Showing papers on "Calcium aluminates published in 1985"
01 Dec 1985-Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science
TL;DR: In this article, the free energies of formation of the calcium aluminates from their constituent oxides were determined in the temperature ranges specified: (1) CaO(s) + 6Al2O3(s), → CaO6Al203(s).
Abstract: Caβ″-alumina solid electrolytes have been used in calcium concentration electrochemical cells to determine the standard free energies of formation of the calcium aluminates, from their constituent oxides, in the temperature ranges specified: (1) CaO(s) + 6Al2O3(s) → CaO6Al203(s) ΔG° =-42709 - 94r(K)(±200)cal = -178694 - 393T (±840)J; 1100 to 1500 K (2) CaO(s) + 2Al2O3(s) → CaO2Al2O3(s) ΔG° = -30871 - 639HK) (±300)cal = -129164 -2674T (±1260)J; 1100 to 1500 K (3) CaO(s) + Al2O3(s)→ CaO-Al2O3(s) ΔG° = -36121 -435T(K) (±200)cal = -151130 - 182r(±840)J; 1050 to 1500 K (4) 3CaO(s) + Al2O3(s) → 3CaO-Al2O3(s) ΔG° = -18687 - 705T(K)(±200)cal = -78186 - 2957(±840)J; 1050 to 1320 K
46 citations
01 Jan 1985
TL;DR: In this article, a calorimetrie differentielle et spectrometrie RMN de l'hydratation du manoaluminate de calcium (CA) entre 0 and 80°C is presented.
Abstract: Etude par calorimetrie differentielle et spectrometrie RMN de l'hydratation du manoaluminate de calcium (CA) entre 0 et 80°C
13 citations
01 Jan 1985
4 citations
TL;DR: The more favourable experimental conditions of cooling and grinding were defined for calcium aluminates obtained by solid-solid reaction with C/A ratio in the range 0.96 -1.04 as mentioned in this paper.
4 citations
TL;DR: In this paper, the hydration behavior of the calcium aluminates as a function of the curing temperature was investigated using a combination thermogravimetric analysis/differential thermal analysis (TGA/DTA) system.
3 citations
TL;DR: In this article, a literature survey reveals that very little work has been done towards understanding their sintering behavior during firing, and the present investigation has been conducted to determine the densiflcation characteristics of mixes of calcium dialuminate (CaAt4Ov) and calcium monoaluminate(CaA12 04).
Abstract: Calcium aluminates are potentially useful ceramic materials. They are important constituents in the high alumina cements and castable refractory products. A literature survey reveals that very little work has been done towards understanding their sintering behaviour during firing. The present investigation has been conducted to determine the densiflcation characteristics of mixes of calcium dialuminate (CaAt4Ov) and calcium monoaluminate (CaA12 04). The material transport in the sintering of a powder compact is governed by several mechanisms under different conditions. Vapour transport and surface diffusion mechanisms were reported first to occur in various crystalline materials [1 ]. The surface curvature of the particles varies from point to point within a powder compact and thus the chemical potential of atoms or ions vary with position. At higher temperature, chemical potential gradients produce diffusion fluxes necessary for material transport. Although this possibility has been mentioned by earlier workers, Berrin and Johnson [2] used the chemical potential as the driving force in their equations. The first attempt in defining the mechanism of material movement was done by Frankel assuming that the material was able to move in a viscous manner because of the driving force provided by surface forces. Kuczynski [3] gave the quantitative approach on mechanism of material movement using an exponent method. The geometries of particles and pores in a
1 citations
TL;DR: The calcium aluminates hydration in water and Na 2 CO 3 solutions have been studied using the microcalorimetry, DTA, TG and XRD methods.
Patent•
05 Mar 1985
TL;DR: In this paper, the authors describe a coal gasification process in which calcium-containing compounds are added in such quantities that calcium aluminates are formed, in particular in an alkali solution from which aluminium hydroxide precipitates which is further processed to give alumina.
Abstract: The invention relates to a process for coal gasification, wherein calcium-containing compounds are added in such quantities that calcium aluminates are formed. The latter are converted into alkali metal aluminates, in particular in an alkali solution from which aluminium hydroxide precipitates which is further processed to give alumina. The remainder of the slag or ash is suitable as a raw material for producing cement clinker.