Comparison of Microstructural and Sliding Wear Resistance of HVOF Coated and Microwave Treated CoMoCrSi-WC + CrC + Ni and CoMoCrSi-WC + 12Co Composite Coatings Deposited on Titanium Substrate

CoMoCrSi-WC + CrC + Ni and CoMoCrSi-WC + 12Co composite coatings are coated on titanium substrate by high velocity oxygen fuel method (HVOF). Prior to spraying, CoMoCrSi feedstock are processed through high energy ball milling (HEBM) in order improve the intermetallic laves phases and to reduce its particle size. The processed feedstock exhibits amorphous nature by improving laves phases and particle size of 60.12 μm. Microwave heating energy is utilized as post heat treatment technique to improve the mechanical and metallurgical properties of as-sprayed coatings. Fused coatings reveals better properties in terms of surface roughness, porosity, microhardness and adhesion strength compared to as-sprayed coatings. Metallurgical bonding is observed in case of fused coatings due to diffusion of substrate elements. Frictional and wear behaviors have been investigated by a pin on disc apparatus at temperatures of 200 °C, 400 °C, and 600 °C under normal loads of 10 N and 20 N. Both wear trace and friction coefficients of the fused coatings are smaller than as-sprayed coatings and substrate at all test temperatures. The wear traces of fused coatings decreased with increasing the surface temperature due to the lubricant effect of cobalt oxides formed on the sliding surface. As a result, cobalt based cermet coatings are highly recommended as a durability improvement coating for the protection of sliding surface, such as high speed spindle.