High temperature Cr-Zr interaction of two types of Cr-coated Zr alloys in inert gas environment

Yang, Jianqiao; Stegmaier, U.; Tang, Chongchong; Steinbrück, M.; Große, M.; Wang, Shuzhong; Seifert, Hans Jürgen

doi:10.1016/j.jnucmat.2021.152806

Cited by 101 publications

(50 citation statements)

References 40 publications

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“…However, the Cr-Zr inter-diffusion at the coating/alloy interface should have a higher impact, considering the low thickness of the as-deposited coatings. According to the last data of Cr-Zr interaction at high temperatures [10], the thickness of the Cr-Zr interlayer can be equal to 0.5-0.9 μm at 1100 °C for 10-40 min. This Cr consumption results in a decrease in diffusion path for oxygen and nitrogen to the Zr alloy.…”

Section: Discussionmentioning

confidence: 99%

“…Growth of a chromia (Cr2O3) layer on surface of Cr-coated Zr alloy decelerates oxygen diffusion to the alloy and significantly increases its oxidation resistance (e.g., by an order of magnitude at 1200 °C for 10 min [7]). However, Cr-Zr inter-diffusion significantly increases at high temperatures especially for a β-Zr phase [8][9][10]. Thus, during oxidation, Cr coatings can be also consumed by diffusion into Zr alloys with subsequent formation of an eutectic Cr-Zr phase with low melting temperature (~1332 °C).…”

Section: Introductionmentioning

confidence: 99%

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Protection of Zr Alloy under High-Temperature Air Oxidation: A Multilayer Coating Approach

et al. 2021

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Metallic Cr and multilayer CrN/Cr coatings with a thickness of 2.5 µm were deposited onto E110 alloy by magnetron sputtering. Oxidation tests in air were performed at 1100 °C for 10–40 min. The gravimetric measurements showed better protective properties of multilayer CrN/Cr coatings in comparison with metallic Cr coating. Multilayer coating prevented fast Cr–Zr inter-diffusion by the formation of a ZrN layer beneath the coating. The appearance of ZrN is caused by interaction with nitrogen formed from the decomposition of CrN to Cr2N phases. Optical microscopy revealed a residual Cr layer for the multilayer CrN (0.25 µm)/Cr (0.25 µm) coating for all the oxidation periods. Additional in situ X-ray diffraction (XRD) studies of coated alloy during linear heating up to 1400 °C showed that the formation of the Cr2Zr phase in the case of multilayer coatings occurred at a higher (~150 °C) temperature compared to metallic Cr. Multilayer coatings can decrease the nitrogen effect for Zr alloy oxidation. Uniform and thinner oxide layers of Zr alloy were observed when the multilayer coatings were applied. The highest oxidation resistance belonged to the CrN/Cr coating with a multilayer step of 0.25 µm.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Protection of Zr Alloy under High-Temperature Air Oxidation: A Multilayer Coating Approach

et al. 2021

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“…Nevertheless, the Cr-Zr interdiffusion can be a problem of coated nuclear rods at HT oxidation conditions, so a coating thickness can be increased. The protective coating can be consumed by diffusion and dissolution of Cr in Zr-based alloys at high temperatures [10]. Moreover, the melting temperature of liquid eutectic Cr 2 Zr phase is in the range of 1305-1332 • C [9,37-39], so surface of Cr-coated cladding can melt that results in loss of protectiveness and cause oxidation of zirconium.…”

Section: Discussionmentioning

confidence: 99%

“…Such an approach seems to be one of the best prospects for short-term development of ATF. The high potential of Cr coatings can be also confirmed by the participation of industrial/research institutes such as CEA (France), VNIINM (Russia), KIT (Germany) and others [7,[9][10][11] in several full-scale tests of ATF Zr-based claddings with UO 2 fuel in nuclear reactors.…”

Section: Introductionmentioning

confidence: 97%

High-Temperature Oxidation of Cr-Coated Resistance Upset Welds Made from E110 Alloy

2021

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The resistance upset welds (RUW) made from E110 alloy without and with Cr coatings were oxidized in air atmosphere at 1100 °C for 2, 10 and 30 min. The cross-section microstructure, elemental composition and hardness were studied before and after oxidation using optical and scanning electron microscopy, and indentations in welding region. The RUW welding does not noticeably change oxidation kinetics of E110 alloy. The most crucial effect has surface non-regularities formed after welding, which prevent uniform coating deposition on full surface of welded cladding tube and end plug. Cr coating deposition can strongly reduce oxidation of welded E110 alloy, while additional post-processing treatment should be applied to improve surface morphology after RUW welding. Several suggestions favorable to development of ATF Zr-based claddings using Cr coating deposition on welded nuclear rods were discussed.

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“…Interdiffusion between Cr and Zr occurs simultaneously with outer oxidation to form an intermetallic layer (ZrCr 2 layer). Yang et al [16] found that the intermetallic layer growth was controlled by a nearly parabolic law in an inert gas environment, and its growth rate was strongly correlated with the temperature and deposition methods. The presence of the ZrCr 2 layer might be beneficial for reducing coating/substrate thermal mismatch, but it might also introduce microcracking in this brittle layer, lowering the interfacial adhesion [17,18].…”

Section: Introductionmentioning

confidence: 99%

Interdiffusion behavior between Cr and Zr and its effect on the microcracking behavior in the Cr-coated Zr-4 alloy

Jiang¹,

Wang²,

Du³

et al. 2021

NUCL SCI TECH

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High-temperature chromium (Cr)-zirconium (Zr) interdiffusion commonly occurs in Cr-coated zircaloys applied for enhanced accident-tolerant fuel (ATF) claddings. Such interdiffusion changes the interfacial microstructure and thus the fracture mechanism of the coating under external loading. In this study, the interdiffusion behavior in a magnetron sputtered Cr coating deposited on a Zr-4 alloy was studied in a vacuum environment at 1160 °C. In addition, the effect of interdiffusion on the microcracking behavior of the Cr coating was determined by in situ three-point bending tests. The experimental results show that the interdiffusion behavior resulted in the formation of a ZrCr 2 layer, accompanied by the consumption of Cr coating and interfacial roughening. The growth of the diffusion layer followed a nearly parabolic law with respect to annealing time, and the residual stress of the annealed coating decreased with increasing annealing time. Under external loading, a large number of cracks were generated in the brittle interlayer, and some interfacial cracks were formed and grew at the ZrCr 2 /Zr-4 interface. Despite the remarkable microcracks in the ZrCr 2 layer, the vacuum-annealed Cr coating has significantly fewer cracks than the original coating, mainly because of the recrystallization of the coating during annealing.

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High temperature Cr-Zr interaction of two types of Cr-coated Zr alloys in inert gas environment

Cited by 101 publications

References 40 publications

Protection of Zr Alloy under High-Temperature Air Oxidation: A Multilayer Coating Approach

Protection of Zr Alloy under High-Temperature Air Oxidation: A Multilayer Coating Approach

High-Temperature Oxidation of Cr-Coated Resistance Upset Welds Made from E110 Alloy

Interdiffusion behavior between Cr and Zr and its effect on the microcracking behavior in the Cr-coated Zr-4 alloy

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