2001 Volume 44 Issue 1 Pages 123-129
Many of the ceramic coating materials can be exposed to harsh working conditions because of their excellent characteristics. Therefore, for producing superior coating materials, it is necessary to establish a methodology for evaluating the mechanical properties of these materials. In this study, nine kinds of TiN film of 5 μm thickness, which were deposited on different parent materials under different N2 partial pressures, were scratched and a method for evaluating the properties of the coating materials with acoustic emission (AE) was developed. The results were as follows: (1) A scratch testing apparatus that can detect AE signals emitted from the TiN film during scratch testing was fabricated. (2) The relationship between the characteristics of the detected AE signals and the fracture modes of the film (i.e., cracking, chipping and flaking) was investigated. (3) It was clarified that fractal dimension m determined from AE peak amplitude distributions become greater than three when the fracture mode was cracking, the dimension became between one and three when the mode was chipping, and the dimension became less than one when the mode was flaking. From these experimental results, it was found that the strength and the adhensivity of thin film can be evaluated from fractal dimension m determined by scratch testing.