Investigation into composition and deposition of artificially produced marine aerosols on austenitic stainless steels

Abstract

This study focused on the effect of organic species on the occurrence of atmospheric-induced stress corrosion cracking (AISCC) in intermediate level waste (ILW) container materials under ‘wetted’ deposits of artificial sea-water (SW). Artificial SW solutions enriched with one of two bio-exudates – with organic carbon concentrations of between 92 and 451 μM – were employed to investigate changes in interfacial behaviour, associated with organic content, at the liquid–solid boundary on type 304L stainless steel (SS). These effects were determined in terms of contact angle and deposit diameter. On evaporation organically-enriched SW droplets deposited on 304L SS maintain a constant contact diameter on exposure to a relative humidity (RH) of 70±1%. By contrast deposits produced from artificial SW alone contract radially inwards. The bio-exudate that remained on the SS surface following the cleaning of deposits formed from organically enriched SW was visualised via cyanoacrylate fuming. This technique confirmed that bio-exudate adheres to 304L SS after removal of the inorganic components. The impact of organic enrichment on AISCC was investigated using droplets of test solutions on 304L U-bend specimens exposed to environmental conditions of 50·0±0·5°C and 30±1% RH.