Superhard cutter having shielded substrate

Abstract

A cutter for use with a drill bit includes: a substrate for mounting in a pocket of the drill bit and made from a cermet material; a cutting table made from a polycrystalline superhard material and mounted to the substrate; and a shield disposed in an outer recess of the substrate adjacent to the cutting table, mounted to the substrate, extending from the cutting table along a partial length of the substrate, and made from a composite material comprising the polycrystalline superhard material and a ceramic.

1 . A cutter for use with a drill bit, comprising:
 a substrate for mounting in a pocket of the drill bit and made from a cermet material;   a cutting table made from a polycrystalline superhard material and mounted to the substrate; and   a shield disposed in an outer recess of the substrate adjacent to the cutting table, mounted to the substrate, extending from the cutting table along a partial length of the substrate, and made from a composite material comprising the polycrystalline superhard material and a ceramic.   
     
     
         2 . The cutter of  claim 1 , wherein an amount of superhard material in the composite material ranges between seventy and ninety-five percent by volume. 
     
     
         3 . The cutter of  claim 1 , wherein the shield and the outer recess extend at least around one-eighth of a side of the substrate. 
     
     
         4 . The cutter of  claim 3 , wherein the shield and the outer recess surround the substrate. 
     
     
         5 . The cutter of  claim 1 , wherein the cermet material comprises the ceramic and a metal binder. 
     
     
         6 . The cutter of  claim 1 , wherein the partial length ranges between one-fifth and two-thirds of a length of the substrate. 
     
     
         7 . The cutter of  claim 1 , wherein the shield has a maximum thickness at an interface with the cutting table and the thickness thereof decreases along the substrate as the shield extends away from the cutting table. 
     
     
         8 . The bit of  claim 1 , wherein an interface between the shield and the substrate is inclined at an angle relative to a side of the substrate 
     
     
         9 . A bit for drilling a wellbore, comprising:
 a shank having a coupling formed at an upper end thereof;   a body mounted to a lower end of the shank; and   a cutting face forming a lower end of the bit and comprising:
 a blade protruding from the body; and 
 the cutter of  claim 8 , wherein:
 the substrate is mounted in a pocket formed in the blade at a back rake angle, and 
 the inclination angle corresponds to the back rake angle such that the interface is parallel or substantially parallel to rock engaged by the cutter during drilling. 
 
   
     
     
         10 . The cutter of  claim 1 , wherein a portion of the cutting table adjacent to a working face thereof and a portion of the shield adjacent to the cutting table are at least substantially free of catalyst. 
     
     
         11 . The cutter of  claim 1 , wherein an interface between the shield and the substrate is undulating. 
     
     
         12 . The cutter of  claim 1 , wherein the cutting table has a non-planar working face with a cutting feature. 
     
     
         13 . The bit of  claim 12 , wherein the cutting feature is at least a portion of a protruding ridge. 
     
     
         14 . The bit of  claim 12 , wherein:
 the cutting feature is a protruding ridge, and   the working face has a plurality of protruding ridges spaced therearound.   
     
     
         15 . The bit of  claim 12 , wherein:
 the working face is concave, and   the cutting feature is an axis of the cutting table.   
     
     
         16 . The cutter of  claim 12 , wherein an interface between the shield and the substrate is undulating and a long portion of the undulation is aligned with the cutting feature. 
     
     
         17 . A method for manufacturing a superhard cutter, comprising:
 forming a cermet substrate having a recessed outer portion;   loading superhard cutting table powder into an inner can;   loading shield powder into the inner can, the shield powder comprising superhard material and a ceramic;   inserting the recessed outer portion into the inner can;   placing an outer can over the inner can;   pressing the cans together, thereby forcing the shield powder into the recessed outer portion;   sealing the cans, thereby forming a can assembly; and   subjecting the can assembly to high pressure and high temperature, thereby forming the superhard cutter.