流态化气相沉积过程中稀释气体流量对颗粒表面SiO2沉积的影响

利用Fe(Si)合金球形粉末为沉积基底，正硅酸乙酯为SiO2气相介质前驱体，采用引入流化环节的化学气相沉积工艺合成了Fe(Si)/SiO2复合粉末。考察了沉积过程中Ar稀释气体流量对Fe(Si)基底粉末表面SiO2绝缘介质沉积过程的影响规律及形成完整核壳异质结构的稀释气体流量范围。实验结果表明，随着流态化气相沉积过程中Ar稀释气体流量的逐渐增大，SiO2绝缘介质在Fe(Si)粉末基底表面的微观形貌从亚微米级团簇转变为完整薄膜再向多孔薄膜转变，沉积速率先减小后增大再降低，在250 sccm时SiO2绝缘介质均匀性最好，沉积速率为0.069 nm/s。此外，形成完整Fe(Si)/SiO2核壳异质结构的Ar稀释气体流量范围为200~300 sccm。

Influence of the dilution gas flow rate on SiO2 deposition on the powder surface during the fluidized vapor deposition

Using Fe(Si) alloy particles as deposition basement materials and tetraethoxysilane as gas SiO2 precursor, Fe(Si)/SiO2 composite powders were synthesized under fluidized vapor deposition. The influence of Ar dilution gas flow rate on deposition process of SiO2 insulating medium, and the formation Ar dilution gas flow rate range of complete Fe(Si)/SiO2 core-shell heterostructure were investigated. The results showed that the microstructure of SiO2 insulating medium on the Fe(Si) particle base surface varied from submicron clusters to integrated films to porous films with the increasing of Ar dilution gas flow rate during a fluidized vapor deposition process, while the deposition rates SiO2 insulating medium first decreased, then increased and decreased again. The homogeneity of the SiO2 insulating medium was the best and the deposition rate was 0.069 nm/s when the Ar dilution gas was at a flow rate of 250 sccm. In addition, when reaction temperature, reaction time, gas SiO2 precursor content and carrier gas flow rate was 930 K, 60 min, 9 mL and 100 sccm respectively, the conversion from Fe(Si) alloy particles to complete Fe(Si)/SiO2 core-shell heterostructure particles during the fluidized vapor deposition occurred within the Ar dilution gas flow rate range from 200 sccm to 300 sccm. The results of the performance test indicated that the Fe(Si)/SiO2 core-shell heterostructure led to a substantial enhancement in the electrical resistivity of the particles and reduction in their saturation magnetization, but hardly affected the coercive force. Compare to Fe(Si) alloy particles, the Fe(Si)/SiO2 core-shell heterostructure particles exhibited much higher electrical resistivity. The varying trend of Fe(Si)/SiO2 core-shell heterostructure particles was consistent with the deposition rate of SiO2 insulating medium. The results in this study may provide a foundation for future kinetics investigations and the application of fluidized vapor deposition technology.