Analysis of gases evolved by AZS refractories and by refractory/glass melt reactions. Techniques and results. Contribution to the bubble-forming mechanism of AZS material

Abstract

To understand the bubble-forming mechanism at the interface AZS material/glass melt, gas-analyzing techniques are necessary. Α review on gas bubble analysis techniques - gas chromatographic and mass spectrometric - as well as on hot extraction techniques is given. Pore gas analyses of pristine, of sustained- and cyclically-heated AZS material without glass contact, analyses of bubbles of the exudation layer, analyses of bubbles in glass melts near the AZS material and hot extraction measurements show that at least two bubble-forming mechanisms take place at the interface refractory/glass melt. The first process is the opening of closed pores of the AZS material filled with nitrogen, oxygen and carbon dioxide due to the normal corrosion of the AZS blocks by the glass melt. The second mechanism is the oxygen release due to a redox process of multivalent ingredients of the refractory material when temperature is increased, which forms additional oxygen bubbles and knots in the glass melt. Both processes generate bubbles whose gas content is almost the same in the glass product.