Researches On The Electrodeposition And Characteristics Of Magnet Films

Because of the nanoparticles, nanocomposite thin films can give various properties, such as wear resistance, antifriction, corrosion resis-tance, magnetic and high temperature oxidation resistance, which can be satisfied with a lot of people, they will become a focus in the study of microelectronic mechanical system.As indispensable functional materials, there are a lot of rare earth resources in China, and they have many unique properties. NdFeB permanent magnet is a hot topic in the field of materials, which is of great research significance. So far there are few reports about the preparation of NdFeB permanent magnet film in aqueous solution, but its application prospect has great appeal for the researchers.In this thesis, we first introduced cyclic voltammetry to prepare nanocomposite CoNiFe-SiC thin films, and studied the effects of princile technological parameters such as terminate potential, the concen tration of the SiC, pH and agitation speed, then optimized a steady technique ultimately. The surface morphology, composition, crystalphases, corrosi-on resistance and hardness of the optimized CoNiFe-SiC thin films were determined using SEM, EDS, XRD, Tafel polts measurements and so on. Base on the above results, the composited film was composed of very spherical and uniform nanoparticles, and it also possessed remarkably improved corrosion resistance and microhardness as compared with that of CoNiFe thin films.According to the above researches, the kinetics and mechanism for electrodeposition of nanocomposite CoNiFe-SiC thin films were studied using cyclic voltammetry, chronoamperometry, electrochemical impedan-ce spectroscopy techniques. The results showed that adding SiC nanopar-ticles make the deposition potential of CoNiFe alloy shift; and SiC nanoparticles adsorpted in the cathode surface also increase the charge transfer resistance with the cathodic reduction; Under the low potential-0.9VSCE,CoNiFe-SiC and CoNiFe alloy system both follow the3d trans-ient nucleation/growth mechanism; Along with further negative potential, the nucleation model of them deviates from the3d transient nucleation/ growth mechanism; The more negative potential, the shorter the nucleate-on/induction time, and the faster nucleation rate。The deposition of NdFeB rare earth permanent magnetic film on copper electrode by means of cyclic voltammetry method was prelimin-ary explored. The bath composition is as follows:FeCl240g/L, H3BO336g/L, ascorbic acid1.2g/L, sodium dodecyl sulfate0.1g/L, complexing agent (30g/L glycine+30g/L ammonium chloride), NdCl38-16g/L. The effect of complexing agent on cyclic voltammetry characteristics in the given bath system was discussed. And the effect of NdCl3content in bath and terminate potential of electrodeposition on morphology and appearance of coatings was also studied. Results showed that the initial deposition potential of Fe2+shifts negatively while the reduction potential of Nd3+moves to positive direction after the addition of complexing agents to bath. The codeposition of Nd element can be induced by Fe element, realizing the preparation of rare earth permanent magnet film by electrodeposition in aqueous solution. The cyclic voltammetry terminate potential and NdCl3content in bath have great influences on morphology and appearance of NdFeB film. Under the condition of NdCl3content in bath8g/L and terminate potential-1.7Vsce， bright and fine NdFeB film with a Nd mass fraction up to5.69%can be obtained.