In the HCLL (He-cooled Lithium-lead) design of TBM’s (Test Blanket Modules) for a future fusion power
plant, Pb-15.7Li is used as liquid breeder which is in direct contact with the structure material, e.g.
EUROFER steel (European ferritic steel). Compatibility testing showed that high corrosion attack
appears and that the dissolved steel components form precipitates with a high risk of system
blockages. A reliable operation needs coatings as corrosion barriers.
An earlier developed Hot-Dip Aluminization (HDA) process has shown that Al-based scales can act as
anti-corrosion as well as tritium (T) permeation barriers. However, disadvantages of HDA-process
initiated the search for advanced coating technologies. Meanwhile two electro-chemically based
processes for deposition of Al scales were successfully developed. The first (ECA = Electro-Chemical
Al-deposition) is working with an organic electrolyte and the second one (ECX = Electro-Chemical Xmetal
deposition) is based on ionic liquids and is not restricted to only Al-deposition. Coatings in the
µm-range were deposited homogeneously with exact controllable thicknesses. Metallurgical
investigations and SEM/EDX-analyses showed the successful generation of protective scales and
compatibility testing demonstrated the barrier function in Pb-15.7Li.
Key words: Pb-Li corrosion, chemical compatibility, anti corrosion barriers, tritium permeation barriers,
Al coating development, electrochemical Al Voltammetrie