Research on the chemical barrier and failure behavior of WS2 and WS2/Ti coatings under high-temperature conditions and the effects on the lifespan of diamond-coated cutting tools

Abstract

With its outstanding performance as a solid lubricant, WS2 has found applications in cutting tools. Diamond-coated tools often experience the formation of a graphite phase during machining of ferrous metals. The WS2 coating effectively hinders the thermochemical reaction between the tool-chip and tool-work, thereby extending the tool's operational lifespan. However, WS2 is susceptible to oxidation at high temperatures, leading to the loss of its lubricating properties. Therefore, improvements in its high-temperature resistance are necessary. This study proposes a WS2/Ti multilayer coating structure, which enables the development of solid lubricating coatings (SLC) that are better suited for high-temperature environments. Through the application of negative bias, Ti atoms are propelled into the gaps within the WS2 dendritic structure at high velocities, thereby forming metallic bonds between the layered structures. This process reduces the transfer film effect and hinders the rapid degradation of the SLC. Additionally, the Ti layer forms a sealing barrier on the surface of WS2, effectively impeding contact between WS2 and O2, minimizing WS2 oxidation, and prolonging the SLC's operational lifespan at elevated temperatures.