SiC/BN ceramic nano-composites powders were synthesized by an in-situ recation method and the composites were sintered by hot pressing in a N2 atmosphere. The microstructure, secondary phase and grain boundaries were characterized using a range of analytical techniques including TEM, SEM and XRD. The mechanical properties were determined, when the BN content is increaed because the nano-sized h-BN crystals were homogeneously dispersed around the SiC grains of the matrix, the fracture strength of the nano-composites decreased more slowly than that of the SiC/h-BN micro-composites, but the hardness of the composites decreased sharply and the machinability properites were improved noticeably.

Keywords: SiC; h-BN, Nano-composites, Mechanical properties, Microstructure.