Graphite-silicon carbide composite and making method

Abstract

A graphite-silicon carbide composite comprises a graphite substrate and a silicon carbide layer formed thereon and comprising silicon carbide particles in fused and contact bonded state. The composite has excellent oxidation resistance and finds a wide range of application as heat resistant material. The method of forming a silicon carbide layer on graphite surface is simple and consistent.

1 . A method for preparing a graphite-silicon carbide composite comprising the steps of:
 thermally spraying a metallic silicon powder onto a surface of a graphite substrate, and   heat treating the sprayed substrate in a non-oxidizing atmosphere at a temperature of 1100° C. to 1700° C. for forming on the substrate surface a silicon carbide layer comprising silicon carbide particles in fused and contact bonded state.   
     
     
         2 . The method of  claim 1 , wherein the metallic silicon powder has an average particle size of 0.5 μm to 50 μm. 
     
     
         3 . The method of  claim 1 , wherein the temperature of heat treating is 1200° C. to 1500° C. 
     
     
         4 . A method of preparing a graphite-silicon carbide composite comprising the steps of:
 plasma spraying a metallic silicon powder having an average particle size of 3 μm to 30 μm onto a surface of a carbon/carbon composite substrate composed of carbon fibers and graphite particles having a mixing ratio of between 7/3 and 3/7 in a thickness of 10 to 300 μm, and   heat treating the sprayed substrate in a non-oxidizing atmosphere at a temperature of 1100° C. to 1700° C. for forming on the carbon/carbon composite substrate a silicon carbide layer comprising silicon carbide particles in fused and contact bonded state, thereby obtaining the graphite-silicon carbide composite having a gas permeability equal to or less than 1.0×10 −2  cm 2 /s.   
     
     
         5 . The method of  claim 4 , wherein the temperature of heat treating is 1200° C. to 1500° C. 
     
     
         6 . The method of  claim 4 , wherein the metallic silicon powder is sprayed in a thickness of 10 to 200 μm. 
     
     
         7 . The method of  claim 4 , wherein the gas permeability of the graphite-silicon carbide composite is equal to or less than 1.0×10 −3  cm 2 /s.