Mechanical properties of carbon-derived Si3N4+SiC micro/nano-composite

In this study the mechanical properties of a recently developed carbon-derived Si3N4+SiC micro/nano-composite have been investigated with the aim to study the influence of the SiC addition on the room-temperature strength and high-temperature creep behavior. The bending strength values are in the interval from σ0 = 675 MPa to σ0 = 832 MPa with the Weibull modulus of 6.4 and 8.6 The contact strength is changing from σ0R = 1997 MPa to σ0R = 1167 with mR = 17 and mR = 15. Fracture origins in the specimens tested in bending are clusters of pores and large SiC grains and in the specimens tested in contact mode cone cracks. The composite exhibits high creep resistance thanks to the changed chemical composition and viscosity of the intergranular phase comparing to the monolithic Si3N4 and due to the interlocked silicon nitride grains by the intergranularly located SiC nanoparticles.