スクラッチ試験によるTiNセラミックス皮膜の破壊特性評価(第1報、AE振幅分布のフラクタル次元の適用)

Many of the ceramics coating materials are in use under the hard working conditions on the ground that these materials have the excellent characteristics. Therefore, it is expected for producing the superior coating materials to establish a methodology for evaluating the mechanical properties of these materials. In this report, 9 kinds of TiN film 5 μm thick that were deposited on the different parent materials under the different N2 partial pressure were scratched and a method for evaluating the properties of the coating materials with Acoustic Emission (AE) is described. Its contents are follows : (1) The scratch testing apparatus that can detect the emitted AE signals from the TiN film during the testing was produced. (2) The relationship between the character of the detected AE signals and the fracture types of film (i.e. crack, chipping and flaking) were investigated. (3) It was became clear that the fractal dimension m led from AE amplitude distribution shows more than 3 when the fracture type is crack, the value shows between 1 and 3 when the type is chipping, the value shows less than 1 when the type is flaking. From these experimental results, it was found that the strength and the tight-adhesiveness of thin film are evaluated by observing the fractal dimensions of AE amplitude distribution during the scratch testing.