HIGH PURITY OPAQUE QUARTZ GLASS, ITS PRODUCTION AND ITS USE

摘要

PURPOSE: To improve the shielding effect against heat rays by compacting a specified high purity amorphous silica powder and sintering. CONSTITUTION: A high purity amorphous silica powder having 0.5-10μm average particle size and containing <=1ppm impurity content of at least one element selected from Li, Na, K, Fe, Ti, Al is dispersed in pure water and cast to obtain a molded body. The molded body is then sintered in 1-2kg/cm<3> nonoxidizing gas atmosphere at 1730-1850 deg.C for 1min to several tens minutes to obtain a high purity opaque quartz glass. The obtd. opaque quartz glass contains 3×10<6> to 9×10<6> cm<-3> independent bubbles of 20-40μm average size including independent bubbles of >=100μm size by <=1% of the whole bubbles and shows <=5% transmittance of straight rays at 900nm wavelength when the glass is 1mm thick.