Abstract: High-density green body is the basis to prepare high performance ceramics. Re-fluidising combined with filtrating was applied to prepare high-density alumina green body, and the effect of re-fluidising combined with filtrating on characteristic of green body was investigated. The results show that the re-fluidising slurry after syneresis for 1 d has better compressibility, and the compressibility of the slurry decreases with the extension of syneresis time. Re-fluidising combined with filtrating is an effective method to improve the physical and mechanical properties of slurry, especially for high solid content slurry. Compared with the green body prepared by direct filtration of slurry with 56.0% solid content, the relative density of the green body manufactured by re-fluidising combined with filtrating increases from 64.5% to 65.7% and the cumulative pore volume decreases from 0.149 mL/g to 0.140 mL/g. Correspondingly, the sintering shrinkage ratio of green body decreases from 13.2% to 12.6% when sintering at 1 550 ℃ for 2 h, and the flexural strength increases from 483 MPa to 545 MPa after sintering at 1 500 ℃ for 6 h. This is important for the preparation of ceramics with large size.

Key words: spontaneous coagulation casting, filtrating, alumina, high solid content, high-density, low shrinkage ratio