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Effect of CaF2 and BaSO4 additives on the corrosion resistance of aluminosilicate castables against molten aluminum.

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Title: Effect of CaF2 and BaSO4 additives on the corrosion resistance of aluminosilicate castables against molten aluminum.
Authors: Zhou, Fangfang1,2 (AUTHOR), Han, Bingqiang1,2 (AUTHOR) hbqref@126.com, Zhong, Hutang1,2 (AUTHOR), Wei, Jiawei3 (AUTHOR), Wei, Yaowu1,2 (AUTHOR), Chen, Junfeng1,2 (AUTHOR), Yao, Xiaoyun4 (AUTHOR)
Source: Ceramics International. Jul2026, Vol. 52 Issue 18, p33113-33122. 10p.
Subjects: Calcium fluoride, Barium sulfate, Liquid aluminum, Microcracks, Corrosion resistance, Corrosion prevention, Minerals, Castable refractories
Abstract: Impermeable materials are crucial for preventing molten electrolyte and aluminum penetration in aluminum electrolytic cells. Although aluminosilicate castables can form a nepheline phase to inhibit electrolyte permeation, they exhibit limited resistance to molten aluminum corrosion. To enhance the resistance of impermeable-layer castables to molten aluminum penetration, the effects of CaF 2 and BaSO 4 additives on the penetration resistance of aluminosilicate castables were comparatively investigated. The results demonstrated that, during molten aluminum attack, molten aluminum reacted with BaSO 4 in the specimen and mullite in the matrix, resulting in the in situ formation of celsian (BaAl 2 Si 2 O 8). Because of its poor wettability toward molten aluminum, celsian formed a protective barrier at the interface, effectively suppressing molten aluminum penetration. By contrast, CaF 2 functions as a strong fluxing agent, promoted excessive liquid-phase formation at high temperatures, disrupted the skeletal structure of bauxite aggregates, and induced microcracks in the castable. Molten aluminum then infiltrated along these microcracks and reacted intensely with SiO 2 via an aluminothermic reduction reaction. The resulting volume expansion further transformed the microcracks into penetration channels, ultimately intensifying molten aluminum attack on the castable. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
Description
Abstract:Impermeable materials are crucial for preventing molten electrolyte and aluminum penetration in aluminum electrolytic cells. Although aluminosilicate castables can form a nepheline phase to inhibit electrolyte permeation, they exhibit limited resistance to molten aluminum corrosion. To enhance the resistance of impermeable-layer castables to molten aluminum penetration, the effects of CaF 2 and BaSO 4 additives on the penetration resistance of aluminosilicate castables were comparatively investigated. The results demonstrated that, during molten aluminum attack, molten aluminum reacted with BaSO 4 in the specimen and mullite in the matrix, resulting in the in situ formation of celsian (BaAl 2 Si 2 O 8). Because of its poor wettability toward molten aluminum, celsian formed a protective barrier at the interface, effectively suppressing molten aluminum penetration. By contrast, CaF 2 functions as a strong fluxing agent, promoted excessive liquid-phase formation at high temperatures, disrupted the skeletal structure of bauxite aggregates, and induced microcracks in the castable. Molten aluminum then infiltrated along these microcracks and reacted intensely with SiO 2 via an aluminothermic reduction reaction. The resulting volume expansion further transformed the microcracks into penetration channels, ultimately intensifying molten aluminum attack on the castable. [ABSTRACT FROM AUTHOR]
ISSN:02728842
DOI:10.1016/j.ceramint.2026.04.359