Influence of Ion Bombardment Process on Adhesion between CrN Coatings and Aluminum Alloy

Scratch tests were carried out to examine the influence of gas pressure during ion bombarding on adhesion between CrN coatings and aluminum alloy using nitrogen and argon gas. The critical load clearly increased with increasing the nitrogen gas pressure. However, argon gas pressure hardly affected the critical load. The result of SIMS showed that ion bombardment in nitrogen gas generated high Cr content layer at the aluminum substrate surface and the Cr content increased with increasing the pressure. The ion bombardment in argon gas generated low Cr content surface layer and the pressure hardly affected the critical load. Thus, the high Cr content layer by ion bombardment in the high nitrogen pressure improved adhesion between CrN coatings and aluminum alloy