J Mater Sci Technol ›› 1999, Vol. 15 ›› Issue (01): 13-16.

• Research Articles • Previous Articles     Next Articles

Thermodynamic Aspect in Synthesis of AlN Powders by Carbothermal Reduction and Nitridation Process

Xiaming DAI, Qingfeng LI, Mingqin DING, Jiemo TIAN   

  1. Beijing Fine Ceramic Laboratory, the State Key Laboratory of New Ceramics and Fine Processing, Tsinghua University, Beijing 102201,China
  • Received:1998-07-20 Revised:1998-09-04 Online:1999-01-28 Published:2009-10-10
  • Contact: Xiaming DAI

Abstract: A thermodynamical calculation shows that AlN powders were synthesized in the process by the overall reaction Al2O3(s)+3C(s)+N2(g)=2AlN(s)+3CO(g) and its minimum reaction temperature T0 = 1852 K, if all reactants and products were in standard states. In the practical experiments, AlN phase appeared obviously at only 1300℃, the major reasons are related to the partial pressure of its gaseous product p CO and the mixed free energy. Either increasing N2 flow rate or elevating N2 pressure could lower the synthesis temperature. On the other hand, as the temperature decreases, the equilibrium constant Km also reduces, and the reducing rate strongly depends on the temperature: the lower the temperature, the higher the rate.

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