Abstract
Several modern power production systems utilize supercritical CO2 (sCO2), which can contain O2 and H2O as impurities. These impurities may degrade the compatibility of structural alloys through accelerated oxidation. However, it remains unclear which of these impurities plays a bigger role in high-temperature reactions taking place in sCO2. In this study, various model and commercial Fe‐ and Ni‐based alloys were exposed in 300 bar sCO2 at 750 °C to low levels (50 ppm) of O2 and H2O for 1,000 h. 18O-enriched water was used to enable the identification of the oxygen source in the post-exposure characterization of the samples. However, oxygen from the water did not accumulate in the scale, which consisted of Cr2O3 in the cases where a protective oxide formed. A 2wt.% Ti addition to a Ni-22%Cr model alloy resulted in the formation of thicker oxides in sCO2, while a 1wt.% Al addition reduced the scale thickness. A synergistic effect of both Al and Ti additions resulted in an even thicker oxide than what was formed solely by Ti, similar to observations for Ni-based alloy 282.
| Original language | English |
|---|---|
| Pages (from-to) | 571-587 |
| Number of pages | 17 |
| Journal | Oxidation of Metals |
| Volume | 96 |
| Issue number | 5-6 |
| DOIs | |
| State | Published - Dec 2021 |
Funding
The authors would like to thank M. Howell, M. Stephens, T. M. Lowe, T. Jordan, and V. Cox for assistance with the experimental work. J. Jun and R. Pillai provided helpful comments on the manuscript. This work has been carried out within the Academy of Finland project “Novel Approaches to Study Corrosion Mechanisms in High-temperature Industrial Processes” (Decision No. 296435). This research also was sponsored by the US Department of Energy, Office of Fossil Energy, Crosscutting Technology Program. ToF-SIMS characterization was conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility, and using instrumentation within ORNL's Materials Characterization Core provided by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the US Department of Energy. The authors would like to thank M. Howell, M. Stephens, T. M. Lowe, T. Jordan, and V. Cox for assistance with the experimental work. J. Jun and R. Pillai provided helpful comments on the manuscript. This work has been carried out within the Academy of Finland project ?Novel Approaches to Study Corrosion Mechanisms in High-temperature Industrial Processes? (Decision No. 296435). This research also was sponsored by the US Department of Energy, Office of Fossil Energy, Crosscutting Technology Program. ToF-SIMS characterization was conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility, and using instrumentation within ORNL's Materials Characterization Core provided by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the US Department of Energy.
Keywords
- Cr-rich oxide scale
- Impurities
- Internal oxidation
- Supercritical CO2
- Ti addition