Spray-based 3D printed cementitious electromagnetic wave absorption materials: Optimization with structures design

In light of the advantages of layer-by-layer construction of spray-based 3D (S-3D) printing technology, an integrated design methodology for S-3D printed cementitious electromagnetic wave absorption materials and structures is proposed by adjusting the functional and electromagnetic properties of each layer. The study investigates the effects of structural parameters, i.e., multilayer configurations, absorber gradient, thickness, and surface roughness, on the electromagnetic wave absorption properties (EWAP) of S-3D printed cementitious materials. Experimental results indicate that a matching-loss-reflection multilayer structure can effectively introduce electromagnetic waves deeper into the material for enhanced EWAP. Additionally, optimizing the gradient concentration of magnetite absorbing agent in each functional layer further improves the EWAP of the S-3D printed structure. For the S-3D printed T147 multilayer structure sample, the average reflection loss reaches −9.67 dB, with a peak reflection loss of −13.31 dB and an effective bandwidth of 9.3 GHz below −10 dB. The addition of grooves to the surface significantly enhances the multiple reflection and impedance matching characteristics. Specifically, the incorporation of a 15 mm × 15 mm grid groove on the S-3D printed T147 sample results in the T147-D15 * 15 sample exhibiting the optimal EWAP, with an average reflection loss of −11.61 dB, a peak reflection loss of −19.72 dB, and an effective bandwidth of 13.8 GHz below −10 dB.