DIAMOND-LIKE NANOCOMPOSITE COATINGS FOR LOW-WEAR AND LOW-FRICTION APPLICATIONS IN HUMID ENVIRONMENTS

Diamond-Like Nanocomposite (DLN, Dylyn(R)) coatings are amorphous, har d and wear resistant coatings, deposited using a plasma-assisted CVD p rocess. These coatings consist of two interpenetrating networks, one b eing a diamond-like carbon (a-C:H) network and the other a glass-like a-Si:O network. This specific structure leads to lower internal stress , better adhesion and higher temperature stability as compared to diam ond-like carbon. The structure and bonding type were investigated usin g grazing-incidence X ray diffraction (GIXRD) and X-ray photoelectron spectroscopy (XPS), respectively. The coefficient of friction of Diamo nd-Like Nanocomposites, as measured in a standard ball-on-disk tribome ter using a steel counterbody, is typically 0.04 to 0.08 in air of 50% relative humidity (RH). Even in humid air of 90% RH and under water, the coefficient of friction stays below 0.1. The wear factor of Diamon d-Like Nanocomposite coatings was determined using profilometric measu rements of the wear track after a ball-on-disk test and is typically 2 x 10(-7) mm(3)/N m. Under water, an extremely low wear factor, below 5 x 10(-8) mm(3)/N m, was measured. This low-friction and low-wear beh aviour of Diamond-Like Nanocomposite coatings, also in humid environme nts, enables industrial applications of these coatings as hard, self-l ubricating coatings on sliding parts in the automotive, chemical, phar maceutical or biomedical industry. (C) 1998 Elsevier Science S.A.