流态化CVD包硅的Fe_3O_4的氧化行为

Oxidation Behaver of Fe_3O_4 Coaded with SiO_2 by Fluidized CVD

采用流态化ＣＶＤ包硅技术制得了表面均匀包覆ＳｉＯ２的Ｆｅ３Ｏ４磁粉．对该包硅Ｆｅ３Ｏ４磁粉的氧化机理和动力学进行了研究．结果表明，氧化反应机理符合三维球对称扩散模型，氧化反应活化能随包硅量的增加而增加，流态化ＣＶＤ包硅能提高Ｆｅ３Ｏ４磁粉的抗氧化作用在于粒子表面形成了均匀的ＳｉＯ２保护层．

Fe_3O_4 magnetic powder coated with uniform SiO_2 layer was obtained by fluidized CVDtechnique. The oxidation mechanism and the kinetics of the SiO2 coated Fe3O4 were investigated.The results show that the mechanism of oxidation of the SiO2 coated Fe3O4 is inferred as phaseboundary reaction, spherical symmetry. The activation energy is increased with increasing silicacontent. The silica protect layer on the Fe3O4 magnetic powder formed by fluidized CVD techniquecan improve the oxidation-resistance of Fe3O4.