Method of forming a fiber-reinforced ceramic matrix composite

Abstract

This invention pertains to a method of forming a fiber-reinforced ceramic matrix composite comprising: (a) impregnating a ceramic fiber coated with at least one layer binary coating comprised of boron nitride and silicon nitride wherein the silicon nitride is applied over the boron nitride with a preceramic composition comprising a curable preceramic polymer; (b) forming the impregnated fibers into a desired shape; (c) curing the formed impregnated fibers; (d) heating the cured impregnated fibers of (c) to a temperature of at least 1000° C. in an inert atmosphere for a time effective to convert the preceramic polymer to a ceramic.

What is claimed is:  
     
         1 . A method of forming a fiber-reinforced ceramic matrix composite comprising: 
 (a) impregnating a ceramic fiber coated with at least one layer binary coating comprised of boron nitride and silicon nitride wherein the silicon nitride is applied over the boron nitride with a preceramic composition comprising a curable preceramic polymer;    (b) forming the impregnated fibers into a desired shape;    (c) curing the formed impregnated fibers;    (d) heating the cured impregnated fibers of (c) to a temperature of at least 1000° C. in an inert atmosphere for a time effective to convert the preceramic polymer to a ceramic.    
     
     
         2 . The method of  claim 1  wherein the cured impregnated fibers are heated in step (d) to a temperature of at least 1200° C.  
     
     
         3 . The method of  claim 1  wherein the preceramic composition additionally comprises fillers.  
     
     
         4 . The method of  claim 1  wherein there is an additional coating over the binary coating.  
     
     
         5 . The method of  claim 1  wherein the additional coating is silicon carbide.