Effect of Graphite Addition on Impregnated Diamond Bit Properties

Abstract

Graphite was used as a solid lubricant to reduce thermal damage in diamond bit when drilling without coolant. Graphite was added to the bit matrix material to reduce friction coefficient and heat. The influence of content, granularity, and surface metallization of graphite on the mechanical property and dry friction properties of the matrix, as well as the effect of diamond lifetime in the working layer were studied. Results showed that the hardness, bending strength, and friction coefficient of matrix gradually decreased with the increase in graphite concentration. Meanwhile, the abrasion loss decreased first and then increased, and the lifetime of diamond in the working layer gradually increased. With the decrease in graphite granularity, the bending strength and friction coefficient of matrix gradually decreased, whereas the hardness, abrasion loss of matrix, and diamond lifetime in the working layer gradually increased. After surface metallization of graphite, the hardness, bending strength, friction coefficient, and abrasion loss of matrix increased, whereas the lifetime of diamond in the working layer decreased. This study lays a foundation for drilling without water.