4. Electrochemical conversion coatings: anodizing

Following the first theories and observations on metal passivation in the 19th century, aluminum anodizing by electrolysis was exploited very early on in the field of electrical components by industrialist Eugène Ducretet to manufacture circuit breakers in 1875, and Charles Pollak to manufacture capacitors in 1897.

In the field of corrosion protection, the first industrial patent application was that of the Englishmen G. D. Bengough and J. M. Stuart in 1923, concerning the chromic acid anodizing of Duralumin-type alloys for aircraft construction between the two world wars