Two-layer high-temperature coating on ceramic substrate and its production

摘要

A high temp. coating for esp. porous ceramic substrates comprises (a) a (prim.) barrier layer of compsn. (by wt.) 90-99.9% quartz glass and 0.1-10% silicon tetraboride (contg. more than 96 wt.% SiB4); and (b) a (final) emissive enamel layer of compsn. (by wt.) 95-98.5% high silica content glass and 1.5-5% silicon tetraboride (contg. more than 96 wt.% SiB4). Also claimed is a process for providing an esp. porous ceramic substrate with the above coating.