With the advancement of modern aeroengines toward higher thrust-to-weight ratios and increased gas temperatures, the control of rotor–stator clearances has become a critical factor influencing engine performance and efficiency. Abradable seal coatings (ASCs), as an effective means of clearance control, have been widely applied to the inner casings of engines. Under high-temperature service conditions (≥1300 ℃), conventional metal-based ASCs are increasingly exhibiting service performance limitations due to their insufficient thermal stability. In contrast, ceramic-based abradable seal coatings, owing to their excellent high-temperature stability and low thermal conductivity, are considered promising candidates for next-generation high-temperature sealing materials. However, the design of such novel ASCs faces numerous key challenges, including crack propagation, the trade-off between abradability and erosion resistance, and coating failure mechanisms under extremely complex service environments. This review systematically summarizes the recent progress in high-temperature ceramic-based ASCs, with a focus on typical material systems, fabrication techniques, key structural design strategies, and their relationship with performance evolution. Comprehensive analysis reveals significant coupling and trade-offs among abradability, hardness, erosion resistance, thermal shock resistance, and corrosion resistance. Achieving balanced performance requires multiscale structural design and multifunctional synergistic optimization. Finally, this paper summarizes the main challenges currently faced in this field and emphasizes that future research should focus more on understanding the evolution of failure mechanisms under complex service environments and on the design and construction of integrated multifunctional coating architectures.

With advances in the thrust-weight ratio, the service temperature of gas turbine engines even exceeds 1500 °C, which is urgent for the development of high/superhigh-temperature thermal protection systems (TPSs) for long-term service. Niobium alloys are increasingly viewed as promising structural materials for high-temperature applications because of their superior high-temperature mechanical strength, but the “pest” catastrophic oxidation greatly restricts their further application. In this study, a HfC–HfO₂-modified silicide coating was prepared via an innovative method of halide-activated pack cementation (HAPC) combined with liquid-plasma-assisted particle deposition and sintering of niobium alloys, resulting in a composite coating with excellent hot corrosion resistance and high-temperature oxidation resistance. This modified multilayer coating is characterized by the synergistic combination of a dense NbSi₂ inner layer and a HfC–HfO₂ porous outer layer, resulting in a significant improvement in high-temperature performance compared with that of the single NbSi₂ coating. The corrosion gain of the composite coating is only 13.94 mg·cm⁻² after a corrosion time of 200 h at 900 °C, and an intact oxide scale surface is observed after oxidation at 1500 °C for 500 min. This improvement is attributed to the formation of a robust Hf-rich skeleton provided by the deposited HfC–HfO₂ layer, which can accelerate the formation of a highly stable corroded layer/oxide scale. In addition, multiple stress release mechanisms of the composite coating at high temperatures also provide substantial contributions to long-term service. All these merits make HfC–HfO₂-modified composite coatings on niobium alloys competitive for the development of high/superhigh-temperature thermal protection systems for long-term service.