Novel Colloidal Silica Technology For In Situ Spinelization in MgO-Containing Refractories

Autor(es)

Salomao, Rafael ; Fernandes, Leandro ; Sundblom, Andreas ; Greenwood, Peter ; Martinatti, Isabela Santos ; Tiba, Paulo Roberto Teruo

• Tipo de documento: Artigo Científico
• Fonte: MATERIALS RESEARCH-IBERO-AMERICAN JOURNAL OF MATERIALS; v. 27, p. 13-pg., 2024-01-01.

Resumo

This study used an aqueous dispersion of silanized colloidal silica (SCS), whose particles' surfaces were modified with an epoxysilane-based coupling agent, as the liquid medium and binder for MgO-Al2O3-containing suspensions. Fine calcined alumina and magnesia sinter particles were dispersed in SCS to form a 65 vol% solids suspension. Equivalent silica-free compositions containing calcium aluminate cement or unsilanized colloidal silica were tested as references. After mixing, the SCS-suspension showed low viscosity and suitable workability and, after curing, a thin protective coating of magnesium silicate hydrate (MSH) was formed, thus preventing MgO hydroxylation and improving bonding strength, generating green-dried structures of significant flexural strength (8 MPa). During initial heating, the decomposition of MSH and the softening of amorphous silica particles reduced the overall expansion of spinel (MgAl2O4) formation. After sintering at 1600oC, the structure showed intense densification (total porosity of 8%) high flexural strength (73 MPa) and large spinel crystals surrounded by a thin layer of amorphous silica and magnesium silicates. (AU)

• Processo FAPESP: 18/19773-3 - Refratários microporosos moldáveis no sistema Al2O3-MgO-CaO para isolamento térmico acima de 1200ºC
• Beneficiário: Rafael Salomão
• Modalidade de apoio: Bolsas no Exterior - Pesquisa
• Processo FAPESP: 22/03655-7 - Redução de perdas energéticas em processos industriais com isolamento térmico de alta eficiência usando revestimentos moldáveis de silicato de cálcio microporoso produzido a partir de elementos de biomassa: cascas de ovos e cinzas de cascas de arroz
• Beneficiário: Rafael Salomão
• Modalidade de apoio: Auxílio à Pesquisa - Programa BIOEN - Regular