Metal refinement and metal composite materials using carbon nanotubes

Abstract

The present invention relates to metals and matrix composites and methods of manufacture. A method of refining a metal oxide is shown. A method of forming a carbon nanotube metal matrix composite is shown using a metal oxide and an amount of carbon nanotubes. Processing is carried out using wave energy radiation such as microwave radiation. In some methods, processing is carried out while substantially isolated from external oxygen sources such as ambient air.

What is claimed is: 
     
         1 . A method, comprising:
 combining an amount of carbon nanotubes with an amount of a metal oxide to form a starting material;   heating the starting material using wave energy radiation; and   reducing the metal oxide to form a metal.   
     
     
         2 . The method of  claim 1 , wherein combining an amount of a metal oxide comprises combining an amount of a rare earth oxide. 
     
     
         3 . The method of  claim 1 , wherein combining an amount of a rare earth oxide comprises combining an amount of a rare earth oxide chosen from a group consisting of Nd, Pr, La, Ce, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Sc and Y. 
     
     
         4 . The method of  claim 1 , wherein reducing the metal oxide to form a metal comprises reducing the metal oxide to form a metal matrix encapsulating at least a portion of the carbon nanotubes. 
     
     
         5 . The method of  claim 1 , wherein the wave energy radiation is microwave radiation. 
     
     
         6 . The method of  claim 1 , wherein combining an amount of carbon nanotubes comprises combining an amount of multi-walled carbon nanotubes. 
     
     
         7 . The method of  claim 4 , wherein combining an amount of a metal oxide comprises combining an amount of copper oxide. 
     
     
         8 . The method of  claim 4 , wherein combining an amount of a metal oxide comprises combining an amount of nickel oxide. 
     
     
         9 . The method of  claim 4 , wherein heating the starting material using microwave radiation comprises heating for between about 30 seconds and 60 seconds. 
     
     
         10 . The method of  claim 4 , wherein heating the starting material using microwave radiation comprises heating the starting material using microwave radiation having a frequency range between about 300 MHz and about 300 GHz. 
     
     
         11 . A method, comprising:
 combining an amount of carbon nanotubes with an amount of a metal oxide to form a starting material;   substantially isolating the starting material from external oxygen;   heating the starting material using microwave radiation; and   reducing the metal oxide to form a metal matrix encapsulating at least a portion of the carbon nanotubes.   
     
     
         12 . The method of  claim 11 , wherein substantially isolating the starting material from external oxygen comprises enveloping the starting material in a gas. 
     
     
         13 . The method of  claim 12 , wherein substantially isolating the starting material from external oxygen comprises enveloping the starting material in an inert gas. 
     
     
         14 . The method of  claim 13 , wherein substantially isolating the starting material from external oxygen comprises enveloping the starting material in argon. 
     
     
         15 . The method of  claim 11 , wherein substantially isolating the starting material from external oxygen comprises placing the starting material substantially in a vacuum. 
     
     
         16 . The method of  claim 11 , wherein combining an amount of carbon nanotubes comprises combining an amount of multi-walled carbon nanotubes. 
     
     
         17 . The method of  claim 11 , wherein combining an amount of a metal oxide comprises combining an amount of copper oxide. 
     
     
         18 . A method, comprising:
 combining an amount of carbon nanotubes with an amount of a powdered metal oxide;   mixing the amount of carbon nanotubes with the amount of powdered metal oxide to form a substantially homogenous starting material;   substantially isolating the starting material from external oxygen;   heating the starting material using microwave radiation; and   reducing the metal oxide to form a metal matrix encapsulating at least a portion of the carbon nanotubes.   
     
     
         19 . The method of  claim 18 , wherein combining an amount of a powdered metal oxide comprises combining an amount of powdered copper oxide. 
     
     
         20 . The method of  claim 18 , wherein combining an amount of a powdered metal oxide comprises combining an amount of powdered copper oxide having particle sizes between about 150 mesh and 250 mesh. 
     
     
         21 . The method of  claim 18 , wherein combining an amount of carbon nanotubes with an amount of a powdered metal oxide comprises combining a weight of carbon nanotubes with an about equal weight of powdered copper oxide. 
     
     
         22 . The method of  claim 18 , wherein substantially isolating the starting material from external oxygen comprises enveloping the starting material in a gas. 
     
     
         23 . The method of  claim 22 , wherein substantially isolating the starting material from external oxygen comprises enveloping the starting material in an inert gas. 
     
     
         24 . The method of  claim 23 , wherein substantially isolating the starting material from external oxygen comprises enveloping the starting material in argon. 
     
     
         25 . The method of  claim 23 , wherein substantially isolating the starting material from external oxygen comprises placing the starting material substantially in a vacuum. 
     
     
         26 . The method of  claim 18 , further including compacting the starting material prior to heating. 
     
     
         27 . A metal matrix composite, comprising:
 a reduced metal oxide matrix; and   a carbon nanotube dispersed phase.   
     
     
         28 . The metal matrix composite of  claim 27 , wherein the reduced metal oxide matrix comprises a reduced copper oxide matrix. 
     
     
         29 . The metal matrix composite of  claim 27 , wherein the carbon nanotube dispersed phase comprises multi-walled carbon nanotubes. 
     
     
         30 . The metal matrix composite of  claim 27 , wherein the metal matrix composite has a hardness in a range of between about 115 and 127 Vickers hardness.