ZnO and MgO as inducers of spinel-like phase formation on alumina-based castables

Author(s)

Borges, O. H. ; Sardelli, J. A. P. ; Neto, C. Pagliosa ; da Luz, A. P. ; Pandolfelli, V. C.

• Document type: Journal article
• Source: Journal of the European Ceramic Society; v. 42, n. 15, p. 8-pg., 2022-12-01.

Abstract

Environmental issues regarding Cr6+ formation lead to replacing chrome-containing refractories with greener alternatives. MgO-containing compositions have been extensively investigated for this purpose, however, few studies evaluated the likelihood of using other chemical elements as inducers of spinel-like phase formation in refractory castables. In this study, the addition of zincite in alumina-based castables was evaluated and compared with its MgO-counterpart. In-situ elastic modulus, assisted sinterability and differential scanning calorimetry pointed out that the gahnite (ZnAl2O4) formation took place at lower temperatures (- 1100 degrees C) than MgAl2O4 (- 1300 degrees C). On one hand, this feature induces anticipated strengthening of the Zn-containing compositions, giving rise to the possibility of firing these compositions at lower temperatures. On the other, the faster kinetics of gahnite formation led to a significant Kirkendall effect, changing the morphology of the pores created during sintering, which became preferentially located at the interface of alumina aggregates, negatively affecting some mechanical properties of the castable. (AU)

• FAPESP's process: 21/00114-2 - Development of advanced eco-friendly spinel-containing castables to replace chromite-based refractories
• Grantee: Otávio Henrique Borges
• Support Opportunities: Scholarships in Brazil - Doctorate