Research on diamond-enhanced tungsten carbide composite button bits

Abstract

At the present time in China, the cutters used in button bits and rock bits are mainly cobalt tungsten carbide. Because of its low abrasive resistance, the bit service life and drilling efficiency are very low when hard and extremely hard formations are being drilled. Owing to its high abrasive resistance, diamond composite material is widely used in drilling operations. However, its toughness against impact is too low to be used in percussion drilling, so it can only be used in rotary drilling. In order to solve the problems encountered by the DTH hammer in hard rock drilling, to increase the life of the bit, to increase the rate of penetration and to decrease drilling cost, a new type of diamond-enhanced tungsten carbide composite button with high abrasive resistance and high toughness against impact, which may be used in percussion drilling, has been developed. The key problems in making the button are to improve the thermal stability of the diamond, increase the welding strength between the diamond and the cemented tungsten carbide, and reduce the sintering temperature of the tungsten carbide. All these problems have been solved effectively by pretreatment of the diamond, low temperature activation hot-press sintering, and high sintering pressure. The properties of the button have been determined under laboratory conditions. The test results show that its hardness is more than 86 HRA, its abrasiveness resistance is 100 times more than that of conventional cemented tungsten carbide, and its toughness against impact is more than 100 J. All these data theoretically that show the button has very good mechanical properties that can meet the needs of percussion drilling, and can solve the problems encountered with button bits of conventional cemented tungsten carbide.