Enhancing densification and mechanical performance of B 4 C ceramics using Y 3 Si 2 C 2 as a novel sintering additive

Boron carbide (B4C) is a highly strong covalent ceramic material with a low surface diffusion coefficient, making it extremely difficult to consolidate at low temperature. Therefore, the development of effective sintering additives that enable low-temperature, high-density consolidation, while maintaining excellent mechanical properties, remains a critical challenge for scalable application of B4C. In this study, Y3Si2C2 was employed as a novel sintering additive to enhance the densification and mechanical performance of B4C ceramics, for the first time. B4C ceramics containing 0-10 wt.% Y3Si2C2 were fabricated using spark plasma sintering (SPS) technique at temperature ranging from 1700 °C to 1900 °C. The effects of Y3Si2C2 sintering additive content and sintering temperature on the densification behavior, microstructure, and mechanical properties of the B4C ceramics were systematically investigated. The results indicate that Y3Si2C2 facilitates the densification of B4C ceramics via an in-situ reactive liquid-phase sintering mechanism. The formation of Y-rich liquid phase significantly enhances particle rearrangement and mass transport, while the in-situ generated YB4 phase pins grain boundaries and suppress abnormal grain growth. As a result, the mechanical properties of the B4C ceramics were significantly improved. Optimal comprehensive mechanical properties were achieved at 1800 °C with 8 wt.% Y3Si2C2, yielding a Vickers hardness of 31.4 GPa, and a flexural strength of 694.0 MPa. This work paves the way for rare earth silicon carbide as a novel sintering additive of B4C ceramics to enhance the densification and mechanical performance for extreme environment applications.