Dec 2017: Chris Sorrell and Pramod Koshy, "Interfacial reactions between Al7075 alloy and BaAl2Si2O8 + CaAl2Si2O8 mixture"

Dec 2017: Chris Sorrell and Pramod Koshy, "Interfacial reactions between Al7075 alloy and BaAl2Si2O8 + CaAl2Si2O8 mixture"

Blended Additive Compositions for Enhanced High-Temperature Corrosion Resistance of Aluminosilicate Refractories

Authored by Esmaeil Adabifiroozjaei, Pramod Koshy, Ebad Rastkerdar, Honghang Ma and Charles C. Sorrell.

Aluminosilicate refractories are quite prone to reactions with molten aluminium and its alloys at high casting temperatures and this results in material loss and lowering of production efficiencies.  Ca- and Ba-based compounds are generally added to these refractories to enhance their corrosion resistance and the mechanism of their action is based on the formation of complex aluminosilicates such as anorthite (CaAl2Si2O8) and celsian (BaAl2Si2O8) which are resistant to molten aluminium attack.  The present work investigates the mechanistic changes in the interfacial reactions between the molten alloy and the refractory ceramic when both additives are present together and at different temperatures.  The work showed that interdiffusion between Ba2+ and Ca2+ would result in the formation of barium calcium aluminate species as an intermediary, thus making the reaction pathway distinct from the case of compositions with one compound alone.  Furthermore, celsian was observed to be more resistant to reactions in comparison to anorthite.