Dry sliding behavior of HVOF WC-CoCr coated counterface against Cu-Sn and SiC-graphite composite materials

Uncoated conventional martensitic stainless steel and HVOF WC-CoCr coated discs were submitted to dry sliding tests against Cu-Sn and SiC-graphite composite materials. The tests were conducted on a pin on disc equipment at a constant velocity, with two pressures of 0.5 and 1 MPa, and at room temperature. The wear of the coated disc was in any case negligible. Friction coefficient and pin wear were found to increase for most of the cases with an increase in pressure. The magnitude of the friction coefficient was higher and the pin wear was lower in the case of the composite materials paired with coated discs when compared to uncoated discs. The Cu based friction material provided for higher friction coefficient when compared to the SiC-graphite composite material. On the other hand, the combination of the SiC-graphite composite material with the coated counterface proved to be a feasible combination, in terms of wear when compared to other pairings. The results were explained through the characteristics of friction layer and the corresponding worn surfaces, and they appear promising for demanding applications, such as in aerospace or train brake systems.