Microstructure and microhardness characterization of Cp-Ti/SiAlON composite coatings on Ti-6Al-4V by laser cladding

Abstract

Failure of engineering components on application is mainly a result of poor surface behavior of materials under certain conditions. Titanium and its alloys have numerous beneficial properties including light weight, high strength and excellent corrosion resistance which have made them desirable in various industries. However, due to low hardness and poor wear resistance their industrial applications are restricted in harsh conditions. In this study Commercially Pure Titanium and SiAlON powders admixed at varied composition (98%Ti/2%SiAlON and 95%Ti/5%SiAlON) were used to fabricate composite coating on Ti6Al4V substrate by Laser cladding at altered scanning speed (0.6 and 1.2 m/min). The microstructures were examined using SEM/EDS and the phase evolutions were identified using XRD. The cross section microhardness measurements were carried out by means of a Vickers hardness tester. The results revealed improvement in the hardness property as compared to the unconditioned substrate. The coating average surface hardness values were about twice that of the as-received substrate which was attributed to the presence of hard phases such as Si3N4, TiN and SiO2 as revealed on XRD.