Diamond-like nanocomposite coatings (a-C:H/a-Si:O) for tribological applications

Diamond-like nanocomposite (DLN) coatings (a-C:H/a-Si:O) are a particular class of modified diamond-like carbon coatings, which can be predominantly described as two interpenetrating amorphous networks, one network being a diamond-like a-C:H network and the other a glass-like a-Si:O network. Structural studies have been performed using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The two-network description of the atomic bonding state is investigated by analysing the C-C, C-Si and Si-O contributions to the C 1s and Si 2p XPS photolines. Tribological properties have been measured using standard ball-on-disk tests against a steel counterbody at 10N load, yielding a typical wear factor between 0.5 and 4 x 10(-7) mm(3) Nm(-1). The coefficient of friction against steel is typically between 0.05 and 0.15, even in humid air and under water. The low-friction and low-wear DLN coatings, combined with low internal stress and good adhesion, make this type of coatings an excellent candidate for many tribological applications in the automotive, textile, chemical or biomedical industry. (C) 1998 Elsevier Science S.A.