Preparation For Magnetic Liquid Iron Nitrogen Compounds

Magnetic fluid suspension has specific magnetorheological effects which are attracting widespread attention. It plays an important role in mechanical, aerospace, chemicals, electronics, metallurgy, energy, medical and other fields. In this research, the preparation of iron nitrides suitable for magnetic fluid and magnetorheological property of magnetic fluid was studied by high frequency thermal plasma.Firstly, selecting iron and Fe2O3 powder as the raw material for preparation of Fe4 N powder. The study of process parameters such as the temperature, reaction atmosphere and time shows that pure Fe4 N can be synthesized by iron and Fe2O3 powder. Using Fe2O3 to synthesize Fe4 N powder was studied. Approximately, reduction temperature was 750℃, nitriding temperature was 500℃, and the ratio of ammonium to hydrogen was 3:4. However, the Fe4 N powder is not only hard to prepare but also compacted. Using iron to synthesize Fe4 N powder, the process is simple and powder dispersion is better, can be mass-produced in large vacuum furnace. Therefore, it is a good choice to use iron as the raw material.Secondly, Fe4 N magnetic fluid was prepared by milling method and its magnetic properties, rheological properties and sedimentary stability were investigated. The results show that saturation magnetization of magnetic fluid increases with the increase of magnetic particle content. The saturation intensity is 51.80emu/g when mass percentage of the magnetic particles is 28.5%. The magnetic fluid shows Bingham plastic fluid characteristics at zero field. With the increase of the magnetic field, the viscosity and shear stress starts increasing and shear thinning phenomenon appears. That is characteristics of pseudoplastic fluid. With the increase of zero-field viscosity, the sedimentation stability increases.Finally, in order to improve the sedimentation stability of magnetic fluid, iron nitrides synthesized by high-frequency thermal plasma is preliminarily studied. The equipment of plasma is designed and built. High-frequency thermal plasma, nitrogen content is more than 30%, is obtained by four-tube diversion control structure.But the device is further improved.