Investigation on dual corrosion performance of magnesium-rich primer for aluminum alloys under salt spray test (ASTM B117) and natural exposure

• DOI: 10.1016/j.corsci.2009.11.032
• Publication Date: 2009-11-28T09:20:01Z
• Authors: Shashi S. Pathak; Michael D. Blanton; Sharathkumar K. M...; James W. Rawlins
• Keywords: Atmostpheric corrosion; Chemistry; XRD; Paint coatings; SEM; Organic coatings; Physical Sciences and Mathematics; Magnesium; 02 engineering and technology; 0210 nano-technology

Abstract Magnesium-rich primers perform very well on outdoor exposure and actual test conditions, yet fail rapidly in accelerated corrosion testing (salt spray test – ASTM B117). To investigate the behavioral dichotomy, Mg-rich primers exposed to salt spray testing and natural weathering were characterized at periodic intervals. The results revealed the presence of a thin and porous magnesium hydroxide layer in primers exposed to salt spray, and in natural exposure, a thicker, protective magnesium carbonate layer was detected and characterized. Samples exposed to atmospheric carbon dioxide exhibit excellent corrosion resistance but salt spray conditions are not conducive to facilitate magnesium carbonate formation.