Journal of Materials Science, Vol.48, No.19, 6673-6681, 2013
Fabrication and mechanical properties of beta-sialon-Fe (x) Si (y) -CNTs composites
Silicon nitride composites were fabricated by adding Fe3Al and carbon nanotubes and hot-pressing at a low sintering temperature of 1600 A degrees C. The resulted composites were characterized by X-ray diffraction, Fourier-transform infrared spectrum, and field emission scanning electron microscopy. It was found that the Fe3Al could react with Si3N4 to form the series of compound of Fe (x) Si (y) , and CNTs could keep chemical stability in the system. Mechanical properties of the composites were also investigated. For Fe3Al as the additive, the relative density could reach to 93.6 % with the maximum hardness of 15.7 GPa. When the Fe3Al and CNTs were added into matrix simultaneously, the relative density reached to 92.6 %, and the maximum fracture toughness was 6.7 MPa m(1/2). Finally, the toughening mechanism of Fe3Al and CNTs in sialon composites, containing crack deflection and bridging, and nanotubes pullout and bridging, were also discussed.