The corrosion of refractory aggregates by molten aluminum

Afshar, S.; Allaire, C.

doi:10.1007/s11837-000-0034-z

Cited by 27 publications

(34 citation statements)

References 3 publications

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“…[24][25][26] Mullite is also known to react with molten Al in a similar manner to pure silica, as shown by Eq. [2].…”

Section: Introductionmentioning

confidence: 99%

“…The presence of Mg, Ti, and Zr in the alloy can also lower the contact angle with alumina. [23][24][25]32,33] High vacuum conditions do not occur in normal industrial casting situations, while an ultra high vacuum could also result in formation of reaction ridges/rings at the triple line of contact, which would influence the measurements [9,13,32] possibly due to metal evaporation. [13] Moreover, in ultra-high-vacuum conditions, critical alloy constituents such as Mg could be lost from the molten droplet as volatiles, [36] and this would hinder the study of the significant role of such components in the interfacial behavior.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Silica on High-Temperature Interfacial Phenomena of Monolithic Refractories with Al Alloy

Koshy

Gupta

Sahajwalla

et al. 2008

Metall Mater Trans B

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An experimental study was conducted to study the interfacial phenomena between monolithic refractories and Al alloy at 1250°C. Dynamic contact angles of monolithic substrates with varying silica levels were measured using the sessile drop technique, while phases present in the preheated monolithic samples and interfacial reaction products were characterized using X-ray diffraction (XRD) and an electron probe microanalyzer (EPMA). The contact angles in the Al alloy/silica system were found to change much more rapidly as compared to that of the alloy/ alumina system, clearly demonstrating the high wetting tendency of silica. Under the tested conditions, the corundum phase forms at the interface while Mg was found to vaporize from the alloy and accumulate at the bottom of the monolithic substrate. Both these phenomena are shown to influence the intensity of contact angle variations with time and, thereby, the wetting behavior of monolithic substrates. Based on dynamic contact angles and equilibrium calculations, monolithic refractories are further classified into three groups, such that the wetting characteristics of those with compositions in the ranges of 0 to 25 pct, 25 to 45 pct, and >45 pct silica were shown to be dictated by the presence of corundum, mullite, and free silica, respectively, as the predominant phase.

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“…[24][25][26] Mullite is also known to react with molten Al in a similar manner to pure silica, as shown by Eq. [2].…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of Silica on High-Temperature Interfacial Phenomena of Monolithic Refractories with Al Alloy

Koshy

Gupta

Sahajwalla

et al. 2008

Metall Mater Trans B

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“…Como se menciona en la literatura la alúmina se forma de la reacción del aluminio puro con la fase mullita (6). No se logró obtener un difractograma de las muestra de mullita con sulfato de estroncio debido a que la capa de corrosión no fue lo suficientemente grande para ser detectada por DRX.…”

Section: Resultsunclassified

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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“…Eq. 2.4 and 2.10 are suggested for the spinel formation mentioned above [54,59,62,66]. Allaire [54] studied the corrosion mechanisms of aluminosilicate refractory exposed to Al-5 wt%Mg alloys at 850°C and 1150°C for the residence time of four days under static conditions.…”

Section: Studies On Refractoriesmentioning

confidence: 99%

“…Figure 2-9: A Schematic View of a Refractory with Inward Corundum Growth [54] It was reported by Allaire [54] as well as other researchers [59,62] that Eq.2.10 mentioned above is accompanied by a volume change (-26 vol% decrease), which allows the fonnation of microchannels and further metal penetration into the refractory (see Figure 2-9).…”

Section: Oamentioning

confidence: 99%

Intéraction entre les particules d'alumines, les alliages d'aluminium et ses inclusions durant la filtration d'aluminium avant la coulée /

Koont¹

2013

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Les échantillons obtenus des expériences aluminium-alumina ont été analysés à l'aide du microscope optique, du microscope électronique à balayage -la spectroscopie aux rayons X à dispersion d'énergie (MEB-EDX), du microprobe MEB, et de la diffraction des rayons X (DRX). Les résultats montrent que les réactions chimiques entre l'alpha-alumine pure à haute densité et les alliages Mg-Al liquides ne sont pas rapide; mais, la présence des impuretés (telle que Na2O en tant que phase de bêta-alumine) et la structure poreuse de l'alumine augmentent l'étendue des réactions significativement. La phase riche en Na2<3(bêta-alumine) qui se trouve dans toutes les alumines commerciales semble être l'un des facteurs les plus importants pour les réactions spontanées avec la vapeur de magnésium, même au temps de résidence le plus court. Mg-spinelle a été trouvé comme le produit de réaction le plus important. L'analyse thermodynamique indique la même tendance. SUMMARYThis project was undertaken to study the interactions between alumina particles, aluminum alloys, and its inclusions under liquid aluminum flow conditions. The objective was to develop a test method which can simulate the conditions similar to those in the aluminum filtration process and to evaluate the interactions taking place between various types of alumina samples, aluminum alloys, and its inclusions. With this test method, it was aimed to determine how various alumina types behave under flow conditions during the filtration process.Chemical interactions between alumina, aluminum alloys, and its inclusions were investigated under both static and dynamic flow conditions. In order to study these interactions under dynamic flow conditions, a knowledge of the velocity field in the vicinity of the alumina particles is necessary. In this project, two unique experimental systems which can simulate the flow condition of the industrial bed were designed and built. A mathematical model was also developed to predict the flow field around the particles in the experimental system. The mathematical model was validated by comparing the predictions with the results from a physical model in which water was used as the fluid.The mathematical model was then used to conduct parametric studies to determine the design and operational parameters for the actual experimental system in which the tests were carried out. This allowed the generation of a flow field similar to that of the industrial filter.The experiments with various liquid Mg-Al alloys (0, 2, 5, and 7 wt% Mg) were conducted for different residence times (from 6 hours to 168 hours) using the above VI experimental systems. The effects of the liquid aluminum alloy velocity, the temperature of the melt, the physical (apparent porosity, surface roughness, etc.) and chemical (impurity content such as Na2Û, SiÛ2 5 etc.) properties of alumina samples on the extent of aluminum

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The corrosion of refractory aggregates by molten aluminum

Cited by 27 publications

References 3 publications

Effect of Silica on High-Temperature Interfacial Phenomena of Monolithic Refractories with Al Alloy

Effect of Silica on High-Temperature Interfacial Phenomena of Monolithic Refractories with Al Alloy

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

Intéraction entre les particules d'alumines, les alliages d'aluminium et ses inclusions durant la filtration d'aluminium avant la coulée /

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