The Experimental Study On Multi-layer Brazed Diamond Bit

One of the major factors influencing the diamond tool’s lifetime and using performance was the bonding strength between metal matrix and diamond. In traditional manufacture technology, diamond grits impregnated in body only relying on mechanical force and did not form chemical and metallurgy combination between them. Diamond grits were broken away from the metal matrix easily, and the diamond tool’s lifetime was shorten. In this paper, the active element of the Ni-Cr alloy formed a carbide layer on diamond surface, which led to a strong chemical and metallurgy combination between diamond and matrix. The protrusion ratio and utilization ratio of diamond grits had been improved obviously. Following works in this paper were carried out.(1) The basic high temperature brazing theory of diamond was studied, the selections of diamond grits and high temperature brazing material were described as well. Advice for the enactment of brazing time and brazing temperature was given.(2) Three kinds of diamond bits were designed for experiment study under different brazing processes. The results showed that the bits of all had a better performance, and diamond grits had longer effective working time in the matrix of bits.(3) The outcropping condition of diamond grits was observed and analyzed by microscope, the results showed that the diamond grits on the matrix surface of three diamond bits, which were in normal working condition, were over 95%, it indicated that the matrix had a strong binding force for diamond grits. The height of the protrusion, was measured, and protrusion ratio was about 49.1%, it also proved the tight adhesion of the metal matrix to diamond grits.(4) The surface topography and composition of the brazing diamond were analyzed by SEM and EDS. The results showed that the chemical and metallurgy combination was the main factor of the tight bond between diamond and metal matrix.