Journal of the Korean Ceramic Society (한국세라믹학회지)

The Korean Ceramic Society (한국세라믹학회)
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Preparation of α-Si3N4 Powder in Reaction System Containing Molten Salt by SHS - Part 2. Scale-Up

용융염계에서 자전연소합성법에 의한 α-Si3N4분말의 제조 - 2. 반응물의 증가

  • 윤기석 (충남대학교 급속응고센터) ;
  • 양범석 (충남대학교 급속응고센터) ;
  • 박영철 (충남대학교 급속응고센터) ;
  • 원창환 (충남대학교 급속응고센터)
  • Published : 2004.09.01
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Abstract

The variation of the reaction pressure and reaction product during the reaction was investigated according to the total mass of the reaction mixture at the optimum composition for the preparation of u-Si3N4 powder which had been confirmed in the former investigation; 'Preparation of $\alpha$-Si$_3$N$_4$ powder in reaction system containing molten salt by SHS - part 1. synthesizing of powder'. When the total mass of the reaction mixture was 100g, the minimum pressure for a complete reaction was 60atm in 5L reactor, whereas the reaction was incomplete in the case that the mass exceeded 200g because of pressure increase. Also, as the mass of the reaction mixture increased, the reactivity linearly decreased. Hence, the complete reaction was realized by decreasing an initial $N_2$ pressure, and thus obtained minimum initial pressure was recorded 20 atm for the initial mixture of 500g. The reason of the incomplete reaction with pressure Increase was found to be that NH$_4$Cl vapour which was suppressed by the gas pressure acted as a diluent.

앞선 논문 분말의 제조에서 정립한 $\alpha$-Si$_3$N$_4$ 분말의 제조를 위한 최적의 조성에서 반응 혼합물의 양에 따른 압력 및 생성물의 변화를 관찰하였다. 5L 반응기 내에서 반응 혼합물의 양이 100g일 때 필요한 최저 $N_2$ 압력은 60atm이었다. 그러나 반응 혼합물의 양이 200g 이상일 때부터 반응기 내부의 압력 증가로 인해 반응은 완료될 수 없었으며, 혼합물이 증가할수록 반응율은 직선적으로 감소하였다. 반응물의 양이 증가할수록 최초 반응기 내부의 $N_2$압력을 감소시킴으로써 반응을 완료시킬 수 있었으며, 500g일 때 초기 $N_2$ 압력을 약 20atm까지 감소시킴으로써 반응은 완료될 수 있었다. 반응이 중간에 멈추는 원인은 반응기 내부의 압력 증가로 인해 기화되지 못한 채 혼합물 안에 존재한 NH$_4$Cl때문인 것으로 밝혀졌다.

Keywords

References

  1. M. H. Ryu, J. H. Lee, C. W. Won, and H. Nersisyan, 'Syn-thesis and Characteristics of LiCo$O_2$ Powders Prepared by SHS Process,' J. Kor. Ceram. Soc., 41 [5] 388-94 (2004) https://doi.org/10.4191/KCERS.2004.41.5.388
  2. I. H. Song, J. Y. Yun, and H. D. Kim, 'Fabrication of Porous Mo$Si_2$ Material for Heating Element through Self-Propagating High Temperature Synthesis Process,' J. Kor. Ceram. Soc., 41 [1] 62-8 (2004) https://doi.org/10.4191/KCERS.2004.41.1.062
  3. K. S. Yun, J. H. Lee, H. Nersisyan, C. W. Won, and H. S. Jung, 'Preparation of $\alpha-Si_3N_4$ Powder in Reaction System Containing Molten Salt by SHS-Part I. Synthesis of Powder'" J. Kor. Ceram. Soc., 41 [3] 235-41 (2004) https://doi.org/10.4191/KCERS.2004.41.3.235
  4. V. V. Zakorzhevskii and I. P. Borovinskaya, 'Some Regularities of $\alpha-Si_3N_4$ Synthesis in a Commercial SHS Reactor,' Int. J. of SHS, 9 [2] 171-91 (2000)
  5. Y. G. Cao, H. Chen, J. T. Li, C. C. Ge, S. Y. Tang, J. X. Tang, and X. Chen, 'Formation of $\alpha-Si_3N_4$ Wihskers Wit of Na$N_3$ as Catalyst,' J. of Crys. Growth, 234 9-11 (2002 https://doi.org/10.1016/S0022-0248(01)01690-6
  6. A. G. Merzhanov, A. K. Filonenko, and I. P. Borovinskaya'New Phenomena in Combustion of Condensed System,' Kokl, Akad, Nauk SSSR, 208 [4] 892-94 (1972)
  7. C. H. Yeo, 'Self-Propagating High-Temperature Synthesis,' Min Urn Sa, 56 (1991)
  8. A. A. Shiryaev,'Macrokinetic Aspects of SHS as Studied by Thermochemical Analysis' Thermochemistry of SHS from 'Thermo' program
  9. A. S. Mukasyan, V. M. Martynenko, A. G. Merzhanov, I. P. Borovinskaya, and M. Y. Blinov, 'On Mechanisms and Regularities of Silicon Combustion in Nitrogen' Fizika goreniya I vzryva, 4 [5] 43-9 (1986)
  10. C. C. Ge, J. T. Li, and Y. L. Xia, 'On the Mechanism of Self-Propagating High-Temperature Synthesis (SHS) of $Si_3N_4$ ,' Int. J. SHS, 5 [2] 107-16 (1996)
  11. I. P. Borovinskaya, 'Chemical Classes of the SHS Processes and Materials,' Pure & Appl. Chem., 64 [7] 919-40 (1992) https://doi.org/10.1351/pac199264070919