Bending Strength and Cutting Performance of WB-Coated-Diamond/Fe-Ni Composites

Diamond particle with tungsten boride (WB) coating was synthesized by the molten salt method. Three different diamond/Fe-Ni composites made from pristine diamond, B4C coated diamond and WB coated diamond with Fe-Ni powders were prepared by powder metallurgy. The composition and microstructure of the tungsten boride coating were investigated. Both bending strength and cutting performance of the composites were investigated. Addition of the WB coating provided an increased bending strength (871.2 MPa) and relative density (93.54%), compared with the composites consist of uncoated diamond and Fe-Ni (746.8 MPa, 92.81%). Three different Fe-Ni-based impregnated diamond drill bits contained 20 vol.% pristine diamond, B4C coated diamond and WB coated diamond were manufactured by powder metallurgy, respectively. Drilling rate of bits was measured by XY-4 geological core drill on granite. The test results show that the drilling rate of bits with WB coated diamond (2.42 m/h) was 40% higher than that with pristine uncoated diamond (1.72 m/h).