MgO crucibles were attacked by synthetic Al203-containing slags at 1500 degrees Celsius in air for various periods from 15 minutes to 8 hours using the drop quench technique. For samples attacked for 2 hours or more, clusters of newly-fanned crystals containing Mg, Fe and AI, presumably spinel, were observed to be separated from the magnesia by a melt region of relatively constant thickness of about 150-200 μm. The separation of the spinel crystals and the magnesia is in broad agreement with previous work by Rait under similar experimental conditions. Examination of samples attacked for shorter times suggests that the crystals initially formed on the MgO surface. Clusters of these crystals appear to have subsequently detached along the MgO / crystals interface and moved to a constant distance in the melt region.
Proceedings of 'Materials 98', the Biennial Conference of the Institute of Materials Engineering Australasia Ltd, Wollongong, New South Wales, Australia, 06-08 July 1998 / Michael Ferry (ed.), pp. 675-680