Abstract
The protective film formed in a defect by leaching of lithium oxalate from model organic coatings during neutral salt spray exposure has been investigated. A scribed area of about 1mm width was introduced on the coated AA2024-T3 aluminium alloy. The scribed area was examined before and after exposure in neutral salt spray environment for 4, 8, 24 and 168 h by scanning and transmission electron microscopies. Itwas found that the lithiumoxalatewas able to leach fromthe organic coating during neutral salt spray exposure and it promoted the formation of a film that provided effective corrosion protection to the alloy. The typical film morphology consists of three different layers, including a relatively compact layer near the alloy substrate, a porous middle layer and a columnar outer layer. Variation of the filmmorphology was also observed at different locations of the scribed alloy surface, which may be related to the difference of local concentration of lithium species. Electron energy loss spectroscopy detected
lithium, aluminium and oxygen in the film. Although the film showed the varied morphologies in different regions of the scribed
area, the alloy substrate was protected from corrosion when the film was formed.
lithium, aluminium and oxygen in the film. Although the film showed the varied morphologies in different regions of the scribed
area, the alloy substrate was protected from corrosion when the film was formed.
Original language | English |
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Pages (from-to) | 798–803 |
Journal | Surface and Interface Analysis |
Volume | 48 |
Issue number | 8 |
Early online date | 7 Mar 2016 |
DOIs | |
Publication status | Published - 6 Jul 2016 |