SiO_2-MgO-CaO-Al_2O_3-TiO_2系合成スラグ融液のガラス化条件(<小特集>セラミック材料小特集)

概要

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As a primary condition for vitrification procedure of molten slag in the SiO_2-MgO-CaO-Al_2O_3-TiO_2 system, the vitrification temperature T_V and the devitrification temperature T_C were determined at three different cooling rates as a function of slag composition. Both T_V and T_C were found to decrease with increasing cooling rate. DTA analysis on heating and cooling runs of the slag apecimen showed that the T_V was well above the liquidus temperature and the T_C was just above it. In order to explain this phenomenon, a new type of liquid model was proposed by which a perceptible amount of muclei are preserved even above the liquidus. Systematic analysis on the compositional dependences of T_V and T_C revealed that constituents SiO_2, Al_2O_3 and TiO_2 lower both T_V and T_C, while MgO and CaO raise them. This is considered to mean that Al_2O_3 and TiO_2 would produce AlO_4 and TiO_4 tetrahedra in the presence of MgO and CaO, and these tetrahedra will work as glass network formers as will do SiO_4 tetrahedra. Excess MgO or CaO, on the other hand, would produce non-bridging oxygens in the AlO_4, TiO_4 or SiO_4 tetrahedra and will weaken vitrification tendency.
社団法人日本材料学会の論文
1989-01-15