Electrochemical investigations were carried out to examine galvanic corrosi
on in preparation for the use of steering gear made from a magnesium, press
ure die-casting. The aim was to characterize various joining elements of th
e steering gear (e.g. hold-down devices, threaded bushings, plugs, screws)
with different types and qualities of protective coating with regard to the
risk of galvanic corrosion in magnesium alloy AZ91. In addition the change
in the polarization resistance was determined for one coating system after
contact with AZ91 and compared with data without contact.
The quality of the coatings is very important to prevent galvanic corrosion
. This was demonstrated using as an example, KTL coated systems of various
quality.
The evaluation of current density potential curves of the coatings only all
ows a gradation of the top coat qualities in relatively short time, but the
problems which can actually appear at contact to AZ91 aren't recognized.