Novel Insights Into MoN-Ag/WN Multilayers to Achieve Low Friction and Wear at High Temperature

Abstract

Ag exhibits excellent lubricating properties owing to its low shear modulus and is therefore widely employed as a solid lubricant in high-temperature wear-resistant coatings. However, rapid Ag diffusion at elevated temperatures can severely compromise coating integrity through microstructural degradation—a critical limitation that must be addressed. In this work, MoN-Ag/WN multilayer coatings were fabricated via magnetron sputtering. Results demonstrate that the WN interlayer suppresses columnar grain growth in the MoN-Ag layer, yielding a fine-grained strengthening effect that enhances both nanohardness and wear resistance. Crucially, at 500 °C and 650 °C, the WN interlayer can effectively prevent the diffusion of silver, thereby reducing the formation of internal voids and the generation of microcracks due to the depletion of silver. Furthermore, this WN interlayer did not exhibit significant adverse effect on the friction and wear properties of the coating. Consequently, the MoN-Ag/WN multilayer coating exhibits outstanding high-temperature wear resistance. These findings provide both a mechanistic foundation and a rational structural design strategy for next-generation high-temperature wear-resistant coatings.