Formation mechanism of high activity aluminide coating on Ni-CeO2 coated Rene 80 alloy

SURFACE & COATINGS TECHNOLOGY

卷:329

Article

Nogorani, Farhad Shahriari¹ 

[1] Shiraz Univ Technol, Dept Mat Sci & Engn, Shiraz 7155713876, Iran

关键词: Aluminide coating;    Reactive element;    Cerium oxide;    Inward growth;    Formation mechanism;    Cyclic oxidation;   

DOI  :  10.1016/j.surfcoat.2017.09.035

来源: Elsevier

【 摘 要 】

High temperature oxidation behavior of protective oxide scales can be improved by surface doping with reactive elements such as cerium. In this investigation, an intermediate Ni-CeO2 layer was electrodeposited on the surface of Rene 80 nickel-based superalloy before pack cementation aluminizing treatment. Electrodeposition of the Ni-CeO2 layer was carried out using direct current and Watts nickel electroplating bath containing 30 g/lit nano ceria particles. Electrodeposited specimens were aluminized in a powder mixture of aluminum, ammonium chloride, and alumina by a two-step treatment at 760 and 1040 degrees C to form an inward growth-type coating. Cross sections of the coated specimens were studied by means of scanning electron microscopy, energy dispersive spectroscopy and X-ray diffractometry. The results showed that after aluminizing the composite intermediate layer converts to an Al-rich NiAI layer with a porous and CeO2-free surface zone below which a CeO2-containing layer exists. Three-zone microstructure of two-step aluminide coatings on nickel-based superalloys was observed below the CeO2-containing layer. The mechanism of coating formation was discussed. The oxidation resistance of the CeO2 modified coating in 10 five-hour cycles at 1050 degrees C was considerably better than the unmodified coating.

【 授权许可】

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