The present situation of production technology of PDC bit
Dec 10, 2017
An important part of PDC bit - poor thermal stability of PDC can say, the main cause of this situation adoption of carbide alloy (tungsten carbide) powder, nanoscale single crystal and polycrystalline diamond USES micro diamond powder, between diamond and tungsten carbide and diamond powder into a binder, generally is cobalt and cobalt compounds, sometimes with graphite powder and sometimes need to add the right amount of catalyzer, let them at about 1500 ℃ high temperature sintering and 60000 pressure. Such as binder and catalytic effect of cobalt element not only causes graphitization of polycrystalline diamond, but also because of the cobalt and cobalt compounds are very different thermal expansion coefficient, thus the polycrystalline layer easy to heat damage. In addition to the influence of cobalt elements, the different thermal expansion coefficients of the polycrystalline layer and the carbonized tungsten layer also tend to cause the serious defects of the polycrystalline layer from the bottom (or substrate). Therefore, it is a key DE technology to insert a specific cutting block such as diamond composite into a PDC bit. Because of the PDC polycrystalline diamond under high temperature above 700 ℃ will cause failure, so the PDC bit in brazing metal melting point should be lower than 700 ℃; If brazing metal melting point is too low, it also affects the connection strength after welding, caused by composite patches on the PDC bit in the process of work easy to fall off, so this is the production process of PDC bit, the present situation of the problem.