The Preparation And Microwave Properties Of Iron Based Magnetic Film And The Magnetic Powder/Paraffin Composite

As an important functional materials, the development of magnetic materials Play an important role in the national economy. China is a magnetic material production and demand for power, which, for high-frequency microwave field of materials in terms of military and civilian has a huge demand, therefore, the high-frequency soft magnetic materials used in the field of microwave absorption increasingly The breadth and depth. This work is mainly of two kinds of soft magnetic materials:Preparation and microwave properties of iron-based magnetic thin film and sheet carbonyl iron/nickel ferrite composites. Fe-based soft magnetic material as an important magnetic material, with other metals or alloys can not be compared to the high saturation magnetization, Curie temperature, high permeability and low coercive force and other advantages, but because of the the snoek limit (μi-1) fr=2γ’Ms/3in restriction can not be guaranteed in the high band still maintained a relatively high magnetic permeability, saturation magnetization unchanged, but with bianisotropic material, the cut-off frequency frthe relationship between the initial permeability μi and the saturation magnetization shown in the following formula (1) Among them, the Hha-plane anisotropy field, Hea, the in-plane anisotropy field, while Hha is often much larger than the Hea, and therefore has a high frequency magnetic properties of bianisotropic materials will have increased exponentially. In this study, the electrochemical deposition method to prepare iron-based magnetic thin film, and an induced magnetic field in the deposition process, the film pairs each to make the film by adjusting the deposition substrate, the bath temperature, deposition parameters and other conditions found with good microwave magnetic properties of experimental conditions. The contents and results are as follows:(1) the deposition substrate, film thickness, the bath pH value, bath temperature, plus the induced magnetic field on the structure of the FeCo films, surface morphology, magnetic domains, static magnetic and high-frequency magnetic.(2) studied the sedimentary basement, composition, plus the induced field on the crystal structure, the static magnetic and high frequency magnetic properties of FeNi alloy film.Carbonyl iron is also a widely used excellent soft magnetic materials in the field of microwave absorption sheet carbonyl iron because of its shape anisotropy has more excellent microwave magnetic, but due to its relatively large dielectric constant ε and permeability μ poor match, causing it to be limited in high frequency applications. In recent years, a lot of work in the study of metal/dielectric composite core-shell structure topical experiments on metal coated with a layer of dielectric material can effectively reduce the dielectric constant. Existing work, most of the dielectric material selection of SiO2, Al2O3, ZnO, polymer, these materials are non-magnetic, Ms and μ values will be reduced at the same time reduce the dielectric constant ε, the impact of material microwave performance. Soft ferrite material itself is a dielectric material with good magnetic shell structure as an alternative to reduce ε without magnetic materials have a great impact. In this study, using the ball milling of carbonyl iron particles prepared flake carbonyl iron, followed by a layer of nickel ferrite particles in the surface chemical coprecipitation coated ferrite good crystal annealing in argon atmosphere, preparation flake carbonyl iron/nickel ferrite core-shell structure.The main content of the work are as follows:(1) milling of carbonyl iron particles flake carbonyl iron as the core structure.(2) using the chemical coprecipitation method and subsequent annealing treatment in a certain thickness of the sheet carbonyl iron surface coated nickel ferrite layer, the core-shell structure. (3) The effects of temperature, metal ions, solution pH, annealing temperature on the shell of nickel ferrite.(4) comparing the microwave absorption properties of carbonyl iron and carbonyl iron/nickel ferrite core-shell structure before and after the orientation.