GELS IN THE SYSTEM CaO-Al2O3-SiO2 PREPARATION AND STRUCTURAL EVOLUTION

F. Pancrazi , J. Phalippou , F. Sorrentino , J. Zarzycki

Gels in the system CaO-Al2O3-SiO2 were prepared by the sol destabilization method. Aqueous solutions of calcium and aluminium nitrate were added to a colloïdal silica solution. In order to avoid a selective precipitation of calcium and aluminium hydroxide, the gelation was done at definite pH. The ranges of gel formation in the binary systems Al2O3-SiO2 and CaO-SiO2 have been established. They lie from 100 to 75 mole % SiO2 and from 100 to 25 mole % SiO2 respectively. The range of formation in the ternary system CaOAl2O3-SiO2 was displaced towards the compositions rich in calcium and gels containing up to 75 mole % CaO were prepared. The gelation time was reduced by calcium ions while the aluminium ions increased it. The structural evolution of these gels were followed as a function of temperature by X-ray diffraction. Calcium nitrate crystals occured at low temperature and decomposed as the temperature increased. This decomposition was facilited in the composition domain rich in aluminium.

Domaines: Articles anciens

F. Pancrazi, J. Phalippou, F. Sorrentino, J. Zarzycki. GELS IN THE SYSTEM CaO-Al2O3-SiO2 PREPARATION AND STRUCTURAL EVOLUTION. Journal de Physique Colloques, 1982, 43 (C9), pp.C9-279-C9-283. ⟨10.1051/jphyscol:1982952⟩. ⟨jpa-00222481⟩