articles+ search results

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.