Friction and wear behavior of tungsten and titanium carbide coatings

The sliding friction and wear behaviors of the detonation-gun sprayed (W,Ti) C-NI and WC-Co ceramic coatings on 1044 steel and Ti-6Al-4V substrates were studied. Sliding wear tests were run under dry and lubricated conditions in a block-on-ring wear test set-up where the coated specimens served as the block and the hardened tool steel as the ring. The WC-Co coating on both the steel and titanium substrates showed higher resistance to dry sliding wear than the (W,Ti) C-Ni coating. The wear resistance of these coatings-on the titanium substrate was higher than that on the steel substrate. The heat treatment of the coated steel specimens resulted in cracking of the coated layer which decreased the wear resistance. The ring wear was always higher than the block wear. Scanning electron microscopy and energy dispersive Xray analysis of the wear surfaces revealed material removal by the mechanisms such as micropolishing, adhesion, delamination, and cracking and provided the evidence of some material transfer from the ring to the block but none in the opposite direction.