The tribological behaviour of detonation sprayed coatings: the importance of coating process parameters

The tribological performance of thermal spray coatings depends on a host of properties like coating composition, nature of phases and their distribution, microstructure, porosity and residual stress. All these properties, in turn, determine the hardness of the coating, which is conventionally used as the primary correlating parameter for evaluating wear resistance. To assess such an interrelationship in the case of detonation sprayed coatings, large varieties of coatings and each coating over a range of process parameters have been deposited utilizing the detonation spray (DS) coating technique. The resulting coatings (94 in all) have been characterized in terms of phase content and distribution, porosity, microhardness, and evaluated for erosion, abrasion and sliding wear resistance. A broad-brush analysis of the data obtained clearly points to the fact that the coatings are substantially poorer than bulk material of identical composition and that the hardness and tribological properties of the coatings are more strongly influenced by the coating process parameters themselves rather than microstructural parameters like phase content and distribution, porosity, etc.