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(Reference retrieved automatically from SciELO through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Hydroxylation Studies on High-Solid Load Magnesia Aqueous Suspensions

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Author(s):
Rafael Salomão [1] ; Leandro Fernandes [2]
Total Authors: 2
Affiliation:
[1] Universidade de São Paulo. Escola de Engenharia de São Carlos. Departamento de Engenharia de Materiais - Brasil
[2] Universidade de São Paulo. Escola de Engenharia de São Carlos. Departamento de Engenharia de Materiais - Brasil
Total Affiliations: 2
Document type: Journal article
Source: MATERIALS RESEARCH-IBERO-AMERICAN JOURNAL OF MATERIALS; v. 26, 2023-01-06.
Abstract

Abstract The magnesia (MgO) hydroxylation behavior in dilute suspensions (below 50% volumetric solid loads) has been extensively studied over the past decades due to its role in refractory castables. However, its equivalent effects on concentrated systems have not been analyzed in such a systemic way, although they are known to be as or more deleterious than those observed in dilute systems. This study focuses on the hydroxylation behavior of different sources of magnesia (sinter and caustic magnesia) in aqueous suspensions prepared at various solids concentrations (17-96 vol%) and shaped by distinct methods. They were analyzed by thermogravimetry, apparent volumetric expansion measurements, X-ray diffraction, scanning electron microscopy, and in situ temperature measurements during curing. The ratio between experimental and theoretical extents of the hydroxylation degree resulted in the reaction yield. A comparison between samples containing the same water amount revealed those with caustic magnesia showed a faster evolution of hydroxylation degree, apparent volumetric expansion, and higher maximum internal temperature during curing. In both systems, the yield levels of compositions of heavier solid loads were higher, despite the small quantity of hydroxylation products formed. Significant differences in the products’ microstructure were observed and related to the ions' mobility toward crystallization nuclei. (AU)

FAPESP's process: 10/19274-5 - Novel methodology for hydrotalcite (Mg6Al2(OH)16CO3.4H2O) synthesis from aqueous suspensions of magnesium oxide (MgO) and aluminum hydroxide (Al(OH)3) and its application in porous ceramics for high temperature thermal insulation
Grantee:Rafael Salomão
Support Opportunities: Research Grants - Young Investigators Grants
FAPESP's process: 18/19773-3 - Microporous castable refractories in the Al2O3-MgO-CaO system for thermal insulation above 1200ºC
Grantee:Rafael Salomão
Support Opportunities: Scholarships abroad - Research