Abstract
As part of round robin testing, specimens of commercial alloys 316, 120, 625, and 740 were exposed to 20 MPa research grade CO2 at 700 °C for up to 1500 h. The first set of specimens had higher mass gain likely due to impurities not flushed from the autoclave at startup. After this issue was corrected, an identical set of specimens exhibited lower mass gains for both the Fe- and Ni-based alloys. The differences in reaction products were characterized to understand the effect of impurities under these conditions. As suggested by the mass change, thicker oxides were formed in each case, primarily for the Fe-based alloys. For the Ni-based alloys, the difference was primarily in the transient stage of oxidation with no change in rate constant. Alloy 120 exhibited increased internal attack, and differences in the scale phases formed were characterized to better understand the effect of impurities. Alloy 740 primarily exhibited a greater depth of internal attack in the first run.
Original language | English |
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Pages (from-to) | 95-111 |
Number of pages | 17 |
Journal | Oxidation of Metals |
Volume | 94 |
Issue number | 1-2 |
DOIs | |
State | Published - Aug 1 2020 |
Funding
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). The research was funded by the U.S. Department of Energy, Office of Fossil Energy, Crosscutting Technology Program and the Office of Nuclear Energy, Nuclear Energy University Program led by J. Tucker at Oregon State Univ. The authors would like to thank M. Howell, M. Stephens, T. M. Lowe and T. Jordan for assistance with the experimental work. Specimens were all provided and prepared by S. C. Kung at EPRI for the round robin experiment. 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). The research was funded by the U.S. Department of Energy, Office of Fossil Energy, Crosscutting Technology Program and the Office of Nuclear Energy, Nuclear Energy University Program led by J. Tucker at Oregon State Univ. The authors would like to thank M. Howell, M. Stephens, T. M. Lowe and T. Jordan for assistance with the experimental work. Specimens were all provided and prepared by S. C. Kung at EPRI for the round robin experiment. J. Jun and R. Pillai provided helpful comments on the manuscript.
Keywords
- Cr-rich oxide scale
- Impurities
- Internal oxidation
- Supercritical CO