Improving the mechanical and tribological properties of TiAlSiN coatings by annealing

The microstructure, mechanical and tribological properties of TiAlSiN coatings with various annealing temperature were studied. Results showed that the oxygen content of the coating raised with the annealing temperature in the range of room temperature to 800 °C, while the hardness decreased monotonically. However, the elastic strain resistance H/E value increased firstly and then decreased. The maximum H/E value of 0.105 was obtained at 400 °C. The deposited coating composed of c-TiN, c-AlN and c-(Ti, Al)N, and Si element mainly existed in the form of SiNx amorphous structure. The adhesive and oxidation erosion were the main wear mechanism against GCr15 steel balls. The coefficient of friction (COF) decreased gradually, but the wear rate increased firstly and then decreased. The minimum wear rate of 1.2 × 10−5mm3/(N·m) was obtained at 400 °C. In addition, oxides including Ti–O, Al–O and Si–O generated on the adhesives play a role of lubricant, which could reduce the shearing resistance and COF of the coating. Therefore, TiAlSiN coatings with optimal annealing temperature has excellent mechanical properties and tribological performance.