical behaviour, Scaffold, and Tissue engineering

In recent years, attention has been focused on the magnesium (Mg) as a promising material in biodegradable metallic scaffolds for bone tissue engineering. Since an orthopedic scaffold is supposed to repair and regenerate fractured bones, its mechanical integrity is vital throughout the healing process. In this study, a biocompatible polymeric layer made of polycaprolactone (PCL) in different concentrations of 3% w/v and 6% w/v was coated on the surface of Mg scaffolds. The structural characteristics and mechanical behaviour of the Mg scaffolds during the immersion in physiological saline solution (PSS) were investigated. According to our results, the PCL coating hindered the diminution of mechanical stability of scaffolds to provide adequate support for bone healing. Specifically, scaffold coated with 3% w/v and 6% w/v PCL demonstrated 24 and 100% improvement in the elastic modulus and 41 and 83% enhancement in compressive strength respectively, after 24 h immersion in PSS, compare to the uncoated scaffold. Thus, PCL coating of Mg scaffolds may be a promising approach in the development of mechanically stable bone scaffolds.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Corrosion, Action des agents de corrosion, Corrosion environments, Protection contre la corrosion, Corrosion prevention, Adhérence, Adhesion, Adherencia, Adhaesion, Alliage base magnésium, Magnesium base alloys, Corrosion, Corrosión, Korrosion, Couche protectrice, Protective layer, Capa protectora, Schutzschicht, Microporosité, Microporosity, Microporosidad, Microporositaet, Protection corrosion, Corrosion protection, Protección corrosión, Korrosionsschutz, Revêtement protecteur, Protective coatings, Revestimiento protector, Schutzueberzug, Simulation, Simulación, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, AZ91D, and Coatings

A notebook computer component with a complex geometry was manufactured with a die cast process (DCP), using an AZ91D alloy. Chemical conversion and organic coatings were sequentially applied to provide protection against physical and chemical damage. Air content in the component, which gives rise to microporosity, was determined with a DCP computer simulation using MAGMA software. The surface layer characteristics of the component were also investigated using scanning electron microscopy coupled with energy dispersive X-ray spectroscopy. The microporosity content was higher at the end of the filling process compared with the regions that filled first. Corrosion resistance was poorer for discontinuous conversion coatings that resulted from surface microporosity. Moreover, adhesion of an organic coating was degraded at areas with higher microporosity.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Métallurgie des poudres. Matériaux composites, Powder metallurgy. Composite materials, Poudres métalliques, Metal powders, Traitements de surface, Surface treatment, Dépôt de métaux et d'alliages, Metallic coatings, Propriétés mécaniques. Rhéologie. Mécanique de la rupture. Tribologie, Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology, Alliage mécanique, Mechanical alloying, Aleación mecánico, Mechanisches Legieren, Dépôt projection, Spray coating, Depósito proyección, Spritzbeschichten, Matériau composite, Composite material, Material compuesto, Verbundwerkstoff, Métallurgie poudre, Powder metallurgy, Metalurgia polvo, Pulvermetallurgie, Projection HVOF, HVOF spraying, Proyeccion HVOF, Projection à chaud, Hot spraying, Proyección en caliente, Spritzen, Propriété mécanique, Mechanical properties, Propiedad mecánica, Revêtement composite, Composite coating, Revestimiento compuesto, Revêtement métallique, Metal coating, Revestimiento metálico, Metallischer Ueberzug, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, HVOF, cold spray, mechanical alloying, mechanical properties, metal matrix composite, and nickel alloys

The purpose of this study is to manufacture metal matrix composite coatings by thermal spraying. In order to improve coating's mechanical properties, it is necessary to increase homogeneity. To meet this objective, the chosen approach was to optimize the powder morphology by mechanical alloying. Indeed, the mechanical alloying method (ball milling) was implemented to synthesize NiCr-Cr3C2 and NiCrBSi-WC composite powders by using cold spraying and high-velocity oxygen fuel process, respectively. After optimizing the process parameters on powder grain size, the composite coatings were compared with standard coatings manufactured from mixed powders. SEM observations, hardness measurements, and XRD analyses were the first technologies implemented to characterize the metal matrix composite coatings. Different characteristics were then observed. When mechanical alloying process is employed to synthesize composite powders strengthened by particle dispersion, the powders tend to fracture into small segments, especially when high content of hard particles is added. Powder microstructures were then refined, which induced thinner coating morphologies and reduced porosity rate. Once an improved microstructure is obtained, manufacturing of coating using milled powders was found suitable in comparison with coatings manufactured only with mixed powders.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Fil composite, Composite wire, Hilo compuesto, Verbunddraht, Fil métallique, Wire, Hilo metálico, Draht, Injection poudre, Powder injection, Inyección polvo, Pulvereinblasen, Matériau composite, Composite material, Material compuesto, Verbundwerkstoff, Métallurgie poudre, Powder metallurgy, Metalurgia polvo, Pulvermetallurgie, Projection arc, Arc spraying, Proyección arco, Lichtbogenspritzen, Revêtement, Coatings, Revestimiento, Ueberzug, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, coating, powder injection, and twin wire arc spraying

