RESIDUAL-STRESSES IN POLYCRYSTALLINE DIAMOND COMPACTS

The effects of residual stress on the integrity of polycrystalline dia mond compact (PDC) cutters was investigated. When the compact cooled f rom the sintering temperature to room temperature, very high radial co mpressive stresses were induced in the diamond table, and (generally) much lower radial tensile stresses were induced in the cemented tungst en carbide backing. The magnitudes of these residual stresses were not affected very much by the diameter of the compact. However, the resid ual stresses were affected significantly by the thickness ratio of the carbide layer to the diamond layer. The higher this ratio the greater was the radial compressive stress in the diamond and the lower was th e radial tensile stress in the carbide. This same effect was obtained by sintering a relatively thin layer of tungsten carbide on top of the diamond table.