Method for silvering aluminum and aluminum alloy

An aluminum alloy and timely technology, applied in the direction of liquid chemical plating, superimposed layer plating, metal material coating process, etc., can solve problems such as corrosion of parts, affecting the bonding strength of the plating layer and the base metal, and difficulty in electroplating

Inactive Publication Date: 2014-12-24
ZHENJIANG JIANGCHENG METAL PROD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Seriously affect the bonding strength between the coating and the base metal
[0006] (3) Aluminum is an amphoteri

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment Construction

[0013] The present invention will be further described below by specific examples.

[0014] 1 Chemical dip galvanizing and its pretreatment:

[0015] The main processes of chemical galvanizing are:

[0016] Degreasing is usually scrubbed with gasoline or weak lye containing surfactants.

[0017] Removal of oxide scale Remove dirt and oxide film remaining on the surface of parts, including lye cleaning and light emitting

[0018] Alkaline cleaning specification

[0019] NaOH 50 ~100g / L

[0020] Temperature 60~80C

[0021] Time 0.5 ~10.min

[0022] For aluminum parts with low surface roughness and high precision, the oxide film should be removed in weak alkali solution without NaOH. work

[0023] The specification is:

[0024] Na2CO3 20 ~30g / L

[0025] Na3PO4 50 ~70g / L

[0026] Temperature 70~80C

[0027] Time 1 ~2min

[0028] There are gray residues on the surface of the parts where the oxide film has been removed, and should be illuminated ...

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PUM

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Abstract

The invention provides a method for silvering aluminum and aluminum alloy, and belongs to the technical field of metal plating. The method for silvering aluminum and aluminum alloy is achieved by the following technical scheme: (1) carrying out chemical zinc immersion on an aluminum part in a zinc dipping solution, removing surface oxides of the aluminum part, and simultaneously replacing a layer of thin and dense zinc coating; (2) timely transferring the aluminum part after zinc immersion into a cyanide copper plating process, wherein the cuprous cyanide in a cyanide plating solution is high in content, and a work-piece is connected with a cathode of a power supply, carrying out flash plating for 1-2 minutes by using current which is 3-5 times greater than normal current, and then plating for 40-60 minutes at normal current; and (3) silvering after copper plating, electrifying and putting in a slot, impacting for 1-2 minutes by using current of 0.6-1.0A/dm<2>, and reducing the current to 0.3-0.4A/dm<2>. The coating obtained by the method disclosed by the invention is bright and silver in surface, and has fine crystal and uniform appearance.

Description

[0001] technical field [0002] The invention belongs to the technical field of metal electroplating, and in particular relates to a silver plating method for aluminum and aluminum alloys. Background technique [0003] Silver plating of aluminum and aluminum alloys is much more difficult than silver plating of copper parts. The reasons are: [0004] (1) Aluminum and aluminum alloys have a strong affinity for oxygen. Once the surface oxide is removed, new inhomogeneous oxides will be formed rapidly, which will affect the bonding force between the coating and the base metal. [0005] (2) The standard potential of aluminum is relatively negative (-1.67V). When aluminum parts are immersed in electrolytes containing other metal ions, displacement reactions can occur, resulting in loose and rough coatings. Seriously affect the bonding strength between the coating and the base metal. [0006] (3) Aluminum is an amphoteric metal, which is easy to react with acid and alkali, which...

Claims

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Application Information

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IPC IPC(8): C23C28/02C23C18/31C25D5/10C25D3/40C25D3/46
Inventor 戴颖锋
Owner ZHENJIANG JIANGCHENG METAL PROD
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