Effect and Mechanism of Alumina on the Morphology and Mechanical Properties of Calcium Ferrite
Abstract
Al2O3 greatly influences the formation of complex calcium ferrite, which is the main binder and iron-bearing phase in sinter. Experiments were carried out in air at 1200 °C with different amounts of Al2O3 mixed with CaO.Fe2O3 (calcium ferrite). The samples contained two phases: CaFe2O4 and Ca3.18Fe15.38Al1.34O28 (CFA). The results showed that the morphology of the complex calcium ferrite was massive (w(Al2O3) = 0 pct), columnar and plate-like (w(Al2O3) = 0.5 and 1 pct), and acicular and plate-like (w(Al2O3) = 2, 3, and 5 pct). A small amount of Al2O3 solid solution in CaFe2O4 increased the preferred orientation of the crystal. The gradual increase in Al2O3 in the sintered samples caused the complex calcium ferrite composition to be closer to that of silico-ferrite of calcium and aluminum (acicular SFCA-I). When Al2O3 dissolved into calcium ferrite, complex calcium ferrite was formed, which increased the hardness of the sample. The fracture toughness of the sample increased with increasing Al2O3 content from 0 to 2 pct, possibly due to a decrease in grain size. When the Al2O3 content exceeded 3 pct, Al2O3 dissolved into calcium ferrite and decreased the fracture toughness of the sample.
- Publication:
-
Metallurgical and Materials Transactions B
- Pub Date:
- February 2020
- DOI:
- 10.1007/s11663-020-01783-2
- Bibcode:
- 2020MMTB...51..776Y