Fine-grained (<1 pm) silicon carbide ceramics with high strength were obtai
ned by using ultrafine (similar to 90 nm) beta-SiC starting powders and a s
eeding technique for microstructural control, The microstructures of the as
-hot-pressed and annealed ceramics without alpha-SiC seeds consisted of fin
e, uniform, and equiaxed grains. In contrast, the annealed material with se
eds had a uniform, anisotropic microstructure consisting of elongated grain
s, owing to the overgrowth of P-phase on cu-seeds. The strength, the Weibul
l modulus, and the fracture toughness of fine-grained SIC ceramics increase
d with increasing grain size up to similar to 1 pm, Such results suggested
that a small amount of grain growth in the fine grained region (<1 mu m) wa
s beneficial for mechanical properties. The flexural strength and the fract
ure toughness of the annealed seeded materials were 835 MPa and 4.3 MPa.m(1
/2), respectively.