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Abstract <p>The phase composition of Si<sub>6 – <i>z</i></sub>Al<sub><i>z</i></sub>O<sub><i>z</i></sub>Ng<sub>8 – <i>z</i></sub> β-sialon samples Si<sub>5</sub>AlON<sub>7</sub> (<i>z</i> = 1) and Si<sub>4</sub>Al<sub>2</sub>O<sub>2</sub>N<sub>6</sub> (<i>z</i> = 2) before and after two-stage firing at 900°C in air and at 1650°C in a nitrogen flow without sintering additives and with addition of 0.5 and 2.0 wt % NaF has been thoroughly investigated by the Rietveld method. It is shown that the initial β-sialon samples (<i>1</i> and <i>2</i>) are two-phase and contain Si<sub>4.8</sub>Al<sub>1.2</sub>O<sub>1.2</sub>N<sub>6.8</sub> and Si<sub>4.4</sub>Al<sub>1.6</sub>O<sub>1.6</sub>N<sub>6.4</sub> in a weight ratio of 70 : 30. Firing without sintering additives barely changes the composition of sample <i>1</i>, while sample <i>2</i> is enriched in the Si<sub>4.4</sub>Al<sub>1.6</sub>O<sub>1.6</sub>N<sub>6.4</sub> phase. Firing with NaF leads to the occurrence of the third phase in the composition of the samples: Si<sub>2.8</sub>Al<sub>3.2</sub>O<sub>3.2</sub>N<sub>4.8</sub>. At a NaF content of 0.5 wt %, the phase compositions of samples <i>1</i> and <i>2</i> after firing are almost identical, while when firing sample <i>2</i> with 2.0 wt % NaF, the dominant phase changes from Si<sub>4.8</sub>Al<sub>1.2</sub>O<sub>1.2</sub>N<sub>6.8</sub> to Si<sub>3.8</sub>SAl<sub>2.2</sub>O<sub>2.2</sub>N<sub>6.8</sub>.</p>

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Investigation of Changes in Structure and Stoichiometry of β-Si6 – zAlzOzN8 – z (z = 1, 2) Sialons during Sintering with Addition of Sodium Fluoride by the Rietveld Method

  • 期刊论文

  • 发表日期：

    2025年2月1日

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  • V. P. Sirotinkin,
  • N. S. Akhmadullina,
  • Yu. F. Kargin

摘要

Abstract

The phase composition of Si6 – zAlzOzNg8 – z β-sialon samples Si5AlON7 (z = 1) and Si4Al2O2N6 (z = 2) before and after two-stage firing at 900°C in air and at 1650°C in a nitrogen flow without sintering additives and with addition of 0.5 and 2.0 wt % NaF has been thoroughly investigated by the Rietveld method. It is shown that the initial β-sialon samples (1 and 2) are two-phase and contain Si4.8Al1.2O1.2N6.8 and Si4.4Al1.6O1.6N6.4 in a weight ratio of 70 : 30. Firing without sintering additives barely changes the composition of sample 1, while sample 2 is enriched in the Si4.4Al1.6O1.6N6.4 phase. Firing with NaF leads to the occurrence of the third phase in the composition of the samples: Si2.8Al3.2O3.2N4.8. At a NaF content of 0.5 wt %, the phase compositions of samples 1 and 2 after firing are almost identical, while when firing sample 2 with 2.0 wt % NaF, the dominant phase changes from Si4.8Al1.2O1.2N6.8 to Si3.8SAl2.2O2.2N6.8.