Mechanisms of wear on a Co-base alloy in liquid-solid slurries

The efficient performance of drilling tools in aqueous environments requires materials to be used, which can effectively resist excessive material loss due to the combined effects of erosion and corrosion. In this paper, the interactions between electrochemical corrosion and mechanical erosion have been assessed in liquid-solid slurries on a Co-base material (Stellite X40), which is currently used in the manufacture of oil tools. The material degradation is assessed as a function of aqueous environment and sand loading. Corrosion has been shown to represent an important factor in the degradation of this material even though it essentially exhibits passivity in static saline conditions. The relative importance of corrosion and its synergistic effect when combined with erosion are quantified and the implications in terms of material performance and of potential methods of reducing oil tool degradation are discussed.