Decorative PVD coatings as an enviromentally clean alternative to chrome plating

The objective of this work is to conduct applied research and development to demonstrate yhat metal or ceramic coatings deposited by Physical Vapor Deposition (PVD)are equivalent or superior in peformance and are a cost-effective alternative to chrome plating in decorative applications. Chromium plating is comercially used to produce wear-resistant and decorative coatings, but the plating bath contains hexavalent chromium, which has adverse health and environmental effects. The present study describes and compares the mechanical and tribological properties of TiN,AlTiN, ZrCN coatings deposited by CAPVD (cathodic arc plasma pgysical vapor deposition), on nickel plated aluminium substrates. The properties of the above mentioned PVD coatings have been compared with the properties of conventional chromium plating.Peer Reviewe

Decorartive PVD coatings as an environmentally clean alternative to chrome plating

Peer ReviewedPostprint (published version

Effect of oxygen/fuel ratio on the in-flight particle parameters and properties of HVOF WC–CoCr coatings

High Velocity Oxy-Fuel (HVOF) spray techniques can produce high performance alloy and cermet coatings for applications that require wear resistant surfaces. In HVOF spraying heat is produced by burning mixtures of oxygen and fuel, mainly hydrogen, kerosene, propane, propylene, natural gas or acetylene. In these processes, the particle velocity and temperature determine the resultant coating properties and in many cases enables a better understanding of the process. The aim of this study is to investigate influences of different oxygen/fuel ratios on velocity and temperature of flying particles as well as properties of the HVOF thermal sprayed WC-CoCr coatings. In this work the feedstock powders were thermally sprayed by two different variants of the high velocity oxy-fuel process, in which the fuels were hydrogen and kerosene. Particle parameters were recorded just prior to impact on the substrate using in-flight particle diagnostic tool Accuraspray-g3®. Detailed correlation of particle parameters and the coating properties is evaluated in order to deduce particle parameter ranges providing coatings with optimum properties.Postprint (published version

The effect of heat treatment on hardness and drye wear properties of a semisolid processed aluminium alloy

Semisolid AlSiMg casting alloys are attractive alternatives for automotive and aeronautical applications. In this work the effects of heat treatments on hardness and tribological properties of A356 aluminium alloy obtained by Sub-Liquidus Casting (SLC) were studied. The optimum heat treatment conditions, in which the material presents the maximum hardening and wear resistance values, were determined. Heat treatment conditions investigated included: A356 SLC as cast, T5 and T6. Furthermore, AC-46500 and A6061/T6 were analyzed for comparison. The tribological properties of the samples were investigated by pin-on-disc tests at 5 N and 0.05 and 0.1 m·s-1 in dry conditions. The samples were studied by SEM-EDX techniques in order to determine the wear mechanisms and the determination of the products produced during the tests. The maximum hardness and the lowest dry wear rate were obtained through T6 thermal treatment condition.Peer ReviewedPostprint (published version

Surface finish effect on the anodizing behaviour of Al-Si components obtained by sub-liquidus casting process.

The aim of this study was to investigate the hard decorative anodizing components of A357 aluminium alloy, obtained in semisolid state by Sub Liquidus Casting® process, to improve its tribological properties and corrosion resistance. Components were heat treated in order to modify the shape and distribution of the eutectic silicon phase. The influence of shot peening pre-treatment on anodizing process was evaluated. Surface modifications were investigated as they might have beneficial effects on the wear and corrosion behaviour. Furthermore, the influence of surface condition on the anodization colouring behaviour of aluminium was studied. The microstructure and the surface finish influence on the anodic oxide film growth were studied by optical and scanning electron microscopy. Experiments using a tribometer (ball on disc configuration) were performed in order to evaluate the tribological properties of the material. Salt spray corrosion tests were used to study the corrosion properties before and after the anodizing process.Peer ReviewedPostprint (published version

The American revolution in military affairs An interim assessment

SIGLEAvailable from British Library Document Supply Centre-DSC:8474.031402(28) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Decorative PVD coatings as an enviromentally clean alternative to chrome plating

The objective of this work is to conduct applied research and development to demonstrate yhat metal or ceramic coatings deposited by Physical Vapor Deposition (PVD)are equivalent or superior in peformance and are a cost-effective alternative to chrome plating in decorative applications. Chromium plating is comercially used to produce wear-resistant and decorative coatings, but the plating bath contains hexavalent chromium, which has adverse health and environmental effects. The present study describes and compares the mechanical and tribological properties of TiN,AlTiN, ZrCN coatings deposited by CAPVD (cathodic arc plasma pgysical vapor deposition), on nickel plated aluminium substrates. The properties of the above mentioned PVD coatings have been compared with the properties of conventional chromium plating.Peer Reviewe

New T6 heat treathments for AlSi alloys conformed in semi-solid state

Se estudian los cambios microestructurales que tienen lugar en los tratamientos térmicos de las aleaciones AlSi, con- formadas en estado semisólido, durante las etapas de puesta en solución y envejecimiento. El estudio ha permitido proponer nuevos tratamientos T6, con tiempos de puesta en solución inferiores a los 30 min, manteniendo o mejorando las propiedades mecánicas que se obtienen con los actuales procesos de tratamiento de 6 a 8 h. Estos tratamientos de corta duración, realizados a 540 o C, permiten una completa disolución del magnesio, minimizando al mismo tiempo el crecimiento de los granos y del silicio eutéctico. Si bien la experimentación se ha realizado con componentes producidos por Sub-Liquidus Casting (SLC) con aleaciones A356 y A357, se considera que los resultados obtenidos pueden ser aplicables a los componentes producidos en estado semisólido por otras tecnologías, con diferentes aleaciones AISi que se endurecen por formación de precipitados coherentes de magnesio. La caracterización del material se ha realizado mediantes análisis micrográficos, ensayos de dureza y ultramicrodureza.Peer Reviewe