Wear behaviour of laser cladded and plasma sprayed WC-Co coatings

The usefulness of WC-Co cermets as wear resistant material for coatings is determined by the cladding technique employed. This paper compares the features of an 83%WC-Co coating on an AISI 1043 steel substrate using two different application techniques: plasma spraying and laser cladding. Results show significantly less porosity, improved coating hardness and better layer-substrate adherence in laser cladded than in plasma sprayed coatings. This causes them to have different wear behaviour which was determined using a method developed on the basis of the PV factor theory using sliding linear contact of nat-cylinder type. The method proved that wear rate (V-d') is directly proportional to the product of coefficient of friction (mu), load (C) and applied speed (V),V-d' = K mu CV, where proportionality constant, K, is different for every material and depends on conditions such as lubrication, temperature, etc. To study wear behaviour, laser cladded and plasma sprayed 83%WC-Co coatings, under extreme lubrication, were placed against a hardened and tempered AISI 1043 steel. at different load and sliding speed rates. As a result constant K was estimated for each coating. The tests also showed that wear rate in laser deposited coatings is approximately 34% lower than in plasma sprayed coatings. (C) 1997 Elsevier Science S.A.