METHOD OF MAKING OPTICAL QUALITY OBJECTS FROM SUPERPURITY GLASS Russian patent published in 2010 - IPC C03B19/06 

FIELD: physics.

SUBSTANCE: pyrogenic powdered silicon dioxide is packet into granules with size less than 1 mm. The pyrogenic powdered silicon dioxide has the following properties: BET surface area ranging from 30 to 90 m²/g; "ДБФ" index equal to or less than 80; average area of the aggregate less than 25000 nm²; average perimetre of the circle of the aggregate less than 1000 nm, in which not less than 70% of aggregates have perimetre less than 1300 nm. The granules are sintered at temperature below 1100°C. Air bricks are made from the granules. The air bricks are dried and partially sintered in a chamber at temperature above 1000°C. Chlorine gas is fed into the chamber and/or a vacuum is created in the chamber and/or inert gas is blown into the chamber. The air bricks are then completely sintered in the chamber by increasing temperature in the chamber from 1200°C to over 1720°C.

EFFECT: prevention of cracking, shrinkage and contamination of air brick during sintering from powdered silicon dioxide.

2 cl, 10 ex, 5 tbl