Si_3N_4粉末在空气中的氧化反应方式

Oxidation Reaction Mode of Si_3N_4 Powders in Air

本文以Si_3N_4粉末作为研究对象,首次采用化学分析的方法发现在Si_3N_4的氧化过程中有NO气体生成,打破了传统的Si_3N_4氧化生成的气态产物只有N_2的看法。采用H_2SO_4+HNO_3的混合液作为NO的吸收液,以KMnO_4作为氧化剂,用氧化——还原滴定法对NO进行检测。并利用XRD和XPS分析了Si_3N_4粉末表面氧化层的组成。根据实验结果和热力学分析,探讨了Si_3N_4粉末在空气中的氧化反应方式。

NO gas was firstly found during the oxidation process of Si3N4 powders. This is a breakthrongh to the conventional concept that only N2 was formed in the xoidation of Si3N4. Oxidation-reduction titration using H2SO4 and HNO3 mixed Solution as an absorbent of NO and KMnO4 as an oxidant, was applied to verify the existence of NO gas. The experimental results showed that when Si3N4 was oxidized at high temperature, the concentrations of formed NO gas were 6-8% at 1300℃ and 5-6% at 1100℃. The composition of Si3N4 oxidation layer was analyzed by XRD and XPS. Based on thermodynamic consideration, oxidation reaction mode of Si3N4 powders in air was discussed.