In the presence of air and oxygen, oxidation of a molten aluminum alloy will easily take place. The oxidation not only harms the operation by contributing to melt losses, but the processing of the oxides present in the melt and refractory is also costly in time and money. Refractory accretions formed due to the interactions between the oxide-layer and base refractory material, especially alumina-lined ones, are a significant problem for the industry. Aluminum alloys containing magnesium are known to oxidize much more easily and rapidly. In the foundry, oxidation of molten aluminum-magnesium alloy is more prominent than that of pure aluminum. Magnesium has a higher affinity for oxygen, causing it to oxidize more easily than aluminum. In previous studies of oxidation of aluminum alloys, it has been found that strontium additions to the alloy reduce the amount of oxidized layer in an undisturbed melt. / The effects of strontium additions on the oxidation behavior of commercial A356, A357 and 5182 aluminum alloys were investigated by monitoring sample weight gains with time with a thermo-gravimetric balance at 700, 750, and 800°C. Sample surfaces were examined using electron microscope and x-ray diffraction techniques. It was found that in the absence of Sr, the A356 and A357 samples gained substantial amounts of weight through the preferential oxidation of magnesium. Samples containing strontium had significantly lower weight gains. For the high magnesium-containing 5182 alloy, an increase of incubation period before the onset of significant oxidation is associated with the presence of strontium. This change in oxidation behavior was linked to the presence of strontium containing oxide species in the oxidizing surface.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.34004 |
| Date | January 2001 |
| Creators | Yuen, Pui Kei, 1976- |
| Contributors | Drew, R. A. L. (advisor), Gruzleski, J. E. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Engineering (Department of Mining, Metals and Materials Engineering.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001873908, proquestno: MQ79107, Theses scanned by UMI/ProQuest. |
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