Rough surfaces have been widely considered as negative factors affecting cavitation erosion resistance. However, this study presented the opposite result. Here, 316L stainless steel substrates and the arc-sprayed 316L stainless steel coatings were subjected to a specific grinding process that introduced scratches on the surfaces. The surface hardness values of these ground specimens were measured to evaluate the influence of the grinding-induced strain hardening. The cavitation erosion performance of the specimens was evaluated. The results showed that rough surfaces with scratches could enhance the cavitation erosion resistance, particularly at the early stage of cavitation erosion. The scratches had a greater effect on the cavitation erosion resistance of the coatings than on the substrates. Moreover, rough surfaces with initial surface scratches could extend the incubation period of the 316L stainless steel substrates due to the inhibition of the plastic deformation. The SEM observation showed that the scratch structure of the coating surface inhibited the growth of cracks and the propagation of cavitation pits. This study could also serve as a reference for investigating the cavitation erosion behaviors of materials with a particular surface feature.

In this study, a nanocrystalline layer composed primarily of martensite phase was prepared on the surface of 304 stainless steel. Furthermore, the martensite phase content in the nanocrystalline layer was adjusted by heat treatment at 500 °C and 550 °C, respectively, and the cavitation erosion resistance of the nanocrystalline layer before and after heat treatment was investigated. The results showed that the nanocrystalline layer before and after heat treatment exhibited excellent erosion resistance, with cumulative mass loss of approximately 1/7, 1/5, and 1/3 that of the traditional 304 stainless steel, respectively. The nanocrystalline layer could significantly inhibit the growth of cavitation pits due to the high density of grain boundaries. However, due to the decrease in hardness of the nanocrystalline layer after heat treatment, the propagation speed of cavitation cracks was accelerated, and the cavitation erosion performance of the nanocrystalline layer showed a downward trend.

The 2011 Fukushima accident highlighted the vulnerability of traditional Zr alloy fuel cladding under loss-of-coolant accident (LOCA) conditions, prompting the development of accident-tolerant fuel (ATF) systems. A promising near-term solution involves depositing protective coatings on existing Zr alloy cladding. Among various deposition techniques, cold spray technology has emerged as one of the leading methods due to its solid-state, low-temperature process, which minimises thermal degradation and allows for the deposition of a wide range of high-performance materials. This review provides a comprehensive examination of recent advances in cold-sprayed coatings for ATF cladding, beginning with an overview of the fundamentals of cold spray technology and its specific advantages for nuclear applications. The core of the review critically analyses three primary coating systems: Cr, FeCrAl alloys, and MAX phase composites, with a particular focus on Cr coatings, as they have been more extensively studied compared to the other two material systems. Key coating properties, including microstructure of the coating-substrate interface, mechanical properties, thermal conductivity, oxidation resistance, irradiation tolerance, and performance under normal operation and simulated LOCA conditions, are discussed in detail, with particular emphasis on the potential of cold-sprayed Cr coatings to enhance Zr alloy cladding. Cr coatings demonstrate significant improvements in oxidation resistance and irradiation stability, but also face challenges such as high-temperature interfacial reactions. To address these issues, promising solutions, such as diffusion-barrier bilayer systems, are being explored. Additionally, the review discusses FeCrAl and MAX phase composite coatings, highlighting their promising long-term performance under extreme conditions. The review concludes with recommendations for further research to optimise cold spray processes and ensure the robustness of coatings in operational reactor environments.