Effect of sintering pressure on the performance of Fe-based pre-alloyed bit matrix with low liquid phase

Abstract

The hot-pressing sintering experiments were carried out under the conditions of sintering temperature of 950 ℃, holding time of 5 mins and different sintering pressures. The effects of sintering pressure on the properties of three kinds of low liquid phase Fe-based pre-alloyed bit matrix and one traditional Fe-based bit matrix were compared and studied, including the hardness, the bending strength, the relative density, the diamond embedding strength of the matrix, the thermal damage of diamond. as well as the microstructure and the morphology of drill bit matrix. The results show that with the increase of sintering pressure, the indentation hardness, the bending strength and the relative density of blank matrix with low liquid phase gradually increase, but the hardness and the bending strength of traditional Fe-based pre-alloyed blank matrix increase at first and then decrease, and the relative density increases. For the matrix containing diamonds, the bending strength of low liquid phase and traditional Fe-based matrix increases with the increase of sintering pressure. When the sintering pressure is 20 MPa, the bending strength of the diamond containing matrix with low liquid phase tends to be stable, while the bending strength of the traditional Fe-based matrix containing diamond decreases slightly. At the same time, with the increase of sintering pressure, the homogeneity of the low liquid phase matrix is enhanced, but the thermal damage of the diamond is gradually aggravated. According to the analysis of the mechanical properties and the fracture morphology of the matrix, the optimal sintering pressure is 20MPa. At this time, the hardness and the bending strength of the low liquid phase Fe-based pre-alloy matrix can meet the requirements of impregnated diamond bits.

Keywords

• hot pressing sintering
• diamond drill bit
• iron-based
• pre-alloy
• low liquid phase