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Boron carbide (B4C) doped with graphene nano-platelet (GNP) as reinforcement has been prepared by pressureless sintering. Effect of GNP addition on mechanical properties of the composite, such as fracture toughness, hardness, flexural strength was investigated. Phase evolution and microstructure was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Results demonstrated that addition of GNP improved the fracture toughness (KIC) of B4C with the decrease of hardness, flexural strength. The fracture toughness (KIC) can reach 4.45 MPam1/2 with 1wt% addition of GNP, which was 49.3% higher than that of the composite without graphene platelets. It was found that the toughening mechanism can be contributed to pulling-out of graphene platelets, crack deflection, bridging and branching.

To further improve the comprehensive performance of existing impact-resistant steel, rare-earth-modified steel samples were experimentally prepared and their performance was analyzed. Different amounts of mixed rare earths were added into the 30MnCrNiMo impact-resistant steel, followed by vacuum smelting, forging, and rolling to prepare the steel plate. The effects of rare earths on the phase transformation critical points, high-temperature deformation behavior, microstructure, and mechanical properties were studied. The results show that rare earths can play a purifying role in the test steel. The Ac1-Ac3 phase transition temperatures were increased, and those of the Bs-Bf phase transition were decreased significantly. When compressed at 1000 °C, the deformation resistance of the test steel with rare earth became higher. Thus, the added rare earths improve the microstructural morphology and inclusions in the steel, as well as the comprehensive mechanical properties.

Hexagonal boron nitride ceramic (h-BN) based on the nitridation of B powders was obtained by reaction sintering method. The dynamic compressive response was investigated using a Split Hopkinson pressure bar tester at high strain rates in a range of 0.8×103−1.6×103s−1. By increasing the strain rate, the dynamic strength and the failure strain increased continuously. The compressive stress–strain curves exhibited universal three deformation regions, including inelastic deformation region, rapid loading region and failure region. The failure mode of the h-BN ceramic depended upon the strain rate.