| 摘要 |
A watch glass which, due to chemical curing by means of ion exchange, has high flexural and good scratch resistance comprises (in % by weight) Si 55-68, Al2O3 11-21, B2O3 0-6, La2O3 0-2, TiO2 0-1, NaO 9-15, K2O 1-8, MgO 0.5-4, CaO 0-2 and other oxides 0-7, including pigment oxides, for example CoO, in order to achieve a blue colouration.
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