Filiform corrosion is a type of localized corrosion which affects painted metals (usually steel, aluminium and magnesium). Filiform corrosion often occurs in marine environments and it produces protective coating damage and thread-like metal base attack.
I am looking for a concrete answer to this question? answer this question with suitable references if possible.
One possible explanation can be attributed to the layer thickness distribution, which is influenced by the geometry of the workpiece and material transitions, for example. The figure shows an image of the coating thickness distribution of a wet paint on a workpiece with the coatmaster Atline 3D measuring system. The coating thickness is higher at the edges and reduced at the edges and in grooves. The barrier effect of the coating against reaction agents is at its lowest in areas with reduced coating thickness and the presence of filiform corrosion is at its greatest.
Thank you Niles,
can you explain the chemistry behind it? If possible, share some research that supports your answer.
Dear Pankaj
diffusion into the coating is described by Fick's law. Je dünner die Beschichtung ist, desto grösser ist die Konzentration am Übergang zwischen Beschichtung und dem Substrat. For further reading, please check also: https://en.wikipedia.org/wiki/Fick%27s_laws_of_diffusion
PS: I just uploaded a presentation on corrosion protection and non-contact coating thickness measurement for critical applications in industry and infrastructure that might be relevant to you.
Thread-like corrosion is a type of corrosion developing on the basis of concentration cells and precisely variable oxygenation. The appearance of damage or natural damage on the surface of the coating causes the formation of a well-oxygenated place (cathode) under the coating, there is an anode zone and the cell can develop. The problem obviously concerns thin coatings through which oxygen diffusion is possible.
stefan krakowiak
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