Alumina coatings deposited with reactive DC magnetron sputtering in a CO2/O2 gas mixture

Reactive DC magnetron sputtering was applied for the deposition of amorphous alumina coatings. Transparent coatings with a thickness of up to 2 vm were deposited on hardened high-speed steel, silicon (wafer material) and S'3N, ceramics with typical growth rates in the region of 0.35 mum/h. The chemical composition of the coatings is comparable to alumina coatings deposited with reactive pulsed magnetron sputtering. The coatings were characterized by depth-sensing indentation measurements and by friction experiments before and after thermal treatments. The hardness and elastic modulus of the as-deposited coatings amount to 10-15 and 250-350 GPa, respectively. After annealing at 500 degreesC under atmospheric conditions, an increase in the hardness and the elastic modulus was observed. The friction coefficient of the coatings before and after thermal treatment against sintered tungsten carbide/cobalt balls amounts to 0.3-0.4. (C) 2002 Elsevier Science B.V All rights reserved.