【作者】 凌子坚；

【导师】 任英磊； 邱克强；

【作者基本信息】 沈阳工业大学 ， 材料学， 2012， 硕士

【摘要】 金属磁粉芯是由铁磁性粉粒与绝缘介质混合压制而成的一种软磁材料,其特殊的软磁性能使其在许多应用场合具有其他磁性材料难以比拟的优势。21世纪以来,科技进步需要各种高性能的电子器件,由此对磁粉芯提出了更高的要求。非晶Fe78Si9B13磁粉芯具有品质因数高、高频损耗低、价格低廉等特点,在高频电感铁芯具有广泛的应用前景。本实验选用Fe78Si9B13非晶带材为原料,分别通过机械破碎和气流破碎成非晶粉末,采用粉末冶金工艺压制成磁粉芯。同时运用扫描电镜分析、X射线衍射分析、差热分析等现代分析手段,研究了制备工艺参数对非晶Fe78Si9B13磁粉芯的磁导率、品质因数、损耗等磁性能的影响规律。结论如下:机械破碎法得到的粉体颗粒形貌为片状,呈多边形和长条形,并存在大量尖角。而气流破碎法得到的粉体颗粒形貌以圆片状为主,边缘比较平滑。气流破碎法得到的粉末制备的磁粉芯磁性能更优,是非晶带制粉更适宜的破碎方法。经过钝化处理,磁粉颗粒表面生成了一层磷化膜。添加钝化剂可以使磁粉芯频率特性变得更加稳定,损耗降低,品质因数提高。绝缘包覆是磁粉芯制备的关键工艺。绝缘剂的添加可以降低磁粉芯的涡流损耗,提高品质因数;但过多的绝缘剂又会使磁粉芯中非磁性物质比例增大,降低其磁导率;最佳的粘结剂添加量为3.5%。适当的磁粉粒度配比可以有效提高磁粉芯的磁导率,降低损耗。实验中最佳的粒度配比为:-100~+150目占60%,-150~+200目占10%,-200~+250目占10%,-250~+320目占20%。热处理对磁粉芯性能影响显著。增加退火温度能够有效地增大非晶磁粉芯的磁导率,降低损耗;但退火温度过高会使非晶磁粉晶化,生成导电性较差的非磁性相,同时也会破坏绝缘剂的包覆效果,降低磁粉芯的性能;最佳退火温度为400℃,时间为1小时。成型压力是保证磁粉芯获得好的磁性能的基础,增大压力有利于增加样品的密度,提高磁导率;但压力过大会破坏磁粉芯的绝缘层,降低粉芯的磁性能;当成型压力为1800MPa(保压1分钟),磁粉芯的综合磁性能最好。更多还原

【Abstract】 Metal magnetic powder core is one of soft magnetic materials, which is compressed by magnetic powder mixed with insulation medium, its special properties can’t be compared by the other materials. In the 21th century, scientific and technological progress needs high performance electronic devices,which put forward higher requirements for magnetic powder cores. Amorphous Fe78Si9B13 magnetic powder core has high quality factor, low loss in high frequency and low price, Which is hope to be widely used as inductor cores in high frequency.In this experiment, amorphous Fe78Si9B13 strip used as raw materials was broken into amorphous powder by mechanical and airflow mill separately, then compressed into magnetic powder cores applying powder metallurgy technology. Effects of process parameters on the permeability, quality factor, and loss of Fe78Si9B13 magnetic powder cores were investigated by modern analysis techniques including x-ray diffraction analysis(XRD), scanning electron microscopy(SEM) and differential scanning calorimeters (DSC). The main conclusions are listed as follows:Powders broken by mechanical mill are flake, mostly polygon and strip, and there are a lot of sharp corners. But the powders broken by airflow mill are round flake mostly, and the edges are smooth. Airflow mill is the more suitable breaking method for amorphous powders.The magnetic powder core prepared by the airflow mill powder has better performance.Magnetic powder has a layer of phosphate coating after passivation. The addition of passivant can improve the frequency character, reduce the magnetic loss and increase the quality factor of amorphous magnetic powder cores.Insulation treating is the most key procedure for the prepatation of magnetic powder core. Increasing insulating compound content can reduce eddy current loss and promote frequency character. but excessive insulating compound can increase the proportion of non-magnetic material of magnetic powder core, and then reduce the permeability. The best binding admixture content is 3.5%.The proper particle ratio can effectively reduce loss of magnetic powder core and promote the permeability. It was found that the optimum particle ratio of Fe78Si9B13 magnetic powder is 60% of -100% of +150 mesh, 10% of -150~ +200 mesh, 10% of -200~ +250 mesh, 20% of -250~+320 mesh.Heat treatment is the most important factor of affecting magnetic performance. Increasing annealing temperature can effectively reduce loss of magnetic powder core and promote the permeability. Over annealing temperature can deteriorate magnetic properties due to the crystallization of amorphous power, the forming of nonmagnetic phase, and the damage of coating insulation. The optimum annealing temperature is 400℃, the time is 1 hour.Shaping pressure is the basis for magnetic powder cores to obtain high magnetic property. Adding pressure can increase the density of the sample and promote the permeability. But much too big pressure will destroy the insulating coating of magnetic powder cores and reduce the magnetic properties. The optimum comprehensive magnetic properties can be obtained when the shaping pressure is 1800MPa(1 minute the pressure).更多还原