Fabrication and mechanical properties of β-sialon-Fe _x Si _y -CNTs composites

摘要

Silicon nitride composites were fabricated by adding Fe_3Al and carbon nanotubes and hot-pressing at a low sintering temperature of 1600 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 Fe_3Al could react with Si_3N_4 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 Fe_3Al as the additive, the relative density could reach to 93.6 % with the maximum hardness of 15.7 GPa. When the Fe _3Al 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 Fe_3Al and CNTs in sialon composites, containing crack deflection and bridging, and nanotubes pullout and bridging, were also discussed.