The sedimentation behavior and suspension stability of submicrometer Al2O3 powder-toluene mixtures have been investigated using various organic surfactants to aid powder dispersion in a dilute solids concentration (4.8 vol.%). The surfactants used include a commercially-available, carbonate-based dispersant (hereafter termed the `SOL') and some fatty acids (e.g. stearic acid `SA', oleic acid `OA' and 12-hydroxystearic acid `HSA') in a concentration range 0.3-5 wt.% of the alumina loading. The experiment reveals that the surfactant nature is critical to the suspension stability. The suspensions follow a decreasing order of stability SOL > HSA > SA > OA for the Al2O3-toluene mixtures. This surfactant-dependent behavior is critically related to the adsorption affinity of the surfactant molecules on the powder surface in the carrier medium. The adsorption isotherms exhibit the Langmuir-typed behavior and reach a saturation plateau over a range of 1.3-2.4 mg m(-2), revealing a surfactant-specific characteristic. (C) 2001 Elsevier Science B.V. All rights reserved.
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MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING Volume: 318 Issue: 1-2 Pages: 102-110
