Mechanical properties of Si3N4 matrix composites reinforced with SiC whiskers with oxide coatings

摘要

SiC whiskers were coated with MgO or TiO2 by a sol-gel method in order to vary the interfacial strength between whisker and matrix. These whiskers with oxide coatings were used to fabricate Si3N4 matrix composites for the purpose of investigating the effects of the coating on mechanical properties such as fracture strength, fracture toughness, and fracture energy. The composite reinforced with whiskers with MgO coating showed higher fracture energy than that with TiO2 coating, while the sample reinforced with whiskers with TiO2 coating exhibited better fracture toughness and strength. These results suggest that MgO coating reduced the interfacial strength, while TiO2 coating increased it.