Mechanical properties of simultaneously synthesized and consolidated carbon nanofiber (CNF)-dispersed SiC composites by pulsed electric-current pressure sintering

Carbon nanofiber (CNF) dispersed beta-SiC composites with the addition of 0.2 mass% boron and 2.0 mass% carbon as sintering aids have been synthesized and consolidated simultaneously from mixtures of Si, amorphous C and B powders and CNF by pulsed electric-current pressure sintering (PECPS). Synthesis and consolidation process, which were observed from their expansion and shrinkage curves during PECPS, have been examined using X-ray diffraction and scanning electron microscopy for the powder compacts. CNF/SiC composites sintered at 1800 degrees C for 10 min under 40 MPa in a vacuum have similar to 96.0% of theoretical density and homogeneous structures consisting of similar to 4.0 mu m grains. A 10 vol% CNF/SiC composite exhibited excellent mechanical properties: a bending strength of similar to 720 MPa, a Vickers hardness of similar to 26.0 GPa, and a fracture toughness of similar to 5.5 MPa m(1/2). High-temperature bending strength of similar to 890 MPa at 1200 degrees C in air was attained with the same nanocomposites. (c) 2006 Elsevier B.V. All rights reserved.