Issue 24, 2011

Controlling the microstructure of ceramic particle stabilized foams: influence of contact angle and particle aggregation

Abstract

Porous cellular alumina ceramic green bodies have been produced by combining the particle stabilized foam method with gelcasting. The suspension foams were stabilized by particles rendered weakly hydrophobic with short chain sulfonate surfactants. Poly vinyl alcohol (PVA) and 2,5-dimethoxy-2,5-dihydrofuran (DHF) were used as the gelcasting reagents. The microstructure (amount of porosity, average pore size, and morphology) of alumina (Al2O3) ceramic green body foams has been studied as a function of surfactant concentration and chain length. The morphology of gelled ceramic foams changes from closed cell (bubble like morphology) to open cell (granular morphology) as the surfactant concentration is increased beyond a critical level. The density (and porosity) of the gelled alumina green body foams changes as a function of the surfactant concentration in a non-linear manner. Measurement of the suspension viscosity, contact angle and aggregate size are used to explain the changes in density and morphology. The transition from the bubble like structure to the granular structure is due to an increase in the particle aggregate size rather than phase inversion induced by an increase in the contact angle. The same behavior is observed with three different chain length surfactants (ranging from 4 to 10 carbon atoms on the hydrophobic portion of the surfactant) but at a lower surfactant concentration as the chain length increases.

Graphical abstract: Controlling the microstructure of ceramic particle stabilized foams: influence of contact angle and particle aggregation

Article information

Article type
Paper
Submitted
01 Aug 2011
Accepted
10 Oct 2011
First published
21 Oct 2011

Soft Matter, 2011,7, 11464-11474

Controlling the microstructure of ceramic particle stabilized foams: influence of contact angle and particle aggregation

C. Chuanuwatanakul, C. Tallon, D. E. Dunstan and G. V. Franks, Soft Matter, 2011, 7, 11464 DOI: 10.1039/C1SM06477K

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