Sintering of CaTiO₃ with the addition of CaCO₃ and LiF

The densification of CaTiO3 with the addition of 4.74, 5.90, 6.88 mol% CaCO3 and 22 mol% LiF was investigated over the temperature range 800° to 1050°C, for sintering times ranging from 1 to 216 hours. It was found that CaCO3 reacts with LiF and to form a liquid at a temperature of about 450°C. This liquid enhances the densification of CaTiO3 . The densification process was followed by making weight loss, shrinkage and porosity measurements. The microstructural development was determined by scanning electron microscope examination of both fractured and polished surfaces. X-ray diffraction and DTA/TGA were used to determine the interaction of the LiF and CaCO3 additions with CaTiO3 . Results show that the highest density achieved was 93%TD for the composition CaTiO3 + 6.88 mol% CaCO3 + 22 mol% LiF. The shrinkages and porosities were consistent with the measured densities. Weight loss is quite dependent upon sintering temperature, sintering time, and CaCO3 content. The weight loss measurements indicated that the maximum weight losses were greater than that calculated from the volatilization of LiF and by the decomposition of CaCO3 alone which suggests that yet unidentified additional volatile compounds must be forming during the sintering process --Abstract, page ii