METHOD OF CLEANSING OF ARTICLE MADE OF QUARTZ GLASS FROM STRUCTURAL IMPURITIES Russian patent published in 1995 - IPC

FIELD: quartz glass production. SUBSTANCE: article made of quartz glass or lumpy quartz is placed in current-conducting medium of positive potential. Thermal treatment is performed at 800-1300 C for at least 1 h, at voltage value 0.5 kV (not less). Cooling is carried out firstly in electric current field up to 600 C and further in inertial current field. Impurities content depending on the article type: Na⁺ is (0.05-1.8) x 10^-4 wt.-%; K⁺ is (0.07-5.2) x 10^-4 wt.-%; Li⁺ is (0.05-0.5) x 10^-4 wt.-%. Silicon, silicon carbide and zirconium oxide were used as current-conducting medium. EFFECT: enhanced quality of quartz glass. 2 cl, 1 tbl, 3 dwg