CORROSION RESISTANCE OF FUSED CR2O3―AL2O3 GRAINS WITH DIFFERENT COMPOSITIONS

Abstract

Six kinds of Cr₂O₃―Al₂O₃ fused grains (the mass percent of Cr₂O₃ was 15, 40, 50, 60, 85 and 99 %, respectively) were prepared using chrome green and Al₂O₃ powder as starting materials by electro-fusion, named as CR15, CR40, CR50, CR60, CR85, and CR99, respectively. The corrosion resistance of six kinds of Cr₂O₃―Al₂O₃fused grains (4‒1 mm) was studied used rotary slag corrosion method. The results show that: (1) the corrosion resistance of fused grains increases with the Cr₂O₃ content and the grain size increasing; (2) the grains of CR99 and CR85 with higher Cr₂O₃ content are corroded at the slag surface layer , because FeO and Al₂O₃ in the slag corrode the grains; FeO reacts with Cr₂O₃ in the aggregates forming (Fe, Cr)3O4 spinel firstly, and the spinel reacts with other phases forming composite spinel; when FeO is fully consumed, Al₂O₃ penetrated into the grains reacts whith Cr₂O₃, forming Cr₂O₃―Al₂O₃ solid solution on the grains surface; (3) for CR60, the corrosion exists both in the slag surface layer and in the penetration layer; in the pentration layer, CaO and SiO₂ react with Al₂O₃ in Al₂O₃― Cr₂O₃ solid solution forming anorthite, gehlenite, and glass phase; the grains of CR50, CR40 and CR15 have the same corrosion mechanism with CR60 in the penetration layer. Ill. 8. Ref. 8. Tab. 1.