Electromagnetic wave absorption performance of magnesium phosphate cement functionalized by nano-Fe3O4 magnetic fluid and hollow glass microspheres

In light of high bonding and early strengths, magnesium phosphate cement (MPC) functionalized with nano-Fe3O4 magnetic fluid and hollow glass microspheres (HGM) that exhibited excellent electromagnetic wave absorption performance (EWAP) was fabricated in this study. Coating a construction surface with multifunctional MPC could effectively withstand electromagnetic radiation hazards. Effects of the Fe3O4-like ferrite content and type (i.e., nano-Fe3O4 magnetic fluid, nano-Fe3O4 particles and magnetite), and the surface roughness of specimens on the EWAP of the MPC were investigated by lab tests. Test results showed that the Fe3O4-like ferrite greatly improved the EWAP of the MPC and the enhancement effectiveness was in descending order of nano-Fe3O4 magnetic fluid > nano-Fe3O4 particles > magnetite. Among the samples tested in this study, MPC blended with 5 wt% nano-Fe3O4 magnetic fluid showed an optimal EWAP as indicated by a peak reflection loss of -11.2 dB and bandwidth of 9.67 GHz below -10 dB. Additionally, the reflection loss of the MPC in the high frequency range could be further improved by carving notches on the surface to increase the number of microwave reflections. The electromagnetic energy absorbing mechanism and the hydration progress of the MPC were further analyzed with SEM/EDS and XRD results. The hydration degree of the MPC got improved due to the lubricating effect of HGM and filling effect of nano-Fe3O4 magnetic fluid, which also optimized its micro structure and compressive and flexural strengths. From this study, the nano-Fe3O4 magnetic fluid and HGM modified MPC had potential application in the construction of buildings for enhanced resistance to electromagnetic radiation. (C) 2020 Elsevier Ltd. All rights reserved.