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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, Chrome III, Chromium III, Cromo III, Corrosion, Corrosión, Korrosion, Dépôt électrolytique, Electrodeposition, Depósito electrolítico, Elektroplattieren, Revêtement métallique, Metal coating, Revestimiento metálico, Metallischer Ueberzug, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Vitesse corrosion, Corrosion rate, Velocidad corrosión, Korrosionsgeschwindigkeit, Chromium plating, and Trivalent

The present paper presents a review of theoretical aspects of deposition of chromium from trivalent chromium electrolytes and a corrosion rate study of the initial rate of corrosion of chromium deposits from these electrolytes on nickel deposits. A higher rate of corrosion was obtained from chromium deposits plated from a chloride based electrolyte as compared with a sulphate based electrolyte. No significant difference in corrosion rate was observed when comparing deposits plated from a sulphate based electrolyte with deposits obtained from a standard hexavalent chromium electrolyte.

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, Adsorption, Adsorción, Matériau composite, Composite material, Material compuesto, Verbundwerkstoff, Métal noble, Noble metal, Metal noble, Edelmetalle, Nanostructure, Nanoestructura, Synthèse, Synthesis, Síntesis, Titane oxyde, Titanium oxide, Titanio óxido, Titanoxid, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Ion exchange, and Metal particles

Methods for the deposition of precious metals (Au, Pt, Pd and ruthenium hydrated oxide) onto the surface of nanotubular titanates are considered. Viable techniques include preliminary ion exchange of precious. metal cations onto the nanotubes followed by chemical, electrochemical or photochemical reduction to the metal. The morphology and size of the metal nanoparticles ranged from spheroidal particles of a few nanometres to larger, rod like particles. The deposits, which were densely loaded onto the surface and were uniformly distributed, had a high surface area and good chemical stability. The size of metal nanoparticles ranged from 1 to 50 nm.

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, Protection contre la corrosion, Corrosion prevention, Chrome VI, Chromium VI, Cromo VI, Corrosion, Corrosión, Korrosion, Protection corrosion, Corrosion protection, Protección corrosión, Korrosionsschutz, Revêtement métallique, Metal coating, Revestimiento metálico, Metallischer Ueberzug, Traitement surface, Surface treatment, Tratamiento superficie, and Oberflaechenbehandlung

Hexavalent chromium is a well established material used in the commercial production of sacrificial zinc coatings for anti-corrosion applications. However, environmental and legislative pressures have been the catalyst for adopting alternatives based upon. trivalent chromium and chromium-free materials. This change has wide implications within the global supply chain. End users and applicators must consider strategic issues such as product availability, cost implications and specific application needs. Experience with the change has illustrated the need for cooperation along the entire supply chain. The chemical supplier becomes the conduit between applicator and end user, and can facilitate a managed change of the process. Suppliers are ideally placed to establish best practice techniques at the applicator, and can work in partnership to achieve lowest operating cost with maximum performance. Developments in trivalent passivates for blue and iridescent colour films will be described, followed by discussion of the use of an audit approval programme to manage the transition to hexavalent chromium free products.

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, Chrome alliage, Chromium alloy, Cromo aleación, Chromlegierung, Corrosion, Corrosión, Korrosion, Dépôt électrolytique, Electrodeposition, Depósito electrolítico, Elektroplattieren, Revêtement métallique, Metal coating, Revestimiento metálico, Metallischer Ueberzug, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Zinc, Zink, Zingage électrolytique, Zinc plating, Zincato electrolítico, Galvanisches Verzinken, Anodic behaviour, Electrodeposited Zn-Cr alloy coatings, XPS, XRD, and Zn alloys

