Preparation of SiC ceramics by aqueous gelcasting and pressureless sintering

Autores: Zhang, T.|Zhang, Z.Q.|Zhang, J.X.|Jiang, D.L.|Lin, Q.L.
Fuente: Mater. sci. eng.
A. 443 (1-2), 257-261
2007

Gelcasting is an attractive forming process to fabricate ceramic parts with complex shape. In the present work, aqueous gelcasting of SiC was studied. SiC slurry (50 vol.%) for gelcasting was prepared with sintering assistants, Al2O3 and Y2O3. The slurry was solidified in situ to green body with relative density of 55.9 +/- 0.9% and flexural strength of 13.9 +/- 0.7 MPa. SEM shows that ceramic powders in green body compact closely by the connection of polymer networks, and that the pores decrease greatly with the size less than I mu m. SiC samples were also obtained by the process of gelcasting and pressureless sintering at 2000 degrees C for I h in Ar atmosphere. The relative density and flexural strength of SiC sintered body are 97.3 +/- 0.4% and 637 +/- 156 MPa, and the hardness and toughness are 20.68 +/- 0.80 GPa and 3.85 +/- 0.23 MPa m(1/2), respectively.