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Wider filaments at the higher humidities. Filiform corrosion has been observed on aluminum and magnesium surfaces, although the humidity fact,or has not been. Download Citation on ResearchGate | Filiform Corrosion of Aluminum | Generally, filiform corrosion occurs on aluminum when it is coated with an organic. Filiform corrosion resistance of two series aluminum alloys was investigated in this work. Test panels were produced with full automotive paint.
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In Situ Studies of Filiform Corrosion of Iron
Therefore it has not been possible to detect and investigate the effect of such small amounts of NaCl that are now available with QCM. The gas flow through the chamber was laminar and approximately 1.
Resonance frequency shifts of the metal-coated quartz crystal sample are measured by the QCM. This change of frequency can be transformed to a mass change through filiform corrosion Sauerbrey equation. The iron films were mechanically polished by diamond pastes down to 0.
Under present exposure conditions iron exhibits a localized atmospheric corrosion behavior. For this reason it is of filiform corrosion importance to obtain in situ information not only of mass changes but also of surface morphology filiform corrosion.
The damage in this case is the result of several types of corrosion having occurred, developed to various stages and eventually coalescing. Corrosion damage was detected along the machined ridge on the upper surface of the strip and the shallow radius on the lower surface of the strip, at the rear edges of the upper and lower edge panels.
An example is shown in Fig.
At these locations the sealant and paint coating along the joint line failed and pits developed. This damage would have originated as a result of moisture and salt penetrating a crack filiform corrosion the sealant along the edge of the strip where the upper panel fits.
The underlying paint coating may have failed at that point or nearby allowing moisture to filiform corrosion to the metal substrate.
At the point of the defect or flaw in the paint coating, a pit would have developed. Filiform corrosion is clear from Fig. The spread in corrosion would have been the result of further pitting and intergranular attack, resulting filiform corrosion lifting of the paint coating known as underfilm corrosion.
The mechanism for corrosion allows water and oxygen to migrate. The dissolved oxygen has its highest concentration at the back of the head.
When the oxygen is reduced in the tail region, the metal ion dissolution and formation proceeds to the head. This type of corrosion has filiform corrosion tendency of taking place in conditions with a high level of humidity.
Nitrates, sulfates, carbonates and condensates that contain halides have been associated with filiform corrosion.
In places where the corrosion has taken place, there is a thread-like filament filiform corrosion that forms under the coating.