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Civil engineering, Génie civil, Metallurgy, welding, Métallurgie, soudage, Polymers, paint and wood industries, Polymères, industries des peintures et bois, 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, Alliage base aluminium, Aluminium base alloys, Corrosion, Corrosión, Korrosion, Cérium, Cerium, Cerio, Cer, Dépôt conversion, Conversion coating, Depósito conversión, Konversionsbeschichten, Lanthanide, Lantánido, Prétraitement, Pretreatment, Pretratamiento, Revêtement, Coatings, Revestimiento, Ueberzug, Traitement surface, Surface treatment, Tratamiento superficie, and Oberflaechenbehandlung

Cerium-based conversion coatings were deposited on Al 7075-T6 and characterized to determine the effect of different surface pre-treatments on the corrosion rate and surface morphology. The methods of potentiodynamic polarization and scanning electron microscopy were employed. The experimental results suggest that cerium-based conversion coating is corrosion resistant in NaCl solution. Corrosion current decreased with alkaline cleaning and acid activation of aluminum surface before cerium oxide deposition. Alkaline cleaning and activation improved deposition of cerium-based conversion coatings compared to only alkaline cleaning. Analysis of the surface morphology of the coatings showed that the coatings deposited on the alkaline cleaning and acid treated panels exhibited lower visible cracks compared to coatings on only alkaline cleaned panels.

Civil engineering, Génie civil, Metallurgy, welding, Métallurgie, soudage, Polymers, paint and wood industries, Polymères, industries des peintures et bois, 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, Corrosion, Corrosión, Korrosion, Dépôt électrolytique, Electrodeposition, Depósito electrolítico, Elektroplattieren, Revêtement métallique, Metal coating, Revestimiento metálico, Metallischer Ueberzug, Traitement surface, Surface treatment, Tratamiento superficie, and Oberflaechenbehandlung

Tin has a strong influence on the electrodeposition of zinc already in concentrations of less than 1 ppm. Tin changes the mechanism, the deposition rate and the morphology of the resulting surface of zinc deposited from an acidic sulfate electrolyte. These severe changes are not obvious since both elements have similar overpotentials for hydrogen evolution as the dominant side reaction. The influence on the electrodeposition of zinc was studied using cyclic voltammetry on a rotating disc electrode, chemical analysis of the zinc layers, chronopotentiometric measurements, and investigations into the microstructure by SEM. It is shown that tin co-deposits with zinc starting at concentrations of about 1 ppm and therefore changes the structure of the zinc layer. A mechanism is presented that explains the significant drop in current efficiency in a pulsed deposition program, in which the codepositing tin acts as cathode during the off cycle leading to drastic anodic redissolution of the zinc.

Civil engineering, Génie civil, Metallurgy, welding, Métallurgie, soudage, Polymers, paint and wood industries, Polymères, industries des peintures et bois, 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, Densité, Density, Densidad, Etat supercritique, Supercritical state, Estado supercrítico, 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, Traitement surface, Surface treatment, Tratamiento superficie, and Oberflaechenbehandlung

In this study, IN625 and a NiCrAlY coated IN625 were tested in high density and low density supercritical water for 500 h.The NiCrAlY coating was applied using plasma spray method. The surfaces were finely polished before testing to assist microstructure observation after testing. The NiCrAlY coated samples were additionally heat treated in air furnace to encourage alumina formation. SEM and XRD analyses were carried out to determine surface microstructure changes, particularly oxide formation. The results showed that when tested under high density supercritical water, the bare IN625 sample suffered from intergranular attacking while low density supercritical water did not have the same effect. Both as-sprayed NiCrAlY and heat treated NiCrAlY did not show any signs of intergranular attack or pitting after being tested in high density and low density supercritical water.

