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Advanced Coatings for Accident Tolerant Fuel Claddings

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A special issue of Coatings (ISSN 2079-6412). This special issue belongs to the section "Surface Characterization, Deposition and Modification".

Deadline for manuscript submissions: 30 July 2025 | Viewed by 28641

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Special Issue Editor

Dr. Egor Kashkarov

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Guest Editor

Division for Experimental Physics, School of Nuclear Science & Engineering, National Research Tomsk Polytechnic University
Interests: accident tolerant fuel; metallic coatings; ceramic coatings; surface modification; ion implantation; magnetron sputtering; cathodic arc deposition; titanium alloys; zirconium alloys; high-temperature oxidation; corrosion; material characterization

Special Issue Information

Dear Colleagues,

The aim of this Special Issue is to highlight and summarize the latest achievements in the field of protective coatings for enhanced accident-tolerant fuel (E-ATF) claddings. This topic was widely developed after the accident at the Fukushima Daiichi plant, which showed low resistance of fuel element claddings in cases of hypothetical design basis accident (DBA) conditions, such as loss of coolant accident (LOCA). Significant international efforts are focused on the development of new cladding materials as well as on a short-term concept to create protective coatings for existing cladding materials. Various metal, ceramic, MAX-phase, high-entropy, and other coatings can be used for this purpose. There are urgent questions about the choice of the type of coating and its architecture, structure, and properties to meet the requirements for the ATF materials. Various methods of physical vapor deposition (PVD), chemical vapor deposition (CVD), laser cladding, cold spraying, and other surface modification methods are available for coating deposition. It is well known that the structure and properties of coatings depend on the deposition method and can be controlled by process parameters. In this regard, the choice of deposition technology for ATF coatings is also important. Therefore, this Special Issue will provide new ideas on current perspectives and discussions on advanced ATF coatings and deposition technologies, as well as corrosion mechanisms with theoretical and experimental research.

The main focus of this Special Issue is to provide and publish recent developments in the area of ATF materials and technologies to protect fuel claddings against high-temperature corrosion and embrittlement. In particular, the topic of interest includes but is not limited to

Advanced ATF coatings;
Characterization of ATF coating materials;
Deposition techniques for ATF coatings;
Diffusion barrier coatings;
Metallic coatings;
Ceramic coatings;
Multilayer coatings;
PVD and CVD coatings;
Surface modification;
Oxidation kinetics;
High-temperature corrosion.

Dr. Egor Kashkarov
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

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Published Papers (12 papers)

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Research

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10 pages, 3093 KiB

Open AccessArticle

Hydrogenation Behavior of Cr-Coated Resistance Upset Welds of E110 Zirconium Alloy

by Egor Kashkarov, Kirill Gusev, Viktor Kudiiarov, Nikita Kurdyumov and Dmitrii Sidelev

Coatings 2023, 13(2), 339; https://doi.org/10.3390/coatings13020339 - 2 Feb 2023

Cited by 1 | Viewed by 1490

Abstract

The hydrogenation behavior of Cr-coated resistance upset welds (RUW) of E110 zirconium alloy was investigated at 360, 450 and 900 °C and a hydrogen pressure of 2 bar. The deposition of Cr coating, via magnetron sputtering, can decrease the hydrogen absorption rate of an RUW Zr alloy. The activation energy for the hydrogen absorption of Cr-coated specimens (84 kJ/mol) is higher in comparison with uncoated ones (71 kJ/mol), which indicates the deceleration of the hydriding of welded Zr alloys in the case of Cr coating deposition. A Cr coating can limit the formation of radially oriented hydrides and the hardening of RUW specimens at 360 and 450 °C. No significant difference in the hydrogen absorption rate was found at 900 °C. The application of Cr coating deposition to protect resistance-upset-welded Zr alloys in a hydrogen atmosphere is discussed. Full article

(This article belongs to the Special Issue Advanced Coatings for Accident Tolerant Fuel Claddings)

