Extreme Materials

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Ceramic-based abradable sealing coatings for advanced aeroengines: Materials design, structural strategies, and multifunctional performance

Leyao Wang, Shuqi Wang, Guoliang Chen, Yongchun Zou, Shuang Yu, Enyu Xie, Qingyuan Zhao, Zhiyun Ye, Jiahu Ouyang, Yaming Wang, Dechang Jia, Yu Zhou

Extreme Materials, 2025, 1(4): 33-58. DOI: 10.1016/j.exm.2025.08.003

Method	Principle Description	Advantages	Disadvantages
Scratch Method	Measures mass loss caused by a stylus scratching the coating under a constant load; greater mass loss indicates better abradability.	Simple and easy to implement	Significant deviation from actual service conditions
Scratch Hardness Method	Uses an indenter of defined shape to create scratches on the coating surface; abradability is characterized by scratch hardness related to scratch width.	Simple and easy to implement	Significant deviation from actual service conditions
Turning Method	A blade is used to machine a rod coated with the sealing layer at a cutting depth of 0.6 mm ; the time required to cut this depth is used to evaluate abradability.	Simple and easy to implement	Lacks heating and temperature control devices
Impact Wear Method	Uses an impact wear tester to measure the wear energy of the coating; lower wear energy indicates better abradability.	Introduces a quantitative evaluation standard	Far from actual service conditions; suitable only for theoretical research
Sliding Wear Method	Employs a ring-on-block wear tester to measure the wear rate between a metallic block and a coated block under specific conditions.	Closely simulates service conditions	Low linear velocity; still deviates from actual conditions
Disc Milling Method	The sealing coating is applied to the end surface of a pin, which is then tested against a rotating disc; abradability is characterized by the measured wear rate.	Higher linear velocity ( $\leqq 150\text{ }\mathrm{m}\cdot {\text{ }\mathrm{s}}^{-1}$)	Lacks heating and temperature control; deviates from actual conditions
Bench Test Method	Simulates real engine operation; abradability is evaluated based on coating performance and blade condition.	Closely simulates service environment	High cost; lacks standardized evaluation criteria

Table 9 Domestic evaluation methods for the abradability of seal coatings.

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Fig. 1. Changes in rotor-stator clearance due to frictional wear [10,11] : (a) initial clearance between stationary and rotating components, (b) rub caused by rotor shaft bending, and (c) post-rub clearance configuration.
Fig. 2. A review of composition and structural design strategies for ceramic-based ASCs.
Fig. 3. Thermal shock life of ceramic ASCs as a function of their porosity[10].
Table 1 Regulation of coating porosity and microhardness [37].
Fig. 4. (a) Schematic illustration and (b) cross-section SEM image of Si/ YbDS EBC system applied to an α-SiC substrate [41,42].
Fig. 5. CMAS corrosion failure mechanism of EBCs [47].
Table 2 Comparison of key performance indicators of coating materials for ASCs.
Table 3 Contradictions among key performance indicators of coatings.
Table 4 Influence of manufacturing process parameters on coatings microstructure and properties[20].
Fig. 6. SEM images of (a) hollow spherical powder particles [59] and (b) radially porous powder particles [60].
Table 5 Comparison of fabrication methods for nanocomposite coatings.
Fig. 7. SEM images of (a) APS coating (C-YSZ) and (b) SPPS coating (M-YSZ) [64].
Table 6 Comparison of lubricating phase materials for high-temperature coatings.
Fig. 8. SEM images of ZrO₂-coated (a) h- BN particles [71], (b) CaF₂ particles [73].
Table 7 The functions of different binding phases[80].
Fig. 9. The diagram of (a) knee articulation and (b) YSZ-based ASC with an articulation mimicking structure [84].
Fig. 10. Schematic diagram of the self-healing mechanism of porous LMA-based ASCs and CMAS corrosion behavior [88].
Table 8 CTEs of the constituent phases in the HfO₂-Si bond coat.
Fig. 11. Structural schematics of (a) A/EBC [33] and (b) gradient A/EBC [48].
Fig. 12. Schematic illustration of the single-layer 75YbDS-25YbMS, 25YbDS-75YbMS, and gradient EBC after water vapor corrosion [102].
Fig. 13. Surface micro-textures for enhanced coating adhesion: SEM and schematic representations. (a) Random micro-texture pattern;(b) Regular circular pore array;(c) Inclined hole texture;(d) Hexagonal texture array;(e) Schematic of multi-scale hierarchical bioinspired structure;(f) Comparative schematic of bioinspired micro-texture versus grit-blasted substrate with top coating;(g) Square-grid micro-texture schematic. [116,115,118].
Fig. 14. Typical wear map of ceramic-based ASCs [128].
Fig. 15. Wear mechanism model of ceramic-based ASCs [130].
Fig. 16. Schematic diagram of the abradability test rig[134].
Table 10 The abradability performance of several typical ceramic-based ASCs.
Fig. 17. Schematic diagram of the erosion test apparatus [139].
Fig. 18. Schematic diagram of the water vapor corrosion testing apparatus [149].

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