On the Compound K<sub>2</sub>O⋅Al<sub>2</sub>O<sub>3</sub>⋅SiO<sub>2</sub> and K<sub>2</sub>O⋅Al<sub>2</sub>O<sub>3</sub>

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.