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11 pages, 4844 KiB

Open AccessFeature PaperArticle

The Microstructure of Zr/Nb Nanoscale Multilayer Coatings Irradiated with Helium Ions

by Roman Laptev, Ekaterina Stepanova, Natalia Pushilina, Egor Kashkarov, Dmitriy Krotkevich, Anton Lomygin, Alexey Sidorin, Oleg Orlov and Vladimir Uglov

Coatings 2023, 13(1), 193; https://doi.org/10.3390/coatings13010193 - 15 Jan 2023

Cited by 3 | Viewed by 2005

Abstract

The effect of helium ion irradiation on the microstructure and properties of composites based on Zr/Nb nanoscale multilayer coatings (NMCs) was studied. X-ray diffraction (XRD), transmission electron microscopy (TEM), and variable-energy Doppler broadening spectroscopy (DBS) were used for the in-depth analysis of defects in the irradiated NMCs. After irradiation of the Zr/Nb NMCs with helium ions at a 10¹⁷ ion/cm² dose, the layered structure was generally retained, but the internal stresses in the layers were increased, which caused wave-like distortion in the ion deposition zone. The Zr/Nb NMCs with an individual layer thickness of 25 nm were characterized by the smallest microstress changes, but single blisters were formed in the near-surface region. The microstructure of the Zr/Nb NMCs with a layer thickness of 100 nm exhibited relatively smaller changes upon helium ion irradiation. The prevailing positron-trapping center was the reduced-electron-density area at the interfaces before and after irradiation of the Zr/Nb NMCs regardless of the layer thickness. However, the layer thickness affected the DBS parameter profiles depending on the positron energy, which was probably due to the different localization of implanted ions within the layers or at the interfaces. Full article

(This article belongs to the Special Issue Advanced Coatings for Accident Tolerant Fuel Claddings)

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15 pages, 11523 KiB

Open AccessArticle

High-Temperature Steam Oxidation of Accident-Tolerant Cr/Mo-Coated Zr Alloy at 1200–1400 °C

by Maxim Syrtanov, Egor Kashkarov, Anastasia Abdulmenova, Kirill Gusev and Dmitrii Sidelev

Coatings 2023, 13(1), 191; https://doi.org/10.3390/coatings13010191 - 15 Jan 2023

Cited by 14 | Viewed by 2347

Abstract

The oxidation resistance under LOCA conditions of bilayer Cr/Mo coating deposited on Zr-1Nb zirconium alloy was investigated in this paper. The bilayer Cr (8 μm)/Mo (3 μm) coatings were deposited by magnetron sputtering. Then, oxidation resistance under high-temperature oxidation at 1200–1400 °C in a water steam was studied. The use of a Mo sublayer resulted in limiting Cr-Zr interdiffusion under high-temperature oxidation. It was shown that the Mo barrier sublayer (~3 μm) can provide the protective behavior of the Cr/Mo-coated Zr at 1330 °C in a water steam for at least 720 s. The weight gain of the bilayer Cr/Mo samples was comparable with the monolayer Cr samples after oxidation at 1400 °C. In addition, the analysis of the Cr/Mo-coated Zr alloy oxidation behavior at 1400 °C was carried out. Full article

(This article belongs to the Special Issue Advanced Coatings for Accident Tolerant Fuel Claddings)

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10 pages, 2899 KiB

Open AccessEditor’s ChoiceArticle

Oxidation and Mechanical Behavior of Cr-Coated Laser Beam Welds Made from E110 Zirconium Alloy

by E. B. Kashkarov, K. S. Gusev, D. A. Ashikhmin, A. V. Abdulmenova and D. V. Sidelev

Coatings 2022, 12(11), 1623; https://doi.org/10.3390/coatings12111623 - 26 Oct 2022

Cited by 1 | Viewed by 1988

Abstract

This article describes the oxidation resistance of laser beam welds made from E110 zirconium alloy with a chromium coating obtained using multi-cathode magnetron sputtering. Oxidation tests of the welded Zr alloy without and with Cr coating were performed in an air atmosphere at 1100 °C for 2–90 min. Then, analysis of their cross-section microstructure in different regions (weld, heat-affected, and bulk zones) was done using optical microscopy. Hardness measurements and three-point bending tests demonstrated the hardening of the Cr-coated welded Zr alloy after the oxidation that is discussed in the article. Brittle fracture behavior was observed for uncoated Zr weld even after a short period of high-temperature oxidation. Full article

(This article belongs to the Special Issue Advanced Coatings for Accident Tolerant Fuel Claddings)

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13 pages, 31471 KiB

Open AccessArticle

Magnetron Deposition of Cr Coatings with RF-ICP Assistance

by Dmitrii V. Sidelev, Vladislav A. Grudinin, Konstantin A. Zinkovskii, Kamila Alkenova and Galina A. Bleykher

Coatings 2022, 12(10), 1587; https://doi.org/10.3390/coatings12101587 - 20 Oct 2022

Cited by 2 | Viewed by 1655

Abstract

The article describes a comparative analysis of chromium coatings deposited by magnetron sputtering with and without ion assistance induced by a radiofrequency inductively coupled plasma (RF-ICP) source. Four series of 2 µm-thick Cr coatings were prepared, and then their cross-sectional microstructure, crystal structure and corrosion resistance were investigated by scanning and transmission electron microscopy, X-ray diffraction and a potentiodynamic polarization method. RF-ICP assistance led to significant enhancement (almost twofold) of ion current density in a substrate. The role of RF-ICP assistance in coating properties for planetary-rotated substrates was defined in terms of ion-to-atom ratio in particle flux entering a substrate. Calculations of particle and ion flux densities revealed an increase in ion-to-atom ratio from 0.18 to 1.43 and 0.11 to 0.84 in substrate positions distant from the magnetron sputtering systems depending on their design. RF-ICP assistance is beneficial for depositing dense Cr coatings with increased corrosion resistance in a 3.5 wt.% NaCl solution. The corrosion rate of AISI 321 steel can be decreased from 6.2 × 10⁻⁶ to 4.0 × 10⁻⁸ mm/year by deposition of the dense Cr coating. Full article

(This article belongs to the Special Issue Advanced Coatings for Accident Tolerant Fuel Claddings)

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24 pages, 13980 KiB

Open AccessArticle

Multi-Elemental Coatings on Zirconium Alloy for Corrosion Resistance Improvement

by Bożena Sartowska, Wojciech Starosta, Lech Waliś, Jerzy Smolik and Ewa Pańczyk

Coatings 2022, 12(8), 1112; https://doi.org/10.3390/coatings12081112 - 4 Aug 2022

Cited by 4 | Viewed by 2523

Abstract

Zirconium alloys are commonly used as a cladding material for fuel elements in nuclear reactors. This application is connected with zirconium alloy’s good resistance to water corrosion and radiation resistance under normal working conditions. In the case of severe accident conditions, the possibly very fast oxidation of zirconium alloys in steam or/and air atmosphere may result in the intense generation of hydrogen and explosion of the hydrogen oxide mixture. The development of a solution to minimize the aforementioned risk is of interest. One of the actual concepts is to improve the oxidation resistance of Zr alloy cladding with protective coatings. This study aimed to develop, form, and investigate new coatings for zirconium alloy Zry-2. Multi-elemental Physical Vapour Deposition (PVD) coatings with Cr, Si, and Zr were considered for Institute of Nuclear Chemistry and Technology) INCT as corrosion protective coatings for nuclear fuel claddings. Heat treatment at 850–1100 °C/argon, air oxidation processes at 700 °C/1–5 h, and a long-term corrosion test in standard conditions for Pressure Water Reactor (PWR) reactors (360 °C/195 bar/water simulating the water used in PWR) were carried out. Initial, modified, and oxidized materials were characterized with Scanning Electron Microscopy (SEM) (morphology observations), Energy Dispersive Spectroscopy (EDS) (elemental composition determination), and X-ray Diffraction (XRD) (phase composition analysis). Slower oxidation processes and a smaller oxidation rate, in the case of modified material investigations, were observed, as compared with the unmodified material. The obtained results displayed a protective character against the oxidation of formed layers in the defined range of parameters in the process. Full article

