Tribology of metal-containing diamond-like carbon coatings

Ball-on-disk tests were run for several commercial and in-house metal-containing diamond-like carbon (Me:DLC) coatings on steel coupons. The balls, which were made from either WC-Co or 52100 steel, developed normal stresses between roughly 100 MPa and 1 GPa during the course of the experiments. The wear resistance of the Me:DLC coatings from the various sources (running against WC balls) differed by up to nearly an order of magnitude, but in each case the wear coefficient was constant until the coating wore away. Abrasiveness of the Me:DLC coatings (running against steel balls) differed by up to almost three orders of magnitude. The rates at which the steel wore away fell drastically for some Me:DLC coatings during the course of the tests. Some possible explanations for this fall are considered. Coating morphology did not correlate with any other measured properties. (C) 1997 Elsevier Science S.A.