| 摘要 |
The present invention relates to a method of producing a borosilicate glass exhibiting a low coefficient of thermal expansion, viz., less than about 20 x 10<->7/ DEG C. over the range of room temperature to 300 DEG C., an ability to withstand repeated thermal cycling between room temperature and temperatures up to 1300 DEG C. and higher without devitrification, and the ability to flow, when present in particulate form, at temperatures between about 1000 DEG -1250 DEG C. The method contemplates impregnating a porous, essentially alkali metal-free, high silica material with a solution or a molten mass of a B2O3-containing compound, the B2O3-containing compound also being essentially free from alkali metals. The impregnated glass is thereafter dried to eliminate any solvent. High emissivity can be imparted by incorporating minor amounts of such materials as CoO, NiO, MoO3, Fe2O3, and V2O5 as dopants during the impregnation step. The impregnated material is especially useful as a glaze to provide an impervious coating on high purity silica insulating tiles.
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