Copper-niobium, copper-vanadium, or copper-chromium nanocomposites, and the use thereof in heat exchangers

Abstract

We propose here a class of new materials for high heat-flux applications including high flux heat exchangers, rocket engines, jet engines, gas turbines, space-plane wings, and fusion reactors. The materials are nano-composites formed from copper and a refractory metal, especially niobium, vanadium, or chromium, but also potentially silver, iron, tantalum, tungsten, or molybdenum. The copper plus refractory mix is fast-melted, e.g. by arc melting, and then fast-cooled and worked. When cast the component metals separate into a fractile metal-metal composite that should have excellent heat-transfer qualities. Working the material makes it a lot stronger by extending the fractile structures into micron, and submicron (nano-scale) filaments and sheets of metal-metal composite. The resulting strong, high thermal-conductivity material should be excellent for demanding heat exchange applications, especially those where the heat flux is so high that ordinary materials of construction would suffer from thermal creep: that is from large forces generated internally by the differential expansion caused by the heat flux. Typical heat exchanger surfaces that might use this material might be tubes or indented flat plates.

1 . A heat exchanger comprising a copper-refractory metal composite that defines a structure of the heat exchanger. 
     
     
         2 . The heat exchanger of  claim 1 , where the refractory metal is niobium 
     
     
         3 . The heat exchanger of  claim 1 , where the refractory metal is vanadium 
     
     
         4 . The heat exchanger of  claim 1 , where the refractory metal is chromium 
     
     
         5 . The heat exchanger of  claim 1  where the composite is worked to a true-strain in excess of 2. 
     
     
         6 . The heat exchanger of  claim 1 , where the composite is worked to a true strain in excess of 5. 
     
     
         7 . The heat exchanger of  claim 1  where the refractory metal content is between 10% and 60%. 
     
     
         8 . The heat exchanger of  claim 1 , where the refractory content is between 20% and 50% 
     
     
         9 . The heat exchanger of  claim 1  as part of a rocket engine. 
     
     
         10 . The heat exchanger of  claim 1 , where the exchanger serves as a fusion reactor first wall. 
     
     
         11 . The heat exchanger of  claim 1 , where the exchanger is part of a jet engine. 
     
     
         12 . The heat exchanger of  claim 1  as part of a gas turbine system. 
     
     
         13 . The heat exchanger of  claim 1  where the exchange surface is in the form of a tube made of the composite. 
     
     
         14 . The heat exchanger of  claim 1  where the exchange surface is in the form a flat sheet. 
     
     
         15 . Heat exchanger of  claim 1 , where the surface is coated with a layer of a metal of nickel, molybdenum, beryllium, or tungsten. 
     
     
         16 . Heat exchanger made of  claim 1  where the refractory metal is tantalum, molybdenum, tungsten, iron, silver, or a combination thereof. 
     
     
         17 . A process of forming a refractory nanofilament filled copper matrix comprising:
 fast casting a molten mixture comprising a refractory copper mixture of more than 20% refractory to form a casting; then mechanical working said casting to form dendrites whose mean diameter is less than 10μ.   
     
     
         18 . The process of  claim 17  wherein said mechanical working is rolling or drawing. 
     
     
         19 . The process of  claim 18  wherein said mechanical working is rolling or drawing and occurs without annealing. 
     
     
         20 . The process of  claim 17  wherein said dendrites have a mean diameter is less than 500 nanometers. 
     
     
         21 . The process of  claim 17  wherein said dendrites have a mean diameter of 40 to 400 atoms width and are formed of copper, refractory, or a combination thereof. 
     
     
         22 . The process of  claim 17  wherein said molten mixture consists essentially of copper with more than 20% percent niobium, vanadium, or chromium or a combination thereof. 
     
     
         23 . The process of  claim 17  wherein said molten mixture has a low oxygen content. 
     
     
         24 . The process of  claim 17  where said molten mixture consists essentially of copper with more that 20% tantalum, molybdenum, tungsten, iron, or a combination thereof