Evaluation of corrosion in crevices where materials with different surface coatings are combined

• Main Author: Siggelkow, Ida
• Format: Others
• Language: English
• Published: Uppsala universitet, Institutionen för kemi - Ångström 2011
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-173676

In modern-day automobile industries the predominant type of corrosion is crevicecorrosion located on door hem flanges and fasteners. Today these areas areprotected by anti-corrosive agents. The appliance of these anti-corrosive agents is acostly process and could be excluded if a more corrosion resistant surface coatingwere to be used. In this thesis work new surface coatings are tested in an attempt toreduce the use of anti-corrosion agents in the concealed spaces. The coatings usedwere two types of zinc-magnesium alloys and a thin organic coating. Tests wereperformed in an accelerated corrosion testing-chamber with three different types ofcrevice models. The analytical methods used were mainly image analysis, X-raydiffraction and Fourier transform infrared spectroscopy. The results show that thethin organic coating gives the best corrosion protection according to this testmethod. It was also discovered that the surfaces with pure zinc coating corrodes lesswhen in contact with a dissimilar material. Furthermore it was seen that the testmethod does not apply to all materials and environments.