Relationship between oxidation behavior and tribological properties of Mo-V-Cu-N coatings

In this study, the relationship between tribological properties and oxidation behavior of Mo-V-Cu-N coatings was explored. Due to tribo-oxidation at RT, some rod-shaped lubricious oxides (e.g., MoO3, CuMoO4, V2O5) formed on worn surfaces, contributing to an excellent wear performance, including a low friction coefficient of 0.3 and wear rate of-10-17 m3/N center dot m. However, due to the abrasive wear under dry friction at 300 degrees C, the friction coefficient sharply increased to 0.57-0.67. The coatings started to be oxidized at 400 degrees C, and showed obvious oxidation delamination at 3.6 at.% V. Many bulk-like (CuMoO4) and plate-like (MoO3) oxides formed on the top layer by outward diffusion and oxidation, resulting in a low friction coefficient of 0.45 at 400 degrees C. Due to serious oxidation at 500 degrees C, double-layer oxides formed, and the wear rate sharply increased to-10-14 m3/N center dot m. With increasing V content, the fraction of CuMoO4 and MoO3 lubricious oxides decreased, resulting in an in-crease in the friction coefficient, whereas the wear resistance was enhanced, especially at high temperatures.

Automated summary

This study explores the relationship between tribological properties and oxidation behavior of Mo-V-Cu-N coatings. The coatings form lubricious oxides at room temperature, resulting in excellent wear performance. However, under high temperature dry friction, the friction coefficient sharply increases. The coatings oxidize at high temperatures, leading to a decrease in the friction coefficient.