A Rigid Composite Structure with a Superhard Interior Surface

Abstract

A rigid composite structure has a first bore formed in a metallic material and a second bore formed by a super hard interior segment or segments disposed within the first bore. Each segment may be lined adjacent to one another and held under compression within the first bore. The segments may be made of super hard materials such as natural diamond, synthetic diamond, polycrystalline diamond, single crystalline diamond, cubic boron nitrate or other superhard composite materials which exhibit low thermal expansion rates and are generally chemically inert. The resultant rigid composite structure may possess higher tolerances to high pressures and high temperatures within the second bore.

1 . A rigid composite structure, comprising: 
 a first bore formed in a metallic material and comprising a longitudinal axis;    a second bore formed by geometric segments comprising a superhard interior surface, the segments being disposed adjacent one another substantially co-axial along the longitudinal axis within at least a portion of the first bore.    
     
     
         2 . The structure of  claim 1 , wherein the superhard interior surface comprises a material selected from the group consisting of natural diamond, synthetic diamond, polycrystalline diamond, single crystalline diamond, cubic boron nitride, and composites thereof.  
     
     
         3 . The structure of  claim 1 , wherein the superhard interior surface comprises region that is depleted of a binder material.  
     
     
         4 . The structure of  claim 1 , wherein the superhard interior surface comprises a binder material selected from the group consisting of cobalt, niobium, titanium, zirconium, nickel, iron, tungsten, tantalum, molybdenum, silicon, a refractory group metal, or combinations thereof.  
     
     
         5 . The structure of  claim 1 , wherein the structure further comprises an intermediate material between the first bore and the geometric segments.  
     
     
         6 . The structure of  claim 5 , wherein the intermediate material is a thermal insulator.  
     
     
         7 . The structure of  claim 5 , wherein the intermediate material is wrapped around the segments.  
     
     
         8 . The structure of  claim 5 , wherein the intermediate material comprises Invar 36, Invar 42, Invar 365, a composite, a ceramic, a refractory metal, carbon fiber or combinations thereof.  
     
     
         9 . The structure of  claim 1 , wherein the metallic material comprises a material selected from the group consisting of aluminum, titanium, a refractory metal, steel, stainless steel, Invar 36, Invar 42, Invar 365, a composite, a ceramic, carbon fiber or combinations thereof.  
     
     
         10 . The structure of  claim 1 , wherein the geometric segments are brazed to one another by an interfacing material selected from the group consisting of gold, silver, a refractory metal, carbide, tungsten carbide, niobium, titanium, platinum, molybdenum, Nickel Paladiium, cadmium, chromium, copper, silicon, zinc, lead, manganese, tungsten, platinum, or combinations thereof.  
     
     
         11 . The structure of  claim 1 , wherein the geometric segments comprise a non-planar end.  
     
     
         12 . The structure of  claim 1 , wherein the superhard interior surface is made of a plurality of grains comprises a size of 1 to 300 microns.  
     
     
         13 . The structure of  claim 1 , wherein the superhard interior surface is under a radial compression of 50-200% of operating pressure.  
     
     
         14 . The structure of  claim 13 , wherein the radial compression is achieved by heat shrinking the tube around the superhard interior surface.  
     
     
         15 . The structure of  claim 1 , wherein the superhard interior surface is under an axial compression of 50-200% of proof pressure.  
     
     
         16 . The structure of  claim 15 , wherein the axial compression is achieved by providing a shoulder in the first end of the first bore and biasing unit in the second end.  
     
     
         17 . The structure of  claim 1 , wherein the superhard interior surface comprises a thermal expansion coefficient of 0.5 to 10 μin/in.  
     
     
         18 . The structure of  claim 1 , wherein the tube further comprises a port through the first bore and the superhard interior surface.  
     
     
         19 . The structure of  claim 1 , wherein superhard interior surface is polished.  
     
     
         20 . The structure of  claim 1 , wherein the superhard interior surface comprises a geometry formed by electrical discharge machining, abrasive lapping or abrasive grinding.  
     
     
         21 . The structure of  claim 1 , wherein the tube is a piston cylinder, a gun barrel, a tube and/or a pipe.  
     
     
         22 . The structure of  claim 21 , wherein the superhard interior surface is disposed within the gun barrel and comprises rifling with a land and groove or polygonal shape.  
     
     
         23 . The structure of  claim 22 , wherein a free bore of the gun barrel is formed in the superhard interior surface.  
     
     
         24 . The structure of  claim 22  wherein a throat of the gun barrel is formed in the superhard interior surface.  
     
     
         25 . A method for forming a rigid composite structure, comprising: 
 providing a structure with a first bore intermediate a first and second end;    providing a plurality of geometric segments with a superhard interior surface;    forming a second bore by joining the ends of the segments together;    thermally expanding the first bore;    placing the segments within the expanded first bore;    and shrinking the expanded first bore around the segments by cooling.    
     
     
         26 . The method of  claim 25 , wherein a geometry of the superhard segments is formed by electrical discharge machining, abrasive lapping or abrasive grinding.