Bulk superhard B-C-N nanocomposite compact and method for preparing thereof

Abstract

Bulk, superhard, B-C-N nanocomposite compact and method for preparing thereof. The bulk, superhard, nanocomposite compact is a well-sintered compact and includes nanocrystalline grains of at least one high-pressure phase of B-C-N surrounded by amorphous diamond-like carbon grain boundaries. The bulk compact has a Vicker's hardness of about 41-68 GPa. It is prepared by ball milling a mixture of graphite and hexagonal boron nitride, encapsulating the ball-milled mixture, and sintering the encapsulated ball-milled mixture at a pressure of about 5-25 GPa and at a temperature of about 1000-2500 K.

1 - 5 . (canceled)  
     
     
         6 . A process for preparing a bulk, superhard, nanocomposite compact consisting essentially of nanocrystalline grains of at least one high-pressure phase of B-C-N surrounded by amorphous, diamond-like carbon grain boundaries, comprising the steps of: 
 (a) ball milling a mixture of graphite and hexagonal boron nitride to produce a mixture of amorphous and/or nanocrystalline graphitic carbon and boron nitride;    (b) encapsulating the ball-milled mixture; and    (c) sintering the encapsulated ball-milled mixture at a pressure of about 5-25 GPa and a temperature of about 1000-2500 K, thereby producing a bulk, superhard nanocomposite compact consisting essentially of nanocrystalline grains of B-C-N surrounded by amorphous diamond-like carbon grain boundaries.    
     
     
         7 . The process of  claim 6 , wherein the ball milled mixture of graphite hexagonal boron nitride consists essentially of about 1-4 parts graphite to about 1 part hexagonal boron nitride.  
     
     
         8 . The process of  claim 7 , wherein the ball milled mixture of graphite and hexagonal boron nitride consists essentially of about 1 part graphite to about 1 part hexagonal boron nitride.  
     
     
         9 . The process of  claim 7 , wherein the ball milled mixture of graphite and hexagonal boron nitride consists essentially of about 2 parts graphite to about 1 part hexagonal boron nitride.  
     
     
         10 . The process of  claim 7 , wherein the ball milled mixture of graphite and hexagonal boron nitride consists essentially of 4 parts graphite to about 1 part hexagonal boron nitride.  
     
     
         11 . The process of  claim 7 , wherein the encapsulated ball-milled mixture is sintered at a pressure of about 10-25 GPa and at a temperature of about 2000-2500 K.  
     
     
         12 . The process of  claim 7 , wherein the encapsulated ball-milled mixture is sintered at a pressure of about 15-25 GPa and at a temperature of about 2000-2500 K.  
     
     
         13 . The process of  claim 7 , wherein the encapsulated ball-milled mixture is sintered at a pressure of about 16-25 GPa and at a temperature of about 2100-2500 K.  
     
     
         14 . The process of  claim 7 , wherein the encapsulated ball-milled mixture is sintered at a pressure of about 20-25 GPa and at a temperature of about 2000-2500 GPa.  
     
     
         15 . The process of  claim 7 , wherein the encapsulated ball-milled mixture is sintered at a pressure of about 20-25 GPa and at a temperature of about 2100-2400 K.  
     
     
         16 . The process of  claim 7 , wherein the encapsulated ball-milled mixture is sintered at a pressure of about 20 GPa and at a temperature of about 2000-2400 K.  
     
     
         17 . The process of  claim 7 , wherein the encapsulated ball-milled mixture is sintered at a pressure of about 25 GPa and at a temperature of about 2100-2300 K.  
     
     
         18 . The process of  claim 6 , wherein step (b) comprises encapsulating the amorphous mixture in capsule comprising platinum, gold, rhenium, or boron nitride.  
     
     
         19 . The process of  claim 7 , wherein said compact has a Vickers hardness of about 41-68 GPa.  
     
     
         20 . The process of  claim 7 , wherein said compact has a Vickers hardness of about 50-68 GPa.  
     
     
         21 . The process of  claim 7 , wherein said compact has a Vickers hardness of about 62-68 GPa.  
     
     
         22 . The process of  claim 7 , wherein said compact has a Vickers hardness of 68 GPa.  
     
     
         23 - 38 . (canceled)  
     
     
         39 . A machining tool comprising a bulk, superhard, nanocomposite compact consisting essentially nanocrystalline grains of B-C-N surrounded by amorphous diamond-like carbon grain boundaries.  
     
     
         40 . The tool of  claim 39 , wherein said compact has a Vickers hardness of about 41-68 GPa.  
     
     
         41 . The tool of  claim 39 , wherein said compact has a Vickers hardness of about 50-68 GPa.  
     
     
         42 . The tool of  claim 39 , wherein said compact has a Vickers hardness of about 62-68 GPa.  
     
     
         43 . The tool of  claim 39 , wherein said compact has a Vickers hardness of 68 GPa.