Corrosion of Industrial Frit Furnace Refractories: a Postmortem Study

Abstract

Microstructural and phase analyses of corroded frit furnace refractories forming the side walls and the bottom of an industrial frit furnace is reported in this study. Reflected light optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, and x-ray diffraction tools were used for the analyses. The microstructural analysis in combination with the saturation solubilities information in the phase diagrams was used to predict the corrosion behavior of the refractories. The frit and the refractory types were compared qualitatively for the dissolution potential and corrosion mechanisms. The dissolution of the refractory material was direct (congruent) for both the side wall refractories and bottom pavers. The first push exudation phenomenon was determined to be effective for the increase of porosity and pore dimensions which in turn caused accelerated wear rates when combined with corrosion. The corrosive potential of the transparent frit for corundum, mullite, and glassy phase in the refractories was determined to be excessive. The dissolution of these species in the molten transparent frit was predicted to start at temperatures between 1000-1340oC while the operating temperature was 1470oC. The decrease in the extent of corrosion by zirconia inclusion either in the refractories or in the molten glass compositions was qualitatively discussed.