The effect of phase on microstructure and mechanical performance in TiAlN and TiSiN films

Abstract

To study the effect of phase on the microstructure and mechanical properties of nitride coatings, three films of TiN, TiAlN, and TiSiN were prepared on the surface of high-speed steel using hollow cathode assisted multi-arc ion plating technique. The XRD lines of the three films were analyzed and calculated by linear analysis. The element and phase of the film were observed and analyzed by x-ray Diffraction (XRD), Transmission Electron Microscope (TEM), energy dispersive x-ray analysis (EDS). The microstructure and film thickness of the coating were characterized by scanning electron microscopy (SEM). The surface roughness of the film was observed by Confocal laser scanning microscope (CLSM). The hardness, friction coefficient, and coating/substrate adhesion of the film were tested by the G200 nanometer hardness tester and CETR UNMT-1 surface micro-nano mechanical test system. We discovered two different reinforcement mechanisms. The high microscopic strain value (1.309 × 10−3) in the TiAlN film was related to the formation of Ti3AlN substitutional solid solution in the film formed a large lattice distortion,however, the coating/substrate adhesion (33.5 N) was lowered. The result of independent nucleation and growth of the Si3N4 phase in the TiSiN film refines the structure of the film, alleviating the increase of microscopic strain. At this time, the coating/substrate adhesion reaches the highest value of 40 N and the film surface roughness reaches the minimum value of 0.451 μm. The results also show that the TiSiN coating can obtain good coating/substrate adhesion without pre-plating.