The Microstructure Analysis Of Brazed Diamond Bit And The Simulation Of Temperature Field While Drilling

Because of its simple structure, high strength, high wear resistance and other advantages, diamond drill bit becomes hotspot of the world’s drilling technology research at present. Now there is a NQ76 resistance furnace brazed diamond bit strengthen the holding force between diamond and matrix, because its surface has generated carbide layer. Actually, the thermal conductivity of diamond is extremely high, but the thermal stability of diamond is poorer, over temperature would result in a bit premature failure, therefore, heat transfer condition of diamond bit has also become the hot spot.Respectively in this article, through experiments and ANSYS finite element simulation, I analysis the single diamond sample’s bonding mechanism of NQ76 resistance furnace brazed bit, as well as the single diamond grinding of rock initial temperature field simulation, analyzing the influence of the carbide layer on the model of heat transfer. The main work accomplished in this paper is as follows: Firstly, by means of the three-dimensional visual microscope, SEM and EDS, the samples are observed and analyzed before and after corrosion. Results:the diamond grits’ exposure on the surface of sample bit is high up to forty-seven point five percent, and the matrix climbs high. Mainly because the high temperature brazing diamond and Ni-Cr alloy generates the chromium carbide compounds in the interface, which improved the holding force between matrix and diamond grits.Secondly, observing and analyzing the transition zone between the diamond and carbide and the carbide fracture morphology after the ion thinning, grinding and fracture of the corrosive diamond grains respectively. The results show that the carbide layer’s thickness is 1.7-3.5um, that is to say diamond surface only generates a layer of carbide.Thirdly, simulating temperature field of single diamond grinding rock, the purpose is to analyze that whether the existence of the carbide layer will influence on the model’s heat transfer. Results show that the high temperature area exists in diamond and carbide layer and a part of matrix, and the temperature of the single diamond model which does not contain the carbide layer is higher than the model containing carbide layer, therefore, the existence of the seamless transition layer avail heat transfer.