Very hard W-C coatings on stainless steel by RF reactive magnetron sputtering

Tungsten carbide films having a single-phase B1 fcc structure have been deposited by rf reactive magnetron sputtering on stainless-steel substrates held at 500°C. These films show a very high microhardness (˜3200 kgf/mm2) as compared to the bulk value (˜1800 kgf/mm2) and have very good adhesion (2.25×107g/cm2). The friction and wear of these films have been investigated by a pin and disk machine. A friction coefficient of 0.13 has been obtained. The wear resistance of coated stainless steel is reduced by a factor of 20. Further improvement in adhesion and reduction in both friction coefficient and wear rate is observed when an interlayer of Ti, Ta, W, Mo, and Si is introduced in between the stainless-steel surface and W-C coatings. The relationship between the mechanical properties and the structure of the coatings and interlayers is discussed