抄録
Titania-opacified enamel frits having the composition varying systematically were subjected to differential thermal analysis. Also X-ray diffraction method was used for the identification of the crystals separted out from glass phase. Two peaks, one the gently sloped and endothermic, and the other sharp exothermic, were observed, respectively at 450-550°C and 550-750°C. The former will very likely be brought out by the stabilization of quenched glass, since the results of dilatometric measurements gave the transformation- and yield points at around the same temperature, while the latter may be attributed to the crystallization of anatase or rutile. Another endothermic effect appearing at higher temperatures will probably be the outcome of the change of the packing of powdered samples occuring at the higher temperature than the yield point. This will, therefore, be of the second importance. The inversion of anatase to rutile occured so slowly that no heat effect was appeared on the thermograms.
With the decreasing amount of titanium oxide the peak became lower and shifted to higher temperature, which might be the result of the reduction of the degree of supersaturation. The same effect was brought out with the decrease of fluorine content, which might be attributed to the increasing grain size of crystallites. The colour change of the normallyfired frit containing various amounts of fluorine seems to justify the authors' inference.
The substitution of boric oxide by phosphoric oxide resulted in the shift of the peak to higher temperature. The curve, however, subjects nothing about the stabilizing effect of titanium oxide.
