Study On The Preparation And Magnetic Properties Of Electroless-deposited Double Magnetic Layer Composite Wires

ABSTRACTThere are many magnetic interactions within the composite magnetic materials,particularly the magnetic dipole interaction has become the research hotspot in recent years.On the one hand,due to the change of the geometric factors and the magnetic domain structure internal will cause the difference between the various internal interaction functionary mechanism,thus such difference might be influencing the magnetic properties and application of materials.On the other hand,because of characteristic of the giant magneto-impedance?GMI?effects under a low magnetic field——very sensitive to the response of magnetic field,it also become one of the important means during the research of the soft magnetic materials'magnetic properties and applying in the research of the magnetic dipole interaction.In order to indicate the mechanism of interactions within the composite magnetic materials,the CoP/Cu single layer composite magnetic structured wires and bilayer CoP/NiCoP/Cu?NiCoP/CoP/Cu composite magnetic structured wires are prepared by the electroless deposition method in this article.And taking the advantages of hysteresis loop and GMI effects to research the optimization of manufacturing technology of CoP composite wires,discuss the magnetic dipole interaction in the magnetism layer under varying outer layer thicknesses.The concrete research content and the result brief elaboration are as follows:1.The preparation of CoP/Cu composite wires by electroless plating and optimized of its reaction conditions.Applying the electroless plating to the change in different scenarios such as,concentration of reducing agent,the pH value of plating bath,and the temperature and time of plating etc.And various kinds of composite wires were prepared,then according to the optimized plating conditions,most advanced formulation and plating condition had obtained by the analysis related to the change of GMI effects.The concentration of CoSO₄ and NaH₂PO₂ is 0.05 M and 0.5 M,respectively,the pH value is 8.6,the plating temperature is95°C and the plating time is 3.5 h.2.Analyzing the composition and nature of CoP/Cu composite structure wires under the most optimum pretreatment conditionsViewing from the samples prepared under the most optimum pretreatment conditions,this thesis analysis on both its surface and cross section morphology,hysteresis loop and GMI curve.The result shows that the average plating rate is 2.6?m/h and the coating is compact and uniform.The samples composition is Co_84.5P_15.5,has low coercivity and excellent soft magnetic properties.The maximum impedance ratio equals 1337%and the magnetic sensitivity is 329%/Oe.3.The research of the preparation and magnetic properties analysis of bilayer CoP/NiCoP/Cu?NiCoP/CoP/Cu magnetic composite wires.Base on the optimal formulation of CoP/Cu to prepare bilayer CoP/NiCoP/Cu and NiCoP/CoP/Cu magnetic composite wires with different thickness and analysis its soft magnetic properties.Funding on the results that,the magnetic structure of inner and outer layer of multilayer composite wires is circumferential compare to the monolayer composite wire.There is an obvious jumping appears on hysteresis loop,also the impedance curve represents a four-peak structure.All phenomenon indicates that there are some strong magnetic dipole interactions between different layers of the multilayer composite wire.Meanwhile,the value of dipole field shows a downtrend with the increase of the frequency which is an opposite scenario of the compensation field.What's more,the data of the peak field came out by the formula fitting method has meet the requirements given by the experiments results.And the relationship between the magnetic interaction and both thickness of external magnetic layers and the frequency of external magnetic field are obtained.