| 摘要 |
PURPOSE:To contrive to improve transparency and corrosion resistance to acid and alkali, by blending SiO2 with oxides of Al, Na, K, Sr and Ba in specific ranges. CONSTITUTION:A high expansive glass composition consisting of 50-60mol.% SiO2, 3-10mol.% Al2O3, 5-15mol.% Na2O, 5-15mol.% K2O, 0.3-0.7mol.% Na2O/(Na2O+K2O), 5-15mol.% SrO and 5-15mol.% BaO. When SiO2 is <40mol.%, chemical durability is lowered and when SiO2 exceeds >60mol.%, melting properties and a coefficient of expansion are dropped. When Na2O and K2O are <5mol.%, raising effects on melting properties and coefficient of expansion are small and when Na2O and K2O exceed 15mol.%, chemical durability is lowered and the component ratio is 0.3-0.7 because too much partiality reduces chemical durability. SrO and BaO improve melting properties and coefficient of expansion without lowering chemical durability in comparison with Na2O and K2O, when SrO and BaO are <5mol.%, the effects are small and when SrO and BaO exceed 15mol.%, chemical durability is lowered and devitrification likely occurs.
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