A new view of the deterioration and wear of WC/Co cemented carbide rock drill buttons

WC/Co cemented carbide is a material developed for highly demanding applications. The unique combination of hardness and toughness makes it especially suitable for wear resistant parts of tools for rock drilling. The wear of cemented carbide rock drill buttons has been the focus of numerous studies, and a large amount of wear data has been published. However, the broad range of possible wear mechanisms, the large number of rock types of very different character, and finally the large local property variations even within a single drill hole, has made it difficult to sort out a good general understanding. One conclusion stands out very clear: the wear data for one rock drill in one rock type is unique to that particular situation and should not be expected to apply to other rock drills in other rock types. Even so, some general wear mechanisms can be observed. Against this backdrop, this paper seeks to present a new, more comprehensive, view on the deterioration and wear mechanisms of cemented carbide rock drill buttons. The new view combines some of most important aspects, including two life limiting factors, five classes of mechanisms of deterioration and five classes of material removal mechanisms. The view is based on careful high resolution investigations of worn rock drill buttons selected from drilling of different rock types. The deterioration includes a fundamental change of material and properties due to intermixing of rock material and cemented carbide in the surface layer of the button. It further includes corrosive decay and oxidation of WC and formation of large-scale cracks in a reptile skin pattern.