(This article belongs to the Special Issue Advanced Coatings for Accident Tolerant Fuel Claddings)

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16 pages, 12304 KiB

Open AccessArticle

The Effect of Annealing Temperature on the Microstructure and Properties of Cr–C–Al Coatings on Zircaloy-4 for Accident-Tolerant Fuel (ATF) Applications

by Chongchong Tang, Martin Steinbrück, Mirco Grosse, Sven Ulrich and Michael Stüber

Coatings 2022, 12(2), 167; https://doi.org/10.3390/coatings12020167 - 28 Jan 2022

Cited by 5 | Viewed by 2913

Abstract

Elemental Cr/C/Al multilayers (stoichiometric ratio: 2:1:1) with and without a Cr overlayer have been synthesized on Zircaloy-4 substrates by magnetron sputtering. The effects of annealing temperatures (400 and 550 °C) on phase/microstructure formation, mechanical properties, and oxidation/corrosion performance have been comparatively studied. Annealing of the multilayers at 400 °C led to the formation of nanocrystalline composite consisting of intermetallic and binary carbide phases. Single-phase Cr₂AlC was obtained after 550 °C annealing, but with microcracking of the coatings. Both annealed coatings displayed similar mechanical properties, high-temperature oxidation, and hydrothermal corrosion mechanisms. The composite coatings annealed at 400 °C significantly enhance the high-temperature oxidation resistance (α-Al₂O₃ scale growth) and hydrothermal corrosion (Cr₂O₃ passivation layer formation) of a Zircaloy-4 substrate without coating microcracking and delamination. Nanocomposite CrCAl-based coatings are promising candidates for coated ATF applications with acceptable processing temperatures and excellent oxidation/corrosion resistances for a zirconium alloy substrate. Full article

(This article belongs to the Special Issue Advanced Coatings for Accident Tolerant Fuel Claddings)

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18 pages, 5096 KiB

Open AccessArticle

Corrosion Behavior of Chromium Coated Zy-4 Cladding under CANDU Primary Circuit Conditions

by Diana Diniasi, Florentina Golgovici, Alexandru Anghel, Manuela Fulger, Carmen Cristina Surdu-Bob and Ioana Demetrescu

Coatings 2021, 11(11), 1417; https://doi.org/10.3390/coatings11111417 - 20 Nov 2021

Cited by 8 | Viewed by 2408

Abstract

The manuscript is focused on corrosion behavior of a Cr coating under CANada Deuterium Uranium(CANDU) primary circuit conditions. The Cr coating is obtained via the thermionic vacuum arc procedure on Zircaloy -4 cladding. The surface coating characterization was performed using metallographic analysis and scanning electron microscopy (SEM) with an energy dispersive spectra detector (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) investigations. The thickness of the Cr coating determined from SEM images is around 500 nm layers After the autoclaving period, the thickness of the samples increased in time slowly. The kinetic of oxidation established a logarithmic oxidation law. The corrosion tests for various autoclaving periods of time include electrochemical impedance spectroscopy (EIS) and potentiodynamic tests, permitting computing porosity and efficiency of protection. All surface investigations sustain electrochemical results and promote the Cr coating on Zircaloy-4 alloy autoclaved for 3024 h as the best corrosion resistance based on decrease in corrosion current density values simultaneously with the increase of the time spent in autoclave. A slow increase of Vickers micro hardness was observed as a function of the autoclaved period as well. The value reached for 3024 h being 219 Kgf/mm² compared with 210 Kgf/mm² value before autoclaving. Full article

