Evaluation of fracture characteristics of TiN ceramics film with scratch testing - (Application of fractal dimension of AE peak amplitude distribution)

Many of the ceramic coating materials can be exposed to harsh working condi tions 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, nin e kinds of TiN film of 5 mum thickness, which were deposited on different p arent materials under different N-2 partial pressures, were scratched and a method for evaluating the properties of the coating materials with acousti c emission (AE) was developed. The results were as follows: (1) A scratch t esting apparatus that can detect AE signals emitted from the TiN film durin g scratch testing was fabricated. (2) The relationship between the characte ristics of the detected AE signals and the fracture modes of the film (i.e. , cracking, chipping and flaking) was investigated. (3) It was clarified th at fractal dimension m determined from AE peak amplitude distributions beca me greater than three when the fracture mode was cracking, the dimension be came between one and three when the mode was chipping, and the dimension be came less than one when the mode was flaking. From these experimental resul ts, it was found that the strength and the adhesivity of thin film can be e valuated from fractal dimension m determined by scratch testing.