Preparation and properties of GNPs strengthened and toughened B₄C

Graphene nanoplatelets/boron carbide(GNPs/B₄C) composites were fabricated by hot-pressing with B₄C and GNPs as raw materials. Thoroughly examines the impact of dispersion processes on the structure of GNPs. This study comprehensively investigates the effect of dispersion processes on the structural integrity of GNPs and systematically explores the influences of GNPs content and sintering temperature on microstructural evolution and mechanical performance. Furthermore, the role of GNPs in densification behavior was elucidated through the analysis of time-displacement sintering curves. The results reveal that ultrasonic dispersion promotes the exfoliation of GNP layers without inducing structural damage. Ball milling effectively disintegrates GNP agglomerates, significantly reducing both their size and quantity, thereby improving their uniform distribution within the B₄C matrix. The density of the GNPs/B₄C composite increases with rising temperature, approaching near-complete densification once the temperature reaches 2000℃. The relative density of the composites increases with the rise in sintering temperature, reaching near-full densification at 2000℃. At 2000℃ and 25 MPa, the B₄C composite with 4wt.% GNPs exhibited the relative density of 99.4%, Vickers hardness of 30 GPa, flexural strength of 433 MPa, and fracture toughness of 5.13 MPa·m^1/2. Analysis of the crack propagation behavior on the fracture surface indicates that toughening mechanisms such as crack deflection, branching, bridging, and the pull-out of GNPs are widely present in the B₄C matrix. These mechanisms are the primary contributors to the improvement in the fracture toughness of the material.