摘要
采用化学气相沉积(Chemical Vapor Deposition,CVD)工艺,在沉积真空度为150mbar、200mbar和250mbar的条件下分别在镍基单晶高温合金基体上制备了三种铝化物涂层,研究了沉积真空度对铝化物涂层相结构和高温氧化行为的影响。借助X射线衍射(XRD)、扫描电子显微镜(SEM)等表征方法系统分析了三种铝化物涂层的相结构、显微形貌和化学组成。结果表明:三种沉积态铝化物涂层的相结构均为β-NiAl相,沉积真空度为200mbar的涂层样品还存在Ni_(1.04)Al_(0.96)和Ni_(1.1)Al_(0.9)双相结构;经1100℃静态氧化后,三种涂层表面均形成了Al_(2)O_(3),β-NiAl相转变为γ′-Ni_(3)Al相,沉积真空度为250mbar的涂层样品中γ′-Ni_(3)Al相的峰强度最低;三种铝化物涂层的氧化增重速率分别为0.037g/(m^(2)·h)、0.022g/(m^(2)·h)和0.018g/(m^(2)·h),沉积真空度为150mbar的涂层样品氧化增重值大于其他两种涂层样品;沉积真空度越低,涂层表面存在的微观孔洞数量越多,高温氧化后涂层表面所形成的氧化膜越易于萌生显微裂纹和出现氧化膜脱落现象。基于本文试验结果,沉积真空度为250mbar所制得的涂层样品,其显微组织、元素含量和高温抗氧化性能最佳。
Three kinds of aluminide coatings were fabricated by chemical vapor deposition(CVD)on the surface of the nickel-based superalloy substrates at the deposition pressure of 150,200 and 250 mbar,respectively.The effect of deposition pressure on phase structure and high temperature oxidation behavior of the specimens with aluminide coating was systematically investigated.The phase structure,surface morphology and elemental composition of the three kinds of aluminide coatings were analyzed by XRD,SEM and EDS.The results indicate that the phase constituents of three kinds of aluminide coatings are detected to be β-NiAl.Two phases including of Ni_(1.04)Al_(0.96) and Ni_(1.1)Al_(0.9) are gained in the coating specimens prepared at the deposition pressure of 200 mbar.After the isothermal oxidation at 1100℃ for different dwelling times,the main phase β-NiAl transforms into γ′-Ni_(3)Al with formation of Al_(2)O_(3).Differently,the peak intensity of γ′-Ni3Al phase is the weakest for the specimens deposited at the pressure of 250 mbar.The oxidative weight gain rate of the three aluminide coatings is 0.037,0.022 and 0.018g/(m^(2)·h),respectively.The oxidation weight gain of the coating specimens at the deposition pressure of 150 mbar is correspondingly larger than that of the other two coating specimens.The lower deposition pressure is,the more micropores on the surface of the coating exist,and the more easily microcracks appear on the thin film of the coating surface and further form into the spllation of oxide scale after high temperature oxidation.Based on the experimental results,the coating specimens prepared at deposition pressure of 250 mbar show the best surface microstructure,elemental content and high temperature oxidation resistance.
作者
王鑫
甄真
牟仁德
何利民
许振华
WANG Xin;ZHEN Zhen;MU Ren-de;HE Li-min;XU Zhen-hua(Aviation Key Laboratory of Science and Technology on Advanced Corrosion and Protection for Aviation Material,AECC Beijing Institute of Aeronautical Materials,Beijing 100095,China)
出处
《真空》
CAS
2022年第5期20-27,共8页
Vacuum
基金
关键技术攻关项目(KH9A200503)
材料专项项目(KH57200513)。
关键词
化学气相沉积
铝化物涂层
沉积真空度
相结构
高温氧化
chemical vapor deposition
aluminide coating
deposition pressure
phase structure
high-temperature oxidation
