Filiform corrosion is a form of corrosion that particularly affects aluminium and low grade steels that have been coated or painted. Exposure to water and oxygen enhances the production of corrosion foci that infiltrate the space between the metal and its coating. The corrosion expands slowly in fine outgrowths, like a caterpillar that has eaten into a leaf.
The filiform corrosion of coated aluminium presents an unresolved problem of great economic impact, producing significant levels of damage to cars, planes and maritime structures as well as in especially susceptible industrial environments. Filiform corrosion is particularly pernicious because it can affect a surface rapidly and irrevocably well within the normal guarantee period, resulting in huge repair costs for the producers of coated aluminium.
In an attempt at assessing the stability of coated elements, variously treated metal test sheets are subjected to different corrosive atmospheres and regimes before assessment of any hints of an improvement. The currently practised manual inspection of the resulting corrosion is extremely tedious and prone to error.

Automated Analysis
This is where the expertise of a company like Schäfter+Kirchhoff in Hamburg sheds light onto the scene. They have been developing CCD-line cameras with integrated brightfield illumination for years, especially for surbilden face analysis applications. Their innovative technology enables the rapid and reproducible acquisition of high contrast images for the automatic documentation of the filiform corrosion.
Their newly developed Filiform Scanner analyses standardized metal test panels with a resolution of 6 megapixels. Their software then characterises the detected structures and evaluates them against the relevant standards, producing accurate results reproducibly and rapidly.
The Filiform Scanner expands the already extensive range of surface inspection technologies for industrial and research applications from Schäfter+Kirchhoff, some used in extremely harsh environments. The Ice Scanner, for example, is designed for operation at -40°C and analyses the constitution of ice cores obtained from deep-drilling at the polar ice caps.