Coatings with nitrogen content up to 16 at.% exhibit a metallic Cr solid solution, even after post-coat annealing at 300 °C and 500 °C.
At higher N/Cr atomic ratios (approaching Cr2N stoichiometry), chromium was still inclined to exist in solid solution with nitrogen, rather than as a ceramic nitride phase, even after annealing at 500 °C.
Transportation of Cu and Ag to the surface depends on annealing temperature, annealing duration, nitrogen concentration and ‘global’ Cu + Ag concentration.
Incorporation of copper appears to be a powerful strategy to enhance Ag mobility at low concentration (∼3 at.% Ag in this study) under moderately high service temperature.
A significant decrease in friction coefficient was obtained at room temperature after annealing, or during sliding wear testing at elevated temperature.