Comparative analysis of structural, mechanical and tribological properties of high-entropy nitrides and carbonitrides coatings over a wide temperature range

Abstract

Motivated by the growing need for advanced coatings capable of withstanding extreme thermal and mechanical conditions in industries such as aerospace, automotive, and energy, this study explores the tribological behavior of high-entropy ceramics coatings at elevated temperatures. The novelty of this work lies in the comparative investigation of (CrAlVTiNb)N_x high-entropy nitrides (HENs) and (CrAlVTiNb)CN_x high-entropy carbonitrides (HECNs), fabricated using high power impulse magnetron sputtering, to elucidate the interplay between material composition, structure, and performance across a wide temperature range. The HENs exhibit an FCC nitride phase structure, while the HECNs display an amorphous structure. HENs achieve a maximum nano-hardness of 34 GPa after 1-hour treatment at 400°C, decreasing to 19 GPa after 600°C treatment, whereas HECNs show a maximum of 15.6 GPa at room temperature, dropping to 1.8 GPa after 600°C treatment. HECNs demonstrate lower friction coefficients than HENs, attributed to the lubricating effect of the amorphous carbon phase and the formation of dense tribo-layers. Despite lower hardness, HECNs exhibit higher adhesion strength after 600°C treatment, enhancing tribological interaction, while the higher hardness of HENs leads to increased brittleness, limiting tribo-layers formation. This work highlights the significance of material composition and structure in optimizing coating performance under thermal stress, providing critical insights for the design of next-generation high-entropy ceramics for advanced mechanical and tribological applications.