The corrosion electrochemical behaviour of Zn-Cr alloy coatings electrodeposited onto Pt and steel substrates from acidic sulphate electrolyte, containing PPG 620 and glycine as additives is studied by means of potentiodynamic polarisation scan and galvanic stripping. The investigations are carried out in slightly acidic sodium sulphate solution. Changes in composition and structure resulting in corrosion treatment are established by energy dispersion spectroscopy (EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The surface morphology is examined by SEM. Dissolution of the alloy coating under polarisation runs through dissolution of ηx-Zn phase, selective dissolution of Zn from the Γx-(Zn,Cr) phase and dissolution of Γx-(Zn,Cr) phase at a potential close to the potential of transpassive dissolution of Cr. A thin Γx-(Zn,Cr) layer, containing ∼58 mass%Cr, remains and is mechanically disintegrated after the potential of oxygen evolution is reached. The corrosion tests by total immersion of the coating into corrosive media show that the time of appearance of red rust is 1.5 times longer than that for Zn 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, Traitements de surface, Surface treatment, Dépôt de métaux et d'alliages, Metallic coatings, Cellule électrolyse, Electrolysis cell, Célula electrolisis, Elektrolysezelle, Efficacité, Efficiency, Eficacia, Wirkungsgrad, Microscopie électronique balayage, Scanning electron microscopy, Microscopía electrónica barrido, Rasterelektronenmikroskopie, Rendement courant, Current efficiency, Rendimiento corriente, Stromausbeute, Revêtement métallique, Metal coating, Revestimiento metálico, Metallischer Ueberzug, Solution basique, Basic solution, Solución básica, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Alloy deposition, Composition and current efficiency, Hull cell studies, and Structure

Cobalt ions were added to a non-cyanide alkaline zinc bath to produce an alloy of zinc containing 0·6-0·8%Co. Bright deposits were produced using organic additives. The effect of different parameters such as cobalt concentration, current density, complexant concentration, additive concentration, temperature, agitation, etc. on the composition of the alloy and current efficiency was studied. Structural characterisation using scanning electron microscopy showed that the deposits are nanocrystalline.

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, Alliage base nickel, Nickel base alloys, Bain dépôt, Plating bath, Baño depósito, Dépôt chimique, Chemical deposition, Depósito químico, Stromloses Beschichten, Nickel, Niquel, Revêtement métallique, Metal coating, Revestimiento metálico, Metallischer Ueberzug, Séquestrant, Complexing agent, Secuestrante, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Tungstène alliage, Tungsten alloy, Wolframio aleación, Wolframlegierung, Aminoacetic acid, and Electroless nickel alloys

Ni-W-P alloy coatings were deposited from a bath containing, nickel sulphate (VI), sodium tungstate (VI), sodium hypophosphite, sodium formate, and a complexing agent. The complexing agents were formic acid, acetic acid, lactic acid, succinic acid, malic acid, malonic acid, aminoacetic acid and.triethanoloamine. It is shown that Ni-W-P coatings are deposited the slowest when complexing agents with the highest stability constants are used. As the deposition rate increases, i.e. in the presence of less stable complexing compounds, the amount of tungsten in the coating decreases. When aminoacetic acid and citric acid were used, the tungsten content in the coating amounted to ∼2 wt-%, depending on the complexing agent concentration and the pH of the bath.

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, Cathode, Cátodo, Kathode, Diagramme polarisation, Polarization diagram, Diagrama polarización, Polarisationsdiagramm, Dépôt électrolytique, Electrodeposition, Depósito electrolítico, Elektroplattieren, Revêtement métallique, Metal coating, Revestimiento metálico, Metallischer Ueberzug, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Polarisation curves, and Zinc

The electrodeposition of zinc onto a zinc cathode was studied through the comparison between theoretical and experimental polarisation curves. The former was constructed using the Butler-Volmer equation with electrochemical parameters, such as Tafel slope values, exchange current densities, equilibrium potential values, etc. The latter was obtained from data derived in a chloride based electrolyte of 0·6 mol dm-3 Zn2+ ions with boric acid (25 g dm-3), pH=5. The electrochemical parameters such as exchange current density, limiting current density, equilibrium potential, Tafel slopes, can be obtained with good agreement with the values from the literature.

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, Brillanteur, Brightener, Abrillantador, Glanzzusatz, Dépôt électrolytique, Electrodeposition, Depósito electrolítico, Elektroplattieren, Oxydation, Oxidation, Oxidación, Revêtement métallique, Metal coating, Revestimiento metálico, Metallischer Ueberzug, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Anode, Ascorbic acid, Copper electroplating, and species mechahism of oxidation and its anti-oxidant

Catalytic anodes are an enabling technology for high speed, horizontal acid copper electroplating. However, their usage is associated with high additive oxidation rates which can be problematic in terms of cost and control of the electrolyte. The addition of certain 'organic reductants' to the electroplating solution has been found to have a dramatic effect on brightener consumption when catalytic anodes are employed. This paper reports an investigation of three such compounds having varying functionality with respect to brightener oxidation. It was found that the ability of a particular organic reductant to influence brightener oxidation was related to its electrochemical properties on a particular anode material. However, it is postulated that the species' mechanism of oxidation and its anti-oxidant properties may also be important factors.

