| At present, reducing energy loss and energy conservation is a topic of great concern to the whole world. According to statistics, the power loss caused by the core loss of electrical steel is about 5% of the country’s annual electricity generation. Reducing the iron loss of electrical steel, not only can save a lot of power, but also can simplify the complex cooling device, and can greatly extend the service life of the motor and transformer.Therefore,Various electrical steel manufacturers always trying to reduce the iron loss of electrical steel,and the iron loss is the most important index to measure the product quality.Electrical steel is commonly referred to as silicon steel, which is indispensable soft magnetic alloy in modern industry. The most important performance is its iron loss, which has a close relationship with the content of Si element. With the increasing of Si element, the resistivity rises up and iron loss reduced, thereby exhibiting excellent soft magnetic properties;and when the content of Si increase to 6.5%(mass percent, hereinafter), the iron loss significantly reduced, at about half of commercial silicon steel, and its magnetostriction coefficient is nearly to zero. Therefore Fe-6.5%Si high silicon steel is an ideal material for iron core. However, when the content of Si reaches 4%, the hardness and brittleness of silicon steel rises up obviously, and the workability becomes worse, at the same time it has a bad impact on application in industry. The effect of Al element on silicon steel is similar to Si element. It improves the resistivity and promotes the grain grow up, thereby it reduces the iron loss, and its impact on workability of silicon steel is not as obvious as Si element.Therefore when the content of Al and Si reaches 6.5%,it may has low iron loss,which is similar with 6.5% high silicon steel.Moreover, it has lower brittleness and better cold workability.In this paper, firstly the Al element is deposited on the Fe-3%Si silicon steel surface by the method of magnetron sputtering; then making Al infiltrate into the low silicon steel matrix by annealing treatment under high temperature at vacuum; at last the Fe-(Si+Al) 6.5% silicon steel is successfully prepared by the cyclic increase of Al.The effect of pressure and power on the deposition rate of Al film are studied. The optimal process conditions are 0.45 Pa and 6.05 W/cm~2.And the structure of the Al film is analyzed under the process conditions, which indicates that the Al film is crystalline.The effect of diffusion temperature and diffusion time on the diffusion depth and uniformity of Al element in Fe-3%Si silicon steel substrate are studied. The optimal process conditions are 1200℃ and 2.5h,which make Al element uniformly distribute in the Fe-3%Si silicon steel matrix. And uphill diffusion happens to Si element in Fe-3%Si silicon steelmatrix because of the infiltration of Al element. Through repeated annealing treatment under high temperature at vacuum of Fe-3%Si silicon steel substrate, it is found that annealing treatment can improve its soft magnetic properties, and the eddy current loss and hysteresis loss are reduced.The effect of diffusion annealing process on the magnetic properties of silicon steel was studied.Through the treatment of Fe-3%Si silicon steel with high temperature vacuum annealing, it is found that the magnetic properties of Fe-3%Si silicon steel substrate has a certain positive effect.With the increase of annealing temperature, the eddy current loss and hysteresis loss are decreased.The effect of Al content on the crystal structure, hardness, electrical resistivity and soft magnetic properties of Fe-3%Si silicon steel was studied. With the increasing of Al content,the crystal lattice constant, hardness and resistivity rises up. When the contents of Si and Al reaches 6.5%, its hardness is 350 HV, which has a better toughness than 6.5% high silicon steel, and its resistivity is 78 μΩ·cm, slightly less than 6.5% high silicon steel. And With the increasing of Al content, the eddy current loss reduces, the hysteresis loss increases, and saturation magnetic induction decreases. When the contents of Si and Al reaches 6.5%, the iron loss decreases obviously. Especially in the condition of high frequency, the iron loss is reduced about 12.5%. |
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