Reactivity in the chromium oxide-calcium fluoride system: An empirical approach

摘要

The reaction mechanisms observed when sintering loose Cr_2O_3-CaF_2 powder mixtures were analyzed, and the influence of the sintering parameters on the reaction behavior is presented. Using x-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), and differential thermal analysis (DTA) measurements, CaCrO_4 was shown to be the reaction product when sintering in air. The reaction occurs in two steps(CaF_2 transforms to CaO at the Cr_2O_3-CaF_2 interface, followed by a CaO-Cr_2O_3 interaction, which creates the reaction product. Scanning electron microscopy (SEM) and x-ray fluorescence (XRF) analysis showed an increasing loss of CaF_2 with increasing sintering temperature and heating rate, while an opposite evolution of the amount of reaction product was observed.