WC-10 wt.% Si3N4 composites toughened with ultrafine porous boron nitride nanofiber (0, 0.01, 0.05, 0.1, and 0.15 wt.%) were prepared for the first time by spark plasma sintering. Compared with the WC-Si3N4 composite sintered in the same condition, the obtained WC-10 wt.% Si3N4 composites with ultrafine porous boron nitride were found to possess better hardness and fracture toughness. In addition, the Si3N4 phase in the UPBNNF toughened composites did not exhibit traditional catastrophic fracture as indicated in most investigations. In this study, the phenomena are discussed, and a probable mechanism is elucidated. It is deduced that the approach could be extended to materials with a feature of internal liquid phase during the sintering process and could improve hardness and fracture toughness.

WC-4.32MgO-3.68B2O3 composite material was prepared by Spark plasma sintering technology, and then Si3N4 ball was used as the counter-grinding material to study the friction and wear behavior under different loading conditions by means of fretting friction. The research results show that: the distribution of the second phase has a significant effect on the wear behavior of the composites. During the fretting friction process, second phase particles peeled off from the structure, causing the abrasion of the matrix to increase. The research found that with gradually increase of the load, the friction coefficient of the material gradually decreases, but the degree of wear gradually increases. The number of furrows also increased significantly, which was related to the wear degree of convex on the surface of the materials. It can be observed from the wear scar that the main wear mechanisms of composite materials are abrasive wear and oxidative wear.