アルカリ珪酸塩ガラスの分相に及ぼすアルカリ以外の成分の影響

抄録

As basic compositions, 15Na₂O⋅85SiO₂ (Na glass) and 25Li₂O⋅75SiO₂ or 30Li₂O⋅70SiO₂ (Li glass) were selected and the effects of addition or substitution of the components such as MgO, CaO, BaO, ZnO, CdO, PbO, Al₂O₃, B₂O₃, TiO₂, ZrO₂, SiO₂, GeO₂ and P₂O₅ on miscibility temperature (T_m), viscosity, texture of phase separated glass etc. were examined.
The addition of small amount of the divalent components lowered T_m of Na glass in the order CaO<BaO<CdO<ZnO<MgO<PbO. But even in the case of CaO the introduction to the amount contained in commercial soda-lime-silica glasses (e. g. sheet glass) prevented the phase separation occurring. Among the polyvalent components, the effects of P₂O₅ and Al₂O₃ on T_m were especially remarkable, the former raised and the latter lowered it. B₂O₃ lowered T_m at first and then raised it with increasing amount of the addition, for viscosity B₂O₃ gave reverse change, though. In the glasses added the components which raised T_m, the interconnected two phase structures were liable to be observed after heat treatment. Similar results were also obtained in Li glass.
It was showed from the plot of T_m of 15Na₂O⋅85SiO₂+2.5RO_x glasses against ionic field strength of added cations that (i) in case of the network modifiers, T_m rose with increasing ionic field strength of added cation, (ii) this was also true for network formers, but (iii) this relation became inverse for intermediates. The possible reason was discussed from the point of the effects of added cations on the compatibility between SiO₂ and Na containing phase.
Moreover it was pointed out that the chemical durability was low in the glass with high T_m.