Civil engineering, Génie civil, Metallurgy, welding, Métallurgie, soudage, Polymers, paint and wood industries, Polymères, industries des peintures et bois, 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 aluminium, Aluminium base alloys, Borure de titane, Titanium boride, Titanio boruro, Titanborid, Corrosion, Corrosión, Korrosion, Dépôt électrolytique, Electrodeposition, Depósito electrolítico, Elektroplattieren, Matériau composite, Composite material, Material compuesto, Verbundwerkstoff, Revêtement métallique, Metal coating, Revestimiento metálico, Metallischer Ueberzug, Traitement surface, Surface treatment, Tratamiento superficie, and Oberflaechenbehandlung

The electrodeposition behavior of aluminum on TiB2/A356 composite from AlCl3-NaCl-KCl molten salt was studied in this paper. The surface morphology, microstructure, and phase composition of aluminum coating were characterized by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). The phase composition of the composite was examined by X-ray diffraction technique. The polarization curves were measured and the corrosion current densities were obtained. The results indicated that the aluminum coating was preferentially electrodeposited on the surface of TiB2 and Si phases. This phenomenon could be largely attributed to the different surface energies of TiB2, Si, and Al phases. With the increasing of deposition time, a continuous, dense, and faceted aluminum coating was finally obtained. It was inferred that the growth of aluminum coating on the surface of the composite was mainly through two-dimensional spreading. However, three-dimensional growth could also be seen. The corrosion current density of the aluminum-coated TiB2/A356 composite (1 min) decreased by an order of magnitude as compared with that of TiB2/A356 composite, and was close to that of A356 alloy, and also in the same order of magnitude with that of pure aluminum. It is evident that, the coverage ofTiB2 and Si phases by aluminum coating (1 min) can effectively improve the corrosion resistance of TiB2/A356 composite. In combination with SEM and EDS results, the behavior can be characterized as preferential electrodeposition.

Civil engineering, Génie civil, Metallurgy, welding, Métallurgie, soudage, Polymers, paint and wood industries, Polymères, industries des peintures et bois, 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, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Cinétique, Kinetics, Cinética, Kinetik, Corrosion, Corrosión, Korrosion, Délaminage, Delamination, Delaminación, Schichtabloesung, Morphologie, Morphology, Morfología, Oxyde de zinc, Zinc oxide, Zinc óxido, Zinkoxid, Polymère, Polymer, Polímero, Revêtement non métallique, Non metal coating, Revestimiento no metálico, and Nichtmetallischer Ueberzug

Industrially prepared materials surfaces often possess complex morphologies and topographies. Using rough model interfaces, the effect of the surface morphology on the delamination of a polymer coating from zinc surfaces is investigated in this work. Zinc oxide particles of different shapes with characteristic dimensions ∼1μm were deposited on zinc surfaces to serve as model corrosion products with well-defined morphologies. Surfaces with spherical, rod-shaped, and twin-plate-shaped zinc oxide particles were prepared and characterized by scanning electron microscopy (SEM) as well as X-ray diffraction (XRD). The surfaces were subsequently coated with poly(vinyl butyral) (PVB) as a model for a weakly bound polymer coating. Scanning Kelvin probe (SKP) measurements were carried out in humid air to study the delamination kinetics. Results were compared to PVB on zinc. While delamination is fastest on zinc without zinc oxide particles, the delamination rate on the particle-covered surfaces strongly depends on the particle morphology. Delamination rate increases in the order sphere < rod < twin-plate, with differences by one order of magnitude between fastest and slowest.The differences in delamination rate can be understood based on the surface energies of the terminating surfaces of the particles, and the resulting differences in stability under conditions of zinc oxide dissolution.

Civil engineering, Génie civil, Metallurgy, welding, Métallurgie, soudage, Polymers, paint and wood industries, Polymères, industries des peintures et bois, 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, Biomasse, Biomass, Biomasa, Charbon, Coal, Carbón, Kohle, Corrosion, Corrosión, Korrosion, Dépôt projection, Spray coating, Depósito proyección, Spritzbeschichten, Modélisation, Modeling, Modelización, Projection à chaud, Hot spraying, Proyección en caliente, Spritzen, Revêtement, Coatings, Revestimiento, Ueberzug, Traitement surface, Surface treatment, Tratamiento superficie, and Oberflaechenbehandlung

