Nanocrystalline ceramic materials reinforced with single-wall carbon nanotubes

Abstract

Composites of ceramic materials, notably alumina or metal oxides in general, with single-wall carbon nanotubes are consolidated by electric field-assisted sintering to achieve a fully dense material that has an unusually high fracture toughness compared to the ceramic alone, and also when compared to composites that contain multi-wall rather than single-wall carbon nanotubes, and when compared to composites that are sintered by methods that do not include exposure to an electric field.

1 - 9 . (canceled)  
     
     
         10 . A high-performance ceramic material prepared by a process comprising consolidating a mixture of ceramic particles of less than 100 nm in diameter and single-wall carbon nanotubes into a continuous mass by compressing said mixture while passing an electric current through said mixture.  
     
     
         11 . A high-performance ceramic material in accordance with  claim 10  in which said ceramic oxide particles are alumina.  
     
     
         12 . A high-performance ceramic material in accordance with  claim 10  in which said single-wall carbon nanotubes constitute from about 3% to about 25% by volume of said mixture.  
     
     
         13 . A high-performance ceramic material prepared by a process comprising consolidating a mixture of ceramic particles of less than 100 nm in diameter and single-wall carbon nanotubes into a continuous mass by compressing said mixture at a pressure of from about 40 MPa to about 100 MPa and a temperature of from about 900° C. to about 1,400° C., while passing a pulsed direct current of from about 500 A/cm2 to about 5,000 A/cm2 through said mixture.  
     
     
         14 . A high-performance ceramic material prepared by a process comprising: 
 (a) forming a mixture of alumina powder and single-wall carbon nanotubes in which said single-wall carbon nanotubes constitute from about 4% to about 20% by volume of said mixture; and    (b) consolidating said mixture so activated into a continuous mass by compressing said mixture at a pressure of from about 40 MPa to about 100 MPa while exposing said mixture to a pulsed direct current of from about 500 A/cm 2  to about 5,000 A/cm 2.