EFFECTS OF THE IN-SITU FORMATION OF BARIUM CELSIAN ON ALUMINOSILICATE CASTABLE REFRACTORIES

摘要

Refractories for molten aluminium contact applications face severe corrosion issues. Non-wetting additives such as barium sulphate are added to these refractories to increase their service life. Above its decomposition temperature, the role of barium sulphate as a refractory additive is limited to providing a source of BaO that can further react with oxides already present in the refractory to form barium aluminate and/or barium aluminosilicate (Ba-celsian) based on the refractory composition. It has been suggested that celsian may contribute to decreased wetting of the refractory or its formation may cause a pore channel blocking effect within the refractory. In-situ formation of celsian within a conventional aluminosilicate castable and its effects on corrosion resistance of the refractory was examined. The addition of BaCO_3 successfully improved corrosion resistance of the refractory by 40%. The reduction in apparent porosity suggested that some pore-blocking effect might have hindered the corrosion process. It may be concluded from the results that the elimination of porosity due to the formation of a non-wetting celsian phase improved the corrosion resistance of the refractory.