The quality indexes of diamond bit include hardness, wear resistance, impact toughness, bending strength and linear expansion coefficient of matrix. In addition, carcass density, carcass thermal properties and diamond embedding ability are also included. The carcass density directly reflects the hardness and wear resistance of the matrix; the thermal properties of the matrix relate to its linear expansion coefficient; while the index of the ability to pack diamond is important, but it is difficult to detect with the instrument. Hardness and wear resistance are the most important indexes in the performance indexes of these matrix, which are related to the adaptability of bit to rock and drilling efficiency. The matrix properties of hot pressed diamond bit are mainly determined by matrix material and hot pressing process, among which the former is the main aspect of contradiction. The basic requirements of deep drilling for the matrix properties of diamond bit diamond bit are as follows:
(1) sufficient compressive strength, impact strength and hardness, and the hardness of the matrix are suitable for the rock to be drilled;
(2) the diamond has good wettability, can firmly pack diamond, and has a certain chemical stability, at high temperature does not react with diamond;
(3) the melting point is low and the hot corrosion of diamond is small;
(4) the coefficient of linear expansion of the matrix is as close to that of diamond as possible, and the stress effect of diamond is reduced;
(5) it is easy to form and can be firmly welded with drill steel body.
The properties of the bit matrix should be adapted to the nature of the drilling strata and ensure that the diamond can come out at the right moment, which is the basic point of the design and selection of impregnated diamond bit. According to the characteristics of deep drilling, the pre alloy powder as matrix material, which is due to pre alloyed powder than mechanical mixed powder elements are uniformly distributed, fundamentally avoid the segregation and make the matrix microstructure and properties consistent; pre alloyed powder alloying fully, the fetal body has higher hardness and impact strength. Can greatly improve the flexural strength, compressive drill, enhance the ability of the diamond package insert, improve the life of diamond bit.
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