The Effect of Thickness of Diamond Layer on Residual Stresses in Polycrystalline Diamond Compact

The effect of thickness of diamond layer on the residual stresses in polycrystalline diamond compact (PDC) was investigated through XRD measurement and finite element analysis (FEA) method. The results show that as the thickness of the diamond layer increases from 0.5 mm to 2.0 mm, the residual compressive stress on the surface of the diamond layer at the center decreases from 1 800 MPa to about 700 MPa, but the stress on the edge changes gradually from compression into tension, and the tensile stress region on the edge of the diamond layer becomes wider. At the same time, the vertical tensile stress on outer edge of the cutter and shear stress near the interface increase significantly. These two stresses are the main factors that cause cracks near the interface of the PDC with a thicker diamond layer. Based on the measured results, the equations of the stresses at the centers and on the edges of the PDC as a function of the thicknesses of diamond layers have been deduced.