| 摘要 |
1307303 Glass-ceramic compositions COMPAGNIE DE SAINT-GOBAIN 6 May 1970 [14 May 1969] 21748/70 Heading C1M A glass-ceramic comprises (weight per cent): where R 2 O is Na 2 O and/or K 2 O, and RO is CaO + MgO + BaO (optional) + ZnO (optional), the constituents totalling at least 95% of the product and the balance, if any, consisting of incidental ingredients or impurities. In making the glass-ceramic the raw constituents are melted by oxidizing fusion, shaped into articles, nucleated and crystallized, the constituents including a felspathic rock containing substantially 1% of Li 2 O, 0À5% P 2 O 5 , 0À1% SnO, and 0À1% BeO and/or a blast furnace slag containing substantially 1% FeO, 1% MnO, 1% TiO 2 , 0À3% P 2 O 5 and 1% S which are acceptable levels of impurities. Preferably the nucleation treatment is started at a temperature lower than the softening temperature of the glass, the temperature being raised at, e.g. up to 5‹ C. per minute to the crystallization temperature. Nucleation may be carried out at not more than 650‹ C. for less than 3 hours, and crystallization at not more than 900‹ C. Nucleation of sheets is carried out while vertically suspended. |
