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

The reaction mechanisms observed when sintering loose Cr2O3-CaF2 powder mix tures were analyzed, and the influence of the sintering parameters on the r eaction behavior is presented. Using x-ray diffraction (XRD), energy-disper sive spectroscopy (EDS), and differential thermal analysis (DTA) measuremen ts, CaCrO4 was shown to be the reaction product when sintering in air. The reaction occurs in two steps: CaF2 transforms to CaO at the Cr2O3 -CaF2 int erface, followed by a CaO-Cr2O3 interaction, which creates the reaction pro duct. Scanning electron microscopy (SEM) and x-ray fluorescence (XRF) analy sis showed an increasing loss of CaF2 with increasing sintering temperature and heating rate, while an opposite evolution of the amount of reaction pr oduct was observed.