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Technology of non-cyanide silver coating

A process method, a cyanide-free silver plating technology, is applied in the field of electrochemical silver plating technology, which can solve the problems of not too ideal brightening effect, poor anti-discoloration ability of the coating, large internal stress of the coating, etc., and achieve strong anti-discoloration, Good wear resistance, uniform color effect

Inactive Publication Date: 2005-10-12
SHANGHAI UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Wherein additive research is more, in addition also has some patent documents to have done report aspect cyanide-free silver-plated brightener, as U.S. Patent USP5302278, USP4925491, Japanese Patent JP2000192279-A etc., but the coating anti-tarnish ability that USP5302278 obtains is relatively poor; USP4925491 because There are many types of polishing components and wetting agents required, which makes it difficult to maintain the plating solution; and JP2000192279-A is not very ideal for brightening due to its low selectivity to metal salts
In addition, although the U.S. patent USP4155817 has a low cyanide ion concentration, the current density is too small to be practical
Although the speed of depositing silver in USP4428804 is very fast, the internal stress of the coating is relatively large because the two acidic complexing agents do not match each other

Method used

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  • Technology of non-cyanide silver coating

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Embodiment 1

[0018] Embodiment one: see figure 1 , which is a simple schematic diagram of the silver plating device used in the pulse silver plating process of a main process in the process flow of the present invention, which represents a device for silver plating under the action of a magnetic field and a pulse current, where the plated parts are used as cathodes and anodes It is a high-purity 99.99% silver plate. Under the action of electrochemical principles, the plated parts are plated with silver.

[0019] In this embodiment, the flow and process of the entire silver plating process include the following steps: chemical degreasing → water washing → chemical deembroidery → water washing → bright nickel plating → water washing → activation treatment → water washing → silver immersion → water washing → Pulse silver plating→water washing→passivation treatment→drying→finished product.

[0020] The main processes and steps are described in detail as follows:

[0021] a. Chemical degreasi...

Embodiment 2

[0028] Embodiment 2: This embodiment is basically the same as the above-mentioned embodiment 1, the difference is that the main process is the pulse silver plating process, and the composition formula and operating process conditions of the silver plating solution are different. In this embodiment, the process formula of the pulse silver plating solution is: silver nitrate 55g / L, sodium thiosulfate 300g / L, potassium metabisulfite 100g / L, potassium sulfate 25g / L, boric acid 30g / L, brightener 5ml / L; the operating process conditions are: the stirring method is mechanical stirring, the pH value of the plating solution is 4.5, the temperature is 30°C, the silver plating time is 10 minutes, and the average pulse current density is 0.9A / dm 2 , pulse width 0.5ms, duty cycle 15%.

Embodiment 3

[0029] Embodiment 3: This embodiment is basically the same as the above-mentioned embodiment 1, the difference is that the main process is the pulse silver plating process, and the composition formula and operating process conditions of the silver plating solution are different. In this embodiment, the process formula of the pulse silver plating solution is: silver nitrate 60g / L, sodium thiosulfate 350g / L, potassium metabisulfite 110g / L, potassium sulfate 30g / L, boric acid 35g / L, brightener 5ml / L; the operating process conditions are: the stirring method is mechanical stirring, the pH value of the plating solution is 4.8, the temperature is 40°C, the silver plating time is 10 minutes, and the average pulse current density is 1.1A / dm 2 , pulse width 1ms, duty cycle 10%.

[0030] In each of the above-mentioned embodiments, the applied magnetic field mode is: the direction of the magnetic field applied in embodiment 1 is perpendicular to the direction of the electric field; the ...

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Abstract

A process of silver coating with no cyanogens at the action of magnetic field and impulse current. The main process is impulsive silver coating. Ingredients of the solution are as follow. AgNO3,50-60g / L; sodium thiosulfate, 250-350g / L; potassium, 90-110g / L; K2SO4,20-30g / L; boracic acid, 25-35g / L; brightener,5m / L. Stir at 20-40deg.C for 10min. pH of silvering solution is 4.2-4.8. Mean impulse current density is 0.5-1ms. Duty ratio is 5-15%. Orientation of magnetic field is parallel with that of impulse current. Square ratio of positive and negative pole is bigger than 2.

Description

technical field [0001] The invention relates to a cyanide-free silver plating process under the action of a magnetic field and a pulse current, belonging to the technical field of electrochemical silver plating. Background technique [0002] Silver plating was once mainly used for decorative purposes, but with the promotion and application of electroplating technology in electronic devices, semiconductors, and instruments, the amount of functional silver plating has soared. So far, cyanide silver plating is still the mainstream of industrial production in the silver plating industry at home and abroad. With the continuous improvement of environmental awareness, cyanide silver plating will be gradually eliminated. The research on cyanide-free silver plating has been carried out for more than ten years. Although some achievements have been made, the technology is still immature. Throughout the history of cyanide-free silver plating, people mainly carry out research work from...

Claims

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Application Information

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IPC IPC(8): C25D3/46C25D5/18
Inventor 成旦红苏永堂曹铁华张庆王建泳
Owner SHANGHAI UNIV
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