抄録
As a primary condition for vitrification procedure of molten slag in the SiO2-MgO-CaO-Al2O3-TiO2 system, the vitrification temperature TV and the devitrification temperature TC were determined at three different cooling rates as a function of slag composition. Both TV and TC were found to decrease with increasing cooling rate. DTA analysis on heating and cooling runs of the slag specimen showed that the TV was well above the liquidus temperature and the TC was just above it. In order to explain this phenomenon, a new type of liquid model was proposed by which a perceptible amount of nuclei are preserved even above the liquidus. Systematic analysis on the compositional dependences of TV and TC revealed that constituents SiO2, Al2O3 and TiO2 lower both TV and TC, while MgO and CaO raise them. This is considered to mean that Al2O3 and TiO2 would produce AlO4 and TiO4 tetrahedra in the presence of MgO and CaO, and these tetrahedra will work as glass network formers as will do SiO4 tetrahedra. Excess MgO or CaO, on the other hand, would produce non-bridging oxygens in the AlO4, TiO4 or SiO4 tetrahedra and will weaken vitrification tendency.
