Reactions at the Interface Between Al2O3–SiO2 Ceramics with Additives of Alkaline-earth Oxides and Liquid Al–Si Alloy

Oliveira, M.I.L.L.; Agathopoulos, Simeon; Ferreira, J.M.F.

doi:10.1557/jmr.2002.0091

Cited by 20 publications

(33 citation statements)

References 21 publications

(39 reference statements)

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“…This glassy phase contains high amounts of silica and alkaline oxides [35][36][37]. This microstructure is similar to those observed in previous studies [33,35,36]. Fig.…”

Section: Effect Of Microsilica/cement Ratio On the Corrosion Resistansupporting

confidence: 90%

The effect of microsilica and refractory cement content on the properties of andalusite based Low Cement Castables used in aluminum casthouse

et al. 2010

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The bonding system in low cement castables is achieved by the use of calcium aluminate cement, microsilica and reactive alumina. The lime/silica ratio critically impacts the liquid phase formation at high temperatures and subsequently the corrosion resistance and the mechanical and physical properties of the refractory. In the current study, the effects of microsilica and cement contents on the corrosion resistance and the physical and mechanical properties of Andalusite Low Cement Castables (LCCs) refractories were investigated. Alcoa Cup test was used to evaluate the corrosion resistance of the castables at 850 ºC and 1160 ºC. The study showed that an increase in the microsilica/cement ratio improves the physical and mechanical properties of the castable, but at the expense of the corrosion resistance. When a fixed amount of BaSO4 was added to the base refractory material, barium celsian along with glassy phase formation was observed to increase with the increase in the microsilica/cement ratio in the refractory. The presence of the glassy phases was noted to lower the positive effect of Ba-celsian formation on improving the corrosion resistance of the refractory. The observed results were validated using thermodynamic calculations which indicated that Ba-celsian phase was more resistant than Ca-anorthite for applications involving contact with molten aluminum.

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“…This glassy phase contains high amounts of silica and alkaline oxides [35][36][37]. This microstructure is similar to those observed in previous studies [33,35,36]. Fig.…”

Section: Effect Of Microsilica/cement Ratio On the Corrosion Resistansupporting

confidence: 90%

The effect of microsilica and refractory cement content on the properties of andalusite based Low Cement Castables used in aluminum casthouse

et al. 2010

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“…[17] Limited work has been carried out on the use of calcium oxide (CaO) as the additive for aluminum casting refractories. [18,19] Thermodynamically, calcium oxide is not reduced by aluminum to calcium but tends to form an intermetallic compound according to the following reaction (Eq. [1]) [20,21] :…”

Section: Introductionmentioning

confidence: 99%

“…[18,19] The Ca (product of anorthite reduction) is concentrated as precipitated particles of b-Al 2 CaSi 2 , which adhere to the interface, thereby decreasing the reaction intensity between the aluminum alloy and the refractory. Ceramic-bondedshaped products based on aggregates of calcium aluminate minerals often are used in the aluminum industry because of their stability against corrosive metals (such as aluminum), [22,23] and other advantageous properties such as high refractoriness and high thermal shock resistance.…”

Section: Introductionmentioning

confidence: 99%

Effects of Different Calcium Compounds on the Corrosion Resistance of Andalusite-Based Low-Cement Castables in Contact with Molten Al-Alloy

Adabifiroozjaei

Saidi

Monshi

et al. 2011

Metall Mater Trans B

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Andalusite containing low-cement castables (LCCs) have been used in aluminum casthouses for several decades. CaF 2 is commonly added to the refractory to improve its corrosion resistance mainly because of its role in the formation of anorthite (CaAl 2 Si 2 O 8 ); the latter has been reported to decrease the penetration of molten aluminum alloys into refractories. This article investigates the effect of the addition of different calcium containing compounds (CaO, CaCO 3 , CaSO 4 , CaF 2 , Clinker white cement, calcia feldspar, wollastonite, and Ca 3 (PO 4 ) 2 ) on reactions with the refractory constituents to form anorthite as well as the effect of the additives on both the subsequent physical properties and the corrosion resistance of andalusite LCC refractories. Corrosion tests using the Alcoa cup test at temperatures (1123 K [850°C] for 150 hours and 1433 K [1160°C] for 72 hours) were conducted to determine the extent of penetration, whereas immersion tests in boiling water were conducted to determine the extent of open porosity in the material. Scanning electron microscopy coupled with energy dispersive spectrometer, optical microscopy, and X-ray diffraction techniques were employed to characterize the phase formations in the materials after the tests. The study demonstrated that both calcia feldspar and clinker white cement had the potential to be used as new additives for decreasing the penetration of molten Al-alloy into the refractory materials. Anorthite formation (in the refractory matrix), along with the absence of glassy phases, were responsible for the improvement in the corrosion resistance of the castables containing calcia feldspar. However, in the sample containing cement, the presence of calcium silicate phases were observed to resist reactions with molten aluminum. The observed results were validated using thermodynamic calculations, which indicated that tricalcium silicates (3CaO.SiO 2 ) and dicalcium silicate (2CaO.SiO 2 ) phases were more resistant than wollastonite (CaSiO 3 ) for applications involving contact with molten aluminum.

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“…El incremento en la concentración de álcalis en la interfase refractario/aluminio provoca la formación de fases vítreas, la cuales contribuyen a incrementar la velocidad de penetración y reacción con el aluminio (8). La cristalinidad de las fases dentro del refractario afecta la velocidad de degradación, ya que las fases vítreas son usualmente más susceptibles a la corrosión que las fases cristalinas (9). Normalmente los refractarios usados en hornos de fusión de aluminio deben tener baja de porosidad y alta densidad.…”

Section: Introductionunclassified

“…La corrosión de los refractarios de aluminosilicatos puede causar graves problemas, tales como el decremento de las propiedades mecánicas del refractario, contaminación del baño metálico, pérdida de aluminio y enormes pérdidas de calor debido a altas conductividades térmicas indeseables del refractario corroído (9). Para minimizar los efectos de la formación de la capa de alúmina y la penetración del aluminio, algunos investigadores han sugerido la adición de agentes "no mojantes", tales como barita (BaSO 4 ) (1, 2, 6 (10) atribuyen el incremento en la resistencia a la corrosión a causas diferentes a la disminución de la mojabilidad.…”

Section: Introductionunclassified

Interacción química entre sustratos mullita-SrSO4 y SiO2-SrSO4 con aluminio líquido

Castro¹,

Almanza-Robles²,

Hernandez³

et al. 2008

Bol. Soc. Esp. Ceram. Vidr.

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Reactions at the Interface Between Al₂O₃–SiO₂ Ceramics with Additives of Alkaline-earth Oxides and Liquid Al–Si Alloy

Cited by 20 publications

References 21 publications

The effect of microsilica and refractory cement content on the properties of andalusite based Low Cement Castables used in aluminum casthouse

The effect of microsilica and refractory cement content on the properties of andalusite based Low Cement Castables used in aluminum casthouse

Effects of Different Calcium Compounds on the Corrosion Resistance of Andalusite-Based Low-Cement Castables in Contact with Molten Al-Alloy

Interacción química entre sustratos mullita-SrSO<sub>4</sub> y SiO<sub>2</sub>-SrSO<sub>4</sub> con aluminio líquido

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