High temperature oxidation of alloy 617, 740, HR6W and Sanicro 25 in supercritical water at 650°C

ABSTRACT

In this study, the oxidation behaviour of alloy 617, alloy 740, alloy HR6W and Sanicro 25 was investigated in SCW and vapour environment at 650°C for 320 h. The weight gain and the thickness of the oxide films of samples after exposure in SCW are higher than that in vapour. Inner oxidation phenomena were observed on alloy HR6W and Sanicro 25, which have higher content of Fe. The structure of the oxide films formed on alloy 617, alloy 740, alloy HR6W and Sanicro 25 after exposure in SCW at 650°C for 320 h is composed by a Fe-rich (mainly hematite) outer layer and a Cr-rich inner layer. The thickness of the outer Fe-rich layer is related with the Fe content in alloy matrix. Oxide films spallation phenomena were found on alloy HR6W after exposure in SCW.

KEYWORDS:

• High temperature oxidation
• supercritical water
• steam
• corrosion
• nickel-based alloy
• Fe-based alloy

Acknowledgements

The authors would like to thank Ms. Wang Yu and Mr. Ren Zijun at the Instrument Analysis Center of Xi'an Jiaotong University for their assistance with LRS and SEM analyses.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Donghai Xu http://orcid.org/0000-0003-0076-3078

Additional information

Funding

This work was supported by the National Key Research and Development Program of China [No. 2016YFC0801904]; Fundamental Research Funds for the Central Universities [xjj2018201]; Fundamental Research Funds for the Central Universities [xjj2018006]; the Project from the national natural science foundation of China [51871179].