研究了流化床反应器中αＦｅＯＯＨ粒子表面脱水与正硅酸乙酯（ＴＥＯＳ）水解反应形成ＳｉＯ２包覆层的过程．结果表明，αＦｅＯＯＨ脱水促进了粒子表面水解反应，有利于形成均匀的ＳｉＯ２包膜．同时还进一步研究了反应温度、反应时间、ＴＥＯＳ浓度和氨浓度对ＳｉＯ２包覆量的影响．采用这一技术，一步实现了脱水、包覆和还原过程，得到了性能良好的ＳｉＯ２包覆Ｆｅ３Ｏ４磁性粉末 The process of dehydration of αFeOOH particles and hydrolysis of tetraethoxysilane (TEOS) to form SiO2 coating in a fluidized bed reactor was studied. The results show that, α  FeOOH dehydration to promote the particle surface hydrolysis reaction is conducive to the formation of uniform SiO2 envelope. The effect of reaction temperature, reaction time, TEOS concentration and ammonia concentration on the coating amount of SiO2 was further studied. Using this technology, the dehydration, coating and reduction processes are realized in one step, and the good performance SiO2-coated Fe3O4 magnetic powder