8YSZ-Al_(2)O_(3)复合热障涂层研究进展

A Review of 8YSZ-Al_(2)O_(3)Composite Thermal Barrier Coatings

热障涂层可以为航空发动机等高温部件提供热防护,对延长其使用寿命具有重要意义。近年来高温部件的使用温度不断提升,对热障涂层的耐温性也提出了更高的要求。长时间高温热循环后,常规热障涂层容易出现开裂、剥落等失效行为,直接影响航空发动机的安全性和可靠性。8YSZ作为经典的热障涂层材料,具有优异的抗热震和隔热性能。但8YSZ致密度较低,涂层中存在较多的空隙和缺陷,其高温抗氧化和耐高温熔盐腐蚀等性能仍有较大的改进空间。而Al_(2)O_(3)作为常用的陶瓷涂层材料,致密度高、力学性能出色,但过小的热膨胀系数使其无法单独用作热障涂层材料。通过对比可以发现,8YSZ和Al_(2)O_(3)的性能具有较好的互补性。基于8YSZ和Al 2O 3各自的性能优势,研究者们开始将Al_(2)O_(3)引入8YSZ制备8YSZ-Al_(2)O_(3)复合涂层,探索将复合涂层用作热障涂层的可行性。研究发现,Al_(2)O_(3)的加入使8YSZ-Al_(2)O_(3)复合涂层中产生无定形相,无定形相的含量、重结晶与其耐温性能紧密相关。随着Al_(2)O_(3)含量的增加,复合涂层的微观结构变得更加致密,其杨氏模量和硬度等力学性能也呈增加趋势。引入Al_(2)O_(3)可以有效调节8YSZ涂层的微观结构和力学性能。受此影响,复合涂层的抗氧化和耐熔盐腐蚀等性能有较为明显的提高,但其抗热循环性能仍需进一步优化。本文按照复合涂层微观结构与力学性能调控、制备工艺与结构优化和高温应用的顺序重点介绍了8YSZ-Al_(2)O_(3)复合涂层的研究现状,阐述了其相对传统8YSZ涂层的主要优点及不足,并简要展望了未来发展趋势。

Thermal barrier coatings(TBCs)can provide thermal protection for high-temperature parts such as aeroengine,which is of great significance to improve its service life.In recent years,the thermal resistance requirements of the TBCs are constantly improving with the rapid development of the aeroengine.After a long thermal cycles,traditional TBCs are prone to crack and peel,which directly affects the safety and reliability of the aeroengine.As we all known,8YSZ coatings have excellent thermal shock resistance and thermal insulation performance.However,the thermal oxidation and corrosion resistance of 8YSZ coatings still have great room for improvement due to the formation of many voids and defects during spraying process.As a common ceramic coating material,Al_(2)O_(3)has high compactness and excellent mechanical properties,but its thermal expansion coefficient is too small to be used as TBCs alone.It can be found that the properties of 8YSZ and Al_(2)O_(3)are complementary.Based on the perfor-mance advantages of each other,researchers began to introduce Al_(2)O_(3)into 8YSZ to prepare 8YSZ-Al_(2)O_(3)composite coatings to exploring the feasibility of using the composite coatings as the candidate for TBCs.The results show that the addition of Al_(2)O_(3)results in the formation of amorphous phase in 8YSZ-Al_(2)O_(3)composite coatings.The content of amorphous phase and its recrystallization are closely related to the thermal resistance of coatings.With the increase of Al 2O 3 content,the microstructure of the composite coatings becomes more compact,the young’s modulus and hardness also show an increasing trend.Thus,Al_(2)O_(3)can effectively adjust the microstructure and mechanical properties of 8YSZ coatings.As a result,the thermal oxidation and corrosion resistance of the composite coatings are obviously improved compared with the 8YSZ coatings,but its thermal cycle resistance still needs to be further optimized.In this paper,the research progress of the 8YSZ-Al_(2)O_(3)composite coatings are mainly introduced according to the order of microstructure,mechanical properties,preparation process and high-temperature applications.The main advantages and disadvantages of the composite coatings compared with traditional 8YSZ coatings are described,and its future development trend is also prospected.