Formation of alumina film by laser PVD

Abstract

Laser PVD of alumina ceramics on Ni and other various metallic substrates was conducted by using cw Nd:YAG laser heat source to clarify the effect of PVD conditions on deposition rate and hardness of a film as well as the effects of substrate materials and thermal expansions on the adhesion, hardness and cracking susceptibility of the film. Optimum PVD conditions were obtained concerning laser power, target-substrate distance, chamber pressure and substrate temperature for the formation of a better adhesive, crack-free, hard alumina film. According to the degree of bent deformation of special thin substrates, higher stress was induced in the film due to the difference of thermal expansion coefficient between film and substrate at higher substrate temperature. Tension was induced in the film on W and Mo substrate, while compression took place in the film on Ta, Ti, Ni and Cu. Cracks were present in the films on W, Ni and Cu at high substrate temperature. This reason was attributed to such higher tension and much higher compression.Laser PVD of alumina ceramics on Ni and other various metallic substrates was conducted by using cw Nd:YAG laser heat source to clarify the effect of PVD conditions on deposition rate and hardness of a film as well as the effects of substrate materials and thermal expansions on the adhesion, hardness and cracking susceptibility of the film. Optimum PVD conditions were obtained concerning laser power, target-substrate distance, chamber pressure and substrate temperature for the formation of a better adhesive, crack-free, hard alumina film. According to the degree of bent deformation of special thin substrates, higher stress was induced in the film due to the difference of thermal expansion coefficient between film and substrate at higher substrate temperature. Tension was induced in the film on W and Mo substrate, while compression took place in the film on Ta, Ti, Ni and Cu. Cracks were present in the films on W, Ni and Cu at high substrate temperature. This reason was attributed to such higher tension an...