Aluminum Oxide Ceramics Obtained by Commercial Starch Consolidation with Gradient Porosity
The starch consolidation technique is commonly used for obtaining porous ceramics due to bonding and porous-maker starch characteristic during gelling process. The method adopted here improved the water drainage by using a plaster porous base (70 and 90 consistency values) improving the water drainage by action of gravity and the capillary effect. It used slip with 50 vol% solids and as precursors oxide A-1000SG and commercial cornstarch with a mass concentration varying from 10 to 40%. For comparison between the present method and the common one, slip was put in impermeable and permeable base moulds. The gelling occurred at 70°C for 2 hours and the drying at 110°C. Pre-sintering was carried out at 1000°C and the sintering at 1600°C with a plateau of 1 hour. Results showed that the plaster consistency of the mould bases was preponderant on ceramics porosity. Porosity and apparent density measurements using light and electron microscopy revealed variation of 5% of porosity from the top to the bottom of the samples.
Pietro VINCENZINI, Ralf RIEDEL, Alexander G. MERZHANOV and Chang-Chun GE
R. P. Mota et al., "Aluminum Oxide Ceramics Obtained by Commercial Starch Consolidation with Gradient Porosity", Advances in Science and Technology, Vol. 63, pp. 175-180, 2010