Boosting Electromagnetic Wave Absorbing Capacity of Al₂O₃ Coating Through In Situ Generating Nano TiO_1.81 From Ti₂AlC MAX Phases

Abstract The narrow electromagnetic wave absorption bandwidth (EAB) of current dielectric loss type materials is desired to be optimized. Here, this study inventes one TiO 1.81 /Al 2 O 3 coating owning almost twice of the widest EAB reported among all the dielectric loss type materials. The fabrication process is composed of the supersonic atmospheric plasma spraying (SAPS) of Ti 2 AlC/Al 2 O 3 powders and following oxidation at 950 °C for 2 h in air. The occurred in situ double decomposition mechanism transformed Ti 2 AlC (45 µm) into O‐vacancy‐defected TiO 1.81 (30 nm) and Al 2 O 3 (200–500 nm). The interfacial polarization contribution is significantly enhanced due to the appearance of a huge amount of nano hetero‐interfaces. The continuous outward diffusion of Ti and Al elements further endows the coating self‐protective capacity through the formation of covered TiO 1.81 and Al 2 O 3 . As Ti 2 AlC is one of 90 MAX phases, this work supports one wide window for fabricating wide EAB of coatings used in high temperatures.

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