Surface damage on cemented carbide rock-drill buttons

Wear phenomena on cemented carbide drill buttons tested in percussive drill ing of Kiruna-magnetite under realistic conditions have been studied with s canning electron microscopy, light optical microscopy and energy dispersive X-ray spectroscopy. In addition, a comprehensive Literature study has been performed. The aim has been to chart wear phenomena, such as crack formati on, occurrence of reptile skin and various wear mechanisms. It is shown that surface cracks form shortly after drilling has started. Al so the valleys and plateaus characterising the reptile skin pattern were fo und after only short drilling periods. It appears that the formation of the initial surface cracks and the reptile skin pattern are separate mechanism s, which presumably interact. In addition to the formation of cracks, there is also a continuous wear of the buttons. This is assumed to be caused by wear fracturing and pullout of tungsten carbide (WC) grains and wear of cob alt (Co) by abrasion, possibly assisted by corrosion. A wear mechanism table, based on a comprehensive Literature review and on e xperience from real drilling conditions, is suggested. (C) 2001 Elsevier Sc ience B.V. All rights reserved.