| Fe based nanocrystalline soft magnetic alloy has excellent soft magnetic properties such as high permeability,low coercivity and low loss.It has good application prospects in many power electronics fields represented by transformer core and motor core.Annealing of amorphous ribbons will improve its soft magnetic properties.However,the nanocrystalline ribbons annealed after annealing are poor in flexibility and easy to break,so it is difficult to achieve the strength of industrial processing.The magnetic properties of Fe based nanocrystalline alloys are very sensitive with stress.If the core is solidified and the strength is higher,the stress in the curing process will have a great influence on the soft magnetic properties of the core.Therefore,it is of great significance to find the preparation process that can improve the soft magnetic properties of the core.In this paper,the amorphous ribbon is made by Jinzhou Tong Chuang FJZ0620-150-160 amorphous ribbon system.By summarizing the ribbon making process,the method of selecting the radian of the nozzle and the method of controlling the gap between the roll and the nozzle are summarized.The nanocrystalline cores were prepared and processed by different processes.The DC and AC soft magnetic characteristics of cores were tested by the Hunan Tian Heng TD-8220A soft magnetic DC testing system and the TD-8120 soft magnetic AC test system.By comparing the changes of the soft magnetic parameters after adding different processes,the influence of the processing technology on the magnetic core’s soft magnetic properties is summarized.The experimental results are as follows:(1)Getting the relationship between the nozzles’ radian ca and the nozzle width L(mm),which is required to ensure the well uniformity of the amorphous ribbon,it is:α=0.001L.Getting the relationship between the thickness T(μm)of the amorphous band and the gap D(mm)between the roll and nozzle,it is:T=66D-1.4.(2)The soft magnetic properties of the core can be batter after annealing,and the optimum annealing temperature is 500 ℃.Under the test condition of Hm=200A/m,the magnetic flux of magnetic core is 0.97T,and the coercivity is 1.23A/m.The loss of the core is 0.04kW/m3 under the test condition of Bm=0.1T and f=1kHz.(3)Solidifying cores with curing agents will result in poor magnetic properties of cores.Compared with three kinds of curing agents,epoxy resin,polyurethane and organosilicon,the best DC soft magnetic properties are obtained by using organosilicon curing agent,the coercivity is 1.416A/m,and the saturation magnetic induction intensity is 0.968T.The best AC soft magnetic properties were obtained by using polyurethane curing agent.The curing effect was best under f=1kHz test condition,and the core loss after curing was reduced by 12%.(4)The AC soft magnetic properties obtained by passivation-curing cores are better than those of solidification cores.The gap is the largest under the test condition of f=10kHz,and the loss of core is reduced by 3%after the passivation-curing process,and the loss of core is increased by 20%after the curing process.(5)Tensile stress is applied to nanocrystalline thin ribbons.Parallel to the stress direction,with the increase of stress,the spacing between the crystal faces becomes larger and the positive strain increases.The stress-strain relationship is:ε=10-6(2.511σ+2.997).Perpendicular to the stress direction,as the stress increases,the spacing between the crystal faces decreases and the negative strain increases.The stress-strain relationship is:ε=-10-6(5.11σ+9.069).The influence mechanism of preparation processes on magnetic core soft magnetic properties:(1)The stress is adding on the cores during the solidification process,which affects the soft magnetic properties of the core.The curing effect of polyurethane and silicone curing agent with smaller shrinkage rate is better than that of epoxy resin curing agent.(2)The passivation treatment of the magnetic core increases the insulativity between the ribbon layers and helps to reduce the eddy current loss of the core. |
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