Development of double-layered coated stainless steel plate against pitting damage in mercury target

Kawai, Masayoshi*; Futakawa, Masatoshi  ; Naoe, Takashi   ; Yamamura, Tsutomu*; Igarashi, Tadashi*

A serious problem encountered when a liquid-Hg target is used for MW-class pulsed spallation neutron source is pitting damage caused to vessel walls. This pitting damage is due to the impact of cavitation-bubble collapse immediately after intense proton beams are made incident on the target. Pitting damage is thought to be as important as or more important than radiation damage in determining the life time of the target. An effectiveness of an SS/Au-double-layer-coated SS plate in reducing pitting damage is investigated. An FEM analysis reveals that the Au layer absorbs the impact from the surface plate and significantly reduced the stress on the SS substrate. SS/Au/SS specimens are fabricated by using the diffusion bonding method, and the development of pitting damage is investigated by using the MIMTM. The specimens are then analyzed by EDX for determining the thickness of the diffusion layer and by laser microscopy for detecting micro-cracks and the extent of pitting damage.