抄録
The effect of the minor components added to 3CaO·SiO2 on the thermal decomposition of 3CaO·SiO2 has been studied by the methods of X-ray diffraction, differential thermal analysis and thermogravimetric analysis. The tricalcium silicate is prepared by heating the mixture of guaranteed reagents of calcium carbonate and silica, and also the guaranteed reagents used for the additives.
The results obtained are summarized as follows;
(1) The minor components, i.e., B2O3, Cr2O3, CoO, CuO, BaO, NaCl and CaF2 accelerate the thermal decomposition of 3CaO·SiO2 in the mixture of 3CaO·SiO2 1mol+the minor component 0.05mol heated at 1200°C for 5 or 10hr, as shown in Table I.
(2) The mixtures of 3CaO3·SiO2+additives, i.e., Cr2O3, MnO2, NiO, CoO, ZnO and CuO are influenced by the heating atmosphere.
(3) It seems that the ions of nearly the same size as Si4+ or having smaller size and larger ions than Ca2+ are possible to stabilize β or α' form of 2CaO·SiO2 and accordingly these ions are effective for the thermal decomposition of 3CaO·SiO2.
