| 摘要 |
Glass composition (not contg. fluorine and contg. small quantities of barium and boron) for the manufacture of hard glass having high melting temp. and high transparency was manufd. from a mixt. of SiO2 59-65, Al2O3 4-8, Na2O 12.5-18, K2O<=3, R2O=Na2O+K2O 15-8, Al2O3 /R2O 0.25-0.40, CaO 4.5-9, MgO<=4, MgO/CaO<=0.75, MgO + CaO 7-9.5, MnO<=4, BaO<=5, Fe2O3 0.1-5, MnO + BaO + Fe2O3 3.5-8, B2O3<=2, others<=1, and SO3 in others<=0.6.
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