Metal Finishing Guide Book

2012-2013

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Step Alkaline soak cleaner Temperature Duration 180���200��F 3���5 minutes Ambient 30���60 seconds Ambient 1���2 minutes 155���160��F 3���15 minutes 130���140��F 6���8 minutes Rinse in demineralized water Chromic acid or phosphoric acid pickle Rinse in demineralized water Phosphoric acid���fluoride etch Rinse in demineralized water Fluoride-containing ���zincate��� Rinse in demineralized water Copper cyanide strike Rinse in demineralized water Electroless nickel plating bath to desired thickness Table 1: Common Procedure for Applying EN to a Magnesium Substrate Step Alkaline soak cleaner Temperature Duration 180���200��F 5���8 minutes Ambient 15���30 seconds Rinse in demineralized water Deoxidize in mild acid solution Rinse in demineralized water Table 2: Zincate-/stannate-free Pretreatment Process for EN Plating processed part for several days before going into the electroless nickel bath is possible. One simply needs to soak the part in demineralized water for about half an hour to reactivate the bonding surface before going into the electroless nickel bath. If you only want to paint the part, the surface is excellent for painting. ALUMINUM Every aluminum alloy will have certain unique cleaning problems associated with it and, as such, it is not possible to give an all-encompassing cleaning process for all aluminum alloys. It can be stated that plating on aluminum will in almost every instance require a zincate or stannate process after cleaning and deoxidization to maintain a receptive surface.6 285

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