Tribological behaviour of HVOF sprayed near-nanostructured and microstructured WC-17wt.%Co coatings

A 'duplex cobalt coated' near-nanostructured WC-17wt.%Co powder was used to produce nanostructured coatings. The tribological performance of this coating was compared with a commercial WC-17wt.%Co microstructured coating using a pin-on-plate method (ASTM G133-05 standard) with a data acquisition software to perform a real time analysis of the sliding wear process. The wear rate was studied using loads from 10 to 60 N and for various sliding distances. The metallurgical analysis of the coatings showed that the duplex Co coated powder could be sprayed to produce dense coating. Furthermore, the near-nanostructured coating showed better fracture toughness values and this corresponded to a difference in wear mechanism between the two types of coatings. The greater plasticity in the near-nanostructured coating was recorded as microgrooves in the wear tracks and, in comparison, brittle fracture was observed in the wear tracks produced on the microstructured coating. (C) 2011 Elsevier B.V. All rights reserved.