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.

Description

BACKGROUND OF THE INVENTIONOf non-composite, ordinary materials, the ones that are most resistant to high thermal stress tend to be alloys of molybdenum and alloys of copper, see Table 1. These alloys excel in their thermal stress parameter, kσT / αE, combining high thermal conductivity, reasonably high strength, low young's modulus, and low thermal expansion coefficients. Applications that need these properties include any highly compact, high value heat exchangers, as in rocket and jet engines, fusion reactor first walls, hypersonic plane wings, or any other high thermal stress and shock applications.Some other high temperature alloys appear attractive, and can be expected to exceed these two for very special applications. Based on their thermal stress parameters, other attractive materials should include Be, Mo—Re, Ta—W, and tungsten (W), but these materials suffer from being more expensive than Mo or Cu alloys, and / or suffer from being hard to fabricate and join.SUMMARY OF THE INV...

AI Technical Summary

Problems solved by technology

Based on their thermal stress parameters, other attractive materials should include Be, Mo—Re, Ta—W, and tungsten (W), but these materials suffer from being more expensive than Mo or Cu alloys, and / or suffer from being hard to fabricate and join.