Effect of silica nano-particles on the performance of manganese-based conversion treatments

Permanganate-based conversion treatments incorporating silica nano-particles + nitrate ions or other inhibitive additives have been examined by corrosion and adhesion tests on samples coated with paint and by polarisation measurements on treated, but uncoated AA 3003 panels. Although electrochemical behaviour is not improved by addition of the silica nano-particles, in many cases they substantially improve the performance of PVDF-coated samples in adhesion and accelerated corrosion tests.