Effects of substrate bias voltage on the microstructure of Cr-Al-N coatings

Cr-Al-N coatings with the thickness of about 2 mu m have been prepared by a reactive magnetron sputtering method. The effects of substrate negative bias voltage (V-B) on the microstructure and critical failure load have been investigated as the V-B varied from 0 to -150 V. With V-B increasing, grain size, lattice parameter and microstrain increase. (111) preferred orientation dominates in the coatings deposited under 0 and -50 V, while a (200) preferred orientation developed when V-B further raised. The reasons for these variation caused by V-B are discussed.