| The traditional metal-based shielding materials have been rarely used due to the drawback such as high cost,heavy weight and poor workability;the application of new electromagnetic shielding coating has been gradually expanded and occupies domestic and foreign markets.Then,the development and application of a new Nickel-based electromagnetic shielding coating were conducted by experiments and analyses from some aspects in this article.The main conclusions are as follows:Firstly,the optimal component of single conductive material needs to confirm for composite material.The optimal preparation method and size of nickel powder were identified by comparing experiments.And the influence and mechanism of the size of nickel powder on conductive filling type electromagnetic shielding composite were analyzed.According to multi criteria judgments of electric resistance and shielding effectiveness,the optimal ratio of nickel powder to macromolecule polymer was determined by adjusting amount of nickel powder.The relationship between electric resistance and shielding effectiveness was also calculated.The results show that refining nickel powder size is propitious to its dissolution into poly resin which contributes to improve the formation of conductive network.However,shielding effectiveness doesn't exhibit a monotonously increasing trend with the increasing amount of nickel powder,it decreases when the content of nickel powder exceeds the optimal ratio.Afterwards,the influences of solvents such as xylene,ethyl acetate and acetone on surface electric resistance and shielding effectiveness of conductive filling type electromagnetic shielding composite were studied.Moreover,the main reason caused the performance difference was analyzed from the material characteristics of solvents.The results demonstrate that the viscosity of electromagnetic shielding coating can be adjusted by choosing xylene,ethyl acetate and acetone as solvents of acrylic resin,however,after spraying the shielding effectiveness of three shielding coatings exhibit a large difference.And in this article,the dielectric constant has an important influence on the shielding effectiveness by studying the effect of solvent.Electromagnetic shielding effectiveness is worst when solvent chooses acetone that has a largest dielectric constant.The best shielding effectiveness can be obtained when xylene uses as solvent,and change of its volume fraction has no impact on the shielding effectiveness of electromagnetic shielding coating.Taking ethyl acetate assolvent,the effect on shielding effectiveness is complex which needs to analyze the properties of convection and film-forming.Finally,the influences of conductive components such as FeNi,NiZn and polyaniline on shielding effectiveness were analyzed by means of orthogonal experiments.The results show that the expressions of shielding effectiveness appear differently at low and high frequency stages by synthetically analyzing the shielding materials,and it has a significant relationship with proportion of added conductive component. |
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