Showing papers on "Calcium aluminates published in 1976"

Dehydration kinetics by non-isothermal techniques

Abstract: The kinetics of thermal degradation of some cementitious calcium aluminates, sulfoaluminates, sulfoferrites and carboaluminates were studied. Activation energies, obtained by Morris and Rogers and Kissinger techniques, were found to be in good agreement with each other.

Process for obtaining mineral charges and their application

Abstract: A hydrated mineral charge is manufactured by grinding a composition selected from the group consisting of calcium aluminates, aluminous cements, and Portland cements, to a powder having an average fineness of from about 3,000 to about 5,000 square centimeters per gram (Blaine's specific surface), hydrating the composition with water to form a paste at a temperature from about 10° C to about 100° C, and adding a sufficient quantity of a liquefying surface active agent to the paste so that its viscosity is less than about 5,000 cps, and so that the paste has a solid content from about 60 percent to about 80 percent by weight.

Physico‐chemical processes in single crystal growing of calcium aluminates by zone melting

Abstract: The growing of single crystals of calcium aluminates of compositions 12 CaO · 7 Al2O2, CaO · Al2O3, and CaO · 2 Al2O3 by zone melting under vacuum of 10−5 mm Hg permitted to establish that some of the Al3+ ions in octahedral coordination have been driven back by the moving crystallization front. Energetically, this process can be represented on the basis of the viscous flow model with the activation energy of −45 kcal/mole. The possible mathematical models have been considered for the processes of preparation of single phase crystals of the aluminates mentioned above which take account of incongruent vaporization of the component oxides and refining of the melt from structural impurities by the moving crystallization front. Die Zuchtung von Calciumaluminat-Einkristallen der Zusammensetzungen 12 CaO · Al2O3, CaO · Al2O3 und CaO · 2 Al2O3 durch Zonenschmelzen unter einem Vakuum von 10−5mm Hg erlaubte die Feststellung, das einige Al3+-Ionen in Sechserkoordination vor der Wachstumsfront hergeschoben werden. Energetisch kann dieser Prozes dargestellt werden mit Hilfe eines Modells des viskosen Fliesens mit der Aktivierungsenergie von −45 kcal/Mol. Die moglichen mathematischen Modelle wurden betrachtet fur Zuchtungsprozesse fur die einphasigen Kristalle der genannten Aluminate, die die inkongruente Verdampfung der oxidischen Komponenten und die Reinigung der Schmelze von strukturellen Beimengungen durch die Bewegung der Kristallisationsfront berucksichtigen.