Impact of Temperature Variation on the Electromagnetic Shielding Behavior of Multilayer Shield for EMC Applications

Abstract

This paper attempts to disclose how temperature variation affects the electromagnetic shielding of a multilayer composite made of copper (Cu) fibers surrounded by silicon (Si). The model of the composite was fabricated by physical vapor deposition method, and tested with the temperature rising from room temperature (RT), 50º C, 85º C to 110º C. Under these temperatures, several electromagnetic shielding parameters of the composite were measured in various operating microwave frequencies (E, F, I and J bands). Among them, dielectric permittivity was acquired by LCR tester, magnetic permeability was measured by vibrating sample magnetometer (VSM), and the electromagnetic (EM) wave attenuation was recorded by typical microwave test bench. The results show that the composite had an EMI shielding of 20dB at 85º and 100dB at the RT; the reflection loss of the composite (volume fraction: 0.32) was also 100dB at the RT. Thus, the temperature rise suppresses the reflection loss; the composite has better electromagnetic shielding effect at the RT than at elevated temperatures; the volume faction enhances the wave attenuation of the composite. The results provide a good reference for the design of stable electromagnetic shielding materials at elevated temperatures.

Coupling between tectonic activity and diagenetic evolution of a clastic buried hill—a case study from Gubei low buried hill in Jiyang Depression of Bohai Bay Basin

“…Drawing on the previous studies, this paper analyzes the diagenesis of the Permian tight sandstone reservoirs in Gubei low buried hill, Jiyang Depression, and discusses the coupling between buried hill tectonic activity and diagenetic evolution. The following analysis and testing methods were adopted to facilitate the research: core observation, casting sheet observation, X-ray diffractometry (XRD) (Hadi et al 2019;Rathanasalam et al 2019;Yan et al 2020), scanning electron microscopy (SEM) (Al Owais and El-Hallag 2020;Merizgui et al 2019;Wang et al 2019), and energy spectrum analysis. The research results provide a reference for the exploration and development of clastic buried hills.…”

Role of cobalt nanowire and graphene nanoplatelet on microwave shielding behavior of natural rubber composite in high frequency bands

“…This maximum permeability is the cause of acquisition of magnetic moments at higher frequency with larger rate. [ 32 ] It is further noted that, the imaginary part of permeability is higher than the real part in all frequency range. This difference is the cause of hysteresis losses due to residual magnetism, which is acquired during the application of an external magnetic field.…”

Synthesis of microcrystalline cellulose from abaca nonfluorescent flower pistil and its twill weaved fiber‐polyester composites: Viscoelastic, fatigue, and mechanical properties

“…After thoroughly mixing the cellulose derived from banana flower and unsaturated polyester, the Methyl‐Ethyl‐Ketone‐Peroxide (catalyst) is added up to 2% with 0.5 wt% cobalt naphthenate as that of an accelerator. [ 29 ] The pistil cellulose in the beaker with a significant amount of resin, and stirred using sonicator for 10 min. Four layers of abaca fiber mats were laid in the mold and the resin‐hardener ready mix was carefully poured on top of the layer of reinforcements.…”