Environmental management for baked enamel coating system onto aluminum alloy building materials

Part21. Discussion on etching process before chromium-free chemical conversion 1

Abstract

A chromium-free chemical conversion as a suface preparation in baking enamel coating system for environmental management that has been a research object has unstable quality. So, the etching process before the conversion stage has been noticed and its methods have been discussed. In this paper, powder coated spcimen including some kinds of etching process has been evaluated by a boiling water dipping and film adhesion after the dipping. It is judged that the etching process is neccesary besed on the initial film physical propeties and the film adhesion after the dipping. However, The difference of the etching method is not clear. It is considered that the combination of the chromium-free chemical conversion with the powder coating shows difference on the film quality due to their compatibility. The etching process effect on the difference has to be synthetically estimated with results of a film analysis, corrosion resistance in neutral salt spray test and weatherability in outdoor exposure test.