Structures and Properties of (TiAlSi)N Films

The current study uses cathode arc evaporation to coat TiAlSiN, TiN, and AlTiN multilayer films on tool surfaces. The specimens were examined by scanning electron microscopy to characterize film structures, thickness and compositions. Wear tests and nanoindentation tests were also performed to evaluate their coefficients of friction and thin film adhesion. Results show that TiAlSiN, TiN, and AlTiN multilayer films bear coefficients of friction 0.44, 0.32 and 0.39, respectively. The coefficient of friction for TiN film is lower mainly due to its lower surface roughness. Nanoindentation tests, on the other hand, show that the film hardness of TiAlSiN, TiN and AlTiN films are 37.4, 22.1 and 27.4 GPa, respectively. The hardness of TiAlSiN and AlTiN films are higher than that of TiN due to grain size strengthening. The three films all have HF1-HF4 level adhesion. On thermal stability of three coatings, TiAlSiN film is shown by X-Ray diffraction to withstand oxidation up to 900 °C indicating that TiAlSiN has better high temperature stability. The different natures of three coatings can affect their performance and thus their applicability for cutting of different materials.