| Gel-casting technology was used for preparing ZrO2 toughen AbOs (ZTA) ceramics. Investigation was conducted into the preparing method and development of the products' microstructure. The influences of factors on the properties of the slurry such as dispersant, pH of the slurry, ZrO2 content, solid loading and organic monomer content were studied.1. On the preparation of slurriesFirstly, the pre-mixture was prepared. Acrylamide, methylene bis-acrylamide and citric acid were used as monomer, crosslinker and dispersant, respectively. The pH value was adjusted by ammonia. Then the ceramics powders were added into the pre-mixture under vigorous stirring.(1) The dispersant had a great influence on the slurries' Theological properties. The ZTA slurry was well dispersed and the viscosity was the lowest when the citric acid was added as dispersant by 0.26wt% (on the basis of the powders weight). It was preferred that the content of monomer was fixed less than 3.0 wt%.(2) The slurry rheological properties were greatly influenced by the pH value. The viscosity was the lowest when the pH reached 9-10.(3) The ZTA slurry rheological properties were also greatly influenced by the content of the zirconia which was added as a toughen phase. The slurry viscosity increased rapidly when the zirconia content was more than 12.5Vol%. And all the time, the slurry viscosity increased with the increase of the ZTA powder content.2. On the solidification reactionThe ammonium persulfate and tetramethyl ethylene diamine solutions were added to the prepared slurries as initiating and catalytic agents. The slurries were well stirred and put into oven to solidify.(1) The added contents of the initiating and catalytic agents had great influences on the velocity of the solidification reactions. It was preferred that the added content of theinitiating and catalytic agents was 0.4% and 0.04%, respectively (on the basis of the slurry volume).(2) The velocity of solidification reaction increased sharply with the increasing of the reaction temperature. The green products developed microstructure defects when the velocity of solidification reaction was too high.It was found that green products with high quality could be obtained when the reaction temperature was kept at 40 . The reaction lasted too long when the temperature was too low, whereas high reaction temperature was unfavorable, which led to many air voids in the green body.3. On products performanceThe performance of ceramics products was mainly depended on their microstructures. The results indicated that the slurry dispersion influenced the products' microstructure greatly. Products with homogeneous and dense microstructure could be obtained from the well-dispersed slurries.Products were prepared from the same components but by gel-casting and dry pressing, respectively. The performance of products prepared by gel-casting technology was much better than those by dry pressing.4. The study conies to conclusions as follows:Green body with solid content of 55vol% and high quality could be obtained underthe following conditions:pH value nearby 9.5,Citric acid equal to 0.26wt% (on the basis of the powders weight), Zirconia content at 12.5% (on the basis of the powders volume),Monomer content at 3.0% (on the basis of the powders weight),Initiating and catalytic agents (APS and TEMED,)at 0.4ml 10wt% and 0.04ml per 100ml of slurry, Solidification reaction at 40 Through sintering of as-prepared green body, products with homogeneous anddense microstructure were obtained. And their performances were much better thanthose prepared by traditional dry pressing method.
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