Investigation On The Magnetic Shielding Coating Materials In Low Frequency

With the rapid development of modern science and technology, the environment andhuman life have been increasingly affected by the radiation of electromagnetic wave.Therefore, it is of great significance to shield the electromagnetic wave in an effective wayand to conduct the research on the shielding materials of the electromagnetic wave.Currently, there are many researches on the high and middle frequency shielding materialsand those materials produce a sound shielding effect. However, the low-frequency (below10kHz) shielding materials are seldom studied.In the thesis, the materials' low-frequency magnetic shielding effectiveness isinvestigated with Helmholtz coil, and the microstructure of Fe-Si-Nb-V-B amorphousmaterials and the process of crystallization under the circumstance of heating are analyzedwith the help of X-ray diffraction and Differential Thermal Analysis.Due to the extreme brittleness of Fe-based belt materials after the annealing, it isdifficult to manufactue. To solve this problem, the annealed Fe-based materials arecomminuted into the coating stuffing. And the factors that greatly affect the low-frequencyshielding performance are analyzed, such as the amount of stuffing material, solvent andthe coupling agent, the coating thickness and the hardening technology.Through the research, it finds out that among the Fe-Si-Nb-V-B, Fe-Si-Nb-Mo-B andFe-Si- B amorphous materials, Fe-Si-Nb-V-B amorphous material has a better shieldingeffect in low-frequency stage than the other two, which amounts to 30dB. Besides, after450℃and 560℃annealing, a better shielding effectiveness is yielded.When the annealed Fe-based material is comminuted into the coating stuffing, theamount of stuffing material, solvent and the coupling agent, the coating thickness and thehardening technology have great influences on the low-frequency shielding effectiveness.When the best radio of Fe-based stuffing and epoxy resin is 4:1, the magnetic shieldingeffectiveness of the materials achieves the high value. When the best radio of Fe-basedstuffing, epoxy resin and solvent is 20:5:8; the magnetic shielding effectiveness is alsoimproved with the increase of coating thickness. However, taking the performance and costinto consideration, it is quite proper to make sure that the coating thickness is about 200μm.Usually, it is useful to improve the coating effectiveness if it is solidified in roomtemperature after 30 minutes solidifying in 60℃.