Interfacial phenomena involving liquid metals and solid oxides in the Mg–Al–O system

Weirauch, Douglas A.

doi:10.1557/jmr.1988.0729

Cited by 60 publications

(31 citation statements)

References 23 publications

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“…Observation of the inside of the cavity shows micro-channels which can act as an easy path allowing the diffusion of Mg, which reacts with the oxygen to develop the nodular structure (MgO). 20) Oxidation persists and the nodular structure coarsening causes the microchannels to gradually fill up the interface between the magnesium matrix and the oxide film. In the AM50A alloy, the fractured surface shows a granular fracture mode.…”

Section: Fracturing Mode Of the Eroded Oxide Filmmentioning

confidence: 99%

Diagnosis and Analysis of Oxide Films in Cast Magnesium Alloys by Ultrasonic-Vibration Treatment

Chen

Wei

2007

Mater. Trans.

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Magnesium alloys with low density are important light metals, widely used in the aerospace and automotive industries and in the manufacture of communication devices, consumer-electronics appliances and computers products in recent years. However magnesium and magnesium alloys are the most reactive metals so that oxide films easily form on them during the melting or pouring process. These films are difficult to observe by optical micrograph. In this study we propose a simple method to observe oxide films entrapped in cast magnesium alloys. The oxide films are fractured as a result of cavitation erosion on the sample surface that occurs during ultrasonic-vibration treatment. The eroded areas become visible as differently shaped foggy marks. This method of observing and identifying foggy marks is shown to be useful in the diagnosis of oxide films in cast magnesium alloys. In addition, the presented method in the diagnosis of oxide films that formed on magnesium and aluminum alloys are also compared.

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Section: Fracturing Mode Of the Eroded Oxide Filmmentioning

confidence: 99%

Diagnosis and Analysis of Oxide Films in Cast Magnesium Alloys by Ultrasonic-Vibration Treatment

Chen

Wei

2007

Mater. Trans.

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“…It has been reported in preparing aluminum matrix composites that the reactions among aluminum, magnesium and SiO 2 results in the formation of MgAl 2 O 4 and MgO. [10][11][12] A peak of silicon was also detected in each profile. This indicates that the silicon which remains in the reaction product (Fig.…”

Section: Methodsmentioning

confidence: 80%

Removal of Magnesium from Molten Aluminum Scrap by Compound-Separation Method with Shirasu

Hashiguchi

Sueyoshi

2010

Mater. Trans.

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The removal of magnesium from the molten aluminum scrap containing magnesium was examined by compound-separation method using Shirasu as an additive. When Sirasu is added to the molten aluminum scrap, which is followed by agitation, MgAl 2 O 4 and MgO are formed by the reactions among SiO 2 and Al 2 O 3 in Shirasu and magnesium in the molten scrap. It is feasible to remove magnesium by separating these reaction products as dross. The effect of addition temperature of Shirasu on magnesium removal is smaller than that of the agitation time. In the case of the addition of flaky Shirasu with 63-150 mm of particle size, the amount of magnesium removed increases linearly with agitation time because the over-all reaction is mainly controlled by a surface-controlled reaction. In the case of the addition of granular Shirasu with 300-590 mm of particle size, the amount of magnesium removed increases parabolically with agitation time because the over-all reaction is mainly controlled by a diffusion-controlled reaction. The amount of magnesium removed can be controlled by changing the amount of Shirasu added.

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“…It is reported by MacZura [45][46] that tabular alumina T-61 grade with <0.01% Na2Û is produced from 0.4-0.5% Na2Û containing calcined alumina feedstock. However, excess usage of boric acid causes channelling problems at the cooler portion of the shaft furnace because of condensation of sodium boride compounds.…”

Section: Tabular Aluminamentioning

confidence: 99%

“…Weirauch [45] reported that no reaction product observed using both optical and scanning electron microscopy methods at Al-3 wt%Mg / saffhire interface after 24 hours of contact time at 800°C. However, experiments conducted using Al-6 wt%Mg alloy by keeping the other experimental conditions constant, a mixture of spinel and (X-AI2O3 was found at the interface.…”

Section: * Mamentioning

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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Interfacial phenomena involving liquid metals and solid oxides in the Mg–Al–O system

Cited by 60 publications

References 23 publications

Diagnosis and Analysis of Oxide Films in Cast Magnesium Alloys by Ultrasonic-Vibration Treatment

Diagnosis and Analysis of Oxide Films in Cast Magnesium Alloys by Ultrasonic-Vibration Treatment

Removal of Magnesium from Molten Aluminum Scrap by Compound-Separation Method with Shirasu

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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