Microstructure and compressive behaviour of 3D needled C/SiC composites

The 3D needled C/SiC composites were fabricated by chemical vapor infiltration combined with liquid melt infiltration. The microstructure and compressive behavior of 3D needled C/SiC composites were investigated. The results indicated that the 3D needled C/SiC composites were composed of the layers of 0 ° non-woven fiber cloth, short fiber web, 90 ° non-woven fiber cloth, and needle fibers. The materials were composed of carbon fiber, PyC, Si, and SiC. SiC and Si were mostly distributed in the short fiber web layers. Local C/C units (local carbon fiber reinforced PyC) were formed in the fiber bundles of non-woven fiber cloth. A great deal of pores and cracks existed in the 3D needled C/SiC composites. The pores less than 10 μm were generally located in the non-woven cloth layers, while the big pores were in the short fiber web layers. The cracks were regularly presented in the Si and SiC region of the composites and were normal to the axial direction of the fiber bundles. The compressive strengths perpendicular and parallel to the non-woven fiber cloth were about 118±18 MPa and 260±41 MPa, respectively. The compressive fractography revealed stepwise fracture along fiber layers direction.