Mechanical and tribological properties of tungsten carbide sputtered coatings

Tungsten carbide (WC) hard coatings have been obtained on steel substrates by an r.f. magnetron sputtering process. Two-layer coatings have been depos ited in order to improve the adhesion on steel. The lower layer was tungste n metal and the upper WC layer was obtained by reactive sputtering of the t ungsten target in an Ar and methane gas mixture. AES and SIMS confirmed tha t the WC layer composition depends on the reactive sputtering gas compositi on. Film microhardness was measured by microindentation, and the coating ad hesion by microscratch. Measurement results showed that high hardness coati ngs can be prepared at a relatively low temperature and that good adhesion on steel is achieved with the two-layer coating. Nanowear measurements show ed a noticeable dependence of this applied functional property on the coati ng compositions. (C) 2000 Elsevier Science S.A. All rights reserved.