Abstract: (opens in a new window)Polycrystalline Diamond Compact (PDC) is a critical superhard material extensively employed in industrial applications, particularly in oil and (opens in a new window)gas drilling. In this study, three diamond powder samples with identical grain sizes but varying (opens in a new window)roundness values of 0.70, 0.85 and 0.94 (referred to as P1, P2 and P3) were selected for the fabrication of PDC cutters (referred to as S1, S2 and S3). This work systematically investigates the effect of diamond grain roundness on the microstructure and mechanical properties of PDC cutters. Experimental results reveal that PDC cutters fabricated with higher roundness diamond grains exhibit improved impact resistance and thermal stability. Conversely, cutters made with lower roundness (sharper) grains demonstrate enhanced initial (opens in a new window)abrasion resistance but show limited long-term performance improvement. This behavior is attributed to differing (opens in a new window)fracture mechanisms under (opens in a new window)high pressure and high temperature (HPHT)conditions. Lower roundness leads to greater fragmentation of diamond grains, resulting in the formation of numerous weak grain boundaries. PDC samples analysis shows a grain size shrinkage of 25 % in S1, which is 19 % and 79 % higher than that of S2 (21 %) and S3 (14 %), respectively.
Furthermore, fragmentation bands were observed in S1, contributed to the formation of cobalt-rich zones, inducing localized bonding defects and reducing grain boundary
(opens in a new window)strengthof diamond grains.
