| 摘要 |
A preform element includes a facing table (21') of superhard material having a front face, an outer peripheral surface, and a rear surface bonded to a substrate (25') which is less hard than the superhard material. The facing table comprising a peripheral region (23)' surrounding an inner region (22)', the peripheral region having an inner surface (30) which is inclined at an angle of greater than 90 DEG to the rear surface (31) of the facing table so as to face in a direction having a component rearwardly away from the facing table as well as inwardly towards said inner region (22'). The inner region of the facing table may be formed with projections (24') extending into the substrate. <IMAGE> |
