硼酸塩系のガラス化範囲について

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Studies have been made on the problems of the glass formation range, which are important as the fundamental data for the science and industry of glass, and the systematic investigation of which has never been carried out.Borate systems were studied using, except B2O3, the oxides of 16 a-group elements-Li, Na, K, Be, Mg, Ca, Sr, Ba, Al, La, Ti, Zr, Th, Nb, Ta, W-and 9 b-group elements-Zn, Cd, In, Tl, Sn, Pb, As, Sb, Bi-to combine into 266 ternary systems in all. The other combinations were regarded as having no glass formation range.The experimental results were compared with the glass forming ranges which may be expected from the conditions of glass formation given by the author (this journal, 67, 364, 1959) with a result that both are, in general in good agreement.It was found that the glass formation range will be limitted by following conditions:i) The limit of one dimensional continuity of the network structure. It depends on the coordination number of network former, and whether the coexisting component takes the position of modifier or enters into the network. In the former case the type of glass formation range is represented by the point A or B, and in the latter case D or E on the triaxial diagrams shown in the text.ii) The limit comes from the condition of network formation. According to the condition of glass formation iv (see below), a limitting point may be given from the difference between the valency and the coordination number of network formers. It is the point C on the triaxial diagrams.iii) The limit of the number of modifier ions. The limit of the number of modifier ions which enter into the glass network is given by the radius of network formers. The relations are shown in Fig. 9.iv) The limit of the substitution of network formers for B3+ ion. Point X in the triaxial diagrams shows this limit. It is highly probable that this limit depends on the radius ratio of network formers and modifiers, although this point does not correspond to a deffinit type of glass structure. In the case of b-group ions, which can form a glass structure by themselves this point corresponds with the limit of the continuity of network. It is shown by the points P, Q, R, ....in the triaxial diagram.Although there are many exceptions and special cases it is the general trend that the mixed systems of similar components, such as mixed alkalies, enlarge the glass formation range.
社団法人日本セラミックス協会の論文
1961-09-01

著者

今岡稔
東京大学生産技術研究所

硼酸塩系のガラス化範囲について

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