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Processing of cordierite foams by direct foaming

Elisabete R. Silva 1Nuno Correia 1João M. Silva 2Fernando C. Oliveira 3Fernando R. Ribeiro 1João C. Bordado 1Filipa Ribeiro 1

1. Instituto Superior Técnico, Departamento de Engenharia Química, Av. Rovisco Pais, Lisboa 1049-001, Portugal
2. Instituto Superior Engenharia de Lisboa, Departamento de Engenharia Química, Av. Cons. Emídio Navarro, Lisboa 1950-062, Portugal
3. Instituto Nacional de Engenhariae Tecnologia Industrial, Departamento de Materiais, Estrada do Paço do Lumiar, Lisboa 1649-038, Portugal

Abstract

Open-cell ceramic foams have properties that make them attractive as catalyst supports. The "replication" process is the most widely and versatile method used for producing cellular ceramic materials. One of the drawbacks of this process is that the ceramic ligaments (struts) contain a hollow cavity possessing sharp edges due to the burnout of the polymeric template. The presence of such voids in the struts decreases the cohesion of the material in comparison to foams possessing dense struts manufactured by conventional direct foaming techniques. The aim of this work was therefore to develop cordierite-based foams by a direct foaming method and to compare the resulting properties with those obtained for foams previously developed by the replication process. The ultimate goal is to fabricate supports for depositing metal zeolites suitable for catalytic combustion of VOCs.In this work reticulated cordierite foams have been prepared by mixing of ceramic particles within a polyol followed by reaction with a MDI type isocyanate to form a polyurethane foam. Some of the experimental parameters, which were optimized, include the type and amount of surfactant, catalyst, polyol as well as the content of solids, plasticizer and blowing agent that need to be added. After curing, the polymer was burnt out under air, and the resulting ceramic foam was then sintered.Up to now, foams possessing porosities higher than 90% were obtained. Efforts are being made in order to increase density by adding coupling agents to promote a better dispersion of the inorganic filler within the polymer mix. The presence of surfactant has been found to play an important role in stabilizing the liquid-gas interface of bubbles during the expansion step, thus affecting significantly the cell characteristics of the resulting cordierite foams. Alternative ways for controlling foam density are discussed.

 

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Presentation: Poster at E-MRS Fall Meeting 2006, Symposium D, by Elisabete R. Silva
See On-line Journal of E-MRS Fall Meeting 2006

Submitted: 2006-05-12 21:32
Revised:   2009-06-07 00:44