Study On Preparation And Performance Of Composite Based On Rubber For Electromagnetic Interference Shielding

Electromagnetic interference (EMI) produced by various electric apparatuses and electronic equipments has been another public nuisance following the noise pollution, air pollution, water pollution and solid waste pollution. Shielding materials based on rubbers have been received extensive attention due to its simple preparation, low cost, easy control of product shape and other advantages.In this thesis, the shielding properties of composites based on Fe73.5Cu1Nb3Si13.5B9 amorphous powders/butyl rubber were studied with emphasis after comparing the shielding performance of three kinds of Fe-based amorphous powders with different components, namely, Fe78Si13B8, Fe73.5Cu1Nb3Si13.5B9, Fe72Co8Si15B5, then the regularities how these factors including content of powders, grain size, annealing technique, thickness of samples, forming pressure and post-heat treatment affected the shielding performance were investigated systematically.The results show that these factors, such as state of heat treatment, grain size, content of amorphous powders and post-heat treatment, thickness, forming pressure of samples have a great effect on the shielding performance of composites. Composites based on Fe73.5Cu1Nb3Si13.5B9 amorphous powders/carbon black/butyl rubber have the best shielding among Fe78Si13B8,Fe73.5Cu1Nb3Si13.5B9,Fe72Co8Si15B5 three different components of Fe-based amorphous powders. Fe73.5Cu1Nb3Si13.5B9 amorphous powders, partially crystallized intoα-Fe(Si) after 550℃×2h, have excellent soft magnetic properties. The shielding performance of the sample is the best when the grain size of annealed powders is 100 mesh, content of powders is 75wt%, thickness of sample after post-heat treatment for 180℃×6h is 4mm, the absolute value of SE is more than 50dB in the range from 1000MHz to 6000MHz. When the grain size is constant, the tensile strength of composite decreased slowly and the shore hardness increased also slowly with the enhancement of content of amorphous powders. The tensile strength of composites is 0.62MPa, shore hardness is 71 when the ratio of butyl rubber/carbon black/amorphous powders is 1/1/6.