Formation Reasons of Surface Corrosion White Spots of Extruded Wrought Aluminum Alloy Profiles for Architecture

A lot of corrosive white-spots and bubbling appeared on the surface of wrought aluminum alloy treated by PVDF coating of sliding doors of aluminium profile after the buildings were installed for a period of time. The methods of macro examination, chemical component analysis, metallographic inspection, electron microscopy analysis and coating property test and so on were applied to inspect the corrosive aluminum alloys. The corrosion mechanism of wrought aluminum alloy extruded profile was discussed. The results showed that the main components of white spots on the wrought aluminum alloy were corrosion products of chloride besides aluminum oxide. Due to plenty of chloride existing on the surface of wrought aluminum alloy, chloride ions cautiously corroded the wrought aluminum alloy and formed corrosion perforation. It caused corrosion failure of the wrought aluminum alloy extruded profile.