Microstructure and tribological behavior of TiAlSiN coatings deposited by deep oscillation magnetron sputtering

Development of pulsed-techniques aimed to generate highly ionized target species and high plasma density opens up a new way to tailor composition, structure, and properties of coatings. In this work, TiAlSiN coatings have been deposited at various negative substrate biases (V-s) using deep oscillation magnetron sputtering by sputtering a TiAlSi compound target in Ar/N-2 mixtures. The increase in V-s from -30 to -120V resulted in a decrease in (111)-preferred orientation and grain size, together with the increase in residual stress and rough morphology. The nc-TiAlN/a-Si3N4 nanocomposite structure was obtained in coatings. The highest hardness and Young's modulus reached 42.4 and 495GPa at -120V, respectively. However, at -60V, the coatings with the highest H/E* and H-3/E*(2) ratios of 0.095 and 0.332 exhibited excellent adhesion with above HF1 level, the lowest coefficient of friction (COF) of 0.35 and specific wear rate of 2.1x 10(-7)mm(3)N(-1)m(-1). Wear mechanism changed from the mixture of severe adhesive, oxidative and abrasive wear to mild oxidative wear to severe oxidative wear. TiAlSiN coatings with high hardness and H/E* and H-3/E*(2) ratios exhibited the decrease in COF and wear rate due to refined grains in uniform distribution, which well promoted oxide layers formed on sliding contact surface.