Hochreines opakes Quarzglas, Verfahren zu dessen Herstellung und dessen Verwendung

摘要

The high-purity, opaque quartz glass containing 3 x 10<6> - 9 x 10<6> of closed cells having an average size of 20-40 mu m per 1 cm<3>, a ratio of closed cells having sizes of 100 mu m or more to the whole of cells being 1% or less, thereby showing 5% or less of linear transmittance for near infrared rays ( lambda =900 nm) at a thickness of 1 mm is produced by compacting amorphous silica powder having an average particle size of 0.5-10 mu m, in which each of impurities selected from Li, Na, K, Fe, Ti and Al is 1 ppm or less, if any, and sintering the resultant green body at 1730-1850 DEG C.