Page 125 - 摩擦学学报2025年第10期

1522 摩擦学学报（中英文） 第 45 卷

of the Zr-4 fuel tube, micro-oscillations induced by the high-speed flow of cooling water can cause wear between the
cladding tube and grids. This leads to wear failure of the Zr-4 alloy tube, which seriously threatens the safe operation of
nuclear stations. The application of protective coatings onto the surface of zirconium alloys serves to enhance their
resistance against wear, while without changing of the existing reactor structure. In this study, FeCrAl/CrN and FeCrAl
coatings were fabricated on the surface of Zr-4 alloy using dual-target co-sputtering technology. The effects of the CrN
interlayer on the microstructure, mechanical properties, and tribological behavior of FeCrAl coating in air and B-Li
water were investigated, and a comparative analysis with Zr-4 alloy was conducted. The results showed that the
application of FeCrAl/CrN and FeCrAl coatings significantly enhanced the hardness and wear resistance of Zr-4 alloy.
The introduction of the CrN interlayer increased the columnar grain size of the FeCrAl coating and caused a change in
the preferred growth direction of the coating from (110) to (211). The CrN interlayer improved the hardness and wear
resistance of the coating, it also led to a decrease in adhesion strength. The wear rates of FeCrAl/CrN coatings in air and
−6 −7
B-Li water were the lowest, about 3.2×10 mm³/(N·m) and 6.0×10 mm³/(N·m), respectively. The lubricating effect of
B-Li water effectively reduced the friction coefficient and wear rate of both FeCrAl/CrN and FeCrAl coatings. In air and
B-Li water, the primary wear mechanisms for Zr-4 are adhesive wear and oxidative wear, while the main wear
mechanisms for FeCrAl/CrN and FeCrAl coatings are abrasive wear and oxidative wear. These findings not only
provided a theoretical basis for understanding the microstructure and wear performance of FeCrAl coatings but also
offered important technical guidance for their practical application in the nuclear industry.
Key words: FeCrAl coating; CrN interlayer; tribological performance; microstructure; zirconium alloy

1 Introduction that wear resistance is a key contributor to the failure of
Zirconium alloy (such as Zr-4 alloy) has been nuclear fuel cladding materials. So, enhancing the anti-
wear performance of zirconium alloy proves to be an
extensively utilized as a material for nuclear fuel
cladding due to its favorable characteristics, which effective strategy for prolonging its service life and
includes low neutron absorption cross-section, improving the safety of pressurized water reactors.
exceptional corrosion resistance and oxidation Research has found that using modern surface
resistance, as well as high thermal conductivity [1-2] . engineering techniques to prepare protective coatings,
Serving as the primary safety barrier against nuclear such as CrSi, Cr, CrAl, FeCrAl, and CrN on the surface
leakage, it plays a crucial role in ensuring the safety of of zirconium alloy can greatly enhance their oxidation
the nuclear station. However, it works in an extremely resistance, and prolong their service life [10-14] . Among
aggressive work environment. For instance, in these coatings, FeCrAl coating demonstrates excellent
pressurized water reactors, the primary loop typically thermal conductivity, corrosion resistance, and high-
uses B-Li water, which is distilled water containing temperature oxidation resistance, thus presenting great
1 200 ppm (Parts Per Million) B and 2.2 ppm Li, as a potential for research on FeCrAl coatings. Terrani first
moderator and coolant, with the zirconium alloy utilized hot pressing to prepare FeCrAl coatings on the
cladding is exposed to corrosive conditions at high Zr-4 surface and investigated their oxidation behavior in
temperature and pressure, along with neutron high-temperature steam environments. The results
irradiation [3-5] . The zirconium alloy cladding is also indicated that the FeCrAl coating could effectively
[15]
subjected to the scouring of high-speed B-Li water flow, protect the Zr-4 substrate from oxidation at 1 300 ℃ .
[16]
resulting in wear between the cladding material and the Ndumia et al. researched the effect of heat-treated
[6-8]
support grid . This leads to wear failure and corrosion temperatures on the corrosion resistance of the
damage of the zirconium alloy cladding, which seriously FeCrAl/Al coating and discovered that the coating
threatens the safe operation of nuclear stations. treated at 300 ℃ exhibited the highest corrosion
Unfortunately the zirconium alloy was susceptible to resistance due to its protective oxide films and lower
[11]
wear due to its low hardness (~230 HV0.2) and poor porosity. Dabney et al studied the frictional properties
wear resistance. Statistics reveal that wear-related of FeCrAl coatings and found that they could enhance
failures accounted for over 70% of fuel rod failures in the wear resistance of Zr alloys, and the aluminum (Al)
[9]
pressurized water reactors . Consequently, it is evident content in the FeCrAl coating exerted a significant