Interaction of Chrome Coating with Cladding Made of EP823-Sh Steel in the Temperature Range 420–650°C

Chromium coatings can significantly improve the corrosion resistance of fuel rod cladding made from EP823-Sh steel in liquid lead environments at temperatures up to 650°C. To ensure the long-term effectiveness of the coating, it is crucial to prevent the diffusion interaction between the chromium layer and the underlying steel throughout the operational lifespan of the fuel rod. High-temperature tests on samples reveal a coating-steel interaction layer. At 420°C, with a holding time of 1000 h, the coating retains its adhesion to the steel, and no interaction is observed between the two materials. However, at 540°C and 650°C with a holding time of 1000 h, a diffusion layer with uneven thickness (ranging from 150 to 600 nm) forms at the coating-steel interface. This layer, which has a complex composition, effectively blocks further diffusion of elements from both the coating and the steel. The EP823-Sh steel contains approximately 1 wt % molybdenum and tungsten, which promote the coating-steel interaction. Overall, the results suggest that chromium coatings are a promising option for enhancing the corrosion resistance and longevity of fuel rod cladding made from EP823-Sh steel.