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<p>The preparation of N-doped conductive SiC ceramics through conventional solid-state sintering typically requires extremely high temperatures and additional nitrogen solid solution treatments. To overcome this limitation, pre-synthesized N-doped SiC nanopowder containing 1 wt.% B<sub>4</sub>C were used to fabricate solid-sintered conductive SiC ceramics via spark plasma sintering (SPS) at sintering temperatures of 1850–1900&#xa0;°C and holding times of 1–10&#xa0;min. Localized overheating during SPS induced the formation of B-Si–O-C-N liquid phase within the ceramic matrix, a phenomenon not observed in conventional solid-state sintering processes, which significantly promoted densification. Notably, short holding times (1–5&#xa0;min) preserved the liquid phase, resulting in incomplete solid-state sintering. In contrast, a prolonged holding time (10&#xa0;min) led to complete decomposition and evaporation of the liquid phase, thereby inducing pores formation. The fracture toughness of the resulting ceramics exceeded 4&#xa0;MPa·m<sup>1/2</sup>, outperforming those produced via traditional routes. Additionally, the N concentration remained below 1000&#xa0;ppm, while the electrical resistivity ranged from 2.68 × 10<sup>–1</sup> to 4.12 × 10<sup>–2</sup> Ω·cm, well below the 100 Ω·cm threshold required for electrical discharge machining. Furthermore, competitive doping between N and B atoms modulated the carrier concentration and mobility, enabling effective tuning of electrical resistivity. Based on these findings, the densification mechanism and doping interaction effects were thoroughly elucidated. This work provides a foundation for optimizing the solid-state sintering process and designing high-performance conductive ceramics for advanced engineering applications.</p>

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Synthesis of conductive SiC ceramics using N-doped SiC nanopowder with B4C additive via spark plasma sintering

  • 期刊论文

  • 发表日期：

    2025年6月26日

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  • Huaxin Li,
  • Ziqiang Luo,
  • Zhi Xiang,
  • Yafei Li,
  • Chen Shi,
  • Chuanyang Lu,
  • Jianguo Yang,
  • Yanming He

摘要

The preparation of N-doped conductive SiC ceramics through conventional solid-state sintering typically requires extremely high temperatures and additional nitrogen solid solution treatments. To overcome this limitation, pre-synthesized N-doped SiC nanopowder containing 1 wt.% B4C were used to fabricate solid-sintered conductive SiC ceramics via spark plasma sintering (SPS) at sintering temperatures of 1850–1900 °C and holding times of 1–10 min. Localized overheating during SPS induced the formation of B-Si–O-C-N liquid phase within the ceramic matrix, a phenomenon not observed in conventional solid-state sintering processes, which significantly promoted densification. Notably, short holding times (1–5 min) preserved the liquid phase, resulting in incomplete solid-state sintering. In contrast, a prolonged holding time (10 min) led to complete decomposition and evaporation of the liquid phase, thereby inducing pores formation. The fracture toughness of the resulting ceramics exceeded 4 MPa·m1/2, outperforming those produced via traditional routes. Additionally, the N concentration remained below 1000 ppm, while the electrical resistivity ranged from 2.68 × 10–1 to 4.12 × 10–2 Ω·cm, well below the 100 Ω·cm threshold required for electrical discharge machining. Furthermore, competitive doping between N and B atoms modulated the carrier concentration and mobility, enabling effective tuning of electrical resistivity. Based on these findings, the densification mechanism and doping interaction effects were thoroughly elucidated. This work provides a foundation for optimizing the solid-state sintering process and designing high-performance conductive ceramics for advanced engineering applications.