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<p>Fused silica (SiO<sub>2</sub>) exhibits exceptional thermal stability and dielectric properties, making it an attractive material for aerospace and military applications. However, its relatively poor mechanical performance has limited its widespread practical utilization. This study proposed an innovative approach to fabricate SiO<sub>2</sub>-hexagonal boron nitride (hBN) composite ceramics via spark plasma sintering (SPS), leveraging the high-temperature phase transformation of cBN to introduce randomly oriented hBN as a reinforcing phase within the SiO<sub>2</sub> matrix. The randomly oriented hBN nanoplates allow cracks to propagate along stronger grain boundaries, rather than along weaker interlayers of hBN, significantly improving the overall strength and fracture toughness of the composite. The maximum flexural strength and fracture toughness achieved are 183.4 MPa and 2.06 MPa m<sup>1/2</sup> respectively, which are 3.6 times and 4 times that of fused SiO<sub>2</sub>. Concurrently, the composites exhibit low dielectric constants (<i>ε</i> = 3.58–3.69) and dielectric losses (tan <i>δ</i> &lt; 0.0087) at 1 MHz. This work successfully enhanced the mechanical performance of fused SiO<sub>2</sub> while preserving its excellent dielectric characteristics, opening new possibilities for its potential applications in advanced structural and functional fields.</p>

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Phase-transition assisted synthesis of high-strength, low-dielectric fused silica/hBN composite ceramics

  • 期刊论文

  • 发表日期：

    2026年1月4日

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  • Xiaoyu Wang,
  • Yang Zhang,
  • Zewen Zhuge,
  • Langlang Huo,
  • Yuqing Chang,
  • Zitai Liang,
  • Lei Sun,
  • Bing Liu,
  • Baozhong Li,
  • Mengdong Ma,
  • Julong He,
  • Yingju Wu,
  • Zhisheng Zhao,
  • Yongjun Tian

摘要

Fused silica (SiO2) exhibits exceptional thermal stability and dielectric properties, making it an attractive material for aerospace and military applications. However, its relatively poor mechanical performance has limited its widespread practical utilization. This study proposed an innovative approach to fabricate SiO2-hexagonal boron nitride (hBN) composite ceramics via spark plasma sintering (SPS), leveraging the high-temperature phase transformation of cBN to introduce randomly oriented hBN as a reinforcing phase within the SiO2 matrix. The randomly oriented hBN nanoplates allow cracks to propagate along stronger grain boundaries, rather than along weaker interlayers of hBN, significantly improving the overall strength and fracture toughness of the composite. The maximum flexural strength and fracture toughness achieved are 183.4 MPa and 2.06 MPa m1/2 respectively, which are 3.6 times and 4 times that of fused SiO2. Concurrently, the composites exhibit low dielectric constants (ε = 3.58–3.69) and dielectric losses (tan δ < 0.0087) at 1 MHz. This work successfully enhanced the mechanical performance of fused SiO2 while preserving its excellent dielectric characteristics, opening new possibilities for its potential applications in advanced structural and functional fields.