Yang Yang, Pan Bingsuo, Yang Kaihua
(Faculty of Engineering, China University of Geosciences, 430074)
Abstract A new type of iron-based matrix formula as a potential substitute for traditional WC-based matrix formula for hot pressed diamond bit was investigated. Iron, phosphor-iron, 663-Cu, nickel, cobalt and certain additives were selected as the studied formula constituents. Among matrix performances, matrix hardness and wear resistance were chosen as experimental indexes in this paper. Constrained uniform design method was used for the formula design of iron-based matrix. Two forms of regression models of matrix hardness and wear resistance were obtained by regression analysis using MATLAB. Moreover, the optimization of matrix formulae and matrix performances were also achieved through constrained nonlinear programming. It was found that matrix hardness, significantly affected by the factor of Ni-Co-additives and Fe, increased with the increment of Ni-Co-additives, Fe and P-Fe, but reduced with the increase of 663-Cu. Matrix wear resistance was mainly affected by Fe; meantime, the interactions between Fe and P-Fe, Fe and Ni-Co-additives were also relatively obvious. The increment of 663-Cu powder may result in a slight improvement in matrix wear resistance. In addition, the results of nonlinear programming revealed that the predictive optimum value of hardness was 139.5 HRB and the optimum wear resistance was 0.056 g, whereas they could not reach the optimum value at the same time.
Keywords formula optimization; stepwise regression; P-Fe alloy; matrix performance