Effect of matrix composition on the performance of Fe-based diamond bits for reinforced concrete structure drilling

Abstract

A prealloyed Fe powder with high wear resistance and cold pressure molding ability was selected for diamond bit drilling into strong abrasive rock formations, such as reinforced concrete. The prealloyed Fe powder was layered along the radial direction of the diamond bit through cold pressing. A special shape was formed on the lip surface of the bit during drilling, which improved the drilling efficiency. In this paper, the matrix properties of a new impregnated diamond bit for reinforced concrete formation, composed of prealloyed Fe, prealloyed CrFe, Cu and 660-Cu, Ni and Co were studied, and the performance difference with the Fe-based formula is discussed. X-ray diffractometry (XRD) was used to determine the phases, and SEM was used to observe the micromorphology of the fracture. A regression model was selected to explore the influence of the matrix composition on the hardness and bending strength. The conclusions are as follows. The Fe-based matrix mixture test was carried out by the extreme vertex design method. The polynomial regression equations for the matrix composition, hardness, and bending strength were fitted. The calculated matrix values and experimental values matched closely. The higher the content of prealloyed CrFe was, the higher the hardness, but the brittle phase fractured the matrix, and the bending strength of the matrix decreased. The hardness and bending strength of the matrix increased with an increase in the Ni and Co contents. Cu enhanced the Ni and Fe, and the increase in Cu and 660-Cu content increased the bending strength of the matrix. The performance data for the Fe-based formula showed that adding an appropriate amount of prealloyed CrFe powder, Cu and 660-Cu, Ni, and Co to the Fe-based matrix effectively improved the mechanical properties of the sintered body. Two formulas were determined through the experiments and sintered into drill bits for on-site drilling. The results show that the use of a prealloyed Fe-based powder formula system effectively improved the drilling efficiency and drilling life of the bit, and the comprehensive performance of the bit was significantly improved.