Macroporous Alumina Ceramics with Aligned Microporous Walls by Unidirectionally Freezing Foamed Aqueous Ceramic Suspensions
Abstract:This paper reports a novel way of producing macroporous ceramics with aligned microporous walls by unidirectionally freezing foamed aqueous ceramic suspensions. The stability of the air bubbles introduced by magnetic stirring was improved remarkably using polyvinyl alcohol (PVA) as both a binder and emulsifying agent. Furthermore, the unidirectional freeze casting method could not only trap the air bubbles in the solidified sample successively but also induce the preferential growth of ice dendrites. This endowed the samples with uniform macropores surrounded by aligned microporous alumina walls after freeze drying and sintering. The sample produced with a PVA content of 8 wt% showed a high compressive strength of 4.6 ± 1.6 MPa at a high porosity of 91 vol%.
Document Type: Research Article
Affiliations: 1: Department of Dental Laboratory Science and Engineering, Korea University, Seoul 136-703, Korea 2: Department of Materials Science and Engineering, Seoul National University, Seoul 151-742, Korea
Publication date: June 1, 2010