On the generation of surface depressions in polishing polycrystalline diamond compacts

This paper investigates the surface depressions generated during the polishing of the (1 1 1) surfaces of polycrystalline diamond (PCD) compacts when using the dynamic friction polishing (DFP) method. It was found that surface depressions of six-sided faces along octahedral planes were the typical features created by the DFP. Although the size of the well-developed depressions can vary significantly, the rectilinear edges are always aligned with the <1 1 0> directions. Pronounced {1 1 1} planar defects (i.e., twins) were revealed underneath a depression apex. The interception of the defect plane with the polished surface accounts for the generation of the <1 1 0> aligned depressions and for the discernible asymmetry of the pyramidal faces with respect to the (1 1 1) plane. It was revealed that the attached debris layer on the PCD surfaces contained sp2-bounded amorphous carbon and nano-sized crystals. (paper)