Microstructure and mechanical properties of SiC/MoSi2 nanocomposites

Using polycarbosilane, Mo and Si powders as raw materials, SiC/MoSi2 nanocomposites were fabricated by precursor conversion and reactive hot pressing. The effects of volume fraction of SiC nanoparticles on the mechanical properties and microstructure of SiC/MoSi2 nanocomposites were studied. The results show that the nanocomposites obtained consist of MoSi2, SiC, less Mo5Si3 and SiO2. The mechanical properties of the nanocomposites are dramatically improved by incorporating of SiC nanoparticles. 15%SiC/MoSi2 nanocomposite has the best comprehensive mechanical properties, with the flexural strength and fracture toughness of 610 MPa and 4.90 MPa/m1/2 at room temperature, which are increased by 141.1% and 58.0% compared with those of MoSi2, respectively. Its flexural strengths at 1200 and 1300°C are 720 and 516 MPa, respectively.