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In situ laser cladding of Al2O3 bearing coatings on aluminium alloy 7075 for improvement of wear resistance

Abstract The wear properties of Al2O3 bearing coatings, produced by in situ laser induced thermite reactions fabricated on aluminium alloy 7075, were examined. The thermite reactions were initiated by the laser cladding of mixed powders of CuO–Al, Cr2O3–Al and TiO2–Al. In order to improve the quality of the laser formed coatings, the laser cladding involved two passes of melting. The results of the XRD and XPS analyses showed that in all the three reaction systems, a reaction layer which comprised mainly Al2O3 and Al phases was formed. Under dry sliding conditions, the wear resistance, in terms of weight loss, of the laser cladded specimens was considerably higher than that of the uncladded specimens. The predominant wear mechanism of the former specimens was found to be characterised by abrasive, while with the latter specimens, it was the adhesive wear that prevailed.