| 摘要 |
<p>A percussion rock bit comprises a steel body (10) having a pin (12) for connection to a drill string at one end and having a plurality of inserts (16) at the other end for crushing rock at the bottom of a hole being drilled. The inserts (16) have a cemented tungsten carbide body (20) partially embedded in the steel bit and at least two layers at the protruding drilling portion of the insert. The outermost layer (26) contains polycrystalline diamond. The remaining layers adjacent the polycrystalline diamond layer (26) are transition layers (28,30) containing a composite of diamond crystals and precemented tungsten carbide, the composite having a higher diamond crystal content adjacent the polycrystalline diamond layer (26) and a higher precemented tungsten carbide content adjacent the tungsten carbide body (20).</p> |