This paper presents a development and evaluation of coating materials for advanced fossil fuel plants and addresses issues related to coal/biomass-derived flue gases. A selection of candidate coatings: 625, NiCr and NiCrAlY were deposited on superheater/reheater materials (T91) using high velocity oxy-fuel (HVOF) spraying. A series of laboratory-based fireside corrosion exposures have been carried out on these coated samples in controlled atmosphere furnaces for 1000 h. The tests were carried out with the deposit-recoat test method to generate the exposure conditions; the gaseous environment simulated that anticipated from air-firing 20 wt% cereal co-product (CCP) mixed with a UK coal. The exposures were carried out using various mixtures of Na2SO4, K2SO4, Fe2O3 and kaolinite to produce different deposition fluxes at a test temperature of 650 °C. After the exposures, the samples were examined by environmental scanning electron microscope/energy dispersive X-ray analysis to characterise the damage. Pre- and post-exposure dimensional metrology was used to quantify the metal damage in terms of metal loss distributions. In all three coatings, the deposit targeted at forming undiluted alkali-iron tri-sulphate was found to be the most aggressive, causing the most corrosion damage to all alloys in simulated air-fired combustion gases. A corrosion model was proposed to predict the incubation time at different alkali deposition fluxes. The transition from incubation to propagation was found to be dependent on the chromium content of the alloys. The HVOF NiCr coating, with 46 wt% chromium, was found to be the best performing coating with the longest incubation times in these tests.

Civil engineering, Génie civil, Metallurgy, welding, Métallurgie, soudage, Polymers, paint and wood industries, Polymères, industries des peintures et bois, 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, Cérium, Cerium, Cerio, Cer, Dépôt conversion, Conversion coating, Depósito conversión, Konversionsbeschichten, Lanthanide, Lantánido, Microstructure, Microestructura, Mikrogefuege, Oxyde de cérium, Cerium oxide, Cerio óxido, Ceroxid, Revêtement, Coatings, Revestimiento, Ueberzug, Traitement surface, Surface treatment, Tratamiento superficie, and Oberflaechenbehandlung

Cerium-based conversion coating was deposited on aluminum 6063 and its corrosion behavior was studied. Corrosion resistance was investigated at different pH in 3.5 wt% NaCl solution by means of electrochemical impedance spectroscopy, potentiodynamic polarization, and surface techniques. The coated samples showed a significant decrease in corrosion rate. The coating obtained by 600 s immersion covers uniformly the alloy surface. Electrochemical impedance data shows that with increasing immersion time, the charge transfer resistance of aluminum increased. Surface morphology and its chemical composition were analyzed by means of scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). SEM images in agreement with the electrochemical results indicated that aluminum surface was not completely covered after short immersion time. The EDS analysis confirmed the presence of cerium oxide on the aluminum surface and the cerium content was increased with increasing immersion time.

Civil engineering, Génie civil, Metallurgy, welding, Métallurgie, soudage, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Corrosion, Action des agents de corrosion, Corrosion environments, Alliage base nickel, Nickel base alloys, Corrosion, Corrosión, Korrosion, Effet composition, Composition effect, Efecto composición, Konzentrationseinfluss, Superalliage, Superalloy, Superaléación, Superlegierung, Traitement surface, Surface treatment, Tratamiento superficie, and Oberflaechenbehandlung

The oxidation resistance of Ni-base superalloys with Al-contents of 2―5 wt% is commonly improved by the use of Al-rich coatings. An alternative way has been proposed by using the halogen effect. In this case, the Al activity on the alloy surface is increased by the transport of Al via gaseous Al-halides. Fluorine was chosen because of the good results obtained in the case of TiAl. The fluorine was applied by ion implantation. After oxidation at 1050 °C a dense protective alumina scale was formed on the surface of the alloy IN738. The fluorine effect was combined with the reactive element effect to improve the adherence of the alumina scale.

