SHOCK CONSOLIDATION OF DIAMOND POWDERS

Fine and coarse diamond powders were shock-compacted at peak pressures of 77, 90, and 108 GPa. The densification and consolidation mechanisms of diamond powders under shock compression were investigated. The densification behavior of the diamond powders depended strongly on the particle size of the starting materials. Fine diamond powders were densified primarily by plastic deformation, while coarse diamond powders were densified mainly by particle fracture. The relative densities of the compacted diamond samples increased with an increase in the initial particle size of the diamond and with shock pressure. The consolidation mechanism of the diamond powders under shock compression was closely related to the densification mechanism, and depended on the initial particle size of the diamond. At a shock pressure of 90 GPa, particle sizes of 2 to 4 mu m grade and 10 to 20 mu m grade were desirable as the starting material in order to produce well-bonded diamond compacts. Diamond compacts having microhardness values over 80 GPa were obtained from 2 to 4 mu m grade and 10 to 20 mu m grade diamond powders at a shock pressure of 90 GPa, and their relative densities were 88. 5% and 91. 0%, respectively.