What is the electroplating process and operation process of industrial aluminum?

by:Zeyi     2021-10-05
Electroplating refers to the use of electrolysis principles to form a dense and uniform metal protective layer on the metal surface. The purpose is to improve the corrosion resistance, strength and wear resistance of the metal surface to enhance its mechanical properties and decorative effects. The following is a practical example to illustrate the specific operation method of the industrial aluminum electroplating process. Example: industrial aluminum polishing → polishing wax removal → hanging → chemical degreasing → strong acid whitening → pickling removal film → prepreg liquid → neutral nickel plating → plating hydrogen removal → bright treatment ① removal of polishing wax: Polished industrial aluminum profiles, especially those with more oily surface, should be cleaned with organic solvents. Surface oily stains or polishing wax can be removed, or normal temperature degreasing and wax removal agent can be used instead of organic solvents to obtain better effect. ②Chemical degreasing: Use 20g/L sodium hydroxide solution, 5ml/L accelerator, and immerse for 30-60s at a temperature of 30-50℃. Once the aluminum profile enters the sodium hydroxide solution, the surface will start It dissolves to remove the oxide film on the surface and at the same time removes the oil stains on the surface. At this time, there is a layer of black dust on the surface of the industrial aluminum, which can only be removed after strong acid. ③Strong acid whitening: that is, acid etching, using 70% concentration of HNO₃ and 30% concentration of HF to prepare a strong acid whitening solution, but the acid concentration should not be too high, otherwise it will cause a large amount of harmful gases to be generated. Operation under these conditions can reduce the escape of harmful gases, reduce the corrosion on the surface of industrial aluminum, increase the brightness of the surface of the aluminum, and improve the bonding force between the coating and the substrate, which is conducive to better electroplating. ④Pickling and film removal: 35% acid and 15% sulfuric acid are used to prepare pickling and film removal solution. ⑤Pre-dipping solution: also called zinc dipping, using 50-150g/L sodium oxyhydride, 5-15g/L hydrogen oxide, and 10-30ml/L thinner, impregnating at room temperature 5- 20s, it is more suitable for electroplating of large-area industrial aluminum profiles in large-scale production. It first dissolves the oxide film on the surface of the aluminum profile, and then generates a 0.1μm uniform zinc alloy layer through micro-etching and micro-battery to prevent the aluminum alloy surface from being oxidized again. The zinc-immersion layer has a very good bridge connection. Improving the bonding force of the coating has played a very important role. There are several points to pay attention to when dipping zinc. First: the hanger for dipping zinc should not contain copper, because the contact part between copper and industrial aluminum profile will have a displacement reaction; second: in order to reduce the generation of bubbles, the hanger must move up and down; Three: In order to prevent the occurrence of mottling, wash thoroughly after the first zinc immersion; Fourth: Do not leave in the air for a long time during zinc immersion. ⑥Neutral nickel plating: use 200g/L nickel sulfate, 15g/L sodium chloride, 220g/L sodium carbonate, and appropriate amount of additives, and dip dye for 5-8min at a temperature of 40-50℃ to obtain Bright opalescent nickel-plated layer, bright copper, double-layer nickel or bright nickel can also be plated on this nickel-plated layer, all of which can obtain very good bonding force. ⑦ Dehydrogenation of the coating: adopt the method of dry dehydrogenation, and dry for 1.5h at a temperature of 800-100℃. ⑧Bright treatment: Use 10% concentration of nitric acid solution to immerse the industrial aluminum profile material for 1-3s at room temperature, and then quickly take it out for cleaning, so as to avoid blackening after oxidation for too long, such as some copper, zinc, cadmium plating Need to carry out plating treatment (that is, the medium and high temperature hydrolysis salt sealing method mentioned in the previous section), you need to use 200g/L sodium dichromate and 10ml/L sulfuric acid solution, and immerse for 15s at room temperature for hydrolysis. Salt sealing treatment to complete the bright treatment of industrial aluminum profile. ————The article comes from the Internet. If there is any infringement, please contact to delete it.
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