ZnO and MgO as inducers of spinel-like phase formation on alumina-based castables. Issue 15 (December 2022)

• Record Type: Journal Article
• Authors: Borges, O.H.; Sardelli, J.A.P.; Pagliosa Neto, C.; da Luz, A.P.; Pandolfelli, V.C.
• Is Part Of: Journal of the European Ceramic Society. Volume 42:Issue 15(2022)
• Page Start: 7335
• Page End: 7342
• Publication Date: 2022-12
• Subjects: Gahnite -- Reaction sintering -- Spinel -- ZnO -- Refractory castables; Ceramic materials -- Periodicals; Composite materials -- Periodicals; Matériaux céramiques -- Périodiques; Composites -- Périodiques; Ceramic materials; Composite materials; Periodicals; Electronic journals; 666.05
• DOI: 10.1016/j.jeurceramsoc.2022.08.030
• Languages: English
• ISSNs: 0955-2219

Abstract

Abstract: Environmental issues regarding Cr 6+ 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 (ZnAl2 O4 ) formation took place at lower temperatures (∼ 1100 °C) than MgAl2 O4 (∼ 1300 °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.