Polycrystalline diamond composite (PDC cutter) is a new type of composite material, which is formed by sintering diamond particles with micron size and tungsten carbide matrix under high temperature and high pressure. PDC not only has the high hardness and wear resistance of polycrystalline diamond, but also has the weldability of cemented carbide. Removing cobalt binder is an important method to improve the thermal stability of PDC cutter. The influence of cobalt content on flexural strength is of great significance for PDC to improve toughness, reduce chip breakage, improve the overall stability of products and extend service life.
Because diamond toughness poor after high temperature and high pressure synthesis of PDC, Co in cemented carbide spread to diamond layer, improve the toughness of diamond layer, but to take off the pdc cutter to reduce Co content after cobalt, toughness, subsequently and carbide layer toughness is large, so the crack of diamond is loading first, but the hard alloy layer to load still affordable, until increase load reached its limit, and eventually compound layer fracture as a whole. Most of the pdc cutter of the composite layer is diamond phase, and the substantial reduction of the content of Co in the binder phase will lead to the enhancement of the brittleness and decrease of the toughness of the composite layer. Therefore, the bending strength of the composite after cobalt removal decreases more.
It can be seen that with the increase of the depth of cobalt removal, the further decrease of CO content, the toughness and bending strength of the composite layer decreased significantly, and the possibility of fragmentation during work would increase and reducing the service life. Therefore, the design work should be comprehensively considered, and the relationship between the various properties of PDC should be balanced. The increase of decobalt depth will increase the bending strength of PDC cutter.