11CaO・7Al_2O_3・Ca(OD)_2の合成と熱安定性

概要

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The formation process of 11CaO・7Al_2O_3・Ca(OD)_2(C_<11>A_7・Ca(OD)_2) and its thermal stability were studied in controlled atmospheres containing heavy water vapor. The formation of 12CaO・7Al_2O_3(C_<12>A_7) solid solution in the system C_<12>A_7-C_<11>A_7・Ca(OD)_2 was examined by X-ray powder diffraction, and OD group included in C_<11>A_7・Ca(OD)_2 was identified by means of Fourier transform infrared spectroscopy (FT-IR). C_<11>A_7・Ca(OD)_2 was formed above 1050℃ in a flow of air containing heavy water vapor. It was difficult to make the distinction of X-ray diffraction patterns among C_<12>A_7, C_<11>A_7・Ca(OH)_2 and C_<11>A_7・Ca(OD)_2, but the stretching vibration band of O-D at about 2620cm^<-1> by FT-IR identified the hydrate. In a flow of dried helium gas, C_<11>A_7・Ca(OD)_2 decomposed into 5CaO・3Al_2O_3(C_5A_3) in the temperature range from 1150 to 1250℃ and finally changed into C_<12>A_7 at temperatures above 1250℃. On the contrary, C_5A_3 changed into C_<11>A_7・Ca(OD)_2 by heating at about 1100℃ in a flow of air containing heavy water vapor. It seemed that the reaction between C_<11>A_7・Ca(OD)_2 and C_5A_3 proceeded reversibly. C_<11>A_7・Ca(OH, OD)_2 including both OH and OD group was formed by burning in a flow of wet air with controlled mixing ratio of light and heavy water.
社団法人日本セラミックス協会の論文
1995-03-01