Plasticizing Aqueous Suspensions of Concentrated Alumina with Maltodextrin Sugar

• Published in: Journal of the American Ceramic Society Vol. 82; no. 1; pp. 57 - 66
• Main Authors: Schilling, Christopher H., Bellman, Robert A., Smith, Rachelle M., Goel, Honey, Giesche, Herbert
• Format: Journal Article
• Language: English
• Published: Westerville, Ohio American Ceramics Society 01.01.1999; Blackwell; Wiley Subscription Services, Inc
• Subjects: Applied sciences; Building materials. Ceramics. Glasses; Ceramic industries; Chemical industry and chemicals; Exact sciences and technology; General studies; Technical ceramics; Viscosity; Filtration; Electrical properties; Ceramic body; Particle suspension; Surface analysis; Experimental study; Sedimentation; Oxide ceramics; Plasticizer; Maltodextrin; Shear stress; Technical ceramics; Extrusion; Electrokinetic potential; Manufacturing; Alumina; Press filter; Rheological properties
• ISSN: 0002-7820; 1551-2916
• DOI: 10.1111/j.1151-2916.1999.tb01723.x

Aqueous suspensions of submicrometer, 20 vol% Al2O3 powder exhibited a transition from strongly flocculated, thixotropic behavior to a low‐viscosity, Newtonian‐like state upon adding small amounts of maltodextrin (0.03 g of maltodextrin/(g of Al2O3)). These suspensions could be filter pressed to highly dense (57%) and extrudable pastes only when prepared with maltodextrin. We analyzed the interaction of maltodextrin with Al2O3 powder surfaces and quantitatively measured the resulting claylike consolidation, rheological, and extrusion behaviors. Benbow extrusion parameters were comparable to, but higher than, those of kaolin at approximately the same packing density of 57 vol%. In contrast, Al2O3 filter cakes without maltodextrin at 57 vol% density were too stiff to be extruded. Measurements of rheological properties, acoustophoresis, electrophoresis, sorption isotherms, and diffuse reflectance Fourier infrared spectroscopy supported the hypothesis that sorbate‐mediated steric hindrance, rather than electrostatic, interparticle repulsion, is important to enhancing the consolidation and fluidity of maltodextrin–Al2O3 suspensions. Viscosity measurements on aqueous maltodextrin solutions indicated that free maltodextrin in solution does not improve suspension fluidity by decreasing the viscosity of the interparticle solution.