Civil engineering, Génie civil, Metallurgy, welding, Métallurgie, soudage, Polymers, paint and wood industries, Polymères, industries des peintures et bois, 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, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Aniline polymère, Aniline polymer, Anilina polímero, Corrosion, Corrosión, Korrosion, Epoxyde résine, Epoxy resin, Epóxido resina, Epoxidharz, Matériau composite, Composite material, Material compuesto, Verbundwerkstoff, Revêtement non métallique, Non metal coating, Revestimiento no metálico, and Nichtmetallischer Ueberzug

Mesoporous MCM-41(M(with template)) whose pore channels were filled with cationic surfactant n-hexadecyltrimethyl-ammonium bromide (CTAB) and a (hydrophobic) poly(propylene glycol) nucleus terminated by two primary hydroxyl groups (Pluronic F-127, molecular weight = 11500) inside the pore channels and on the outer surface of the particle, MCM-41 (M(without template)) whose mixture template inside the pore channels and on the outer surface of the particle were calcinated, were used as new fillers for waterborne epoxy. The corrosion studies were carried out on steel plates coated with formulations containing polyaniline prepared with M(with template) and M(without template). Correspondingly, corrosion performance of the coatings was studied by electrochemical impedance spectroscopy (EIS) in 3.5% NaCl aqueous solution and salt spray test. Coatings prepared from polyaniline (PANI)/M(without template) particles synthesized by in situ polymerization were found to exhibit excellent corrosion resistance much superior to PANI/M(with template) in aggressive environments due to the different interfacial structures between the fillers and the matrix.

Civil engineering, Génie civil, Metallurgy, welding, Métallurgie, soudage, Polymers, paint and wood industries, Polymères, industries des peintures et bois, 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, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Aniline polymère, Aniline polymer, Anilina polímero, Composé organique, Organic compounds, Compuesto orgánico, Organische Verbindung, Corrosion, Corrosión, Korrosion, Délaminage, Delamination, Delaminación, Schichtabloesung, Pigment anticorrosion, Anticorrosion pigment, Pigmento anticorrosión, Pigment métallique, Metallic pigment, Pigmento metálico, Metallpigment, Revêtement non métallique, Non metal coating, Revestimiento no metálico, and Nichtmetallischer Ueberzug

In-coating dispersions of the para-toluene sulfonic acid emeraldine salt (ES) of polyaniline (PAni-pTS) are shown to be highly effective inhibitors of corrosion-driven organic coating delamination on zinc surfaces. However, this inhibition is achieved without the characteristic ennoblement of substrate potentials typically observed for ferrous metals. At high humidity, galvanic interaction of oxidizing PAni-pTS pigments with the underlying zinc causes the growth of an interfacial oxide film. The period of oxide growth coincides with the duration over which the Zn surface is temporarily ennobled by the PAni-pTS. The results of experiments designed to elucidate the inhibition mechanism are presented, where substrate potentials, along with delamination and oxide growth kinetics are compared with equivalent in-coating compositions of ES and emeraldine base (EB). It is demonstrated that the basic nature of the interfacial oxide layer causes PAni-pTS re-oxidation to the non-conducting EB form, accounting for the loss of ennoblement. Efficient inhibition is achieved by a combination of a PAni-pTS-induced oxide layer and a zinc para-toluene sulfonate phase, acting as a reservoir of underfilm Zn2+ ions, producing a suppression of cathodic oxygen reduction. Availability of Zn2+ ions at the organic coating-metal interface both reinforces and prevents the dissolution of the amphoteric zinc oxide surface layer.

Civil engineering, Génie civil, Metallurgy, welding, Métallurgie, soudage, Polymers, paint and wood industries, Polymères, industries des peintures et bois, 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, Dépôt de matériaux non métalliques, Nonmetallic coatings, Barrière thermique, Thermal barrier, Barrera térmica, Composé intermétallique, Intermetallic compound, Compuesto intermetálico, Intermetallische Verbindung, Corrosion vapeur eau, Steam corrosion, Corrosión vapor agua, Wasserdampfkorrosion, Frittage, Sintering, Sinterización, Sintern, Métallurgie poudre, Powder metallurgy, Metalurgia polvo, Pulvermetallurgie, Oxydation, Oxidation, Oxidación, Revêtement non métallique, Non metal coating, Revestimiento no metálico, Nichtmetallischer Ueberzug, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Vapeur eau, Water vapor, Vapor agua, and Wasserdampf

