Evolution of an alumina-magnesia/self-forming spinel castable. Part I: Microstructural features

Abstract

Refractories containing magnesium aluminate spinel (MgAl2O4) are materials for emerging technology in several applications like cement and steelmaking processes. In order to deep the understanding of these castables, this work presents the microstructural characteristics of an alumina-magnesia/self-forming spinel castable. Several variables such as MgO content, firing temperature and spinel formation are analyzed through XRD and SEM analysis. The results showed that the processes of spinel formation and nucleation are not strongly affected by the MgO content, but that the crystal growth is enhanced for samples with 6.0 wt% MgO. Hibonite (CA6) bonding in the castable matrix showed a needlelike structure that could increase hot properties of the material. MgO content in the castable seems to affect the hibonite development. The development of a self-forming spinel castable without any synthetic spinel grains appears to be promissory for optimum refractory linings.

Alumina‐spinel castable for steel ladles: An overview

“…44 However, a large number of cracks were generated with magnesia grain size finer than 100 µm and degraded the properties like mechanical strength and creep resistance. 44 Physicochemical, mechanical, and microstructural properties of in situ spinel castables were evaluated by Gutiérrez-Campos et al 45,46 at three different temperatures 1000, 1200, and 1400 • C with MgO content 5, 5.5, and 6 wt.%, respectively. Hu et al 47 investigated the role of a 5-µm size magnesium carbonate additive on the in situ spinel containing castable.…”