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Novel colloidal silica technology for MgO-containing refractories - Part 1: Anti-hydroxylation binder

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Author(s):
Saloma, Rafael ; Martinatti, Isabela S. ; Fernandes, Leandro ; Andreas, Sundblom ; Greenwood, Peter ; Tiba, Paulo R. T.
Total Authors: 6
Document type: Journal article
Source: OPEN CERAMICS; v. 15, p. 12-pg., 2023-07-04.
Abstract

Refractory castables play major roles in high-temperature applications and two important types are MgOcontaining and colloidal silica-bonded castables. Whereas the former shows high refractoriness and resistance to slag corrosion, the latter offers straightforward mixing, curing, and drying processes. However, their association in a same system has not been synergistic. During mixing, MgO particles release Mg2+ ions that trigger the gelling of colloidal silica. Therefore, small MgO additions gradually hard high-alumina colloidal silica-bonded castables; conversely, larger amounts instantly set the system, hindering homogenization and casting. Despite the challenges, there is potential for making these systems compatible towards technological application. This study successfully combined fine MgO sinter with a novel aqueous dispersion of epoxysilane-modified colloidal silica, creating self-flowing suspensions of good workability. Cured samples exhibited no signs of damage by MgO hydroxylation, sufficient strength for demolding and safer drying. Thermal treatments resulted in a dense microstructure with MgO grains surrounded by Mg2SiO4. (AU)

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
FAPESP's process: 22/03655-7 - Reducing energy losses in industrial processes with high-efficiency thermal insulation of microporous castable calcium silicate produced from elements of biomass: eggshells and rice husk ash
Grantee:Rafael Salomão
Support Opportunities: Program for Research on Bioenergy (BIOEN) - Regular Program Grants