Evaluation of Delamination Characteristics of TiN and SiC Sputtered Thin Films by Cyclic Indentation under Load Control

Abstract

Cyclic indentation tests were carried out on TiN or SiC film sputter-coated on titanium or tool steel substrate by using a Rockwell C-scale indenter, and delamination behavior of the films was investigated. The observation using a laser microscope shows that the delamination of TiN film on titanium substrate occurs around a region just outside of indenter-film contact edge after the initiation of circular cracks near the region. Delamination probability is larger when the cyclic load and number of load cycles are larger. The SiC film on titanium substrate does not show delamination within a maximum cyclic load of 10N and 1000cycles perhaps due to a larger interfacial strength. The delamination of SiC film on tool steel substrate occurs by spalling also around the region just outside of indenter-film contact edge. In some cases the delamination of SiC film occurs from bottom of indentation. FEM analysis of indentation into TiN film on titanium substrate shows that a large tensile stress appears on the film surface in the radial direction just outside of indenter-film contact edge. When there is a crack in the edge, both shear and compressive stress appear in the radial direction along interface. These stresses will cause the cracking of film and delamination of film after cracking, respectively.