Study On The Preparation Process Of Alumina Ceramic Plate By Aqueous Gelcasting

Aqueous gelcasting is of short process cycle and can be used to form different near net shapes of ceramic, by which the green body prepared is of high strength and can be mechanical processed, so the technology is widely used in various ceramic research and production. In this paper, acrylamide monomer polymer gel system and gelatin macromolecules system, two water-based gel systems, were chosen to prepare alumina ceramic plate. Homogeneous internal structure and excellent mechanical properties of alumina ceramic plate was made by studying the forming process parameters in the process.For acrylamide monomer system, solid content of 54 vol% alumina slurry was prepared by controlling the content of dispersing agent, PH value, ball grinding time. During the experiment, effect of solid content on the properties of green body was studied. The drying and discharging curve were determined by lots of experiments. The best adding content of monomer was decided by studying its impacts on ceramic density and flexural strength as well as microstructure. The optimum sintering temperature was set by investigating the influence on the microstructure and mechanical properties of ceramic. Results show that, when the solid content was 54 vol%, dispersant content is 1.2 wt%, PH=9, milling time of 6 hours, the monomer content was 2.7 wt%, the properties of ceramic were the best. Flexural strength of the green body reached 23.87 MPa, the shrinkage rate is only 1.99 %. After discharge and sintered at 1640 °C, porosity of the ceramic was 1.78 % while bulk density and the flexural strength reached 3.64 g/cm3 and 313.62 MPa respectively, on which conditions the performance was best.As to gelatin system, alumina slurry with good fluidity was prepared by adjusting the concentration of dispersing agent, PH value, ball grinding time and gelatin content. The relationship between solid loading and mechanical properties or shrinkage rate was studied. Impacts of gelatin content and sintering temperature on the properties and microstructure of ceramics were researched. Results: when the solid content is 50 vol%, dispersant content is 1 wt%, PH=9, milling time 5 hours, 4.5wt% gelatin, properties of the ceramic were best. Flexural strength of the green body reached 5.69 MPa, the shrinkage rate was 2.36 %. Sintered at 1640 °C, porosity of the ceramic was 3.24 % while bulk density and the flexural strength reached 3.60 g/cm3 and 269.20 MPa respectively, and the performance was best.Alumina ceramic plates prepared by acrylamide monomer polymerization system were with uniform internal microstructure and high strength which could be machining on green body. Ceramic plates under the best processing conditions were with high density and uniform microstructure, which was almost pore-free. So the monomer system was fit for industrial production; Ceramic plates which prepared by gelatin macromolecules were with relative high porosity and less uniform microstructure, and the gelatin macromolecules system need to be improved.