Corrosion behavior of Cr coating on ferritic/martensitic steels in liquid lead-bismuth eutectic at 600 °C and 700 °C
Li Wang, Qing Liao, Jintao Zhang, Sijie Liu, Shuyun Gan, Renda Wang, Fangfang Ge, Liming Chen, Shuai Xu, Tomáš Polcar, N. Daghbouj, Bingsheng Li
Abstract
The surface coating technology, encompassing ceramics, refractory materials, metallic alloys containing Al or Si, and multicomponent composites, presents a viable approach to improve the corrosion resistance of ferritic/martensitic (F/M) steels with (9–12) wt.% Cr in liquid lead-bismuth eutectic (LBE) environment. Among these coating materials, chromium (Cr) coating emerges as a particularly noteworthy option. This study specifically focused on depositing a 3 μm thick Cr coating on on T91 and SIMP steels using magnetron sputtering. Subsequently, the corrosion behavior of the Cr coating was investigated in LBE at temperatures of 600 °C and 700 °C. The results revealed that, after 300 h at 600 °C, T91 and SIMP steels formed oxide scales with approximately 32.6 μm and 19.3 μm thicknesses, respectively. At 700 °C for 140 h, these oxide scales increased to about 82.4 μm and 73.1 μm for T91 and SIMP steels, respectively. However, the application of a Cr coating resulted in the formation of a dense layer of chromium oxide with a thickness of 4–5 μm. This layer effectively impeded oxygen diffusion and Fe migration leading to a significant reduction in the corrosion rate of the steel. Notably, the Cr coating maintained secure attachment to the steel even after exposure to high-temperature LBE corrosion. These findings underscore the capacity of coating to markedly enhance the corrosion resistance of T91 and SIMP steels in high-temperature LBE environments, providing robust protection against the detrimental effects of challenging conditions. Consequently, Cr coating emerges as a promising solution for future fission nuclear reactors.