Abstract
Processes of corrosion of mullite by vapors of different potassium salts were investigated. Small size test pieces or powders taken from mullie refractories were exposed to the vapors of potassium carbonate, potassium sulfate and potassium chloride at temperatures ranged from 1000° to 1300°C. Phase assemblies of the samples were determined petrographically after each run.
Although potassium chloride was found to evaporate faster than potassium carbonate and potassium sulfate, K2CO3 vapor was the most corrosive against mullite.
The corrosion products of mullite differed from each other depending on the kinds of vapors. With K2CO3 vapor, a small amount of leucite and kalsilite were formed at the initial stage of the corrosion process, but gradually they were replaced by the final products, i.e, potassium aluminate and glassy phase. Leucite, kalsilite, corundum and β-alumina were the common products of the corrosion by vapors of K2SO4 and KCI, and additional phase in the case with K2SO4 was solid solution potassium and sodium sulfate.
