WANG Huiming (1999-), male, Master, Junior Engineer. E-mail: hmwang@lam.ln.cn
Silicon carbide fiber reinforced silicon carbide (SiCf/SiC) ceramic matrix composite material exhibits exceptional mechanical properties (i.e., low density, high specific modulus, high temperature resistance, etc.) due to the direct and complex interactions among the matrix, fibers, and interface phases, thus overcoming the low fracture toughness and poor performance against external impact load defects of original SiC ceramic. Consequently, SiCf/SiC composites used as aeroengine structural components can significantly reduce the need for gas cooling in the engine's hot-end components, leading to decreased engine weight, enhanced thrust-to-weight ratio, and improved component durability.
Some international enterprises like General (GE), Pratt & Whitney (PW) and SAFRAN Group of France have realized the large-scale production of SiCf/SiC composite components, which are successfully applied to the inner and outer rings of various aero engine combustion chamber flame tubes, high pressure turbine outer rings, guides and other core components. For instance, the ceramic matrix composite seal/regulator developed by GE is commercialized and applied to military engines such as F100, F414 and F110. Pratt & Whitney (PW) adapts the F119 engine of the world's most advanced fighter jet, the F22, with ceramic matrix composite nozzle regulator and seal validated under the IHPTET program. SNECMA develops composite systems such as A500 C/SiBC, A410 SiC/SiBC (1200 ℃) and A416 SiC/SiBC (1400 ℃). The F100-PW-229 engine nozzle regulator of F15/F16 fighter jet is prepared by A410 SiC/SiBC system and is needed to pass the 265-h test.
When the hot-end components made of the ceramic matrix composite are used in the extreme gas environment of aircraft engine, the surface of the components can be faced with corrosion from high-temperature water vapor, high-temperature molten salt, and molten oxide CaO-MgO-Al2O3-SiO2 (CMAS), leading to a rapid performance degradation of SiCf/SiC composites and premature failure of structural components. Therefore, protective coatings that are resistant to typical gas environment are needed to protect the SiCf/SiC components, such as high-temperature oxidation resistance coating, environmental barrier coating, abrasion resistance coating, etc.. These functional coatings are expected to provide a long-term and reliable protection for SiCf/SiC components. An investigation on the design of high-quality coatings and advanced coating preparation technology is thus an essential method to reduce damage to the SiCf/SiC composite matrix and a critical factor in achieving breakthroughs in next-generation high thrust-to-weight ratio aeroengine technology.
The existing domestic research and applications of SiCf/SiC composites on static parts of turbine engines is not mature yet, and that on rotor parts is still in a preliminary research stage. For instance, the working conditions for the rotor blade are extremely harsh and its configuration is complex, which make the component structure design a core and critical technology. The turbine rotor blade must ensure the structural integrity of the blade body and tenon, as well as the continuity of the fiber in the bearing direction due to the huge centrifugal mechanical load, thereby leveraging a high tensile strength of the fibers. The structural design of turbine rotor thus must consider the characteristics of composite materials, forming a structure/material integration design method.
The upper limit of long-term service temperature for SiCf/SiC composites based on the third-generation SiC fibers is approximately 1400 ℃. However, the wall temperature requirements for the combustion chambers of the new generation of aero-engines exceed 1600 ℃. To ensure the long-term service reliability of SiCf/SiC composite hot-end components in high-temperature gas and corrosive environments, the design and preparation of high-quality protective coatings become one of the key breakthroughs in the technological iteration of aero-engine research and development. The development of protective coatings for the hot-end components of the new generation of aero-engines must rely on advanced technologies such as efficient screening and design of new multi-functional coating materials, innovative coating structure design and precise control of coating microstructure, large-scale preparation of coating feedstock powders, and performance evaluation and failure control of coating systems under typical service environments.
In summary, there remains a significant gap between domestic SiCf/SiC composite materials and protective coatings, as compared with those of the Western developed countries such as the United States. There is an urgent need to systematically and progressively develop the application technology for ceramic matrix composite materials suitable for aero engines, accelerate the establishment of technical reserves, and provide competitive hot-end components materials and technological support for the high-performance aero engines in China.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |