INSERTS FOR EARTH-BORING BITS

摘要

A polycrystalline diamond enhanced insert is disclosed. The insert includes a body portion adapted for attachment to an earth-boring bit and a top portion for contacting an earthen formation. The top portion of the insert is provided with two different compositions of polycrystalline diamond. In the primary surface of the top portion, a tougher or less wear-resistant polycrystalline diamond layer is provided, whereas a more wear-resistant polycrystalline diamond layer is provided in the remaining region of the top portion. In addition to polycrystalline diamond, polycrystalline boron nitride and other superhard materials also may be used.