The development of electronic technologies and the requirement for high-speed electronic systems and devices have led to an increased improvement in the performance of electronic and telecommunication devices (mobile phones, wireless or navigation systems etc.). Long-term exposure to electromagnetic (EM) fields poses serious risks to human health (EM pollution). EM shielding materials like traditionally-used metals need to be replaced with lighter materials, which also achieve the sufficient mechanical strength and resistance.This work deals with the topical problem of developing non-metal composites (geopolymer composites) with the aim to increase their EM shielding capabilities. Geopolymer composites consist of carbon or basalt fiber grids (size 16 12; 22 22 or 34 34 mm) and nanoparticles of MgO (concentration 0.0; 5.0; 7.5 or 10 %) incorporated into the matrix. Carbon (CF) and basalt fibers (BF) from roving were soaked in various different solutions (distilled water, calcium hydroxide, sodium water glass, and potassium water glass) for two weeks, six weeks and three months, and their tensile strength was examined.The shielding efficiency (SE) of sheet materials (with different fillers) was evaluated in the 30 MHz – 1.5 GHz frequency range. The electromagnetic SE was 5 dB for the pure geopolymer material (without any modification) and reached up to 32 dB for the geopolymer material with CF grids. Moreover, the modified composite material achieved different SE for altered frequencies. The results reveal the possibility to use the composite geopolymer material in the production of shielding coatings with lower costs and with environmental considerations.Keywords: Electromagnetic shielding efficiency, geopolymer composite material, carbon fiber, basalt fiber, MgO nanoparticles
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