(This article belongs to the Special Issue Advanced Coatings for Accident Tolerant Fuel Claddings)

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16 pages, 13573 KiB

Open AccessArticle

On the Use of Chromium Coating for Inner-Side Fuel Cladding Protection: Thickness Identification Based on Fission Fragments Implantation and Damage Profile

by Rofida Hamad Khlifa, Nicolay N. Nikitenkov and Viktor N. Kudiiarov

Coatings 2021, 11(6), 710; https://doi.org/10.3390/coatings11060710 - 12 Jun 2021

Cited by 6 | Viewed by 2578

Abstract

Inner-side coatings have been proposed as a complementary solution within the accident tolerant fuel (ATF) framework, to provide enhanced protection for the nuclear fuel cladding. Unlike external surface, the degradation of irradiated internal cladding surface has not been studied extensively. Fission fragments produced during the fission of nuclear fuel is one of the key players in this degradation. This study aimed to estimate the minimum thickness of the thin chromium film, required to protect the inner side of the nuclear fuel cladding. The approach used is based on a set of calculations, of Ion ranges and damage profiles, for a group fission fragments, using the TRIM code. The calculation results were verified by comparison with the experimental data associated with the phenomena of the inner cladding degradation of thermo-releasing elements. The recommended minimum thickness for such a film was found to be 9 microns. Calculations also showed that chromium metal has a greater stopping power compared to the zirconium-based alloy E110, which indicates an increased ability of chromium to withstand exposure to energetic fission fragments during reactor operation. Full article

(This article belongs to the Special Issue Advanced Coatings for Accident Tolerant Fuel Claddings)

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13 pages, 10078 KiB

Open AccessArticle

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

by Dmitrii Sidelev, Sergey Ruchkin and Egor Kashkarov

Coatings 2021, 11(5), 577; https://doi.org/10.3390/coatings11050577 - 15 May 2021

Cited by 5 | Viewed by 2363

Abstract

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. Full article

(This article belongs to the Special Issue Advanced Coatings for Accident Tolerant Fuel Claddings)

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15 pages, 26319 KiB

Open AccessArticle

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

by Dmitrii V. Sidelev, Maxim S. Syrtanov, Sergey E. Ruchkin, Alexey V. Pirozhkov and Egor B. Kashkarov

Coatings 2021, 11(2), 227; https://doi.org/10.3390/coatings11020227 - 13 Feb 2021

Cited by 25 | Viewed by 3249

Abstract

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. Full article

(This article belongs to the Special Issue Advanced Coatings for Accident Tolerant Fuel Claddings)

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Review

Jump to: Research

32 pages, 11036 KiB

Open AccessReview

Recent Advances in Protective Coatings for Accident Tolerant Zr-Based Fuel Claddings

by Egor Kashkarov, Bright Afornu, Dmitrii Sidelev, Maksim Krinitcyn, Veronica Gouws and Andrey Lider

Coatings 2021, 11(5), 557; https://doi.org/10.3390/coatings11050557 - 9 May 2021

Cited by 86 | Viewed by 7108

Abstract

Zirconium-based alloys have served the nuclear industry for several decades due to their acceptable properties for nuclear cores of light water reactors (LWRs). However, severe accidents in LWRs have directed research and development of accident tolerant fuel (ATF) concepts that aim to improve nuclear fuel safety during normal operation, operational transients and possible accident scenarios. This review introduces the latest results in the development of protective coatings for ATF claddings based on Zr alloys, involving their behavior under normal and accident conditions in LWRs. Great attention has been paid to the protection and oxidation mechanisms of coated claddings, as well as to the mutual interdiffusion between coatings and zirconium alloys. An overview of recent developments in barrier coatings is introduced, and possible barrier layers and structure designs for suppressing mutual diffusion are proposed. Full article

(This article belongs to the Special Issue Advanced Coatings for Accident Tolerant Fuel Claddings)

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