Isotropic pitch-based materials for thermal insulation

Abstract

Insulation materials suited to high temperature applications, such as the insulation of furnaces, are formed from a mixture of pitch carbon fibers, such as isotropic pitch carbon fibers, and a binder comprising a solution of sugar in water. The sugar solution is preferably at a concentration of from 20-60% sucrose to yield a low density material having high flexural strength and low thermal conductivity when carbonized to a temperature of about 1800° C.

1. An insulation material formed by the method of: combining carbon-containing fibers having an average length of from about 400 to about 800 micrometers, which include pitch-based carbon fibers, with a binder which includes a soluble sugar to form a mixture; forming the mixture into a solid perform having a general shape of the thermal insulation material; and heating the perform to a sufficient temperature to carbonize the perform and form the thermal insulation material, wherein the thermal insulation material has a thermal conductivity of between about 0.15 W/m-K and less than about 0.4 W/m°K-K at 25° C. 
     
     
       2. A low density thermal insulation article formed from a mixture of isotropic pitch carbon fibers having an average length of from about 400 to about 800 micrometers and a sugar binder which has been heated to a sufficient temperature to carbonize the mixture, the article having a density of from about 0.1 to about 0.4 g/cm3 g/cm 3  and a thermal conductivity of between about 0.15 W/m-K and about 0.4 W/m-K at 25° C. 
     
     
       3. The article of claim 2 wherein the mixture further includes at least one of mesophase pitch carbon fibers or other carbonized fibers. 
     
     
       4. The article of claim 2 wherein the mixture further includes carbon fibers from cotton. 
     
     
       5. The article of claim 2 wherein the article includes carbon fibers derived from rayon or PAN. 
     
     
       6. The material of claim 1 wherein the material further includes other carbonized fibers. 
     
     
       7. The material of claim 6 wherein the other carbonized fibers are derived from at least one of rayon or PAN. 
     
     
       8. A low density thermal insulation article formed from a mixture of carbon fibers having an average length of from about 400 to about 1600 micrometers and a sugar binder which has been heated to a sufficient temperature to carbonize the mixture, the article having a density of from about 0.1 to about 0.4 g/cm 3  and a thermal conductivity of between about 0.15 W/m-K and about 0.4 W/m-K at 25° C., wherein at least a portion of the carbon fibers are derived from cotton. 
     
     
       9. The low density article of claim 8 wherein at least a portion of the carbon fibers are derived from rayon fibers or PAN fibers. 
     
     
       10. A low density thermal insulation article formed from a mixture of carbon fibers which comprise carbon fibers derived from rayon having an average length of from about 400 to about 1600 micrometers and a sugar binder which has been heated to a sufficient temperature to carbonize the mixture, the article having a density of from about 0.1 to about 0.4 g/cm 3  and a thermal conductivity of between about 0.15 W/m-K and about 0.4 W/m-K at 25° C. wherein the carbon fibers derived from rayon comprises a portion of the carbon fibers in the article. 
     
     
       11. The article of claim 10 wherein the average length of the carbon fibers comprises about 400 to about 1200 micrometers. 
     
     
       12. The article of claim 10 further comprising carbon fibers derived from cotton. 
     
     
       13. The article of claim 10 further comprising carbon fibers derived from PAN.