Influence of the quality of diamond micropowder on the properties of PCD compacts

The diamond volume content in the PCD layer of the polycrystalline diamond compact should account for more than 98%, and the rest is the catalyst metal diffused and infiltrated from the cemented carbide base. Therefore, the quality of diamond micropowder plays a very important role in determining the final properties and consistency of sintered products. Usually, the diamond micropowder used for the production of pcd blank is a by-product produced in the synthesis process of industrial diamond powder, and the diamond single crystal is mainly used in the stone cutting market, such as diamond saw blades, diamond grinding wheels, etc.

There are two main catalysts for diamond synthesis: one is cobalt series, the other is iron-nickel alloy series.

The industrial diamond micropowders currently available on the market have an extremely wide quality range and are uneven. The micropowder used in the PCD sintering process is usually obtained by crushing the coarse-grained diamond single crystal, so the quality of the initial coarse-grained diamond single crystal will affect the quality of the pcd material compact. Depending on the pressure and temperature parameters of the diamond sintering process, diamond particles may grow into various shapes, such as being cubic rather than octahedral. Moreover, if the diamond single crystal grows too fast in the catalyst molten pool, it is possible to find metal inclusions inside the grain after sintering is completed.

Other quality problems are related to the purification and cleaning process of diamond abrasive powder, mainly to clean and remove the solid alloy catalyst material that occurs in the diamond synthesis process. The usual cleaning process involves dissolving diamond fines in hot hydrochloric and nitric acids, then washing and removing any remaining impurities. If this process is not carried out thoroughly or correctly, the surface of the diamond powder will become contaminated with impurities and the sintering process will not be performed as effectively, causing PCD performance and quality problems.