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<p>α-Si<sub>3</sub>N<sub>4</sub> and SiC powders were prepared from reaction between SiO<sub>2</sub> and carbon black in different atmosphere. The effects of atmospheres, raw material particle sizes, and C/SiO<sub>2</sub> molar ratio on the syntheses of Si<sub>3</sub>N<sub>4</sub> and SiC powders were investigated. The optimal parameters for preparing α-Si<sub>3</sub>N<sub>4</sub> were determined to be a temperature of 1500&#xa0;°C for 8&#xa0;h with a C/SiO<sub>2</sub> molar ratio of 4.0. In addition, the results demonstrated that H<sub>2</sub> atmosphere facilitated SiC synthesis by lowering its formation temperature. SiC powders were synthesized under a flowing H<sub>2</sub> atmosphere at 1500&#xa0;°C for 5&#xa0;h. N<sub>2</sub>-H<sub>2</sub> mixed atmosphere inhibited Si<sub>3</sub>N<sub>4</sub> formation while promoting SiC synthesis, with increasing SiC content as the H<sub>2</sub> partial pressure rose. Meanwhile, the size reduction of raw materials was conducive to promoting the formation of Si<sub>3</sub>N<sub>4</sub> and SiC and reducing the granularity of the final product. However, if the particle size of the raw materials was too fine, the product will tend to agglomerate.</p>

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Preparation of α-Si3N4 and SiC powders by carbothermic reduction of SiO2

  • 期刊论文

  • 发表日期：

    2026年5月27日

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  • Long-Pan Yan,
  • Guo-Hua Zhang

摘要

α-Si3N4 and SiC powders were prepared from reaction between SiO2 and carbon black in different atmosphere. The effects of atmospheres, raw material particle sizes, and C/SiO2 molar ratio on the syntheses of Si3N4 and SiC powders were investigated. The optimal parameters for preparing α-Si3N4 were determined to be a temperature of 1500 °C for 8 h with a C/SiO2 molar ratio of 4.0. In addition, the results demonstrated that H2 atmosphere facilitated SiC synthesis by lowering its formation temperature. SiC powders were synthesized under a flowing H2 atmosphere at 1500 °C for 5 h. N2-H2 mixed atmosphere inhibited Si3N4 formation while promoting SiC synthesis, with increasing SiC content as the H2 partial pressure rose. Meanwhile, the size reduction of raw materials was conducive to promoting the formation of Si3N4 and SiC and reducing the granularity of the final product. However, if the particle size of the raw materials was too fine, the product will tend to agglomerate.