Formation of different alumina phases and magnesium aluminate spinel during contact of molten AlSi7Mg0.6 alloy with mullite and amorphous silica
2017
Abstract
Corrosion of alumina-based metal melt filters functionalized by 3Al(2)O(3)center dot 2SiO(2) or fused SiO2 was investigated using local chemical and microstructure analyses and thermodynamic calculations. Molten aluminium alloy AlSi7Mg0.6 was employed as corrosion medium.
The aluminium alloy was melted in a Spark Plasma Sintering apparatus in order to avoid the melt flow. During the reaction with the AlSi7Mg0.6 melt, 3Al(2)O(3)center dot 2SiO(2) partly decomposed, and Al2O3 reacted with magnesium from the melt and with oxygen from SiO2 to MgAl2O4.
Silicon precipitated in the aluminium alloy. For corundum functionalized by fused SiO2, metastable gamma-Al2O3 was detected additionally to the above phases for short reaction times.