Parametric effects of residual stress in pulsed d.c. plasma enhanced CVD TiN coatings

In order to design coatings with optimized wear and corrosion performance, knowledge of residual stress in hard coatings and its dependence on the processing parameters is required. In the present paper, TiN coatings deposited onto tool steels using pulsed d.c. plasma enhanced chemical vapor deposition were investigated. The processing parameters, including pulse voltage, pulse frequency and pre-nitriding time were varied. The residual stress was measured with X-ray diffraction and the interfacial adhesion between the coating and the substrate was evaluated using both indentation test (Pc) and scratch test (Lc). It was found that the residual stress and the adhesion could be adjusted by the processing parameters, and a correlation between these two properties was established. It was also evident that the residual stresses in coating deposited in the industrial-scale pulsed d.c. plasma CVD facility were much smaller than in those deposited in a conventional laboratory-scale chamber with d.c. power.