Reactive imbibition of WC-Co substrate for PDC cutters used in oil and gas and mining drilling

Cemented carbides are used in rock drilling for mining tools and wear resistant parts. These composite materials possess an excellent compromise between hardness and toughness. Nowadays, the concept of graded structure is widely studied to improve these two properties simultaneously, and so to increase the service life of drilling tools. A continuous composition gradient on several millimetres is generated in commercial WC-Co substrate for PDC cutters by using Reactive Imbibition method. The effects of this process are analysed in terms of microhardness, cobalt concentration and WC grain size. A continuous gradient of about 300HV on 8mm-height substrate is obtained in one-step by imbibition process into combination with a boron-rich coating deposed on its free surface. In part, this gradient of hardness and its shape are preserved after HPHT (high pressure-high temperature) process that is used for the diamond table deposition on the WC-Co substrate. Such gradient must significantly increase the cutter service life.