Temperature-Dependent Effect of Microstructure of Aluminide Coating Prepared by CVD

Abstract

Owing to the advantages of non-line-of-sight deposition，the aluminide coating preparation technology is widely used on key hot-end components of gas turbines， and can prepare oxidation-resistant and corrosion-resistant aluminide coatings on the outer surface and inner cavity surface of the components.The microstructure of the coating is the key factor affecting its service performance，but how to adjust the microstructure of the aluminide coating to obtain a coating with ideal performance is a difficult problem in current research.Aiming at this problem， the effect of temperature， a key preparation parameter， on the microstructure of aluminide coatings was studied in this work.Firstly， aluminide coatings at different deposition temperatures were prepared on the surface of Mar-M247 nickel-based superalloy by chemical vapor deposition(CVD).Then， the microstructure， phase composition and distribution of alloying elements in the aluminide coating were analyzed by scanning electron microscope (SEM)， X-ray diffractometer (XRD) and energy spectrum analyzer (EDS).Results showed that the aluminide coatings obtained at different deposition temperatures had a double-layer structure， the outer layer was a β-NiAl layer rich in Al， and the inner layer was an interdiffusion layer rich in topological close-packed phase (TCP).With the increase of deposition temperature，the thickness of β-NiAl layer and interdiffusion layer increased gradually， and there was a positive correlation between the two and temperature.Moreover， the effect of temperature parameters on the microstructure of aluminide coatings revealed in this study could provide a reference for the preparation of highperformance CVD aluminide coatings.

Keywords

• aluminide coating|coating thickness|cvd|deposition temperature