BLACK QUARTZ GLASS HAVING TRANSPARENT PART AND ITS PRODUCTION

摘要

PROBLEM TO BE SOLVED: To provide black quartz glass which extremely lessens the emission of contaminants during production, has high mechanical strength, has high light shieldability and far IR radiatability and is easily workable and a process for producing the same. SOLUTION: The black part of the quartz glass consisting of a black part and a transparent part consists of the black quartz glass which contains a blackening metal element and has an apparent density of 2.15 to 2.40 g/cm2 and has the black color degree in a Hunter color specification chart of 0 to 10 in lightness (L value), -0.5 to 0.5 in chromaticness index (a value) and -5.0 to 2.0 in chromaticness index (b value). The transparent part consists of the transparent quartz glass of 2.19 to 2.21 g/cm3 in apparent density and <=1000 pieces/cm3 in the quantity of air rubbles of a diameter of >=200μm.