Koroze žárovzdorných keramických materiálů za vyšších teplot

Abstract

Refractory lining in the cement aggregates are often exposed to alkali attack. Fuel is the primary cause. Chemical attack is a growing problem, caused by the increasing use of wastes as a secondary fuel source. The alkali salts and vapors are adsorbed by the backing and react with so-called castables matrix. The problem can occur mainly by the temperatures 700-1000°C. This thesis sought to explore selected typical subsystems of castables matrix components in the effect of K2CO3, K2SO4 and their mixtures in detail, to identify emerging phases and other effects on the volume changes of castables in the temperature range 700 to 1000 ° C. For the study of volume changes was chosen an original method consisting in pressing of the tablets from a mixture of selected castables matrix components with the alkali addition and subjected to heat exposure. Granulometric curves were prepared for all model mixtures, phase composition of selected samples were determined using X-ray diffraction analysis and relationships between volume changes, phase composition and granulometry were sought. Some connections between alkali resistance and grain size composition have been found and it was confirmed the influence of matrix composition - the ratio of SiO2 to Al2O3 and SiC addition, on the formation of undesirable phases causing volume expansion.