Cavitation silt erosion behaviour of HVOF sprayed nickel based alloy coatings

In this work, the cavitation silt erosion behaviour and the mechanisms of high velocity oxygen fuel sprayed nickel based alloy coatings under different sediment concentration conditions were studied. The coating with low porosity of 0·88±0·06% consists of γ-Ni, Ni 3 B, Cr 23 C 6 , Cr 7 C 3 and WC phases. The mass loss and mass loss rate of the coatings are found to increase with sediment concentration increasing as a result of more interaction between sand particles and specimen. For the coating in 0 kg m −3 solution, crater and lip are observed on the eroded surface. For the coating in 20 kg m −3 solution, signatures of crater and microcutting are observed. When the sediment concentration rises up to 40 kg m −3 , a process of crater and microcutting first, followed by ploughing and microcutting, is observed. The results suggested that the cavitation silt erosion mechanism for the coating is a ductile erosion mode.