Ceramics-Silikáty 39, (3) 87 - 91 (1995)

On the basis of experience gained with melting glasses containing chromates in the batch, the authors assume that alkali chromates react at high temperatures in air spontaneously with silica, forming Cr₂O₃ and alkali silicate, and liberating oxygen. The assumption was experimentally verified on mixtures of SiO₂ with sodium and potassium chromates, at 2:1 and 4:1 ratios, using DTA, GTA, X-ray diffraction and gas chromatography of the gaseous reaction products. It has been proved by GTA that the reaction of SiO₂ with Na₂CrO₄ takes place over the range of 1073 to 1120°C, and that with K₂CrO₄ at 1220 to 1360°C.