为探究不锈钢纤维长度与填充量对导电膜片导电性能与电磁屏蔽性能的影响,将不锈钢纤维均匀地铺撒在涂有脲醛树脂和丙烯酸树脂的表层纸上热压,制备具有电磁屏蔽功能的不锈钢纤维填充导电膜片。首先通过微观结构表征,分析不锈钢纤维在导...为探究不锈钢纤维长度与填充量对导电膜片导电性能与电磁屏蔽性能的影响,将不锈钢纤维均匀地铺撒在涂有脲醛树脂和丙烯酸树脂的表层纸上热压,制备具有电磁屏蔽功能的不锈钢纤维填充导电膜片。首先通过微观结构表征,分析不锈钢纤维在导电膜片平面和断面内的搭接状况;然后采用四电极法与同轴线法测试导电膜片的体积电阻率及电磁屏蔽效能;最后通过理论模拟探究不锈钢纤维填充导电膜片的电磁屏蔽机理。结果表明：1）随着不锈钢纤维填充量的增加,导电膜片平面和断面内不锈钢纤维之间交叉排列的混乱程度不断增加,并以随机排列的形式相互交织形成了有效的＂三维导电网络＂。2）随着不锈钢纤维长度和填充量的不断增加,导电膜片的体积电阻率逐渐减小,而其电磁屏蔽效能逐渐增大。3）不锈钢纤维的填充量、导电膜片厚度对导电膜片的导电性能影响显著。4）当不锈钢纤维长度为15 mm、填充量为250 g/m2时,导电膜片的体积电阻率降低为6.493×10-3Ω·cm,电磁屏蔽效能为37.77-51.42 d B,达到中等屏蔽效果,适用于对电磁兼容要求较高的场合。5）理论模拟结果表明,吸收损耗在导电膜片对电磁辐射的屏蔽效果中占有很大的比重,导电膜片表现出了很好的吸波特性。展开更多
The three systems of pure Zn, Zn-0.10% Mg(mass fraction), and Zn-0.15% Mg(mass fraction) were cast under controlled atmosphere and their microstructures were characterized by SEM/EDS analysis. The electrochemical corr...The three systems of pure Zn, Zn-0.10% Mg(mass fraction), and Zn-0.15% Mg(mass fraction) were cast under controlled atmosphere and their microstructures were characterized by SEM/EDS analysis. The electrochemical corrosion behavior of these three samples was examined in the very aggressive solution of 50% H2SO4(mass fraction) using electrochemical impedance spectroscopy(EIS) and potentiodynamic polarization measurements. The results show that magnesium improves in some extent the corrosion resistance of pure Zn in 50% H2SO4(mass fraction) confirmed by EIS test. Results of polarization measurment also demonstrate that small amount of Mg significantly improves the passivation of Zn in the test solution. Results of surface morphology of the samples and EDS analysis reveal that Mg reduced the corrosion attacks to pure Zn.展开更多
The solid state interdiffusion between NiFe204 and NiO in nitrogen atmosphere was studied by means of diffusion couple technique. NiFe204/NiO diffusion couple with plane interfaces was made by clamping method and sint...The solid state interdiffusion between NiFe204 and NiO in nitrogen atmosphere was studied by means of diffusion couple technique. NiFe204/NiO diffusion couple with plane interfaces was made by clamping method and sintering at 1 300℃ for 10 h. Scanning electronic microscopy （SEM） and energy-dispersive X-ray spectrometry （EDS） were used to analyze the microstructure and phase composition of the diffusion couples. The results indicate that a porous layer of uniform thickness forms along the NiFe2O4/NiO bonding interface and exhibits a deep penetration in the NiFe2O4 due to the Kirkendall effect. Furthermore, SEM observations reveal that the needle-like nickel ferrite precipitates form in NiO near the interface and the formation mechanism of them are inferred to be diffusion type solid-state phase changes.展开更多
文摘为探究不锈钢纤维长度与填充量对导电膜片导电性能与电磁屏蔽性能的影响,将不锈钢纤维均匀地铺撒在涂有脲醛树脂和丙烯酸树脂的表层纸上热压,制备具有电磁屏蔽功能的不锈钢纤维填充导电膜片。首先通过微观结构表征,分析不锈钢纤维在导电膜片平面和断面内的搭接状况;然后采用四电极法与同轴线法测试导电膜片的体积电阻率及电磁屏蔽效能;最后通过理论模拟探究不锈钢纤维填充导电膜片的电磁屏蔽机理。结果表明：1）随着不锈钢纤维填充量的增加,导电膜片平面和断面内不锈钢纤维之间交叉排列的混乱程度不断增加,并以随机排列的形式相互交织形成了有效的＂三维导电网络＂。2）随着不锈钢纤维长度和填充量的不断增加,导电膜片的体积电阻率逐渐减小,而其电磁屏蔽效能逐渐增大。3）不锈钢纤维的填充量、导电膜片厚度对导电膜片的导电性能影响显著。4）当不锈钢纤维长度为15 mm、填充量为250 g/m2时,导电膜片的体积电阻率降低为6.493×10-3Ω·cm,电磁屏蔽效能为37.77-51.42 d B,达到中等屏蔽效果,适用于对电磁兼容要求较高的场合。5）理论模拟结果表明,吸收损耗在导电膜片对电磁辐射的屏蔽效果中占有很大的比重,导电膜片表现出了很好的吸波特性。
文摘The three systems of pure Zn, Zn-0.10% Mg(mass fraction), and Zn-0.15% Mg(mass fraction) were cast under controlled atmosphere and their microstructures were characterized by SEM/EDS analysis. The electrochemical corrosion behavior of these three samples was examined in the very aggressive solution of 50% H2SO4(mass fraction) using electrochemical impedance spectroscopy(EIS) and potentiodynamic polarization measurements. The results show that magnesium improves in some extent the corrosion resistance of pure Zn in 50% H2SO4(mass fraction) confirmed by EIS test. Results of polarization measurment also demonstrate that small amount of Mg significantly improves the passivation of Zn in the test solution. Results of surface morphology of the samples and EDS analysis reveal that Mg reduced the corrosion attacks to pure Zn.
基金Project(50721003) supported by the National Natural Science Fund for Innovation Group of ChinaProject(2008AA030501) supported by the National High Technology Research and Development Program of China
文摘The solid state interdiffusion between NiFe204 and NiO in nitrogen atmosphere was studied by means of diffusion couple technique. NiFe204/NiO diffusion couple with plane interfaces was made by clamping method and sintering at 1 300℃ for 10 h. Scanning electronic microscopy （SEM） and energy-dispersive X-ray spectrometry （EDS） were used to analyze the microstructure and phase composition of the diffusion couples. The results indicate that a porous layer of uniform thickness forms along the NiFe2O4/NiO bonding interface and exhibits a deep penetration in the NiFe2O4 due to the Kirkendall effect. Furthermore, SEM observations reveal that the needle-like nickel ferrite precipitates form in NiO near the interface and the formation mechanism of them are inferred to be diffusion type solid-state phase changes.
