Hydrogen-containing gas-ceramics

A method for preparing a gas-ceramic body having a SiO.sub.2 -rich glassy surface layer and consisting essentially of very fine-grained crystals of cubic BPO.sub.4 and very small, unconnected gas-containing cells uniformly dispersed within a SiO.sub.2 -rich glassy matrix, wherein said gas consists predominantly of hydrogen, comprising the steps of:

• (a) melting a batch for a glass consisting essentially, expressed in terms of weight percent on the oxide basis, of 30-60% SiO.sub.2, 10-40% B.sub.2 O.sub.3, 15-45% P.sub.2 O.sub.5, and up to 20% total of at least one material in the indicated proportion selected from the group consisting of 5-15% BN, 5-10% Si, 5-10% SiC, and 10-20% Si.sub.3 N.sub.4 ;
• (b) cooling said melt to at least within the transformation range thereof and simultaneously shaping a glass body of a desired configuration therefrom;
• and thereafter
• (c) exposing said glass body to a temperature between about 900.degree.-1050.degree. C. for a period of time sufficient to cause the development of cubic BPO.sub.4 crystals and gas-containing cells therein.