Abstract
The dehydration behaviors of CaCrO4 powders were followed by the AE and TG-DTA-MS methods. TG-DTA-MS mesurements showed that four kinds of waters were contained in the powders, which were released in the temperature regions of 20-145(stage I), 145-230(II), 230-420(III), and 420-620°C(IV). AE signals were generated in three temperature regions of 220-400, 400-620, and 700-900°C, the former two corresponding to the stages III and IV observed on TG-DTA-MS measurements. The particles heated up to 700°C were found to become small in size by SEM, which probably gave rise to AE signals in the stage IV. Up to about 400°C no fracture of particles was observed. It was also found that partial decomposition of CaCrO4 occurred at about 700°C, which is associated with small AE signals, small weight loss, and traces of lower valent Cr-ions on ESR measurement.
