Tribological Characterization of TiAlC Nanostructured Coatings Deposited by DC Pulse Magnetron Sputtering

To reveal the effect of carbon content on tribological performance of coatings, TiAlC films having four different amounts of carbon content were synthesized using DC pulse magnetron sputtering. The amount of carbon was varied by using different graphite target powers of 400, 450, 500, and 550 W while keeping the TiAl target power fixed at 80 W. Sliding friction and wear behavior of TiAlC nanostructured coatings deposited on Si (100) substrates by (DC) pulse magnetron sputtering was examined against steel ball using a ball on disk configuration' at a load of 1 N and sliding speed of 7 mm/s. The coating deposited at 500 W graphite target power attained a hardness of 20.24 GPa and elastic modulus of 246 GPa. Tribological test results indicate that the coating deposited at (500 W, 25 at% C) has the lowest coefficient of friction (COF) of 0.29 as well as the wear-rate of 6.52 x 10(-13) (mm(3)/Nm). The observed behavior has been attributed to the increase in crystalline nano graphite phase, increase in compactness of coating, and the formation of compact oxide layer. The nano indentation statistics showed that resistance to plastic deformation (H-3/E*(2)) and elastic strain to failure (H/E*) increased with the increasing target power and reached the highest value at (500 W, 25 at%C) in TiAlC films.