Corrosion behaviour of Ni-based alloy Inconel 740H in supercritical carbon dioxide at 650–700°C

ABSTRACT

Corrosion tests of Ni-based alloy Inconel 740H were carried out in supercritical carbon dioxide (S-CO₂) at 650–700°C under 25 MPa. The corrosion kinetics were measured by weight change as a function of time, and the surface oxide layers were characterised and identified by a series of characterisation methods. It is found that Inconel 740H experienced general oxidation, localised exfoliation and internal oxidation. A dense Cr₂O₃ oxide scale rapidly formed on the surface of Inconel 740H at 650–700°C, resulting in good general corrosion resistance. Nodular oxidation was triggered by Ti-rich and Nb-rich oxides. Internal oxidation selectively oxidised Al. The causes of oxide-induced exfoliation are discussed.

KEYWORDS:

• Nickel-based alloy
• high-temperature corrosion
• supercritical carbon dioxide
• exfoliation

Acknowledgements

The presented project was funded by the National Natural Science Foundation of China (Nos. 52071140 and 52006067) and the Fundamental Research Funds for the Central Universities (Nos. 2020JG001 and 2022MS012).

Additional information

Funding

This work was supported by National Natural Science Foundation of China: [Grant Number 52071140]; Fundamental Research Funds for the Central Universities: [Grant Number 2020JG001]; National Natural Science Foundation of China: [Grant Number 52006067]; Fundamental Research Funds for the Central Universities: [Grant Number 2022MS012].