Thermal study of chromium–phosphorus-doped tricalcium aluminate

Abstract The evolution with the temperature of the composition of some mixtures of CaCO 3 , Al 2 O 3 , Cr 2 O 3 and P 2 O 5 has been investigated. The influence of chromium and phosphorus additions on the thermal decomposition of CaCO 3 and the formation of the tricalcium aluminate have been observed. The synthesized solid solutions have been characterized through X-ray diffraction (XRD). The free lime content has been determined by chemical analysis. The formation of the cubic polymorph of C 3 A with Cr and P additions less than 4.24 wt.% Cr 2 O 3 and 3.97 wt.% P 2 O 5 was shown. The temperatures of the decarbonation and the enthalpy variations during the raw firing have been studied. The results showed that the presence of the Cr 2 O 3 and P 2 O 5 oxides lowered the decomposition of CaCO 3 . The enthalpy of decarbonation and the enthalpy of the formation of the solid solutions based on tricalcium aluminate formation decreased when the concentrations of additives increased.