Thermal behavior and crystallization of alkali aluminosilicate sealants for SOFC: Effect of Al2O3 to Y2O3 substitution

The influence of the gradual replacement of Al2O3 with Y2O3 in alkali-containing silica glass sealants is studied with a detailed discussion of crystallization kinetics. Such substitution has a complex effect on Tg, Tsphere, THS, and Tflowing which might be connected with the role of yttrium in the glass network. An increase in the Y2O3 content is found to intensify crystallization, causing the growth of the crystalline phase fraction. At the same time, intense crystallization appears to have no pronounced effect on the coefficient of thermal expansion: its average increment after 1000 h of exposure at 850 °C in air atmosphere is