Mechanical properties and oxidation behavior of silicon carbide–molybdenum silicides composites

SiCMoSi2 porous preforms with different SiC/MoSi2 weight ratios were densified by means of the melt infiltration method. Mixture of SiC–MoSi2Mo≤5Si3C≤1 was used as infiltrant. The resultant infiltrated composites showed high density, good mechanical properties and oxidation resistance. In particular, fracture toughness determined at 1773 K was 6.80 MPa m1/2 and 6.28 MPa m1/2 with SMI-80 (preform with SiC/MoSi2 weight ratio 80/20) and SMI-50 (preform with SiC/MoSi2 weight ratio 50/50) composites, respectively. The same composites showed high temperature (1773 K) flexural strength values: 214 MPa (SMI-80) and 242 MPa (SMI-50). Long term oxidation behavior was also tested at 1773 K and results confirmed the refractoriness of these materials.