1993 Volume 42 Issue 5 Pages 297-304
The action of ultraviolet radiation on painted steel was examined using a xenon weather meter and a salt spray cabinet. The impedance, gloss, contact angle and adhesion of the paint film were decreased by ultraviolet radiation. The blistering area of the pait film, and the rusting area were increased. Paint film containing a pigment had roughened and porous surfaces. The roughened surface is easily wettable with the corrosive solution which then penetrates through the pores to the base metal, probably accelerating the corrosion of the steel. The alkyd resin clear paint film had slightly roughened surfaces and had no noticeable fine pores. A phosphate coating applied to the base metal under the paint film suppressed the corrosion accelerating effects of ultraviolet radiation of painted steels.