Lightweight superhard B4C/SiC ceramic composites by Al4SiC4 assisted low-temperature transient liquid phase sintering

Maintaining the hardness and density of boron carbide (B₄C) while improving its sinterability and fracture toughness is crucial for its application in advanced armor ceramics and other engineering fields. In this work, lightweight and superhard B₄C/SiC ceramic composites were synthesized via in situ formation by Al₄SiC₄-assisted Transient Liquid Phase Sintering. The composites sintered at 1700°C and 1850°C exhibited Vickers hardness values of 33.7 GPa and 37.9 GPa, bulk densities of 2.52 g/cm³ and 2.55 g/cm³ , relative density of 98.13 % and 99.99 % and fracture toughness values of 3.03 MPa·m^1/2 and 3.36 MPa·m^1/2, respectively. The densification of B₄C matrix composites was achieved by the low additive content of Al₄SiC₄ to reduce the activation energy of densification and to provide a liquid-phase sintering mechanism, which enhanced the microstructure of the material and improved its hardness. This additive contributes to maintaining low density while enhancing the material's resistance to extreme conditions, such as high temperatures, through the in-situ formation of SiC and the absence of detrimental by-products. The platelet-like morphology of SiC plays a crucial role in grain refinement and extending crack propagation paths, thereby leading to substantial improvements in the material's mechanical properties. This renders it a promising strategy for ballistic applications.