SURFACE TREATMENT METHOD FOR ALUMINUM-BASED SUBSTRATE

摘要

PROBLEM TO BE SOLVED: To provide a pretreatment method which imparts a chromium-free chemical conversion coating adhesiveness to a paint film and corrosion resistance equivalent to or better than those of a chromating conversion coating containing hexavalent chromium ions, when an aluminum-based substrate is subjected to the chromium-free chemical conversion treatment as an alternative method for the chromate conversion treatment. SOLUTION: A surface treatment method for the aluminum-based substrate comprises the steps of: subjecting the aluminum-based substrate to a treatment process including the chemical conversion treatment; and then painting it. The method also includes treating the aluminum-based substrate with a strongly alkaline aqueous solution or electrolyzed alkaline water before the step prior to the painting step including the chemical conversion treatment to enhance a cleanliness degree of the surface of the aluminum-based substrate. COPYRIGHT: (C)2007,JPO&INPIT