Influence of Holding Time on Properties of Cemented Carbide- Polycrystalline Diamond Compact Joints

Abstract

The influences of brazing holding time on properties of cemented carbide-polycrystalline diamond (PCD) compact joints were investigated in this study. The microstructure and phase composition of joints were investigated by scanning electron microscopy, electron probe microanalyzer, and X-ray diffraction. Microstructural investigations revealed Ag-based solid solution, Cu-based solid solution, Cu0.64Zn0.36, and a small amount of MnNi phase at the joint interface. The max shear strength of brazed joints 350.6 MPa was determined in the samples joined at 15 s, which was partially due to the dispersion strengthening effect of gray-black grains containing Cu-based solid solution, Cu0.64Zn0.36 and MnNi phase in the joints. Equal-area-circle grain diameter of the gray-black grains grew with longer holding time, whereas the shear strength decreased because of the formation of continuous intermetallic compounds layer along the joint boundary. Thermal damage of the PCD layer also deteriorated with increased holding time, and shorter holding time was preferable in the production.