In this work, the effect of water vapour on a new thermal barrier coating system synthesised from a slurry containing Al microparticles was studied under isothermal regime at 1100 °C for short oxidation times (50 h). Both dry air and argon gas atmospheres were investigated with increasing water vapour contents (0, 5, 10% RH, relative humidity) and the oxidation mechanisms and growth kinetics of the oxide scales were compared to conventional aluminide coatings up to 50% RH. The phase transformations occurring in the coating were characterised by local Raman micro-spectrometry with complementary analytical techniques (X-ray diffraction and FEG-ESEM/EDS). The results demonstrated that water vapour does not exert a great influence on the oxidation of this type of coatings once an α-Al2O3 scale is stabilised after an appropriate sintering of the coating. In contrast the combined effect of water vapour and oxidation onto oxide scales grown from raw aluminide coatings was shown to trigger delayed transformation of θ into α-Al2O3, the appearance of pores and spallation, in particular in air + x %RH.

Civil engineering, Génie civil, Metallurgy, welding, Métallurgie, soudage, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Corrosion, Action des agents de corrosion, Corrosion environments, Corrosion, Corrosión, Korrosion, Hydrogène, Hydrogen, Hidrógeno, Wasserstoff, Traitement surface, Surface treatment, Tratamiento superficie, and Oberflaechenbehandlung

Anodizing of AZ91D magnesium alloy in the alkaline borate-potassium hydrogen tartrate (PHT) environmental friendly electrolyte was studied. The effect of PHT on the anodizing process and anodic film properties was investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectrometry (EDS), and potentiodynamic polarization. The results showed that the anodizing parameters, surface morphology, thickness, phase structure, and corrosion resistance of the anodic film were strongly dependent on the concentration of PHT. Moreover, the anodizing mechanism of the AZ91D magnesium alloy in the presence of PHT was also studied. That is, by adsorption on the surface of magnesium alloy, PHT decreases the anodizing current density and make the anodizing condition moderate, which is conducive to the performance improvement of the anodic film.

Civil engineering, Génie civil, Metallurgy, welding, Métallurgie, soudage, Polymers, paint and wood industries, Polymères, industries des peintures et bois, 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, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Activation, Activación, Acétate, Acetate, Acetato, Corrosion, Corrosión, Korrosion, Phosphate de zinc, Zinc phosphate, Zinc fosfato, Zinkphosphat, Revêtement, Coatings, Revestimiento, Ueberzug, Résistance corrosion, Corrosion resistance, Resistencia corrosión, Korrosionsbestaendigkeit, Zingage, Zinc coating, Galvanización con cinc, and Verzinken

Zinc phosphating is a chemical conversion process that has been widely used in industry for corrosion protection and primer for painting. In this investigation, the effect of activation treatment with nickel acetate on the microstructural evolution and corrosion resistance of the zinc phosphate coating on mild steel was studied. The chemical composition and morphology of the coatings were analyzed via scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The corrosion resistance of the coatings was evaluated using polarization curves and electrochemical impedance spectroscopy (EIS) in an aerated 3.5% NaCl solution. Surface morphology observations revealed that the activation treatment increased the population density and refined the grain size of the coating. The electrochemical results showed better barrier protection characteristics and corrosion resistance for activated phosphate coatings compared with inactivated coatings.

Civil engineering, Génie civil, Metallurgy, welding, Métallurgie, soudage, Polymers, paint and wood industries, Polymères, industries des peintures et bois, 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, Corrosion effet pile, Galvanic corrosion, Corrosión galvánica, Kontaktkorrosion, Revêtement métallique, Metal coating, Revestimiento metálico, Metallischer Ueberzug, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Zinc, and Zink

The hot-dipped zinc-aluminum alloy coating was used to avoid galvanic corrosion problems of titanium-aluminum alloy. The microstructure and corrosion properties of the coating were investigated by scanning electron microscopy, electrochemical measurement, and immersion test. The microstructure indicated that the coating consisted of outermost layer and middle interdiffusion layer, which metallurgically combined with the substrate. The electrochemical properties indicated that the coating on the titanium alloy decreased the electrochemical potential difference of galvanic couple. The corrosion current density showed that aluminum alloy contact with the coating changed the electrode, in other words, aluminum alloy specimen turned out to be the cathode in the galvanic couple. Immersion test was carried out to evaluate the performance of coating for galvanic corrosion, results confirmed that aluminum alloy contacted with coating on titanium-aluminum alloy exhibited less surface corrosion.