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, Etat surface, Surface conditions, Estado superficie, Oberflaechenzustand, Traitement surface, Surface treatment, Tratamiento superficie, and Oberflaechenbehandlung

An attempt is made to assess the state of the UK surface finishing sector on the basis of available statistics and discussions with the industry. The age distribution of firms in the sector is considered and the threats from increasing legislative pressures and the tendency to move manufacturing, and hence coating operations, offshore are discussed. Part 2 will look at the international situation, the role of the supply chain and suggest how the industry should respond to the threats identified.

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 électrolytique, Electrodeposition, Depósito electrolítico, Elektroplattieren, In situ, Milieu acide, Acid medium, Medio ácido, Saures Medium, Revêtement métallique, Metal coating, Revestimiento metálico, Metallischer Ueberzug, Sulfate, Sulfates, Sulfato, Sulfat, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Copper electrodeposition, ERS, Levellers, and SERS

This paper deals with a study of the adsorption behaviour of three molecules which can be employed as levellers in Cu electrochemical plating from acidic sulphate solutions: 4-cyanopyridine (4CP), 3-diethylamino-7-(4-dimethylaminophenylazo)-5-phenylphenazinium chloride (Janus Green B, JGB) and a benzyl-phenyl modified polyethyleneimine (BPPEI). This investigation was carried out by in situ surface enhanced Raman spectroscopy (SERS) during electroplating and by in situ electroreflectance spectroscopy (ERS) on electrodeposited Cu layers. Variations of SERS effect with potential and potentiostatic polarisation time were studied. Cathodic reactivity of JGB and BPPEI was highlighted by the analysis of spectral changes as a function of applied potential and by time resolved spectroscopy. The formation of surface electronic states related to the formation of chemisorption bonds between the levellers and the Cu electrode was revealed by ERS.

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, Microstructure, Microestructura, Mikrogefuege, Revêtement non métallique, Non metal coating, Revestimiento no metálico, Nichtmetallischer Ueberzug, Titane nitrure, Titanium nitride, Titanio nitruro, Titannitrid, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Zingage, Zinc coating, Galvanización con cinc, Verzinken, Process optimisation, Surface modification, and Tin cementation

The process of tin cementation on zinc resulting in the formation of fine grained tin coatings was studied. The influence of the experimental conditions such as Sn(II) concentration, duration of the reaction, solution temperature and pH on the microstructure of the cemented tin films was investigated. The dependence between the experimental conditions and the grain sizes of the deposited tin films was established using the method of the design of experiment. The diminution of Sn(ll) concentration, the decrease in temperature and the increase in solution pH were found to promote the deposition of fine grained tin coatings with the grain sizes 0-3-1 μm. The fine granulation of tin films was shown to be insufficient for obtaining coatings suitable for the use as protective and/or intermediate layers on zinc surface. The evolution of hydrogen was found to be the most negative factor deteriorating the quality of coatings owing to the formation of pores.

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, Contrainte résiduelle, Residual stress, Tensión residual, Eigenspannung, Couche mince, Thin film, Capa fina, Duennschicht, Déformation résiduelle, Residual strain, Deformación residual, Energie déformation, Strain energy, Energía deformación, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Anodising, and Stoney equation

Residual stresses in thin films are usually evaluated either by measurement of elastic strains in the film or from the curvature or deflection of a film coated substrate material (the Stoney technique). Both methods are prone to serious measurement errors particularly for thinner films or smaller curvatures or deflections. The Stoney technique is popular because the analysis does not require the elastic modulus of the film. However, residual stress can be determined more accurately using the film modulus. A simple strain-energy analysis using this modulus has been developed to investigate residual stresses in boric acid-sulphuric acid (BSA) anodised films, based on bending measurements of thin coupons. The method is an improvement over Stoney's equation because the square root of the thickness of the film, rather than the thickness itself, is involved, therefore reducing one of the larger sources of error. The modulus of the film was determined from nanoindentation measurements. The strain-energy method allows analysis of residual stress development in the coupons as functions of film thickness and time. The results show that the residual stress in BSA anodised films formed on high strength Al-Cu alloy is highly tensile with stress levels up to 400 MPa. The effects of coupon geometry on stress development were also studied and were found to influence the final levels of residual stress developed. These results have implications for the measurement of residual stresses by beam deflection methods.

