Corrosion of pure Cr and W in molten FLiNaK with hydrogen fluoride solution

Corrosion of pure Cr and pure W in molten FLiNaK at 773 K was investigated to deeply understand the effect of the alloying elements on the corrosion mechanisms of reduced activation ferritic/martensitic (RAFM) steels. The molten salt blanket environment was simulated by hydrogen fluoride gas bubbling. Electrochemical polarization and weight change measurements were conducted to estimate corrosion rates. The oxidation reaction rate of pure Cr was extremely high (instantly reached 2.9 x 10(4) mm/year). The corrosion rate of W was lower than that of the RAFM steel, JLF-1 steel, and pure Fe by one order of magnitude. W was nobler than Ni, which is known as a corrosion-resistant metal to the molten fluoride salts and hydrogen fluoride. The compatibility of W coating with the first wall structure of blankets was evaluated with the local tritium breeding ratio (TBR). When a Pb neutron multiplier was used, thin W coating almost did not affect the local TBR.

Automated summary

The study showed that the corrosion rates of pure Cr and pure W in molten FLiNaK differ, with W showing better corrosion resistance compared to RAFM steel. Additionally, the oxidation reaction rate of W was lower than that of Cr, demonstrating better corrosion resistance.