High-Temperature Wear Performance of Laser-Cladded NiCrBSi/60 wt% WC Composite Coating on SS316L Alloy

Abstract This investigation reports on the processing and characterization of NiCrBSi/60 wt% WC composite claddings on SS316L steel substrates by laser cladding process. Microstructural analyses conducted using a scanning electron microscope, an energy dispersive spectrometer, and X-ray diffraction confirmed the successful development of dense cladding layers containing WC reinforcement phases. Microhardness testing revealed a substantial increase in hardness within the clad layer, reaching approximately 1086 HV0.2, significantly higher than the 190 HV0.2 of the SS316L. As the testing temperature increases, the wear-rate and the coefficient of friction (COF) of the coated sample decrease, making it applicable in high-temperature applications. The observed reduction in the COF at higher testing temperatures is attributed to the formation of a lubricious oxide layer that serves as a protective barrier, preventing direct contact between the coated sample and the hard counter disc. Tribological experiments conducted at room temperature, 350 °C, and 700 °C demonstrated a progressive increase in wear-rate with temperature, especially beyond 350 °C, attributed to thermal softening, oxide layer formation, and wear transformations. At 700 °C, oxidation and delamination were the prominent mechanisms. Compared to room temperature, wear resistance decreased by 559.5% at 700 °C, with reductions of 381.1% observed at 350 °C. These findings underscore the critical role of WC reinforcements in retaining wear resistance up to 350 °C. Conversely, at 700 °C, intensified oxidation and matrix softening led to an enhanced coefficient of friction till stabilization occurred after approximately 150 m of sliding distance.