The powder injection parameters, the location of the injection port, as well as the metal matrix composites are important features, which determine the deposition efficiency and embedding behavior of hard materials in the surrounding matrix of the twin wire arc-spraying process. This study investigates the applicability of external powder injection and aims to determine whether the powder injection parameters, the location, and the material combination (composition of the matrix as well as hard material) need to be specifically tailored. Therefore, the position of the injection port in relation to the arc zone was altered along the spraying axis and perpendicular to the arc. The axial position of the injection port determines the thermal activation of the injected powder. An injection behind the arc, close to the nozzle outlet, seems to enhance the thermal activation. The optimal injection positions of different hard materials in combination with zinc-, nickel- and iron-based matrices were found to be closer to the arc zone utilizing a high-speed camera system. The powder size, the mass of the particle, the carrier gas flow, and the electric insulation of the hard material affect the perpendicular position of the radial injection port. These findings show that the local powder injection, the wetting behavior of particles in the realm of the molten pool as well as the atomization behavior of the molten pool all affect the embedding behavior of the hard material in the surrounded metallic matrix. Hardness measurement by means of nanoindentation and EDX analysis along transition zones were utilized to estimate the bonding strength. The observation of a diffusion zone indicates a strong metallurgical bonding for boron carbides embedded in steel matrix.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Assemblage et découpage thermique: aspects métallurgiques, Joining, thermal cutting: metallurgical aspects, Collage, Adhesive bonding, Propriétés mécaniques. Rhéologie. Mécanique de la rupture. Tribologie, Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology, Rupture, Fractures, Alliage mémoire forme, Shape memory alloy, Aleación memoria forma, Formgedaechtnislegierung, Assemblage collé, Adhesive joint, Ensambladura pegada, Klebverbindung, Charge cyclique, Cyclic load, Carga cíclica, Zyklische Belastung, Dispositif CCD, Charge coupled device, Dispositivo carga acoplada, Effet mémoire forme, Shape memory effect, Efecto memoria forma, Formgedaechtniseffekt, Endommagement, Damaging, Deterioración, Energie libre, Free energy, Energía libre, Freie Energie, Epaisseur, Thickness, Espesor, Dicke, Joint recouvrement, Lap joint, Junta recubierta, Microfissure, Microcrack, Microfisura, Mikroriss, Monitorage, Monitoring, Monitoreo, Nickel alliage, Nickel alloy, Níquel aleación, Nickellegierung, Propriété thermomécanique, Thermomechanical properties, Propriedad termomecánica, Rugosité, Roughness, Rugosidad, Rauhigkeit, Résistance mécanique, Strength, Resistencia mecánica, Festigkeit, Titane alliage, Titanium alloy, Titanio aleación, Titanlegierung, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, adhesive bonding, shape memory alloys, and surface preparation

In this study, adhesive joints made up of commercial NiTi sheets with shape memory capabilities are analyzed. Suitable surface pre-treatments, i.e., degreasing, sandblasting, and chemical etching, are preliminary compared in terms of surface roughness, surface energy, and substrate thinning. Results indicate that chemical etching induces marked substrate thinning without substantial gains in terms of surface roughness and free energy. Therefore, adhesive joints with degreased and sandblasted substrates are prepared and tested under both static and cyclic conditions, and damage development within the adhesive layer is monitored in situ using a CCD camera. Sandblasted specimens have a significantly higher mechanical static strength with respect to degreased ones, although they essentially fail in similar fashion, i.e., formation of microcracks followed by decohesion along the adhesive/substrate interface. In addition, the joints show a good functional response with almost complete shape memory recovery after thermo-mechanical cycling, i.e., a small accumulation of residual deformations occurs. The present results show that adhesive bonding is a viable joining technique for NiTi alloys.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Propriétés mécaniques. Rhéologie. Mécanique de la rupture. Tribologie, Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology, Frottement. Usure, Contact of materials. Friction. Wear, Contrainte résiduelle, Residual stress, Tensión residual, Eigenspannung, Laser, Láser, Nanoparticule, Nanoparticle, Nanopartícula, Projection HVOF, HVOF spraying, Proyeccion HVOF, Projection à chaud, Hot spraying, Proyección en caliente, Spritzen, Propriété mécanique, Mechanical properties, Propiedad mecánica, Revêtement, Coatings, Revestimiento, Ueberzug, Résistance usure, Wear resistance, Resistencia al desgaste, Verschleissfestigkeit, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Tribologie, Tribology, Tribología, Usure, Wear, Desgaste, Verschleiss, B4C nanoparticles, H188 alloy, HVOF coating, laser treatment, residual stress, and wear resistance

