Erosion–corrosion behaviour of WC-based MMCs in liquid–solid slurries

Abstract

In the oilsands industry erosive wear and erosion–corrosion can cause high rates of material loss, particularly in the hydrotransport system where corrosive slurries are encountered. Metal Matrix Composites (MMCs), comprising a ductile binder with a reinforcing hard phase, are seeing greater applications as coatings and hardfacing for critical components, where there is a requirement for high durability. In this paper the erosion–corrosion performance of WC-MMCs applied by the PTA process is evaluated. Four MMCs, with varying WC-size range, all with a Ni–Cr–Si–B matrix, have been considered. The erosion–corrosion behaviour of the MMCs is compared to UNS S31603 austenitic stainless steel. The material degradation is assessed as a function of sand particle size and sand loading. The materials were eroded by two sizes of silica sand with stream velocities of 10 and 17 m/s at 65 °C. The solid loading (wt.%) was varied from 1%, 5%, 10%, 15% and 20% with most tests being conducted at 1% and 5%. With the smaller sand size the MMCs showed considerably reduced damage due to erosion–corrosion compared to UNS S31603. Using the coarse sand, the MMCs show inferior resistance to erosion–corrosion compared to UNS S31603; the finding are explained by careful consideration of the material degradation mechanisms.