Electrical conductivity and electromagnetic shielding properties of Ti₃SiC₂/SiC functionally graded materials prepared by positioning impregnation

Ti₃SiC₂/SiC functionally graded materials (FGMs) were prepared by hot-pressing/positioning impregnation. Positioning impregnation is a novel local impregnation technique targeted at layers exhibiting poor sintering behaviour, resulting in uniform densification across the different layers and minimizing the deviation from the designed composition distribution. With the increased Ti₃SiC₂ content in the layer, the resistivity decreased significantly firstly and then decreased slowly and finally tended to be a constant. The resistivity of the layers with SiC content of 80–100 vol.% decreased significantly via positioning impregnation and further decreased by introducing γ-Al₂O₃. However, introducing γ-Al₂O₃ facilitated the decomposition of Ti₃SiC₂ into TiC. The FGMs had a total shielding effectiveness over X band of 43–52 dB and is suitable for potential applications in excellent electromagnetic shielding materials. The dominating shielding mechanism of the FGMs is reflection, and the FGMs had high intrinsic absorption capabilities.