Laser treatment under nitrogen assisting gas environment of cobalt-nickel-chromium-tungsten-based superalloy and high-velocity oxygen-fuel thermal spray coating of nickel-chromium-based superalloy on carbon steel was carried out to improve mechanical and tribological properties. Superalloy surface was preprepared to include B4C particles at the surface prior to the laser treatment process. Material and morphological changes in the laser-treated samples were examined using scanning electron microscopy, energy-dispersive spectroscopy, and x-ray diffraction (XRD) analysis. Residual stresses present at the surface region of the laser-treated layer were determined from the XRD data. The microhardness of the laser-treated surface was measured by indentation tests. Fracture toughness of the coating surfaces before and after laser treatment were also measured using overload indentation tests. Macrowear and macrofriction characterization were carried out using pin-on-disk tests.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Corrosion, Action des agents de corrosion, Corrosion environments, Application, Aplicación, Anwendung, Corrosion, Corrosión, Korrosion, Dépôt projection, Spray coating, Depósito proyección, Spritzbeschichten, Electronique, Electronics, Electrónica, Elektronik, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Applications, Cold spray, Medical, and Plastics

Modern cold spray, first implemented 30 years ago, has since expanded rapidly in system designs and applications. While initially considered to be a method to deposit a ductile metal coating onto another metal, subsequent innovations in design and use have allowed new applications to areas as diverse as medical and electronics. This paper describes some new methods and applications that are currently being developed. Twenty-four new applications are presented, chosen to represent the diversity of actual and potential uses of cold spray technology.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Dépôt de métaux et d'alliages, Metallic coatings, Dépôt de matériaux non métalliques, Nonmetallic coatings, Barrière thermique, Thermal barrier, Barrera térmica, Plasma, Projection plasma, Plasma spraying, Proyección plasma, Plasmaspritzen, Projection à chaud, Hot spraying, Proyección en caliente, Spritzen, Revêtement métallique, Metal coating, Revestimiento metálico, Metallischer Ueberzug, Revêtement non métallique, Non metal coating, Revestimiento no metálico, Nichtmetallischer Ueberzug, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Vitesse, Velocity, Velocidad, MCrAlY, Triplex torch, atmospheric plasma spraying, bondcoat, and thermal barrier coating

MCrAlY bondcoats (M = Co, Ni) are used to protect metallic substrates from oxidation and to improve adhesion of ceramic thermal barrier coatings for high temperature applications, such as in land-based and aviation turbines. Since MCrAlYs are prone to take up oxygen during thermal spraying, bondcoats often are manufactured under inert gas conditions at low pressure. Plasma spraying at atmospheric conditions is a cost-effective alternative if it would be possible to limit the oxygen uptake as well as to obtain sufficiently dense microstructures. In the present work, high-velocity spray parameters were developed for the TriplexPro 210 three-cathode plasma torch using MCrAlY powders of different particle size fractions to achieve these objectives. The aims are conflictive since the former requires cold conditions, whereas the latter is obtained by more elevated particle temperatures. High particle velocities can solve this divergence as they imply shorter time for oxidation during flight and contribute to coating densification by kinetic rather than thermal energy. Further aims of the experimental work were high deposition efficiencies as well as sufficient surface roughness. The oxidation behavior of the sprayed coatings was characterized by thermal gravimetric analyses and isothermal heat treatments.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Alliage base titane, Titanium base alloys, Aluminium alliage, Aluminium alloy, Aluminio aleación, Aluminiumlegierung, Cinétique, Kinetics, Cinética, Kinetik, Courbe TTT, TTT curve, Curva TTT, ZTU Schaubild, Etat solide, Solid state, Estado sólido, Fester Zustand, Formage, Forming, Conformado, Umformen, Plasma, Projection plasma, Plasma spraying, Proyección plasma, Plasmaspritzen, Projection à chaud, Hot spraying, Proyección en caliente, Spritzen, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Traitement thermique, Heat treatment, Tratamiento térmico, Waermebehandlung, Vanadium alliage, Vanadium alloy, Vanadio aleación, Vanadiumlegierung, TTT diagram, Ti-6Al-4V, characterization, heat treatment, net-shape forming, and vacuum plasma spray

