Study On Preparation And Soft Magnetic Properties Of Amorphous FeSiB Magnetic Powder Cores

Soft magnetic composite materials are produced by powder metallurgy process, their special properties are can’t be compared by other materials. In the21th century, soft magnetic composite materials have recently regained interest as magnetic cores for electrical converts.In this study, Fe78Si13B9amorphous powder was used as raw material. Then powder coated with adhesives was pressed into magnetic powder cores. Modern analysis techniques including X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and differential scanning calorimeters (DSC) were applied in our experiments. The effects of process parameters on the permeability, quality factor, the loss of Fe78Si13B9magnetic powder cores were investigated. The main conclusions are listed as follows:In the process of producing powder cores, Heat treatment was most sensitive. When the annealing temperature was too low, inner stress was not fully eliminated. When the annealing temperature was too high, the magnetic cores were crystallized, insulation coating was destroyed, and the performance of magnetic cores was reduced.The magnetic powder cores with bigger particle size had a higher permeability and loss. The proper particle ratio could effectively decrease loss of magnetic powder core and promote the frequency characteristic. It was found that the optimum particle ratio of Fe78Si13B9magnetic powder is70%of-150～+200mesh,10%of-200～+250mesh,20%of-250～+320mesh.Different kinds and different contents of the binders seriously influenced the magnetic properties. With the content increasing of the binder, both magnetic permeability and quality factor were first increased and then reduced.Appropriate coating could make power cores get high and stable magnetic permeability, high quality factor, and good frequency stability. With the content increasing of the insulating compound, both magnetic permeability and quality factor were first increased and then reduced.Compaction pressure could ensure that the magnetic powder cores have good magnetic properties and mechanical properties. Increasing the pressure, density and magnetic permeability were increased, too. While the pressure was too high, the network structure of binder was destroyed, and then the loss was increased.After surface passivating treatment, permeability of the magnetic cores was increased, quality factor was increased, and the frequency characteristic was promoted. Hysteresis loss and eddy current loss were significantly reduced.Optimum process:surface passivating treatment, binder with3.4%, insulation with4%mica, compaction pressure is1800MPa, annealing at350℃, annealing time is60min. The results showed that the permeability of the core had the optimal stability of frequency in the frequency range of0-3500kHz.