This paper attempts to improve the drilling efficiency of diamond bit in hard and complex formation by adding a proper concentration of hard brittle grits into the matrix. For this purpose, the most suitable material for hard brittle grits was selected, the effects of hard brittle grits on matrix wear features were studied through drilling experiments and scanning electron microscope (SEM) examination, and the impact of grit distributions on the cutting performance of single diamond was discussed in great details. The experimental and analysis results show that 300μm SiC is the most suitable material for hard brittle grits; the most efficient diamond bit should have a diamond size of 45/50 US mesh, diamond concentration of 67%, hard brittle grit concentration of 37% and matrix hardness of 15 (Rockwell hardness, HRC). It is also found that the distribution pattern of hard brittle grits in the matrix directly bears on the cutting performance and failure mode of single diamond, and the impact of hard brittle grits on drilling performance is the combined effect of the grits obeying different distributions. The research findings shed new light on the improvement of diamond bit in actual engineering
diamond bit, hard brittle grits, hard rock drilling, wear morphologies
This work was financially supported by the National Natural Science Foundation of China (No.41702390), Hunan Provincial Natural Science Foundation of China (No.2018JJ3173) and the Research Foundation of Education Bureau of Hunan Province (No.17C0634)
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