Effect of solid contents on the mechanical properties of SiC–10 wt.%AlN ceramic composites prepared by gelcasting

Silicon carbide–aluminium nitride ceramic composites were prepared by gelcasting method. The effect of the solid contents of the slurry on the relative densities, mechanical properties of the green bodies and the pressureless sintered ceramic composites were investigated. When the solid contents increased from 35 to 40 vol.%, the mechanical properties, such as elastic modulus, flexural strength and fracture toughness simultaneously increased due to the improving of the relative density. But when the solid contents reached to 42 vol.%, the mechanical properties became noticeably worse, which caused by the sharply increase of the slurry viscosity, and many defects such as large scale and uneven pores also can be observed in the green bodies and the sintered ceramic composites.

► SiC–AlN composites were prepared by gelcasting using different solid contents.
► The key factors that affect the viscosity of slurries were revealed.
► Over high solid content cause more defects in green bodies and sintered ceramics.
► The best mechanical properties are got when the solid content is 40 vol.%.