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, Apatite hydroxylée, Hydroxyapatite, Hidroxiapatito, Application médicale, Medical application, Aplicación medical, Medizinische Technik, Biomatériau, Biomaterial, Décharge étincelle, Spark discharge, Descarga chispa, Revêtement non métallique, Non metal coating, Revestimiento no metálico, Nichtmetallischer Ueberzug, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Bioactive coatings, Spark anodising, and Titanium

Spark anodising of titanium enables fabrication of coatings with potential biocompatibility. In the present study, coatings were produced in electrolytes containing various amounts of CaHPO4, Ca(H2PO4)2, Na6P6O18 and Ca(CH3COO)2. The findings disclose formation of coatings with compositions, morphologies and structures dependent upon the growth conditions. Calcium and phosphorus species are distributed throughout most of the coating thickness, with typical Ca/P atomic ratios of ∼0.45 and (Ca+P)/Ti atomic ratios in the range 1·0-2·6 in the near surface regions. Calcium contents in particular reduced towards the metal. Dissolution behaviour in physiological solution was investigated by potentiodynamic polarisation measurements and immersion tests, the latter indicating titanium loss rates of ∼0-3 μg cm-2 day-1. Preliminary adhesion studies using primary human osteoblast cells revealed favourable cell responses to the anodic coatings. Further, the deposition of hydroxyapatite by cathodic deposition in selected electrolytes indicates scope for additional tailoring of coating surfaces. More limited studies of Ti-6AI-4V alloy demonstrated coating formation broadly similar to that on titanium, but with incorporation of aluminium and vanadium species and increased loss rates of titanium, ∼4 μg cm-2 day-1, in immersion 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, Dépôt de métaux et d'alliages, Metallic coatings, Corrosion, Action des agents de corrosion, Corrosion environments, Corrosion, Corrosión, Korrosion, Dépôt physique phase vapeur, Physical vapor deposition, Deposición física fase vapor, Physikalisches Aufdampfen, Faisceau électronique, Electron beam, Haz electrónico, Elektronenstrahl, Revêtement métallique, Metal coating, Revestimiento metálico, Metallischer Ueberzug, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Corrosion Nyquist plot, Electron beam evaporation, Metallic coatings, and PVD

Sequential deposition of Cu-Ni was carried out on glass and mild steel substrates by electron beam evaporation technique. The films were vacuum annealed at 200°C for 1 h. A smooth deposit with 7·8 μm thickness was observed using a profilometer. The polycrystalline nature with FCC structure of the films was determined with X-ray diffraction analysis. The uniform coverage of film surface was observed with atomic force microscopy (AFM). X-ray fluorescence (XRF) showed a change in composition for the vacuum annealed Cu-Ni film. A high transmittance in the visible region and a very low transmittance in the infrared region were observed for these films. Corrosion behaviour of the evaporated Cu-Ni films in 3·5% w/v NaCI solution was examined.

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, Chromate, Chromates, Cromato, Corrosion, Corrosión, Korrosion, Dépôt électrolytique, Electrodeposition, Depósito electrolítico, Elektroplattieren, Molybdate, Molybdates, Molibdato, Passivation, Pasivación, Passivierung, Revêtement, Coatings, Revestimiento, Ueberzug, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Zingage électrolytique, Zinc plating, Zincato electrolítico, Galvanisches Verzinken, Chromate replacement, and SVET

Chromate replacement in passivation processes has formed the basis of much research, molybdates having already been studied as one entirely chromium free alternative. Molybdate conversion coatings from three different solutions have been examined using the scanning vibrating electrode technique (SVET) to determine whether molybdates are capable of 'self-repair', one of the beneficial features of chromates. Additionally, morphological studies and neutral salt spray corrosion tests have been used to characterise the samples. Chromate passivated samples have been used as the standard against which the molybdates have been assessed throughout the study. SVET line scans conducted over a period of ∼74 min suggest that molybdates are capable of some form of self-repair when damaged. However, the anodic potential perturbation during repassivation is larger than that observed with chromates.