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Melt differentiation induced by crystallization of cement clinker materials in a CaO-SiO2-Al2O3-Fe2O3 pseudoquaternary system
The phase stability in part of the P2O5-bearing pseudoquaternary system CaO-SiO2-Al2O3-Fe2O3 has been studied by electron probe microanalysis, optical microscopy, and X-ray powder diffractometry. At 1663-1623 K, the four phases of melt, calcium aluminoferrite solid solution (ferrite), Ca3SiO5 solid solution (C3S(ss)), and alpha-Ca2SiO4 solid solution (alpha-C2S(ss)) coexisted in equilibrium. On the basis of the chemical variations of these phases as a function of temperature, a melt-differentiation mechanism has been suggested to account for the crystallization behavior of Ca3Al2O6 solid solution (C3A(ss)). When the melt with Al2O3/Fe2O3 = 0.25 was cooled from 1663 K, it underwent differentiation by the crystallization of ferrite, C3S(ss) and alpha-C2S(ss). The Al2O3/Fe2O3 value of the melt steadily increased to 1.74 when cooled to 1613 K. Because the local equilibrium would be continually attained between the rims of the precipitating ferrite and the coexisting melt during cooling, the resuiting ferrite crystals would show a zonal structure with the Al/(Al+Fe) value steadily increasing from 0.203 to 0.57 from the cores toward the rims. During cooling from 1623 to 1613 K, the C3A(ss) would crystallize out of the differentiated melt. The resulting phase compositions at ambient temperature were C3S(ss), beta-C2S(ss), ferrite, and C3A(ss). On the other hand, when the melt of Al2O3/Fe2O3 = 4.0 coexisting with alpa'H-C2S(ss) and C3A(ss) was cooled from 1615 K, the Ca12Al14O33 solid solution (C12A7(ss)) eventually crystallized out of the melt, with the phase composition of beta-C2S(ss), ferrite with Al/(Al+Fe) = 0.7, and C3A(ss) and C12A7(ss) at ambient temperature.
Melt differentiation induced by crystallization of cement clinker materials in a CaO-SiO2-Al2O3-Fe2O3 pseudoquaternary system
The phase stability in part of the P2O5-bearing pseudoquaternary system CaO-SiO2-Al2O3-Fe2O3 has been studied by electron probe microanalysis, optical microscopy, and X-ray powder diffractometry. At 1663-1623 K, the four phases of melt, calcium aluminoferrite solid solution (ferrite), Ca3SiO5 solid solution (C3S(ss)), and alpha-Ca2SiO4 solid solution (alpha-C2S(ss)) coexisted in equilibrium. On the basis of the chemical variations of these phases as a function of temperature, a melt-differentiation mechanism has been suggested to account for the crystallization behavior of Ca3Al2O6 solid solution (C3A(ss)). When the melt with Al2O3/Fe2O3 = 0.25 was cooled from 1663 K, it underwent differentiation by the crystallization of ferrite, C3S(ss) and alpha-C2S(ss). The Al2O3/Fe2O3 value of the melt steadily increased to 1.74 when cooled to 1613 K. Because the local equilibrium would be continually attained between the rims of the precipitating ferrite and the coexisting melt during cooling, the resuiting ferrite crystals would show a zonal structure with the Al/(Al+Fe) value steadily increasing from 0.203 to 0.57 from the cores toward the rims. During cooling from 1623 to 1613 K, the C3A(ss) would crystallize out of the differentiated melt. The resulting phase compositions at ambient temperature were C3S(ss), beta-C2S(ss), ferrite, and C3A(ss). On the other hand, when the melt of Al2O3/Fe2O3 = 4.0 coexisting with alpa'H-C2S(ss) and C3A(ss) was cooled from 1615 K, the Ca12Al14O33 solid solution (C12A7(ss)) eventually crystallized out of the melt, with the phase composition of beta-C2S(ss), ferrite with Al/(Al+Fe) = 0.7, and C3A(ss) and C12A7(ss) at ambient temperature.
Melt differentiation induced by crystallization of cement clinker materials in a CaO-SiO2-Al2O3-Fe2O3 pseudoquaternary system
Schmelzdifferenzierung, induziert durch Kristallisation von Zementklinkermineralien in einem CaO-SiO2-Al2O3-Fe2O3-Pseudovierstoffsystem
Fukuda, Koichiro (author) / Iwata, Tomoyuki (author) / Yoshida, Hideto (author)
Journal of the American Ceramic Society ; 91 ; 4093-4100
2008
8 Seiten, 8 Bilder, 11 Tabellen, 21 Quellen
Article (Journal)
English
Calciumoxid , Siliciumoxid , Aluminiumoxid , Eisenoxid , Vierstoffsystem , Portlandzementklinker , Kristallisation , Schmelze , Differentiation , feste Lösung , Ferrit , Silicat , Phasengleichgewicht , Temperatureinfluss , Abkühlen , Phasenzusammensetzung , Röntgenbeugung , optische Mikroskopie , Röntgenmikroanalyse , Fällung (Chemie) , chemische Zusammensetzung , Mikrogefüge
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