Gel casting based on thermal solidification andits interfacisl chemistry for production of defect-free ceramics

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This research applies the new solidification phenomenon of ceramic slurry, which was found by the present investigator, for the production of ceramic green body. Powerful characterization tools, which were also developed by the present investigators, were applied to examine the structure of the body to made green bodies without flaw. These new approaches are indispensable for developing novel forming method called gel casting based on thermal solidification and also for developing high performance ceramics without flaw.This study shows that alumina green body without large flaws can be formed by the present method. The green body was found to have highly uniform microstructure. The body has high sinterability and was densifled to 98% of theoretical value at a temperature 1OOK below the normal sintering temperature. The sintering temperature may be further reduced by improved homogeneity The solidification mechanism involves the thermal change of interface chemistry between the poly-acrylic acid used as a dispersant and the alumina surface. The increased adsorption due to an apparent endo-thermal heat of adsorption is responsible for the solidification.