Modern electronic devices need effective shielding from external Electromagnetic Interference (EMI) to function correctly. The Electromagnetic (EM) waves emerging from communication systems and medical devices must be isolated to safeguard humans from exposure. The mechanics of EMI shielding as well as several characterization methods are discussed in this paper. Existing trends and practices of designing, fabrication and use of polymer matrix composites for EMI shielding applications are covered. Several approaches and new solutions for fabricating composites either by modification of filler or matrix are discussed and prominent features of EMI shielding material are also discussed. Conducting polymers such as polyaniline, polypyrrole and polythiophene make them adept for EMI shielding applications. An assessment of the different factors affecting the performance of EMI shielding materials is also presented.

Purpose The purpose of this paper is to manufacture an aluminium square cross-sectional bar by using conventional lathe machine from aluminium scraps through friction stir back extrusion (FSBE) process and study the viability of the process to produce the square bar. Design/methodology/approach The important tasks involved in this work are as follows: designing and manufacturing the chamber and plunger components used for experimental work, experimentally studying the thermo-mechanical progression of FSBE process on adapted conventional lathe machine and analyzing the relation between controlled parameter (like rotational speed and consolidation time) and response parameter (like extrusion time, extrusion rate, grain structure and hardness). Findings Preliminary results show that increasing or decreasing rotational speeds results in defects. Cold crack and twisting defect were shown on square bar fabricated using low rotational speed, and hot crack defects were observed on surface of the bars produced by higher rotational speed. The manufactured square bars were tested using optical microscope and Vickers hardness tester. Microstructural studies reveal that initial grains of aluminium wire undergo significant refinement and result in equiaxed and recrystallized grains in the square bar fabricated through FSBE method. The hardness tests show almost even distribution of hardness in the specimen, but hardness was lower than parent aluminium; in comparison, uneven distribution of hardness was seen in parent aluminium. Originality/value FSBE process is the new method to produce the bars and rods with better mechanical properties. The ambition of this work is to convert the existing scrap materials to useful products. Based on the literature review, the work has planned to perform extrusion process with the minimum effort and limited sources. In this manner, the work is highly original and under scientific mandate.

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