Effects of Substrate Bias Voltage on the Critical Failure Load of Cr-Al-N Coatings

Abstract

Cr-Al-N coatings with the thickness of about 2 mm have been prepared in a magnetron sputtering system by reactive co-sputtering from a chromium target and an aluminum target in a mixed Ar/N2atmosphere. The effects of substrate negative bias voltage (VB) on the microstructure and critical failure load have been investigated by a scratch test as the VB varied from 0 to –150 V. The critical failure load reached the maximum value for the coating deposited under VB = –50 V, then decreased with VB further increasing. Re-sputter effect of The heavy bombardment of the ion to the substrate improve the critical failure load for the coating deposited under VB = –50 V. The decrease of the critical failure loads for the coatings deposited under –100V and –150 V probably resulted from the high microstrain in the crystal lattice.