Study On Preparation Of Fe-Si Coating By Composite Double-pulse Electroplating On The Surface Of Silicon Steel And Magnetic Properties After Annealing

6.5wt%Si electrical steel has excellent characteristics,such as low core loss and near-zero magnetostriction at high frequency,but it is difficult to produce by traditional rolling process because of its brittleness.The paper is to obtain the high silicon steel produced by diffusion annealing after composite plating a Fe-Si coating on the surface of common grain-oriented electrical steel by dual-pulse voltage power.First of all,the optimal parameters of electro-deposition liquid was obtained by orthogonal test and single factor experiment under DC electrical source after analyzing the silicon content of coating by SEM.The final liquid composition is350g/L FeCl₂·4H₂O,3g/L KI and 30g/L silicon powder.The pH value of plating bath is 1.3.Then the procedure parameters of dual-pulse voltage power,current density and duty cycle,was optimized by measuring the surface morphology,thickness and the silicon content of coatings.The optimal parameters are 10.0A/dm² positive current density,1.0A/dm² negative current density,60% positive duty cycle and 10% negative duty cycle.The result showed that applying negative current density can improve the surface morphology and eliminate the cracks.The thickness of the best coating is 46?m and the silicon content is 22wt%,and then the sample with the coating were heat treated for 3h at 1000? in an atmosphere of 66.6%N₂and 33.3%H₂.The result showed the silicon content of surface is 8.92wt%and the concentration of silicon in the deepness of 90?m in sample is 4.89wt%.The P_2/1k core loss of the sample is 3.01W/kg and B₈ is 1.79 T,which are greatly improved compared with the 3.5wt%Si electrical steel.