EROSION RESISTANCE OF NI-WC SELF-FLUXING ALLOY COATING AT HIGH-TEMPERATURE

The erosion behavior of Ni-base self-fluxing alloy, thermally sprayed coating on a metal substrate is affected by several factors, including the microstructure of the coatings, the porosity, the angle of imping ement of solid particles and the hardness of the coatings. In this stu dy, the erosion properties of thermally sprayed coatings with differen t tungsten carbide contents were investigated. Reinforced by tungsten carbide in the Ni(gamma) matrix, the erosion resistance of the coating has been modified. With increasing tungsten carbide content, an erosi on mechanism that involved a large amount of plastic deformation in th e Ni(gamma) matrix was found to represent the brittle fracture of carb ides. Test results showed that an Ni-WC coating with an optimum compos ition ratio of Ni-base alloy to WC of 65:35 has the highest microhardn ess and improved erosion resistance compared with coatings of other co mpositions. (C) 1997 Elsevier Science S.A.