Investigation of process factors in the synthesis of Ca7ZrAl6O18 cement by solid state method in order to eliminate undesirable secondary phases

One of the widely used cements for filling teeth and bones can be calcium zirconium aluminate cement Ca7ZrAl6O18, which of course can also be used as a refractory. The behavior and properties of this cement are more similar to tricalcium aluminate C3A cement. In this study, C7A3Z cement was synthesized by using commercial calcium carbonate, alumina and zirconia powders and after grinding for 4-6 hours and sintering at different temperatures of 1200-1400C for three hours. X-ray diffraction showed that C12A7, C3A, C7A3Z, CaZrO3, CaO phases exist at temperatures below 1400C, and at 1400C, almost cement only has calcium zirconium aluminate phase. The setting time of this cement was less than 5 minutes, which can be adjusted to longer times by adding citric acid. The hydrated phases of this cement included different phases of C3AH6, Al(OH)3, and similar phases, which obtained more information about their behavior using simultaneous thermal analysis (STA). The microstructure of the hydrated samples also led to the formation and growth of hydrated phases. The 3 and 7 days compressive strength of the samples was 48 and 40MPa, respectively.