[China Aluminum Industry] aluminum and aluminum alloy plating is more difficult, because aluminum has a strong affinity for oxygen, the surface is easily oxidized; aluminum is amphoteric metal acid, alkali is not stable; aluminum potential is very negative, in the plating solution Easily etched and replaced with the metal being plated; Aluminum's expansion coefficient is larger than most metals, so the coating is easy to air bubbles, fall off, affecting the binding force.
The key to the electroplating of aluminum and aluminum alloys is the special pre-plating treatment that removes the natural oxide film and prevents its re-formation, as well as preventing the displacement reaction when the aluminum parts are immersed in the electrolyte. As a naval overhauled aircraft factory, aluminum and aluminum alloy plating are often encountered in the repair process. Through the experiment, the better process conditions were explored. The surface of the aluminum alloy plating blessing parts not only has a good gloss, but also has good bonding and corrosion resistance and meets the requirements for navigation marks. This article describes the old-fashioned repair of aluminum alloy plating process Fu 1 process oil degreasing) removal of the old coating → two cleaning → alkaline etching → two cleaning → to gray descaling (light) two cleaning → a sink zinc → Two-way cleaning → zinc removal → two cleaning → secondary zinc sink → sulfuric acid neutralization, activation → cleaning → electroless nickel plating → two cleaning → activation → rhodium plating → two cleaning → passivation → two cleaning → Blow dry → ageing → inspection database.
2 Main process description 2.1 Composition of degreasing solution and process conditions Sodium hydroxide 40-609/L70-90c1-Zmin
Heavy oil is first cleaned with organic solvents.
2.2 Withdrawal of the old coating Removal of the old coating is one of the key processes for the tinning of aluminum alloys.
2.2.1 Retire the composition and operating conditions of the old fortune layer solution.
2.2.2 Retirement of the old zinc layer solution composition and operating conditions Sulfuric acid 10 - 150 stay L at room temperature, retired so far.
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