scispace - formally typeset
Search or ask a question
Topic

Calcium aluminates

About: Calcium aluminates is a research topic. Over the lifetime, 490 publications have been published within this topic receiving 9200 citations.


Papers
More filters
Journal Article
TL;DR: The thermodynamics of the reactions of alumina(Al2O3) with CaCO3,CaO,SiO2 and FeO in the sintering process of high-iron gibbsite-type bauxite was investigated in this article.
Abstract: The thermodynamics of the reactions of alumina(Al2O3) with CaCO3,CaO,SiO2 and FeO in the sintering process of high-iron gibbsite-type bauxite was investigated.The results show that alumina reacts with calcium carbonate much easier than ferri oxide(Fe2O3) at the industrial sintering temperature of 1 473-1 673 K.Alumina can not react with calcium ferrites(2CaO·Fe2O3 and CaO·Fe2O3) to form 3CaO·Al2O3,but when temperature is over 1 000 K alumina reacts with 2CaO·Fe2O3 to form 12CaO·7Al2O3.SiO2 reacts with CaO much easier than Al2O3.The possibility of alumina silicate from direct reaction of Al2O3 with SiO2 is little.Except for CaO·2Al2O3 and CaO·Al2O3,the other calcium aluminates can transform into calcium silicate by reacting with SiO2.Gehlenite(2CaO·Al2O3·SiO2) can not be formed from the reaction of calcium silicate(CaO·SiO2) with calcium aluminate(CaO·Al2O3),but it can be directly formed from the reaction of CaO,Al2O3 and SiO2.When CaO,Fe2O3,Al2O3 and SiO2 coexist in the sintering process,they are more likely to form ternary compound 2CaO·Al2O3·SiO2 and 4CaO·Al2O3·Fe2O3,which is consistent with the sintering results in laboratory.

7 citations

DOI
01 Jan 1973

7 citations

Journal ArticleDOI
TL;DR: In this paper, l'influence d'additifs sur les reactions entre D 2 O and les composants du clinkes de ciment Ca 3 Al 2 O 6, Ca 12 Al 14 O 33 and CaAl 2 O 4, au moyen de la diffraction de neutrons a temperatures jusqu'a 120°C.
Abstract: Etude de l'influence d'additifs sur les reactions entre D 2 O et les composants du clinkes de ciment Ca 3 Al 2 O 6 , Ca 12 Al 14 O 33 et CaAl 2 O 4 , au moyen de la diffraction de neutrons a temperatures jusqu'a 120°C. Les additifs etudies sont CaSO 4 •1/2D 2 O, CaSO 4 •2D 2 O, CaCO 3 , Ca(OD) 2 , CaCl 2 et SiO 2

7 citations

Journal Article
TL;DR: In this article, the authors identify non-metallic inclusions occurring in aluminium-killed steel with regulated sulphur content and modified with calcium, explain the reaction between calcium and nonmetall inclusions and identify secondary metallurgy parameters, which condition obtaining such forms of inclusions to be favorable to improvement in steel machinability.
Abstract: The objective of this paper is to identify non-metallic inclusions occurring in aluminium-killed steel with regulated sulphur content and modified with calcium, explain the reaction between calcium and non-metallic inclusions and identify secondary metallurgy parameters, which condition obtaining such forms of inclusions to be favourable to improvement in steel machinability. Computer-aided thermodynamic calculations and production experiments were carried out. They enabled to determine technological parameters of treatment in liquid steel ladle deoxidised with silicon and aluminium, with low (0.01%) and increased (up to 0.03%) sulphur content. By comparison of the computer-aided simulations and production experiment results it was found that calcium in the steel both modifies the aluminium oxide inclusions and reacts with sulphur, whereas deep desulphurisation (below 0.01%) is favourable to oxide modification. Non-metallic inclusions of calcium aluminates, which affect positively the machinability of steel, appear in liquid state in the steel bath. During conventional casting and cooling down large ingots of steel with increased sulphur content, aluminates are significantly depleted in calcium as a result of reaction between calcium and sulphur dissolved in these aluminates and steel matrix. To obtain aluminates and (Ca,Mn)S sulphides rich in calcium in finished products accelerated steel cooling is to be applied, which takes place during continuous steel casting. In steels modified with calcium, there is higher homogeneity of distribution and sizes of inclusions on finished products' cross-section and higher globularisation of these inclusions in comparison to non-modified steels. Improved steel machining properties in these steels and improved isotropy of mechanical properties in bars made from it were found.

7 citations

Journal ArticleDOI
TL;DR: In this paper, the authors studied the metastability of tricalcium aluminate with respect to calcium aluminate monosulphate hydrate at pH more than about 12.8 and showed that the increased surface area of the precipitates formed at high pH is not sufficient to account for the observed increase in solubility.
Abstract: Electron optical techniques have been used to study the hydration of tricalcium aluminate in the presence of gypsum at various pH levels. Calcium aluminosulphate hydrates are precipitated, which have compositional variations and structures that range from highly disordered to highly ordered. Results derived from solubility measurements are able to account for the metastability of ettringite with respect to calcium aluminate monosulphate hydrate at pH more than about 12.8. It is shown that the increased surface area of the precipitates formed at high pH is not sufficient to account for the observed increase in solubility. Consideration of the crystal structure of ettringite and the monosulphate hydrate suggests a further proposal for the type of defect occurring in the ettringite structure at high pH.

7 citations


Network Information
Related Topics (5)
Sintering
76K papers, 892.1K citations
77% related
Microstructure
148.6K papers, 2.2M citations
75% related
Thermogravimetric analysis
37.2K papers, 862.1K citations
75% related
Alloy
171.8K papers, 1.7M citations
73% related
Corrosion
152.8K papers, 1.9M citations
73% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20221
202112
202010
201914
201819
201715