Because of the nature of the plasma spraying process, the physical and mechanical properties of vacuum-plasma-sprayed structures of Ti-6AI-4V alloy are completely different from those of conventionally manufactured alloys such as bulk materials from casting and forging. To obtain desired mechanical and physical properties, vacancy and internal defects must be reduced, splat boundaries must be eliminated, and optimal phase compositions should be obtained through postdeposition heat treatments. To determine appropriate heat treatment processes, one needs to study the kinetic behavior of the as-sprayed microstructure at elevated temperatures. In the current study, the kinetics of the solid transformations found in Ti-6AI-4V alloys produced during the vacuum plasma spraying process was studied based on the Johnson-Mehl-Avrami theory. For the kinetic behavior of this alloy, the nonconstant temperature dependence of the transformation rate constant exhibits an irregularity at 900 °C, marking a change in the transformation mechanism. For the lower-temperature (<900 °C) curves, the constant gradient indicates a lack of change in the transformation mechanism, including homogeneous nucleation, with growth of a phase. For higher temperatures (>900 °C), a gradient change indicates a change in the transformation mechanism. The first mechanism was the formation of α-phase grain boundary, and the second mechanism was α-plate nucleation and growth from grain boundaries. The value of the transformation rate constant in the kinetics study of as-sprayed Ti-6AI-4V alloy was much higher than for material produced by the casting method. Using the results obtained from the kinetics of the β → α + β phase transformation at different constant temperatures, a time-temperature-transformation (TTT) diagram for as-sprayed Ti-6AI-4V alloy was developed.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Dépôt de matériaux non métalliques, Nonmetallic coatings, Etat surface, Surface conditions, Estado superficie, Oberflaechenzustand, Barrière thermique, Thermal barrier, Barrera térmica, Durée vie, Lifetime, Tiempo vida, Lebensdauer, Interface, Interfase, Grenzflaeche, Modélisation, Modeling, Modelización, Méthode élément fini, Finite element method, Método elemento finito, Finite Element Methode, Revêtement non métallique, Non metal coating, Revestimiento no metálico, Nichtmetallischer Ueberzug, Rugosité, Roughness, Rugosidad, Rauhigkeit, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, finite element modeling, interface roughness, lifetime, stress state, and thermal barrier coatings

Failure in Atmospheric Plasma-Sprayed (APS) thermal barrier coatings (TBCs) is associated with the thermo-mechanical stresses developing due to the thermally grown oxide (TGO) layer growth and thermal expansion mismatch during thermal cycling. The interface roughness has been shown to play a major role in the development of these induced stresses and lifetime of TBCs. Modeling has been shown as an effective tool to understand the effect of interface roughness on induced stresses. In the previous work done by our research group, it was observed that APS bondcoats performed better than the bondcoats sprayed with High Velocity Oxy-Fuel process which is contrary to the present literature data. The objective of this work was to understand this observed difference in lifetime with the help of finite element modeling by using real surface topographies. Different TGO layer thicknesses were evaluated. The modeling results were also compared with existing theories established on simplified sinusoidal profiles published in earlier works. It was shown that modeling can be used as an effective tool to understand the stress behavior in TBCs with different roughness profiles.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Cavitation, Cavitación, Kavitation, Chrome alliage, Chromium alloy, Cromo aleación, Chromlegierung, Durcissement déformation, Strain hardening, Endurecimiento deformación, Verfestigung, Microstructure, Microestructura, Mikrogefuege, Plasma, Projection arc, Arc spraying, Proyección arco, Lichtbogenspritzen, Projection à chaud, Hot spraying, Proyección en caliente, Spritzen, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, arc spraying, cavitation, plasma remelting, and strain hardening

Surface remelting is an important technique for modifying the microstructure of thermally sprayed coatings as it reduces the porosity and promotes a metallurgical bond between substrate and coating. Many studies have been carried out in the field of materials selection and surface engineering in an attempt to reduce cavitation damage. In this work, an Fe-Mn-Cr-Si alloy was deposited by arc spraying and then remelted by a plasma-transferred arc process. The base metal was a soft martensitic stainless steel. The influence of remelting current on coating and base metal microstructure and cavitation resistance was studied. The use of a lower mean current and a pulsed arc reduced the thickness of the heat-affected zone. In specimens remelted with constant arc current, dendrites were aligned parallel to the path followed by the plasma torch; while in those remelted with a pulsed plasma arc, the alignment of the microstructure was disrupted. The use of a higher peak current in pulsed-current plasma transferred arc remelting reduced mass loss due to cavitation. Fe-Mn-Cr-Si coatings exhibited cavitation-induced hardening, with martensite formation during cavitation tests. This transformation helps to increase the cavitation resistance of the remelted coating compared with the soft martensitic stainless steel base metal.