| 摘要 |
LEAD-FREE OPTICAL LIGHT FLINT AND DOUBLE-LIGHT FLINT GLASSES HAVING A REFRACTIVE INDEX ND OF BETWEEN 1.52 AND 1.57 AND AN ABBE COEFFICIENT VD OF BETWEEN 43 AND 52 ARE DESCRIBED, WHICH HAVE THE FOLLOWING COMPOSITION (IN % BY WEIGHT BASED ON OXIDES) : SIO2 48-55, B2 O3 7-9, K2O 18-20, A12 O3 7-9, LA2O3 0.1-2, ZRO2 0-1, (ALGEBRAIC SUM) LA2O3+ZRO2 0.5-2, TIO2 5.5-12, F- 1.5-6, (A12O3+LA2O3) / (TIO2+ZRO2) = 0.73-1.15. THE GLASSES SHOW OUTSTANDING CRYSTALLIZATION STABILITY AND VERY GOOD CHEMICAL RESISTANCE.FINING AGENTS SB203 AND/OR C1 MAY BE PRESENT IN AMOUNT UP TO 0.5 WT %.
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