Wear behavior of microwave-processed Ni-WC8Co-based functionally graded materials

Functionally graded materials are inhomogeneous materials with the gradual change in properties with position. In this research work, functionally graded clad layers of Ni-WC8Co-based materials with varying compositions of WC8Co from 0 to 30 wt% were processed using a cost-effective and energy-efficient microwave hybrid heating technique. Single-layer clads of compositions corresponding to different functionally graded clad layers were also developed through microwave heating for comparing different properties. The processed functionally graded clads were characterized through microstructural analysis (scanning electron microscopy/energy-dispersive X-ray spectroscopy) and Vicker's microhardness quantification. Microstructure results showed the functionally graded clad of approximately 2 mm thickness was free from any visible pores and interfacial cracks. Microwave heating resulted in the formation of hard phases in the functionally graded clad layers, and these layers exhibited significantly higher microhardness values. Further, the tribological performance of developed functionally graded clad was examined under dry sliding conditions using pin-on-disk-type tribometer. The influence of varying sliding velocities and sliding distances on the wear characteristics of microwave-processed functionally graded clads were investigated. It was observed that microwave-processed functionally graded clad exhibited approximately 95%, and 29% higher wear resistance than the SS-304 substrate and Ni + 30%WC8Co-based single-layer clad respectively owing to its better mechanical properties.