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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 article, a thermodynamic model has been developed for predicting the formation of oxide-sulfide duplex inclusions arising out of competitive reactions between [O], [S] and [Ca] in Al-killed steel.
Abstract: Calcium is widely used for improving the castability of liquid steel, as well as for improvement of steel cleanliness and inclusion modification for better quality steel. Calcium modifies solid alumina inclusions, arising out of deoxidation of liquid steel, into liquid calcium aluminate. Depending upon the steel composition, calcium sulfide (CaS) and/or various forms of calcium aluminates may form. Sulfides are often associated with the oxide phase, which is typically known as oxide–sulfide duplex inclusion. Formation of solid calcium sulfide must be avoided during the ladle treatment of liquid steel, since it is detrimental to the castability of steel. In the present work a thermodynamic model has been developed for predicting the formation of oxide–sulfide duplex inclusions arising out of competitive reactions between [O], [S] and [Ca] in Al-killed steel. The model predictions of the present work were compared with those reported in literature, as well as with the types of inclusions observed in steel samples collected from the plant. Reasonably good agreements amongst them were observed. The results indicated that in order to achieve completely liquid calcium aluminate without forming any sulfides the sulfur content of liquid steel must be sufficiently low. With increasing S content of liquid steel, complete modification of alumina inclusions into liquid calcium aluminate becomes difficult. The maximum sulfur content to avoid formation of CaS depends upon the steel composition, principally aluminum. The sulfide inclusions are often a solid solution of CaS and MnS. Thermodynamic analysis for this system was also carried out. Based on the analysis in the present work, it is possible to predict the influence of sulfide composition on formation of duplex inclusions.
81 citations
TL;DR: In this article, a basic slag corrosion mechanism was proposed to evaluate the overall microstructural effect on the corrosion resistance of spinel-containing refractory castables, and the results pointed out that lower penetration can be attained by reducing the pore size diameters, whereas chemical corrosion resistance is a consequence of higher content of fine alumina, lower amount of calcium aluminates and the lack of liquid phase in the castable matrix.
80 citations
TL;DR: In this paper, the formation of CA2 obeyed the rate law equation 1 - (1 - x)1/3=Kt/r2, and the activation energy for the system (140 kJ·mol−1 (33.4 kcal · mol−1)) was determined by the Arrhenius equation.
Abstract: The kinetics of formation of calcium aluminates was studied by firing the reaction mixes in the temperature range 12000° to 1460°C for reaction times from 15 to 360 min. Phases formed were determined by taking X-ray diffractograms of the samples. It was observed that all stable calcium aluminates were formed and that monocalcium aluminate (CA) grew with calcium dialuminate (CA2) in a 1:2 reaction mix of CaO and Al2O3. CA reacted further with Al2O3 to form CA2. The formation of CA2 obeyed the rate law equation 1 - (1 - x)1/3=Kt/r2. The activation energy for the system (140 kJ·mol−1 (33.4 kcal · mol−1)) was determined by the Arrhenius equation.
77 citations
TL;DR: In this paper, the long-term aging reactions of LFS and the properties of various soil-LFS mixes, to gain further knowledge of the behaviour of this byproduct as a construction and building material and the inherent risk of volumetric instability associated with its use.
76 citations
TL;DR: In this article, a one-dimensional differential equation related to the diffusion reaction behavior of sulfate ions in concrete is presented, and based on chemical reactions between sulfate and calcium aluminates in concrete, the expansive volume strain caused by ettringite growth is analyzed.
76 citations