Method for forming a cutting element and downhole tools incorporating the same

Abstract

Cutting elements include an ultrahard material body formed at high pressure and high temperature conditions in the absence of catalyzing material to provide a material microstructure comprising a matrix phase of bonded together ultrahard material particles and interstitial regions disposed throughout the matrix phase providing porosity of less than about 6 volume percent. The body may include a substrate attached thereto, and may include an infiltrant material disposed in a population of the interstitial regions. The body may have regions with different porosities, e.g., with a higher porosity region located adjacent a substrate interface and/or along a central region. The body may include more than one infiltrant, each located in different regions. The infiltrant may be introduced into the body during a separate high pressure/high temperature process. The body may include a region which extends a depth from a working surface that is substantially free of any infiltrant.

What is claimed is: 
     
         1 . A bit for drilling earthen formations comprising:
 a bit body; and   one or more cutting elements attached thereto, wherein one or more of the cutting elements are prepared by:
 subjecting a material comprising a plurality of ultrahard material particles to a sufficiently high pressure/high temperature condition to form a sintered ultrahard material body, wherein the ultrahard material body has a material microstructure comprising a matrix phase of bonded together ultrahard material particles and interstitial regions disposed throughout the matrix phase providing a porosity in the range from about 1 to 6% volume, based on the total volume of the ultrahard material body; 
 removing the sintered ultrahard material body from the high pressure and temperature conditions; and 
 introducing an infiltrant material into the interstitial regions of the ultrahard material body subsequent by subjecting the ultrahard material body and an infiltrant material to a second high pressure/high pressure condition. 
   
     
     
         2 . The bit of  claim 1 , further comprising one or more fixed blades projecting outwardly from the bit body and having one or more cutting elements disposed thereon. 
     
     
         3 . The bit of  claim 1 , further comprising one or more legs extending from the bit body, each leg comprising a journal having a cone rotatably attached thereto, wherein one or more cutting elements are disposed thereon. 
     
     
         4 . The bit of  claim 1 , wherein the porosity of the ultrahard material body after the step of subjecting is in the range of from about 2 to 5 volume %, based on the total volume of the ultrahard material body. 
     
     
         5 . The bit of  claim 1 , wherein at least a portion of the ultrahard material particles comprise diamond particles. 
     
     
         6 . The bit of  claim 1 , wherein the infiltrant material is selected from Group VIII metals, combinations, and alloys thereof. 
     
     
         7 . The bit of  claim 1 , wherein the infiltrant material is selected from Groups IIA, IB, IIB metals, combinations, and alloys thereof. 
     
     
         8 . The bit of  claim 1 , wherein the infiltrant material is selected from the group consisting of Si, Ti, Ge, combinations, and alloys thereof. 
     
     
         9 . The bit of  claim 1 , wherein the infiltrant material is selected from carbonates of Group IA or IIA metals, their combinations or compounds which include them. 
     
     
         10 . The bit of  claim 1 , wherein during the step of introducing, controlling introduction of infiltrant material to provide a first region in the ultrahard material body comprising the infiltrant material, and a second region that is substantially free of the infiltrant material. 
     
     
         11 . The bit of  claim 14 , wherein the second region extends a depth from a working surface of the ultrahard material body. 
     
     
         12 . The bit of  claim 1 , wherein the ultrahard material body produced during the step of subjecting comprises a first region having a porosity that is different from a second region. 
     
     
         13 . A method of making a bit for drilling earthen formations comprising operatively connecting one or more cutting elements to a bit body, wherein one or more of the cutting elements have been prepared by:
 subjecting a material comprising a plurality of ultrahard material particles to a first high pressure/high temperature condition to form a sintered ultrahard material body in the substantial absence of a catalyzing material, wherein the ultrahard material body has a material microstructure comprising a matrix phase of bonded together ultrahard material particles and interstitial regions disposed throughout the matrix phase providing a porosity in the range from about 1 to 6 volume percent based on the total volume of the ultrahard material body;   removing the ultrahard material body from the first high pressure/high temperature condition; and   introducing an infiltrant material into at least a portion of the interstitial regions of the ultrahard material body during a second high pressure/high temperature condition.   
     
     
         14 . The method of  claim 13 , wherein after the step of removing, a material containing the infiltrant material is positioned adjacent a surface of the ultrahard material body. 
     
     
         15 . The method of  claim 14 , wherein during the step of introducing, the high pressure/high temperature condition is sufficient to melt the infiltrant material and cause it to infiltrate into at least a portion of the interstitial regions of the ultrahard material body. 
     
     
         16 . The method of  claim 14  wherein during the temperature during the step of subjecting is higher than the melting temperature of the infiltrant material during the step of introducing. 
     
     
         17 . The method of  claim 13 , further comprising treating the ultrahard material body to remove a portion of the infiltrant material from a region extending a depth from a working surface of the ultrahard material body, wherein the infiltrant material remains in another region of the body. 
     
     
         18 . The method of  claim 13 , wherein during the step of introducing, controlling introduction of infiltrant material to provide a first region in the ultrahard material body comprising the infiltrant material, and a second region that is substantially free of the infiltrant material. 
     
     
         19 . The method of  claim 18 , wherein the second region extends a depth from a working surface of the ultrahard material body. 
     
     
         20 . The method of  claim 13 , wherein the ultrahard material body produced during the step of subjecting comprises a first region having a porosity that is different from a second region.