On the Compound K₂O⋅Al₂O₃⋅SiO₂ and K₂O⋅Al₂O₃

Abstract

Two compounds, K₂O⋅Al₂O₃⋅SiO₂ and K₂O⋅Al₂O₃, were studied in order to identify the corrosion products of the mullite exposed to K₂CO₃ vapor. The compounds of various ratio of K₂O⋅Al₂O₃⋅SiO₂ and K₂O⋅Al₂O₃ were prepared from the fired mixtures of K₂O⋅Al₂O₃ and SiO₂. From the results of the powder X-ray diffraction analysis, the following were obtained. The K₂O⋅Al₂O₃⋅SiO₂ and K₂O⋅Al₂O₃ were cubic. Their lattice constants were 7.650±0.005Å and 7.720±0.005Å, respectively, and between these compounds a complete series of solid solution was formed. The corrosion products of the mullite consisted mainly of this solid solution and with prolonged time of exposure to the K₂CO₃ vapor, the solid solution changed into that rich in K₂O⋅Al₂O₃.