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Formula uniform design method was adopted to study the performance of iron-based matrix with high content of phosphorus and boron. Two forms of regression models on matrix hardness and wear resistance and the optimum matrix formulae were obtained respectively by regression analysis and constrained nonlinear programming using MATLAB. Regression analyses indicate that matrix hardness was mainly affected by the factor of Ni, Co and Fe; matrix hardness and brittleness increased with the increment of P-Fe alloy, but decreased with the increase of 663-Cu. These results can be used as a rough guide for design of highly adaptive diamond bits for different rock formations. After the indoor experiments, diamond bit based on 3# matrix formula was made to perform field drilling tests. The results were that the penetration rate was 1.91m/h and the average diamond bit life was 67.37m.

To increase the manufacture efficiency of electroplated diamond tools, a nickel plating solution containing ammonium sulphate and sodium formate was investigated. The effects of concentration of ammonium sulphate, sodium formate and pH value on throwing power, covering power, ability to resist Cu2+ contamination and deposit microhardness were studied. Surface topography of deposits was also observed by SEM. Compared to watts bath, the plating solution studied is advantageous in terms of the performance of plating solution, deposit hardness and diamond bit behavior. Ammonium sulphate can refine deposit crystal grains and result in crystal form change.