Preparation And Performance Research Of Magnetic Shielding Film To Low Frequency

This dissertation mainly research on the difficult part of electromagnetic shielding--low-frequency magnetic field shield, contents low-frequency magnetic shielding theory, effecting factors on magnetic shielding effectiveness, stability of pretreatment immerse zinc alloy solution, preparation technique of low-frequency magnetic shielding film and properties of plating layer.First of all, the dissertation analyzed low-frequency magnetic shielding theory, educed magnetic shielding effectiveness'precise analytic equation of magnetic field upright shield frame and magnetic field parallel shield frame; Magnetic conductivity, thickness and semidiameter of shielding system markedly influence magnetic shielding effectiveness.Secondly, the stability of pretreatment immerse zinc alloy solution was analyzed. Experimentation results show that NaOH,complex agent,ZnO and NiCl2 markedly influence on the stability of the immerse zinc alloy solution and the quantity of immerse layer. When NaOH100~150g/L,KNaC4H4O6·4H2O10~20g/L,ZnO5~10g/L,NiCl25~10g/L, the zinc alloy immerse solution have optimal stability, and can obtain compact,glossiness immerse film, the cover rate is 95%, plating layer is brightness and integrate well with fundus.Thirdly, the preparation technics of low-frequency magnetic shielding film was researched. Experimentation results show that metal salt in plating solution and plating voltage markedly influence on alloy content in plating layer. For 0.25dm2 single aluminum foil, when plating voltage between 1.5 and 1.7V, can obtain brightness and symmetrical plating layer, crystal,nano-crystal and un-crystal structure of plate layer can be obtained when P content between 1~20%in plating solution. P element in plating layer mainly come from NaH2PO4; electric current efficiency of six different kinds of plating solution is 79~85%.Lastly, the property of the plate layer was analyzed. Test result show that the thickness of the plate layer is consistent and has high integrate with the fundus. Plate layer growth in grain shape accumulate mode, grain diameter is fine; X-ray shows that diffraction peak at 2θ=44.5°is obviously broadened, indicate that the frame of the plate layer is nano-crystal. magnetic characteristic test show that the soft magnetic performance of the plate layer is fine. It's electromagnetic shielding effectiveness attains 80~100dB at 100MHz~1.5GHz and 12dB at 50Hz and 3.5~5.2dB at static magnetic field of different intensity.