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<p>A&#xa0;composite of Si<sub>3</sub>N<sub>4</sub>-Si<sub>2</sub>N<sub>2</sub>O‑TiN is synthesized by nitriding a&#xa0;mixture of ferrosilicon-ilmenite-ammonium fluoride under a&#xa0;combustion mode followed by the acid leaching of iron-containing phases. The influence of the principal parameters of self-propagating high-temperature synthesis on the combustion rate, the amount of absorbed nitrogen, and the phase composition of the combustion products is studied. It is found out that an addition of 1% NH<sub>4</sub>F causes a&#xa0;more complete nitrification of ferrosilicon, compared to that of 0.5%, due to an intensification of the processes of iron silicide nitrification by ammonium released during decomposition of ammonium fluoride. In the course of oxidation of the composite in air at 800 °C, TiN is completely oxidized to TiO<sub>2</sub>, and an oxidation of Si3N4 starts at a&#xa0;temperature higher than 1000 °C to form SiO<sub>2</sub>.</p>

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Synthesis of a Si3N4-TiN-Si2N2O-Fe composition by combustion of mixtures of the ferrosilicon-ilmenite-ammonium fluoride system in nitrogen

  • 期刊论文

  • 发表日期：

    2025年6月1日

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  • O. G. Kryukova,
  • T. V. Tatarinova

摘要

A composite of Si3N4-Si2N2O‑TiN is synthesized by nitriding a mixture of ferrosilicon-ilmenite-ammonium fluoride under a combustion mode followed by the acid leaching of iron-containing phases. The influence of the principal parameters of self-propagating high-temperature synthesis on the combustion rate, the amount of absorbed nitrogen, and the phase composition of the combustion products is studied. It is found out that an addition of 1% NH4F causes a more complete nitrification of ferrosilicon, compared to that of 0.5%, due to an intensification of the processes of iron silicide nitrification by ammonium released during decomposition of ammonium fluoride. In the course of oxidation of the composite in air at 800 °C, TiN is completely oxidized to TiO2, and an oxidation of Si3N4 starts at a temperature higher than 1000 °C to form SiO2.