Semiconductive polycrystalline diamond, cutting elements incorporating the same and bit bodies incorporating such cutting elements

Abstract

An ultra-hard semiconductive polycrystalline diamond (PCD) material formed with semiconductive diamond particles doped with and additive, as for example, Li, Be or Al and/or insulative diamond particles having semiconductive surfaces, tools incorporating the same, and methods for forming the same, are provided. The ultra-hard PCD material may be formed using a layer of insulative diamond grit feedstock that includes additives therein, then sintering to convert a plurality of the diamond crystals to include a semiconductive surface. In another embodiment, the ultra-hard PCD material is formed by sintering semiconductive diamond grit feedstock consisting of diamond crystals doped with an additive as for example Li, Al or Be. The ultra-hard semiconductive PCD cutting layer exhibits increased cuttability, especially in EDM and EDG cutting operations. A cutting element is provided having such a PCD layer. Furthermore, a bit is provided having a cutting element having such a PCD layer.

What is claimed is:  
     
         1 . A polycrystalline diamond material formed by sintering diamond crystals doped with an additive at sufficient temperature and pressure for forming polycrystalline diamond.  
     
     
         2 . The polycrystalline diamond material as in  claim 1  wherein the additive is selected from the group of additives consisting of Be, Li and Al.  
     
     
         3 . The polycrystalline diamond material as in  claim 1 , wherein said polycrystalline diamond material is characterized as being a semiconductive material.  
     
     
         4 . The polycrystalline diamond material as in  claim 1 , wherein said polycrystalline diamond material is characterized as being a P-type semiconductive material.  
     
     
         5 . The polycrystalline diamond material as in  claim 1 , in which said polycrystalline diamond material has a resistance of no greater than 10 ohms.  
     
     
         6 . The polycrystalline diamond material as in  claim 1 , wherein said polycrystalline diamond material has a resistance being less than 10% of a corresponding resistance of a substantially similar polycrystalline diamond material formed substantially only of Type I diamonds.  
     
     
         7 . The polycrystalline diamond material as in  claim 1 , wherein said polycrystalline diamond material has a thermal conductivity being about 15 times greater than a corresponding thermal conductivity of a substantially similar polycrystalline diamond material formed substantially only of Type I diamond crystals, at 80° K.  
     
     
         8 . The polycrystalline diamond material as in  claim 1 , in which said polycrystalline diamond material is substantially void of any metal binder material and has a resistance no greater than 1000 ohms.  
     
     
         9 . A cutting element comprising the polycrystalline diamond material as in  claim 1 , formed over a substrate.  
     
     
         10 . A polycrystalline diamond material formed by sintering Type I diamond crystals at sufficient temperature and pressure for forming polycrystalline diamond, wherein after sintering a plurality of said Type I diamond crystals comprising a semiconductive surface layer.  
     
     
         11 . The polycrystalline diamond material as in  claim 10 , in which said polycrystalline diamond material further includes impurity species therein, said impurity species selected from the group consisting of Li, Be, B, and Al.  
     
     
         12 . The polycrystalline diamond material as in  claim 10 , in which said semiconductive surface layers include impurity species therein, said impurity species selected from the group consisting of Li, Be, B, and Al.  
     
     
         13 . The polycrystalline diamond material as in  claim 10 , wherein said polycrystalline diamond material is a P-type semiconductive material.  
     
     
         14 . The polycrystalline diamond material as in  claim 10 , wherein said polycrystalline diamond material has a resistance no greater than 50 ohms.  
     
     
         15 . The polycrystalline diamond material as in  claim 14 , further comprising a metal binder therein at a weight percentage no greater than 10 percent.  
     
     
         16 . The polycrystalline diamond material as in  claim 10 , wherein said polycrystalline diamond material is substantially void of any metal binder material and has a resistance of no greater than 1000 ohms.  
     
     
         17 . A cutting element comprising the polycrystalline diamond material as in  claim 10 , formed over a substrate.  
     
     
         18 . A drill bit comprising a cutting element comprising a substrate and a polycrystalline diamond layer over said substrate, said polycrystalline diamond layer comprising Type I diamond crystals therein, a plurality of said Type I diamond crystals comprising a semiconductive surface layer.  
     
     
         19 . A drill bit as in  claim 18  wherein the polycrystalline diamond is formed by sintering Type I diamond crystals at a sufficient temperature and pressure for forming polycrystalline diamond.  
     
     
         20 . A drill bit comprising a cutting element comprising a substrate and a polycrystalline diamond layer over said substrate, said polycrystalline diamond layer formed by converting diamond crystals doped with a doping additive to polycrystalline diamond.  
     
     
         21 . A drill bit as is  claim 20  wherein the additive is selected from the group of additives consisting of lithium, beryllium and aluminum.  
     
     
         22 . A drill bit as recited in  claim 20  wherein the said diamond crystals are converted to polycrystalline diamond by sintering.