Near-Net-Shape Fabrication of Porous Alumina-Spinel Castings
2005 年 46 巻 12 号 p. 2647-2650
詳細
2005 年 46 巻 12 号 p. 2647-2650
The dispersion and fluidity of aqueous platelet γ-alumina slurries were enhanced by addition of ammonium polyacrylate (PAA) as a dispersant at pH 10. Magnesia powder was mixed with the slurries using a planetary mixer for 150 s after ball milling of the slurries for 24 h. Magnesia was eluted gradually into the aqueous media by formation of a chelate with PAA. The slurries were solidified by PAA deficiency because of reduction of the electrostatic repulsive force between the alumina particles. The degree of shrinkage of the green body on drying was very small, and this was therefore regarded as a near-net-shaping process. A porosity of about 60% and strength of 45 MPa were obtained in bodies fired at 1300°C and the mean pore diameter was 0.6 μm.
