Abstract: The instant invention is directed toward a process for enhancing the permselective properties, selectively sealing defects and pinholes, controllably altering the pore size and stabilizing the permselective properties of articles having apperatures therein comprising the steps of: simultaneously contacting an article having a first and second surface, said first and second surfaces being capable of passing ozone and silicon compounds therethrough and said first and second surfaces being oriented such that said silicon compounds and ozone can react across said first and second surfaces, with ozone on said first surface and a silicon compound on said second surface and wherein said contacting is conducted for a time and at a temperature and pressure sufficient to allow said ozone and said silicon compound to form a silicon oxide.

Abstract: The present invention provides for microporous ceramic materials having a surface area in excess of 70 m.sup.2 /gm and an open microporous cell structure wherein the micropores have a mean width of less than 20 Angstroms and wherein said microporous structure comprises a volume of greater than about 0.03 cm.sup.3 /gm of the ceramic. The invention also provides for a preceramic composite intermediate composition comprising a mixture of a ceramic precursor and finely divided silicon carbide or silicon nitride, whose pyrolysis product in inert atmosphere or in an ammonia atmosphere at temperatures of up to less than about 1100.degree. C. gives rise to the microporous ceramics of the invention. Also provided is a process for the preparation of the microporous ceramics of the invention involving pyrolysis of the ceramic intermediate under controlled conditions of heating up to temperatures of less than 1100.degree. C. to form a microporous ceramic product.