Wear improvements of stainless steel and tungsten carbide substrates covered by thin carbon films combining ion beam assisted deposition and plasma enhanced chemical vapor deposition from pure CH 4 deposition methods

Abstract

A combination of ion beam assisted deposition (IBAD) and plasma enhanced chemical vapor deposition (PECVD) was used to deposit tetrahedral amorphous carbon layers, known as amorphic diamond (a-d), onto 304 stainless steel and tungsten carbide (WC) substrates. The so-obtained thin (∼300 nm) a-d layers exhibit good adhesion properties to the substrate. The PECVD step was done using only pure methane at room temperature. Tribological tests were conducted in air and in dry nitrogen atmosphere under loads varying from 1 N to 15 N with a pin-on-disk system. Good wear and friction properties were obtained, even on a relatively soft substrate such as 304 stainless steel. The best wear results were obtained with a-d layers deposited on WC. The lowest friction coefficients were obtained when the tests were run in a nitrogen atmosphere. We propose an interpretation about observed differences of friction coefficient depending on surrounding atmosphere and sliding velocities.