Boosting Electromagnetic Wave Absorbing Capacity of Al2O3 Coating Through In Situ Generating Nano TiO1.81 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.