Anodising the aluminium body of a pen

Written by Lorenz Marti, Rita Oberholzer and Walter Caprez

Contents	lab instruction for the electrolytic oxidation of the aluminium body of a pen
Suitable for	second or third year students
Prerequisites	basic lab experience, redox reactions, electrolysis, corrosion
Time	2 lessons

What's it about?

Given that aluminium is a reactive metal (more so than iron), one would expect it to naturally corrode more rapidly than it actually does. The reason it does not is that the initial formation of an oxide layer on the surface protects the base metal underneath. Aluminium oxide is a tough material but its formation in air usually results in an amorphous layer with little mechanical strength: a white powder that can easily be scraped off leading to further oxidation.
Anodising on the other hand, is a process which forms a particularly structured and dense oxide layer which resists abrasion and thus protects the underlying metal. This experiment therefore involves anodising the aluminium body of a pen.

Downloads

Anodising the aluminium body of a pen
	Handout	PDF [62 KB] · Word [2 MB]