Micro-Raman Stress Investigation of Polycrystalline Diamond Compact (PDC)

The residual stresses on the top surface and side face of the diamond layer of PDC with 25.4mm in diameter and 3.2mm in thickness were measured using Micro-Raman Spectroscopy, thus the stresses and their radial and vertical distributions were obtained. To evaluate the magnitude of the thermal residual microstress in the diamond layer of PDC, the tungsten carbide substrate of PDC was cut by electric discharge machining (EDM), and several Raman measurements were performed on the top surface of the diamond layer. The results show that 1) the stresses in the central part of the diamond surface are compressive, the biggest stress is about 600 MPa, the magnitude of the stress decreases from the center to the edge of PDC, and at about 2mm near the edge of PDC, the stress becomes tensile; 2) the stresses on the side face of the diamond layer are tensile, the maximum is about 580 MPa near the interface. These tensile stresses are thought to be one of the main factors to cause delamination of PDC used for cutting tools; 3) the measured value of the microstress in the diamond layer is 62.5MPa.