Role of three-body abrasion wear in the sliding wear behaviour of WC–Co coatings obtained by thermal spraying

WC–Co coatings obtained by high velocity oxy fuel spraying (HVOF) are widely used in applications where good abrasion, erosion or sliding wear resistance is required, due to the high toughness that the cobalt matrix provides combined with the wear resistance that the hard carbides give to the coating. The sliding properties of this coating are excellent due to the formation of oxides during the sliding process which act as a solid lubricant and give the coatings low friction coefficients. In the present paper the effect of the counterfaces (Al2O3, hard metal, Si3N4 and martensitic steel) on the friction coefficient and wear damage of the coating in the sliding tests carried out have been studied. For this purpose SEM and atomic force microscopy (AFM) were used to obtain information on the wear mechanisms. Also the results of friction coefficients and wear damage for both the balls and the coating are reported. A relationship between the quantity of debris produced by the counterfaces during sliding and the friction coefficient and wear resistance of the coating was found.