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Adhesion And Wear Resistance Of PVD Nitride-Based Coatings On Zircaloy Substrates

The Fukushima Daiichi Accident in 2011, which was the result of the Great East Japan Earthquake, tsunami, and prolonged station blackout, increased the focus on developing accident tolerant fuel cladding (ATFC), especially on the use of protective coatings. Coatings have been widely used in a variety of industries, including automotive, aerospace, and nuclear to improve corrosion resistance, enhance hardness and physical properties, and reduce wear. In an accident scenario, a coating may aid in reducing the oxidation kinetics and hydrogen evolution rates. The present study investigates the benefits that physical vapour deposited nitride-based coatings may have for ATFC.

Product Number: ED22-17266-SG
Author: C.Dever, H.M. Nordin, M.Mattucci
Publication Date: 2022
$20.00
$20.00
$20.00

If the core-cooling systems are impaired, temperatures within the fuel cladding may reach up to 1200°C, leading to hydrogen generation and thermal energy release. Research has focused on accident tolerant fuel cladding (ATFC) coatings to mitigate this. Physical vapour deposited (PVD) nitride-based coatings have been demonstrated to act as barrier materials for Zircaloys. PVD coatings can be used to improve performance related to: surface hardening, wear resistance, electrical insulation, and, most importantly for zirconium, in-reactor applications, as an added barrier for corrosion resistance, and for the reduction of hydrogen ingress. Five nitride-based coatings from two suppliers were deposited onto Zircaloy substrates through PVD. The adhesion, nanohardness, and wear resistance of a variety of PVD nitride-based coatings on Zircaloy substrates were tested using nanoindentation and scratch testing at room temperature and 300°C. For nanohardness tests, displacement rates were varied from 5 nm/s to 50 nm/s to assess if there was any effect on the measured hardness. It was found that the displacement rate did not affect the hardness values at room temperature. The AlCrN-coating was found to have the highest hardness of the tested nitride-based coatings, with the CrN-coating being the softest. A number of analytical techniques, including scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and transmission electron microscopy (TEM), were used to evaluate the effectiveness of the coatings.

If the core-cooling systems are impaired, temperatures within the fuel cladding may reach up to 1200°C, leading to hydrogen generation and thermal energy release. Research has focused on accident tolerant fuel cladding (ATFC) coatings to mitigate this. Physical vapour deposited (PVD) nitride-based coatings have been demonstrated to act as barrier materials for Zircaloys. PVD coatings can be used to improve performance related to: surface hardening, wear resistance, electrical insulation, and, most importantly for zirconium, in-reactor applications, as an added barrier for corrosion resistance, and for the reduction of hydrogen ingress. Five nitride-based coatings from two suppliers were deposited onto Zircaloy substrates through PVD. The adhesion, nanohardness, and wear resistance of a variety of PVD nitride-based coatings on Zircaloy substrates were tested using nanoindentation and scratch testing at room temperature and 300°C. For nanohardness tests, displacement rates were varied from 5 nm/s to 50 nm/s to assess if there was any effect on the measured hardness. It was found that the displacement rate did not affect the hardness values at room temperature. The AlCrN-coating was found to have the highest hardness of the tested nitride-based coatings, with the CrN-coating being the softest. A number of analytical techniques, including scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and transmission electron microscopy (TEM), were used to evaluate the effectiveness of the coatings.