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<p>The present study investigates the synthesis of ZrB<sub>2</sub>-based powders using the sol-gel reduction route, focusing on the impact of different carbon and silicon precursors besides zirconium oxychloride and boric acid to tailor the powder composition and morphology. Carbon black and sucrose were selected as the carbon source, whereas tetraethyl orthosilicate (TEOS) and elemental silicon were used as the silicon source. The sol-gel method enabled a uniform distribution of precursors, which were pyrolyzed at 1500&#xa0;°C and 1600&#xa0;°C. Carbon black proved to be significantly more effective, yielding ZrB<sub>2</sub> powder with 89.0 vol.% purity at 1600&#xa0;°C, compared to 75.1 vol.% purity achieved using sucrose. Both systems formed ZrB<sub>2</sub>-ZrC composites after sintering at 1900&#xa0;°C. Crucially, the incorporation of elemental silicon (Si powder) as the precursor led to the formation of an oxide-free ZrB<sub>2</sub>-SiC composite (89.6 vol.% ZrB<sub>2</sub>, 10.4 vol.% SiC) synthesized at 1600&#xa0;°C, achieving a 94.5% relative density and hardness of 13.6 ± 0.2 GPa after pressureless sintering at 1900&#xa0;°C. In sharp contrast, the use of TEOS resulted in no ZrB<sub>2</sub> and SiC formation, a failure attributed to precursor volatility and the formation of an inhibitory borosilicate glassy phase. This research provides critical, quantitative insight into optimizing precursor selection for cost-effective, highly dense ZrB<sub>2</sub>-based ultra-high-temperature ceramics with tailored microstructures.</p>

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Processing ZrB2-SiC-ZrC Based Composites: Role of Different Carbon and Silicon Precursors in Sol-Gel Reduction Route

  • 期刊论文

  • 发表日期：

    2026年1月9日

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  • Jyoti Kumari,
  • Jacopo Matteo Tabaglio,
  • Annalisa Natali Murri,
  • Andreana Piancastelli,
  • Laura Silvestroni

摘要

The present study investigates the synthesis of ZrB2-based powders using the sol-gel reduction route, focusing on the impact of different carbon and silicon precursors besides zirconium oxychloride and boric acid to tailor the powder composition and morphology. Carbon black and sucrose were selected as the carbon source, whereas tetraethyl orthosilicate (TEOS) and elemental silicon were used as the silicon source. The sol-gel method enabled a uniform distribution of precursors, which were pyrolyzed at 1500 °C and 1600 °C. Carbon black proved to be significantly more effective, yielding ZrB2 powder with 89.0 vol.% purity at 1600 °C, compared to 75.1 vol.% purity achieved using sucrose. Both systems formed ZrB2-ZrC composites after sintering at 1900 °C. Crucially, the incorporation of elemental silicon (Si powder) as the precursor led to the formation of an oxide-free ZrB2-SiC composite (89.6 vol.% ZrB2, 10.4 vol.% SiC) synthesized at 1600 °C, achieving a 94.5% relative density and hardness of 13.6 ± 0.2 GPa after pressureless sintering at 1900 °C. In sharp contrast, the use of TEOS resulted in no ZrB2 and SiC formation, a failure attributed to precursor volatility and the formation of an inhibitory borosilicate glassy phase. This research provides critical, quantitative insight into optimizing precursor selection for cost-effective, highly dense ZrB2-based ultra-high-temperature ceramics with tailored microstructures.