Studying the fragmentation and densification of diamond powder as well as the diversification in the intergranular stress is crucial to produce high-quality polycrystalline diamond (PCD). It is also essential to explore the mechanism of preparing pure-phase polycrystalline diamond^[1-3].

In our study, we analyzed the characteristics of fragmentation and intergranular stress distribution of diamond using different sizes of diamond powder under high pressure. We used scanning electron microscopy (SEM) to gain insights into the cataclastic crystal morphology and a laser particle size analyzer (LPSA) to quantify the amount of broken particles. The results show that the fragmentation of diamond comprises three stages with increasing pressure: (i) fracturing of edges and corners, (ii) cracking of the crystal plane, and (iii) densifying of particle disorder.

In addition, we used in situ synchrotron radiation x-ray diffraction techniques to analyze the intergranular stress of diamond powder under high pressure in a diamond anvil cell at ambient temperature. We obtained the distribution of diamond intergranular stress in the fragmentation and densification processes, and we explained why diamond fragments under very low pressure.

References

[1] Z. Bo, Y. Yang, J. Chen, K. Yu, J. Yan, and K. Cen, Nanoscale 5, 5180 (2013).

[2] J. Qian, C. Pantea, G. Voronin, and T. W. Zerda, Journal of Applied Physics 90, 1632 (2001).

       [3] G. S. Bobrovnitchii, O. S. Osipov, and M. Filgueira, International Journal of Refractory Metals & Hard Materials 21, 251 (2003).