硅粉在高压氮气中自蔓延燃烧合成氮化硅

SELF-PROPAGATING HIGH TEMPERATURE SYNTHESIS OF SILICON NITRIDE POWDER IN PRESSURIZED NITROGEN ATMOSPHERE

本文对硅粉在高压氮气中的自蔓延燃烧合成(SHS)氮化硅粉末的行为进行了详细研究。结果表明:(1)在遥当条件下,硅粉在SHS过程中可以完全氮化,生成氮化硅,产物含氮量高,含氧量低,但为β相;(2)在硅粉SHS反应中,必须加入适量的Si_3N_4晶种;(3)硅的SHS燃烧波传播速度随氮气压力升高、反应物填装密度减小而增大,但与反应物组成和样品直径无关;(4)燃烧波温度随氮气压力升高、样品直径增大而升高,与反应物组成和填装密度无关。此外本文对产物形貌与上述各实验因素的关系也进行了研究。

The self-propagating high temperature synthesis of silicon nitride powder under pressurized nitrogen has been studied. It is found that silicon powder can be completely nitrided during combustion reaction. The product obtained is the pure β-phase Si_3N_4 with high nitrogen and low oxygen content. An appropriate amount of Si_3N_4 added is indispensible to the synthesis. The wave propagation rate of combustion reaction increases with the nitrogen pressure and decreases with the increase of the packing density of reactants, and is not affected by the vessel diameter and composition of the raw materials. The maximum combustion temperature increases with nitrogen pressure and vessel diameter, and is not dependent on the composition and packing density of the raw materials. The relationship between the combustion parameters and the morphology of powder synthesized is also studied.