Aluminium; Contact Corrosion - Ferrari 458 Italia Technical Documentation Manual

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1.11 Aluminium

Aluminium is obtained from bauxite and is the second most

commonly used metal today after steel. Magnesium and

silicon are the main alloying components used in high-quality

aluminium alloys. These alloys form the basis of the extruded

sections, die-cast node joints and panels in aluminium.

When aluminium is in contact with oxygen in the air, a passivating

oxide layer is formed on its surface that protects the material

underneath from environmental factors. Consequently, an

unpainted aluminium component will not normally corrode.

However, if aluminium comes into contact with another metal

that is higher in the electromotive series than itself and an

electrolyte is present at this point, contact corrosion will occur.

Electromotive series:

Chromium (Cr)

Aluminium (Al)

Since aluminium is usually lower in the electromotive series

and is the more common metal, it will decompose.