The Si3N4-SiC nanocomposites with high strength at elevated temperatures.

摘要: Effects of nano-size dispersions on mechanical properties such as hardness, fracture toughness and strength were investigated for the Si3N4-SiC nanocomposite system. The Si3N, -SiC nanocomposites fabricated by hot-pressing mixtures amorphous Si-C-N precursor powder with various C/N ratio sintering additives. Transmisson electron microscopic observation indicated that Sic particles less than approximately 0.1μm in diameter dispersed whithin Si3N4, matrix grains. No apparent impurity phases was observed at intertfaces Si3N4 Sic. grain morphology strongly influenced dispersion, indicating formation elongated equiaxed grains acceralated lower higher SiC volume fractions, respectively. As expected from this change morphology, showed maxmima, 155OMPa 6.5MPam1/2, certain fraction SiC. high-temperature also improved dispersion high over 1GPa even 1400°C.