Tribological characterization of siliconized Hastelloy C276 alloy

Abstract In this study, the surface/subsurface microstructural components, hardness variation in the coating cross-section, and tribological behavior of Hastelloy C276 superalloy subjected to siliconizing at varying temperatures (900 and 950 °C) and time (2–6 h) are investigated. Structural characterization studies have shown that as the process temperature and time increase, the amount of deposition increases, a thicker coating is obtained, and the coating discontinuities at the coating-substrate interface increases relatively under high-temperature and long-duration diffusion conditions. It is determined that Ni-rich (950–1100 HV) and Mo-rich (1300–1500 HV) silicides with different hardness values are formed within the coating layer under the process conditions. Dry friction test findings on silicide coated and uncoated alloys have revealed that (i) the coefficient of friction and volume loss due to wear decrease with the coating and (ii) Mo-rich silicides improve wear resistance by reducing friction. This coating method provides a practical solution to increase the durability and lifespan of components used in harsh wear conditions.