Abstract: Heterogeneous precipitation methods were used to produce 5wt% SiC-15wt% ZrO₂(3Y)-Al₂O₃ nanocomposite powders.
The aqueous suspension’s pH controlled between 9 and 10, and the resulting gel calcined at 1000℃ are two key processes for preparing nanocomposite powders. 5wt% SiC-15 wt% ZrO₂(3Y)-Al₂O₃
nanocomposites were superfast densified using spark plasma sintering (SPS) process by heating to a sintering temperature between 1350 to 1600℃
at a heating rate of 600℃/min, without holding time, and then fast cooling to 600℃ within 3 minutes. Bending strength of 5wt% SiC-15wt%
ZrO₂(3Y)-Al₂O₃ nanocomposites sintered at 1450℃ reached a value as high as 1200MPa, while the fracture toughness of the sample
sintered at 1450℃ was above 5MPa·m^1/2, which is significantly higher than that of SiC-Al₂O₃ nanocomposites and Al₂O₃ ceramics. Microstructure studies found that nano-SiC particles
were mainly located within Al₂O₃ grains and the fracture mode of the nanocomposites was mainly transgranular fracture. It is the main reason
why the intra-type nanocomposites show excellent mechanical properties, while in present research system, a part of contribution to high mechanical
properties is from ZrO₂ phase transformation toughening.

Key words: SiC nanocomposites, spark plasma sintering, mechanical property