Microstructure, mechanical properties and friction performance of SiC whisker and SiC particle synergistic toughening ZrB₂-based ceramic material for potential cutting tool

ZrB₂ is a prominent ultra-high-temperature ceramic with good thermal stability, high hardness, and strong thermal shock resistance. However, its relatively low indentation fracture resistance limits its application as a ceramic cutting tool material. Therefore, the present study focuses on adding SiC_p and SiC_w to matrix ZrB₂ to enhance the mechanical properties of ZrB₂-based composites for cutting tool applications. ZrB₂-SiC_p-SiC_w composites were fabricated by hot-pressing sintering. The effects of SiC_w/SiC_p content, sintering temperature 1750–1950 °C, and hot-pressing dwell time 30–60 min on the microstructure and mechanical properties were systematically investigated. The frictional performance was evaluated through ball-on-disk wear tests against TC4 titanium alloy. In addition, turning experiments of TC4 were conducted at different cutting depths. The results demonstrate that the incorporation of SiC_w and SiC_p significantly enhances both the mechanical properties and relative density of ZrB₂. With the addition of 20vol%SiC_w-15vol%SiC_p, the composite achieves a indentation fracture resistance of 6.48 ± 0.07 MPa·m^1/2, a flexural strength of 891 ± 47 MPa, and a hardness of 18.60 ± 0.35 GPa, meeting the requirements for cutting tool applications. The ZrB₂-based ceramic material exhibited a stable dynamic friction coefficient of approximately 0.55. As the applied load was increased from 5 N to 20 N, the wear rate increased from 1.22 × 10⁻⁴ mm³/N·m to 2.52 × 10⁻⁴ mm³/N·m. The wear mechanisms are a combination of abrasive and adhesive wear by the worn surface characterization. During TC4 machining under high pressure-temperature conditions, diffusion and oxidative wear mechanisms were observed in addition to adhesive and abrasive wear.