Effects of duty cycle on the grain size and growth mechanism of nanostructured TiAlN coatings deposited by pulsed-DC PACVD method

The purpose of this paper is to investigate the relationship between duty cycle and the nucleation and growthmechanism of nanostructured titanium-aluminum nitride (TiAlN) coatings using pulsed-DC plasma-assisted chemicalvapor deposition (PACVD). In order to evaluate the effects of duty cycle, TiAlN coatings were applied for 150 minutein the 30, 40, and 50 % of duty cycle at 470 °C substrate temperature, 10 kHz frequency, and 3 mbar working pressure.The results obtained from SEM, XRD, and EDS tests imply the possibility of homogeneous and heterogeneous nucleationand island-layer growth of the TiAlN coatings. Due to the fact that nucleation and growth occurs in the off-time, thenumber of nuclei significantly increases with decreasing the duty cycle. Consequently, with reducing the duty cycle from50 to 30%, the grain size of the TiAlN coatings decreases from 24 to 14 nm.

Keywords:

nanostructured TiAlN coatings , grain size , duty cycle , PACVD