High-entropy boride ceramic cutting tools by SPS-HF dual sintering: Preparation process, composition, and properties

High-entropy boride (HEB) ceramics demonstrate significant potential for cutting tool applications, yet conventional synthesis methods face challenges in achieving full densification and optimal mechanical performance. (Mo_0.2Zr_0.2Ta_0.2Nb_0.2Ti_0.2)B₂ HEB ceramics were prepared using the spark plasma sintering-high-frequency (SPS-HF) dual sintering method. The optimal mechanical properties of the HEB ceramic cutting tool materials were achieved at a sintering temperature of 1750°C. Compared with the HEB ceramic tool material without Al₂O₃ (HEB0), the HEB ceramic tool material containing 3 wt% Al₂O₃ (HEB3A) exhibited improved mechanical properties. The Vickers hardness and flexural strength of HEB3A were 20.07 GPa and 492.85 MPa, representing increases of 2.87% and 17.28%, respectively, compared to HEB0. The HEB3A tool achieved a cutting distance of 1000 m and a coefficient of friction of 0.62 during dry cutting tests on 45 steel, representing a 66.67% increase and an 11.29% reduction, respectively, compared to the HEB0 tool. The results indicate that the addition of Al₂O₃ improves the cutting performance of HEB ceramic tools. This work shows that the HEB-based ceramics with high hardness, high toughness, and high flexural strength have potential applications in the field of cutting tools.