Abstract
Laser PVD of alumina ceramic on metallic substrate was conducted using a cw Nd : YAG laser heat source at a wide range of PVD conditions such as degree of vacuum in the chamber and substrate temperature to clarify the effect of the conditions on the characteristics of the prepared film. Various materials such as W, Mo, Ta, Ti, Ni and Cu were used as substrates to clarify the effect of thermal expansion of the substrate on the adhesion, hardness and cracking susceptibility of the film. Optimum PVD conditions were obtained concerning chamber pressure, substrate temperature and the kind of substrate materials for the formation of a hard, crack-free and better adhesive alumina film. According to the direction of bent deformation of thin substrates, tension was included in the film on W and Mo substrates while compression took place in the film on Ta, Ti, Ni and Cu substrates due to the difference of thermal expansion coefficient between film and substrate at higher substrate temperature.
