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 CH4 deposition methods

A combination of ion beam assisted deposition (IBAD) and plasma enhanced ch emical vapor deposition (PECVD) was used to deposit tetrahedral amorphous c arbon layers, known as amorphic diamond (a-d), onto 304 stainless steel and tungsten carbide (WC) substrates. The so-obtained thin(similar to 300 nm) a-d layers exhibit good adhesion properties to the substrate. The PECVD ste p was done using only pure methane at room temperature. Tribological tests were conducted in air and in dry nitrogen atmosphere under loads varying fr om 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 s teel. 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 differenc es of friction coefficient depending on surrounding atmosphere and sliding velocities. (C) 1999 Elsevier Science S.A. All rights reserved.