Korean Journal of Materials Research (한국재료학회지)

Materials Research Society of Korea (한국재료학회)
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Corrosion Characteristics of Fe-Si, Ni-Ti and Ni Alloy in Sulfuric Acid Environments

황산 환경에서 Fe-Si, Ni-Ti계 및 Ni 합금의 내부식성 특성

  • Kwon, Hyuk-Chul (Korea Atomic Energy Research Institute (KAERI) SMART Development Division and Nuclear Materials Research Division) ;
  • Kim, Dong-Jin (Korea Atomic Energy Research Institute (KAERI) SMART Development Division and Nuclear Materials Research Division) ;
  • Kim, Hong-Pyo (Korea Atomic Energy Research Institute (KAERI) SMART Development Division and Nuclear Materials Research Division) ;
  • Park, Ji-Yeon (Korea Atomic Energy Research Institute (KAERI) SMART Development Division and Nuclear Materials Research Division) ;
  • Hong, Seong-Deok (Korea Atomic Energy Research Institute (KAERI) SMART Development Division and Nuclear Materials Research Division)
  • 권혁철 (한국원자력연구원, 원자력재료연구부) ;
  • 김동진 (한국원자력연구원, 원자력재료연구부) ;
  • 김홍표 (한국원자력연구원, 원자력재료연구부) ;
  • 박지연 (한국원자력연구원, 원자력재료연구부) ;
  • 홍성덕 (한국원자력연구원, 원자력재료연구부)
  • Received : 2010.10.15
  • Accepted : 2010.11.24
  • Published : 2011.01.27
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Abstract

Methods of producing hydrogen include steam reforming, electrochemical decomposition of water, and the SI process. Among these methods, the Sulfur iodine process is one of the most promising processes for hydrogen production. The thermochemical sulfur-iodine (SI) process uses heat from a high-temperature-gas nuclear reactor to produce $H_2$ gas; this process is known for its production of clean energy as it does not emit $CO_2$ from water. But the SI-process takes place in an extremely corrosive environment for the materials. To endure SI environments, the materials for the SI environment will have to have strong corrosion resistance. This work studies the corrosion resistances of the Fe-Si, Ni-Ti and Ni Alloys, which are tested in SI-process environments. Among the SI-process environments, the conditions of boiling sulfuric acid and decomposed sulfuric acid are selected in this study. Before testing in boiling sulfuric acid environments, the specimens of Fe-4.5Si, Fe-6Si, Ni-4.5Si, Ni-Ti-Si-Nb and Ni-Ti-Si-Nb-B are previously given heat treatment at $1000^{\circ}C$ for 48 hrs. The reason for this heat treatment is that those specimens have a passive film on the surface. The specimens are immersed for 3~14 days in 98wt% boiling sulfuric acid. Corrosion rates are measured by using the weight change after immersion. The corrosion rates of the Fe-6Si and Ni-Ti-Si-Nb-B are found to decrease as the time passes. The corrosion rates of Fe-6si and Ni-Ti-Si-Nb-B are measured at 0.056 mm/yr and 0.16 mm/yr, respectively. Hastelloy-X, Alloy 617, Alloy 800H and Haynes 230 are tested in the decomposed sulfuric acid for one day. Alloy 800H was found to show the best corrosion resistance among the materials. The corrosion rate of Alloy 800H is measured at -0.35 mm/yr. In these results, the corrosion resistance of materials depends on the stability of the oxide film formed on the surface. After testing in boiling sulfuric acid and in decomposed sulfuric acid environments, the surfaces and compositions of specimens are analyzed by SEM and EDX.

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References

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