微弧氧化及包埋渗铝法制备的复合涂层高温抗蚀性能

采用包埋渗铝技术在C103铌合金基体上制备Al/C103,通过微弧氧化(MAO)处理获得Al_2O_3陶瓷膜外层。利用X射线衍射仪(XRD)和配有能谱仪(EDS)的扫描电镜(SEM),分析复合涂层高温腐蚀前后的成分和组织结构,并研究其高温氧化和热腐蚀行为与机理。结果表明:包埋渗铝处理的Al/C103经1000℃氧化10h后增重为6.98mg/cm^2,微弧氧化结合包埋渗铝制备的MAO/Al/C103增重为2.89mg/cm^2;氧化20h后,MAO/Al/C103增重为57.52mg/cm^2,高于Al/C103的28.08mg/cm^2。在900℃熔融混合盐(75%Na2SO4和25%NaCl,质量分数)中腐蚀50h后,Al/C103和MAO/Al/C103的增重分别为70.54,55.71mg/cm^2,表面生成了Al_2O_3和钙钛矿结构NaNbO3相;部分NaNbO3堵塞MAO微孔,阻碍熔盐向内扩散,MAO/Al/C103试样表现出较优的抗热腐蚀性。

High-temperature Corrosion Resistance of Composite Coating Prepared by Micro-arc Oxidation Combined with Pack Cementation Aluminizing

Al2O3 ceramic film was obtained by micro-arc oxidation (MAO) process on Al/C103 specimen,which was prepared by pack cementation aluminizing technology on C103 niobium alloy.With the aid of XRD and SEM equipped with EDS,chemical compositions and microstructures of the composite coatings before and after high-temperature corrosion were analyzed.The behavior and mechanism of the composite coatings in high-temperature oxidation and hot corrosion were also investigated.The results indicate that oxidation mass gain at 1000C for 10h of the Al/C103 specimen is 6.98mg/cm2,and it is 2.89mg/cm2 of the MAO/Al/C103 specimen.However,the mass gain of MAO/Al/C103 specimen (57.52mg/cm2) is higher than that of Al/C103 specimen (28.08mg/cm2)after oxidation 20h.After hot corrosion in 75 ％0Na2SO4 and 25％NaCl at 900C for 50h,the mass gain of Al/C103 and MAO/Al/C103 specimens are 70.54mg/cm2 and 55.71mg/cm2 respectively,Al2O3 and perovskite NaNbO3 phases are formed on the surface;the diffusion of molten salt is suppressed,due to part of NaNbO3 accumulated in the MAO micropores.Therefore,MAO/Al/C103 specimen exhibits better hot corrosion resistance.