Zhang, Qiang
(National Key Lab. For Nuclear Fuel and Materials, Nuclear Power Institute of China)
,
Tang, Rui
(National Key Lab. For Nuclear Fuel and Materials, Nuclear Power Institute of China)
,
Li, Cong
(China Nuclear Power Technology Research Institute)
,
Luo, Xin
(National Key Lab. For Nuclear Fuel and Materials, Nuclear Power Institute of China)
,
Long, Chongsheng
(National Key Lab. For Nuclear Fuel and Materials, Nuclear Power Institute of China)
,
Yin, Kaiju
(National Key Lab. For Nuclear Fuel and Materials, Nuclear Power Institute of China)
Corrosion of nickel-base alloys (Hastelloy C-276, Inconel 625, and Inconel X-750) in $500^{\circ}C$, 25MPa supercritical water (with 10 wppb oxygen) was investigated to evaluate the suitability of these alloys for use in supercritical water reactors. Oxide scales formed on the samples wer...
Corrosion of nickel-base alloys (Hastelloy C-276, Inconel 625, and Inconel X-750) in $500^{\circ}C$, 25MPa supercritical water (with 10 wppb oxygen) was investigated to evaluate the suitability of these alloys for use in supercritical water reactors. Oxide scales formed on the samples were characterized by gravimetry, scanning electron microscopy/energy dispersive spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The results indicate that, during the 1000h exposure, a dense spinel oxide layer, mainly consisting of a fine Cr-rich inner layer ($NiCr_{2}O_{4}$) underneath a coarse Fe-rich outer layer ($NiFe_{2}O_{4}$), developed on each alloy. Besides general corrosion, nodular corrosion occurred on alloy 625 possibly resulting from local attack of ${\gamma}$" clusters in the matrix. The mass gains for all alloys were small, while alloy X -750 exhibited the highest oxidation rate, probably due to the absence of Mo.
Corrosion of nickel-base alloys (Hastelloy C-276, Inconel 625, and Inconel X-750) in $500^{\circ}C$, 25MPa supercritical water (with 10 wppb oxygen) was investigated to evaluate the suitability of these alloys for use in supercritical water reactors. Oxide scales formed on the samples were characterized by gravimetry, scanning electron microscopy/energy dispersive spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The results indicate that, during the 1000h exposure, a dense spinel oxide layer, mainly consisting of a fine Cr-rich inner layer ($NiCr_{2}O_{4}$) underneath a coarse Fe-rich outer layer ($NiFe_{2}O_{4}$), developed on each alloy. Besides general corrosion, nodular corrosion occurred on alloy 625 possibly resulting from local attack of ${\gamma}$" clusters in the matrix. The mass gains for all alloys were small, while alloy X -750 exhibited the highest oxidation rate, probably due to the absence of Mo.
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제안 방법
1 mg was used to measure the mass change of each alloy. Scanning electron microscopes (JEOL JSM-6490 and FEI Nano400) equipped with EDS were used to observe oxide morphology and thickness and to analyze the chemical compositions. Surface oxide phases were identified through X-ray diffraction (Philips X’ Pert PRO MRD) using a Cu K« radiation source.
To identify the oxide phase structure, XRD analyses of the alloys exposed for 1000 hours were performed, and comparisons with the unexposed alloys were made (Fig. 7). All measured peaks in the exposed alloys are accounted for by the presence of two crystalline solids: an oxide spinel (AB2O4) and a metallic nickel phase representative of unoxidized base metal.
후속연구
No gradient in Cr and Fe concentrations across the oxide films was confirmed by EDS point analysis. However, further examinations, such as grazing incidence X-ray diffraction (GIXRD) and XPS in-depth profiling, will be conducted to characterize both the Cr-rich inner and Crpoor outer spinels.
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