Combined effects of graphene nanoplatelet and zirconium diboride additions on spark plasma sintered boron carbide composites with square geometry

In the present work, graphene nanoplatelets (GNPs) in varying amounts (1, 2, and 3 vol%) were incorporated into B 4 C composite powders containing 5 and 15 vol% ZrB 2 . The square-shaped composites were produced by spark plasma sintering (SPS) at 1540°C under 50 MPa with a 7 min holding time. The effects of GNP addition on the densification behavior, homogeneity, mechanical properties, and microstructure of the composites were evaluated. The results showed that adding GNPs into the B 4 C-ZrB 2 matrix enhanced the relative density and improved the homogeneity across different sections (center, edge, corner) of the square-shaped composites. Composites containing 15 vol% ZrB 2 and 1 vol% GNP demonstrated optimal performance with relative density, hardness, and fracture toughness of ∼99.5 %, 34.76 GPa, and 4.15 MPa.m 1/2 , respectively. Moreover, crack deflection, branching, and bridging were identified as primary toughening mechanisms. • The combined effect of ZrB 2 and GNP on B 4 C ceramics were investigated. • Square-shaped B 4 C-ZrB 2 -GNP composites were fabricated using the spark plasma sintering method. • Fracture toughness was determined by both indentation and surface crack in flexure method with a 4-point bending fixture. • GNP-added composites showed better homogeneity than GNP-free ones, with improved density and microstructure uniformity. • Processing time was significantly reduced, leading to more homogeneous samples and lower energy consumption.