We investigate the temperature field variation in the growth region of a diamond crystal in a sealed cell during the whole process of crystal growth by using the temperature gradient method （TGM） at high pressure and high temperature （HPHT）. We employ both the finite element method （FEM） and in situ experiments. Simulation results show that the temperature in the center area of the growth cell continues to decrease during the process of large diamond crystal growth. These results are in good agreement with our experimental data, which demonstrates that the finite element model can successfully predict the temperature field variations in the growth cell. The FEM simulation will be useful to grow larger high-quality diamond crystal by using the TGM. Furthermore, this method will be helpful in designing better cells and improving the growth process of gem-quality diamond crystal.
Thermal residual stress in Polycrystalline Diamond Compacts （PDCs） is mainly caused by the mismatch in the Coefficients of Thermal Expansion （CTE） between the polycrystalline diamond （PCD） layer and WC-Co substrate. In the PCD layer, the CTE of cobalt exhibit magnitudes four times larger than those of diamond. Cobalt content in the PCD layer has important effects on the thermal residual stress of PDCs. In this work, the effects of cobalt content on thermal residual stress in PCDs were investi- gated by the Finite Element Method （FEM）. The simulation results show that the thermal residual stress decreases firstly, and then increases with increasing cobalt content （1 vo1.%-20 vol.%）, which reaches a minimum value when the cobalt content is about 10 vol.%. The FEM analysis results are in agreement with our experimental results. It will provide an effective method for further designing and optimizing PDC properties.
LI ZhanChangJIA HongShengMA HongAnGUO WeiLIU XiaoBingHUANG GuoFengLI RuiJIA XiaoPeng
