高温含水气氛对Pt改性NiCoCrAlY合金氧化行为的影响

Influence of Water Vapor Within Air on Oxidation Behavior of Pt-Modified NiCoCrAlY Alloy

为了研究Pt改性NiCoCrAlY合金在高温含水气氛中的高温抗氧化行为,进一步理解高温含水气氛对Pt改性涂层表面形貌以及产物的影响,采用电镀方式在NiCoCrAlY合金表层制备了一层1.5μm厚的Pt层,然后对涂层进行热处理。对Pt改性NiCoCrAlY涂层在1 050℃的空气和含水气氛下的高温氧化行为进行对比研究。采用扫描电镜(SEM)观察表面形貌,采用X射线衍射仪(XRD)、能谱(EDS)分析了涂层的相结构及成分。结果表明:在含水气氛下,Pt改性合金表面生成针状Al_2O_3,基体不同相β-NiAl与γ'-Ni_3Al在含水气氛中表现出不同的Al_2O_3生长速率,从而导致氧化层中生长应力的堆积,导致氧化层的剥落。

Pt layer with a thickness of 1.5μm was prepared on NiCoCrAlY coating by electroplating method, and then the layer was treated by heat treatment. The high-temperature oxidation behaviors of Pt-modified NiCoCrAlY alloy at 1 050℃ in air atmosphere and water vapor atmos- phere were studied and compared. Scanning electron microscope （SEM）, X-ray diffractometer （XRD） and energy dispersive spectrometer （EDS） were used to analyze the morphology, phases and composition of coating. Results showed that in water vapor atmosphere, needle- like Al203 was formed on the surface of Pt-modified alloy. The Al203 growth rates of β-NiAl and γ-Ni3Al in water vapor atmosphere were different, which led to the accumulation of growth stress in oxide layer and further caused the coating stripping.