Aluminum phosphate compositions, coatings and related composites and applications

Abstract

Composites comprising an aluminum phosphate-based coating component and methods for sealing porous substrate surfaces.

1 . A configured composite comprising a silicon carbide substrate and a coating thereon comprising an aluminum phosphate compound containing Al—O—Al bonds and having an aluminum to phosphorous ratio from about 0.5 to 1 to about 25 to 1. 
     
     
         2 . A configured composite of  claim 1  in which the coated silicon carbide is planarized. 
     
     
         3 . A configured composite of  claim 2  suitable as an optical device. 
     
     
         4 . A configured composite of  claim 1  formed by coating a silicon carbide substrate with a precursor alcoholic solution containing an aluminum salt and an phosphorus ester and drying and curing the coating. 
     
     
         5 . A configured composite of  claim 4  in which the aluminum salt is aluminum nitrate. 
     
     
         6 . A configured composite of  claim 4  in which the alcoholic solution is formed in ethanol or methanol. 
     
     
         7 . A configured composite of  claim 4  in which the phosphorus ester is formed from phosphorus pentoxide.