The mechanisms of solid cobalt diffusion, molten cobalt infiltration and two wave-like cobalt peaks movement through diamond layer during the sintering process were discussed theoretically according to the experiment data. Results showed that the solid cobalt diffusion coefficient under 5.8GPa and at 1300C was about 1.6 x 10-7cm2/s, which was almost the mean value between the solid cobalt diffusion coefficient (3 x 10-10cm2/s)at the same temperature under atmospheric pressure and the liquid cobalt diffusion coefficient (5 x 10-5cm2/s) under 5.8GPa and at 1300C. It also showed that the infiltration time of molten cobalt through diamond layer for diamond grain size 10 and 1μm were about 0.5 and 28s, respectively, and the moving velocity of the two wave-like cobalt peaks were about 50 and 100μm/s, respectively.

Diffusion and Infiltration Mechanisms of Cobalt through Diamond Layer during the Sintering of Polycrystalline Diamond Compacts. Deng, F.M., Chen, Q.W.: Chinese Journal of High Pressure Physics, 2004, 18[1], 53-8