Role of cobalt of polycrystalline diamond compact (PDC) in drilling process

The contact surface between polycrystalline diamond compact (PDC) and rock was divided into three main areas according to the distinction in heat caused by various frictional forces during drilling process. As temperature rising during drilling, Co played a dominant role in the thermal stability of PDC, however the influence from Co oxidation could be negligible. Usually PDC has a self-sharpening ability with Co removing during drilling, while the injected cooling water (generally mixtures consisting of water and soil) breaks the formed shape. That is because water molecules and soil adhere to the frictional surface thereby forming an absorbed film which prevents direct contact between PDC and rocks, thus the effect from continuous impact forces is enhanced which brings about more unfavorable results. Controlling the content of Co is not only a vital problem existing in PDC industry but an effective way to improve drilling performance. (C) 2016 Elsevier B.V. All rights reserved.