Civil engineering, Génie civil, Metallurgy, welding, Métallurgie, soudage, Polymers, paint and wood industries, Polymères, industries des peintures et bois, 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, Chrome, Chromium, Cromo, Chrom, Corrosion, Corrosión, Korrosion, Mécanisme, Mechanism, Mecanismo, Revêtement décoratif, Decorative coatings, Revestimiento decorativo, Dekorationsueberzug, Revêtement métallique, Metal coating, Revestimiento metálico, Metallischer Ueberzug, Traitement surface, Surface treatment, Tratamiento superficie, and Oberflaechenbehandlung

Microscopic studies suggested accelerated nickel corrosion to account for the extensive failure of decorative nickel chromium coatings. Electrochemical experiments further confirmed the crucial role of chloride, cupric, and ferric ion containing salts, which were found before on the corroded surface. Density functional theory calculations were used in the following to explain experimental observations and to obtain a detailed understanding of the mechanism of the accelerated corrosion under specific corrosive environments on the molecular level. The results of the calculations were discussed taking into account literature known models for pitting corrosion.

Civil engineering, Génie civil, Metallurgy, welding, Métallurgie, soudage, Polymers, paint and wood industries, Polymères, industries des peintures et bois, 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, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Aluminium, Aluminio, Corrosion, Corrosión, Korrosion, Matériau composite, Composite material, Material compuesto, Verbundwerkstoff, Nanocristal, Nanocrystal, Revêtement composite, Composite coating, Revestimiento compuesto, Résistance corrosion, Corrosion resistance, Resistencia corrosión, and Korrosionsbestaendigkeit

High velocity arc spraying (HVAS) process was used to deposit Al-Ni-Y-Co amorphous and nanocrystalline composite coating on AZ91 magnesium alloy substrate. The microstructure of the coating was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS) and transmission electron microscopy (TEM). The results show that the coating with thickness of 500 μm presents a dense layered structure with low porosity (1.8%). The coating consists of amorphous, nanocrystalline, and crystalline phases. The microhardness was measured by a microhardness tester. The average values of Vickers hardness for the Al-Ni-Y-Co coating, pure Al coating and AZ91 alloys are about HV0.1 310, HV0.1 70, and HV0.1 60, respectively. The electrochemical corrosion resistance of the coating in 5 wt% NaCl aqueous solution was also investigated, and the results showed that the Al-Ni-Y-Co coating exhibits better corrosion resistance than pure Al coating and AZ91 magnesium alloy.

Civil engineering, Génie civil, Metallurgy, welding, Métallurgie, soudage, Polymers, paint and wood industries, Polymères, industries des peintures et bois, 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, Revêtement métallique, Metal coating, Revestimiento metálico, Metallischer Ueberzug, Sulfate de sodium, Sodium sulfate, Sodio sulfato, Natriumsulfat, Traitement surface, Surface treatment, Tratamiento superficie, and Oberflaechenbehandlung

In this study, the effect of sodium sulfate on the microstructure and corrosion resistance of high phosphorus Ni-P electroless coatings has been investigated. Ni-P electroless coating was deposited on AISI 1045 steel substrate with using sodium sulfate as an additive in the plating bath (with concentration of 0-1.5 g/L). Electrochemical behavior and corrosion resistance of the coatings were investigated by evaluation of open circuit potential (OCP) and potentiodynamic polarization curves. The results showed that at an optimum concentration of sodium sulfate (~1 g/L), deposition rate was maximum and the size and number of microporosities in the coating decreased to the minimum values. In addition, the best corrosion resistance and the most extensive passive region in potentiodynamic polarization curve was obtained at the optimum concentration of additive. Also its OCP was the same as pure nickel.

