| 摘要 |
PROBLEM TO BE SOLVED: To produce glass for chemical tempering capable of producing glass of high homogeneity, having the low melting temperature and exhibiting excellent weather resistance even after chemical tempering by specifying the glass composition consisting of SiO2, Al2O3, Li2O, Na2O, ZrO2, ZnO and P2O5. SOLUTION: The composition of this glass is set by maintaining the content of ZrO2 for increasing viscosity at high temperatures within a relatively low level and by including ZnO and P2O5 in a preferred quantity respectively for increasing resistance to weather and for promoting chemical tempering. The glass contains 58-65 wt.% SiO2, 8-15 wt.% Al2O3, 4-10 wt.% Li2O, 9-13 wt.% Na2O, 0.5-2 wt.% ZrO2, 2-5 wt.% ZnO and 0.5-2 wt.% P2O5. The glass is prepared by throwing a raw material mixture into a platinum crucible, by heating it in an electric furnace at 1,450 deg.C for 6 h, by molding the resulting glass into a preferred product form and by the ion-exchange treatment through dipping the glass in a mixed fused salt consisting of 40 wt.% sodium nitrate and 60 wt.% potassium nitrate and through retaining the glass at 380 deg.C for 3 h.
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