Effects of intrinsic properties of TiN coatings on acoustic emission behavior at scratch test

Acoustic emission (AE) behavior at scratch test has been studied for TiN coatings that deposited in an ion plating system. The AE intensity of the coatings measured by the scratch test depended not only on the adhesion of a coating-substrate interface but also on the intrinsic properties of a deposited film. In this work, a careful separation of coating parameters was investigated to clarify the relationship between the AE intensity and the intrinsic properties of coated films. For identical coating conditions, the AE intensity increased with coating thickness since the elastic energy released during the scratching is proportional to film thickness. It has been found that the coatings prepared at higher substrate temperature and/or at higher substrate bias voltage had a larger crystallite size and lower internal stress. With increasing bias voltage and substrate temperature, the AE intensity of TiN coatings decreased. An explanation for this behavior has been proposed in terms of the internal stress and the toughness of the deposited films.