HIGH-TEMPERATURE REACTIONS OF SODIUM CHROMATE WITH SILICA

Reactions between sodium chromate and silica were studied on mixtures of silica sol with chromate solutions. After thermal exposure the conv ersion degree was determined by chemical analysis and gas chromatograp hy. The reaction products were identified by X-ray diffraction and opt ical microscopy. The mixtures were found to react at temperatures abov e 900 degrees C in two stages: the ternary compound NaCrSi2O6 (kosmoch lor) forms at lower temperatures and above 1050 degrees C decomposes t o Cr2O3,, Na2Si2O5 and silica.