Civil engineering, Génie civil, Metallurgy, welding, Métallurgie, soudage, Polymers, paint and wood industries, Polymères, industries des peintures et bois, 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, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Alliage mémoire forme, Shape memory alloy, Aleación memoria forma, Formgedaechtnislegierung, Apatite hydroxylée, Hydroxyapatite, Hidroxiapatito, Biomatériau, Biomaterial, Corrosion, Corrosión, Korrosion, Dépôt électrophorèse, Electrophoresis coating, Depósito electrofóresis, Elektrophoretisches Beschichten, Nickel alliage, Nickel alloy, Níquel aleación, Nickellegierung, Revêtement non métallique, Non metal coating, Revestimiento no metálico, Nichtmetallischer Ueberzug, Titane alliage, Titanium alloy, Titanio aleación, and Titanlegierung

Natural hydroxyapatite (HA) was coated on NiTi alloy using electrophoretic deposition method to improve the corrosion resistance and biocompatibility. Coating process was performed at 120 s in various applied voltages of 40, 60, and 80 V. Sintering process was done at 800 °C under inert gas for 2 h. Electrochemical behavior of the coated samples was investigated in simulated body fluid by using electrochemical impedance spectroscopy and polarization tests. Furthermore, the nickel ions release from NiTi and HA coated-NiTi samples were analyzed by atomic absorption analysis. Ultimately, scanning electron microscopy micrographs and X-ray diffraction patterns were used to evaluate the morphology and phase analysis of HA coatings. The results show that the sample coated at 60V reveals a uniform, dense coating accompanied with a higher corrosion resistance. Moreover, after 4 weeks, nickel ions release was reduced to 0.205 μg/cm2 for coated sample at 60 V.

Civil engineering, Génie civil, Metallurgy, welding, Métallurgie, soudage, Polymers, paint and wood industries, Polymères, industries des peintures et bois, 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, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Corrosion, Corrosión, Korrosion, Produit corrosion, Corrosion product, Producto corrosión, Korrosionsprodukt, Revêtement métallique, Metal coating, Revestimiento metálico, and Metallischer Ueberzug

The formation of corrosion product at the cut edge of aluminum-rich metal-coated steel is reported in the present work. Painted metal-coated steel samples with different amounts of Al in the metal coating, were immersed in a 0.05 M NaCl solution.The ex situ analysis of the corrosion products formed was carried out by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDX), Raman and Fourier transform infrared (FT-IR) spectroscopy. The role of these products is discussed along with the influence of Al content in the metal coating.

Civil engineering, Génie civil, Metallurgy, welding, Métallurgie, soudage, Polymers, paint and wood industries, Polymères, industries des peintures et bois, 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, Autres traitements de surface, Other surface treatments, Corrosion, Action des agents de corrosion, Corrosion environments, Anodisation, Anodizing, Anodización, Elektrolytisches Oxidieren, Corrosion, Corrosión, Korrosion, Traitement surface, Surface treatment, Tratamiento superficie, and Oberflaechenbehandlung

Corrosion behavior of anodic oxide layers on the surface of TiAlZr alloys formed using glycerol + 15 vol% H2O + 0.2 M NH4F under variable anodizing voltage (15 V, 30 V) was investigated and compared with corrosion of the native films. Electrochemical behavior analysis of all samples was composed of linear polarization, potentiodynamic polarization and electrochemical impedance and was correlated with the morphology data obtained from scanning electron microscopy and atomic force microscopy. Nanotubular structures appeared on the surface of the TiAlZr sample anodized at 15 V while on the TiAlZr sample anodized at 30 V a porous oxide layer was observed, denoting a transition from nanotubes to nanopores at higher voltage. All tests indicate that TiAlZr anodized at 30 V has greater resistance against corrosion compared to TiAlZr anodized at 15 V or bare TiAlZr sample.