Stabilization of nano-particles in concentrated colloidal suspension to porous ceramics
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This study presents a novel method to study the stabilization mechanism of wet foams in concentrated colloidal suspension. The thermodynamic instability of wet foam bubbles in water due to the large and highly energetic interfacial area is the main challenge of processing such foams from colloidal suspension. Smaller bubbles under pressure diffuse into larger bubbles. This is known as Ostwald ripening, and it results in coarsening of the wet foam. Hence, the bubble size distribution broadens. To optimize the bubble size and the stability of wet foam, the adsorption free energy and Laplace pressure of nano-particle stabilized colloidal suspensions are investigated. Porous ceramics with more than 90% wet foam stability can be prepared easily with this novel approach. The sintered foam shows a particle free energy of 1.7 × 108 ~ 3.2 × 108 kTs and pressure difference of 20 mPa to 25 mPa for colloidal Al2O3 and SiO2 particles with particle size of 40 nm and 20 nm respectively.
Abstract
This study presents a novel method to study the stabilization mechanism of wet foams in concentrated colloidal suspension. The thermodynamic instability of wet foam bubbles in water due to the large and highly energetic interfacial area is the main challenge of processing such foams from colloidal suspension. Smaller bubbles under pressure diffuse into larger bubbles. This is known as Ostwald ripening, and it results in coarsening of the wet foam. Hence, the bubble size distribution broadens. To optimize the bubble size and the stability of wet foam, the adsorption free energy and Laplace pressure of nano-particle stabilized colloidal suspensions are investigated. Porous ceramics with more than 90% wet foam stability can be prepared easily with this novel approach. The sintered foam shows a particle free energy of 1.7 × 108 ~ 3.2 × 108 kTs and pressure difference of 20 mPa to 25 mPa for colloidal Al2O3 and SiO2 particles with particle size of 40 nm and 20 nm respectively.
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