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Calcium aluminates
About: Calcium aluminates is a research topic. Over the lifetime, 490 publications have been published within this topic receiving 9200 citations.
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TL;DR: In this paper, the authors investigated the hydrolysis of pure and sodium-substituted calcium aluminates and cement clinker phases in situ in the temperature range 25°-170°C using the angle dispersive powder synchrotron powder X-ray diffraction technique.
Abstract: The hydrolysis of pure and sodium-substituted calcium aluminates and cement clinker phases was investigated in situ in the temperature range 25°-170°C, using the angle dispersive powder synchrotron powder X-ray diffraction technique. The final hydrolysis product in all cases was Ca 3 Al 2 (OH) 12 . The intermediate phase Ca 4 Al 2 O 7 .19H 2 O was formed from the pure calcium aluminates, and the intermediate phases Ca 4 Al 2 O 7 .xH 2 O, x = 11, 13, or 19, were formed from the cement clinker phases.
18 citations
TL;DR: In this article, a high-performance material based on incorporation of CaO particles into calcium aluminates was developed by authors exhibiting high sorption capacity and stability in multi cycle process.
18 citations
TL;DR: In this paper, the structural, thermal and photoluminescence properties of calcium aluminate samples were compared by solid state sintering in the temperature range of 1386-1450°C.
18 citations
24 Apr 2018-Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science
TL;DR: In this paper, a steel-inclusion kinetic model is used for mass transfer to the inclusion interface and diffusion within the calcium aluminate phases formed on the inclusion, which is then coupled with a previously developed steel-slag kinetic model.
Abstract: Calcium treatment of steel is typically employed to modify alumina inclusions to liquid calcium aluminates. However, injected calcium also reacts with the dissolved sulfur to form calcium sulfide. The current work aims to develop a kinetic model for the evolution of oxide and sulfide inclusions in Al-killed alloyed steel during Ca treatment in the ladle refining process. The model considers dissolution of the calcium from the calcium bubbles into the steel and reduction of calcium oxide in the slag to dissolved calcium. A steel–inclusion kinetic model is used for mass transfer to the inclusion interface and diffusion within the calcium aluminate phases formed on the inclusion. The inclusion–steel kinetic model is then coupled with a previously developed steel–slag kinetic model. The coupled inclusion–steel–slag kinetic model is applied to the chemical composition changes in molten steel, slag, and evolution of inclusions in the ladle. The result of calculations is found to agree well with an industrial heat for species in the steel as well as inclusions during Ca treatment.
18 citations
TL;DR: In this paper, the same unground compositions form mixtures of α-alumina and various calcium aluminates (but not CaAl4O7) on heating as high as 1250°C.
Abstract: Calcium dialuminate (CaAl4O7) powders were synthesised from mechanochemically treated mixtures of aluminium hydroxide + calcium hydroxide and aluminium hydroxide + calcium carbonate. On grinding, both mixtures produce X-ray amorphous precursor phases which show 27Al MAS NMR resonances characteristic of Al in octahedral and tetrahedral sites, and a site identified by a resonance at 37–39 ppm (possibly pentahedral Al). Although grinding does not completely destroy the carbonate XRD reflections in the carbonate mixture, both precursors show a high degree of homogeneity and behave similarly on heating, forming monophase CaAl4O7 at <1050 °C. By contrast, the same unground compositions form mixtures of α-alumina and various calcium aluminates (but not CaAl4O7) on heating as high as 1250 °C. Calcium dialuminate synthesised from the carbonate-containing mechanochemical precursor had a smaller particle size which may be advantageous for subsequent fabrication and sintering.
18 citations