Chemical interaction between SrAl2Si2O8 and molten aluminum

Wetting and corrosion experiments by molten aluminum alloy were performed on mullite (Al6Si2O13) and/or SrAl2Si2O8 substrates. The SrAl2Si2O8 sustrates were synthesized from a mixture of alumina, silica and strontium carbonate at 1500 °C for 4 h. The formation of pure monoclinic SrAl2Si2O8 was corroborated by XRD analysis. The mullite sample showed a severe corrosion after the test, while the SrAl2Si2O8 sample showed a discontinue corrosion layer of about 100 μm. The wetting angles, obtained from the sessile drop test, were 124° and 128° for mullite in contact with pure Al and Al-Si, respectively, while for SrAl2Si2O8 were 140° and 152°, showing a no wetting behavior.