Foam Sprayed Porous Insulating Refractories

A.P. Luz, V.C. Pandolfelli, V.R. Salvini

Federal University of São Carlos, Materials Engineering Department, 13565-905 São Carlos – SP/Brazil

Revision 19.04.2012, 16.07.2012

Volume 4, Issue 4, Pages 93 - 97

Abstract

Porous ceramics can be applied as filters for molten metals, gases or water filtration, orthopedic implants and insulating refractories. The production of these materials is mainly based on techniques involving the addition of gases, lightweight compounds and/or combustible pore forming additives to the ceramic suspensions. The present work evaluates insulating refractory compositions designed according to the Andreasen packing model and prepared by using a novel direct foaming procedure (applying compressed air in equipment specially developed for large-scale production of porous ceramics). Density, porosity and pore size distribution, splitting tensile strength and thermal conductivity of the foamed specimens were measured. According to the results, the prepared refractories presented a high porosity content (>69 %), low thermal conductivity (0,3–2,3 W/m·K in the range of 200 to 1200 ºC) and improved splitting tensile strength (1,8–15,2 MPa). The evaluated foaming method is a feasible alternative for producing homogeneous refractory porous ceramics for thermal insulating applications. Additionally, by adjusting the composition particle size distribution, ceramic suspensions with enhanced fluidity and, consequently, fired samples with higher mechanical strength can be attained.

Keywords

foamed ceramics, porous, ceramics, insulating refractory materials

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