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High silicon content aluminum alloy (hypereutectic) possess good tribological characteristics with low coefficients of friction, when embedded with short carbon fiber (C), making this composite a good material choice where good wear and high strength properties are required in light weight components. There is no previously published information available, to the knowledge of the authors, regarding the influence of wear parameters and their interactions on the tribological behavior of C reinforced metal matrix composites. In this study a Taguchi design of experiment (DoE) was conducted to optimize and analyze the effects of the wear parameters on the tribological properties of Al/C metal matrix composite. A novel thixomixing method which was used to process the metal within the semisolid state was employed to embed short carbon fibers homogenously into the metal matrix. The influences of the sliding speed, applied load and volume fraction, of C on the specific wear rate and coefficient of friction were examined, with each of these input parameters tested at three levels(0, 4.2, 8.1%vol.). The results were indicated that Al/C composite had better tribological properties than Al alloy due to which contains carbon as solid lubricant. According to the statistical analysis, the influence of volume fraction of carbon fiber on wear parameters was ranked first; so the load and sliding speed are at the following rankings. The contribution percentage for each parameter was determined by the analysis of variance. The relatively good interfacial adherence of carbon fiber and matrix alloy were demonstrated. The coherent and adherent graphite-rich layer on the worn surface was characterized using scanning electron microscopy (SEM). [ABSTRACT FROM AUTHOR]

This work is a contribution to improve understanding about the behaviour of components produced by semi-solid processes. The present study shows the effect of different conformation parameters on automotive cranking cover production obtained by Semi-Solid Rheocasting Process (SSR®). The components were produced using EN AC-46500 alloy, by an industrial plant with a 700 Ton HPDC machine and an IDRA SSR Station. The process parameters studied were slurry temperature, agitation time, speed injection and lubrication system. The characterization was carried out by microstructural analysis, X-rays and mechanical tests. The components show good mechanical properties, similar to those obtained by die cast. The process was simulated using the PROCAST program. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The goal of this investigation was to determine the usefulness of CrC-NiCr coatings in order to improve wear resistance of tools made from hot work steels. CrC-NiCr powders were sprayed using the high velocity oxy fuel thermal spray process (HVOF) to form coatings on steel substrates approximately 150 μm thick. Coatings were heattreated in a range of temperatures between 900 and 1100°C. The coatings were then evaluated in the as sprayed and heat treated conditions. Inspections by SEM and phase analysis by XRD were carried out. The microindentation technique was applied to measure the variation of the coatings’ hardness. Experiments using a tribometer (ball on disc configuration) at room temperature and dry conditions were performed in order to evaluate the friction and wear properties of the coatings. The mechanical properties and wear behaviour of the coatings were correlated with the coating integrity and microstructure. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The aim of this work is to analyze and compare two anodized components: a cast A356 T6 alloy produced by an SLC technique and an extruded A6061 T6 alloy. The corrosion mechanisms of anodized specimens are studied by electrochemical test, salt spray test and optical and scanning electron microscopy. The mechanical properties and corrosion resistance of the two alloys are compared and the viability of the SLC components as an alternative to extruded alloys for marine applications is discussed. [ABSTRACT FROM AUTHOR]

This work demonstrates the possibility to apply T5 and T6 heat treatments to EN AC-46500 aluminium components conformed by Semi-Solid Rheocasting (SSR). The study of temperature and time effect in annealing, tempering and artificial aging conditions has permitted to optimize the component mechanical properties. The experimentation has been accomplished by means of hardness Brinell tests, tensile tests, optic and electronic microscopy. The mechanical properties obtained in SSR components, reach analogous values to the ones obtained by die cast components and submitted to the same heat treatments. [ABSTRACT FROM AUTHOR]

Certain diols can undergo polycondensation in aqueous emulsion with either dicarboxylic acids or aliphatic aldehydes to give polyester or polyyacetals. The process occurs under mild conditions and requires water insoluble liquid monomers, the presence of a sulfonate surfactant and mobile cations which can ion exchange at the oil-water interface. An acidic catalyst is not necessary. The degrees of polymerization are modest but they exceed those normally expected of polyesterifcations in such an environment. The driving force is thought to be the heat of condensation of the water produced as vapor in the oil phase. [ABSTRACT FROM AUTHOR]