Electroplating: It is the process of forming a uniform, dense, well-bonded metal or alloy deposit on the surface of the part by electrolysis. Compared with other metals, zinc is a relatively cheap and easy-to-plated metal. It is a low-value anti-corrosion coating. It is electrogalvanized by electro-galvanizing concept: it uses electrolysis to form a uniform, dense and well-bonded surface on the surface of the part. The process of depositing a layer of metal or alloy.
Compared with other metals, zinc is a relatively inexpensive and easily plateable metal. It is a low-value anti-corrosion coating that is widely used to protect steel parts, especially to prevent atmospheric corrosion, and is used for decoration. Plating techniques include slot plating (or hanging plating), barrel plating (for small parts), automatic plating and continuous plating (for wire and strip).
Electroplating zinc classification Currently, domestic classification by electroplating solution can be divided into four categories:
1. ** galvanized
Since (CN) is highly toxic, environmental protection imposes strict restrictions on the use of electroless zinc in electroplating, and it is constantly promoting the development of electroplating zinc plating system for reducing and replacing yttrium. ) Plating solution.
After electroplating with this process, the product quality is good, especially for color plating, and the color is kept good after passivation.
2. Zinc galvanizing
This process is derived from the galvanization of the material. At present, there are two major factions in China: a) the “DPE†series of Wuhan Material Protection Institute; and b) the “DE†series of the Broadcasting and Television Institute. Both are zincate galvanized as an alkaline additive with a pH of 12.5~13.
By adopting this process, the plating lattice structure is columnar and has good corrosion resistance, and is suitable for color galvanizing.
Note: After the product is out of the tank -> washing -> light (nitrate + hydrochloric acid) -> washing -> passivation -> washing -> washing -> hot drying -> drying -> aging treatment (80 ~ 90 ° C in the oven.
3. Chloride galvanizing
This process is widely used in the electroplating industry, accounting for up to 40%.
After passivation (blue) can be zinc-based chromium (comparable to chrome-plated), especially after the addition of water-soluble varnish, it is difficult for laymen to identify whether it is galvanized or chrome-plated.
This process is suitable for white passivation (blue, silver).
4. Sulfate zinc plating
This process is suitable for continuous plating (wire, strip, simple, large and large zero, parts), and low cost.
Electrogalvanizing process
1. Electroplating zinc process
Taking galvanized iron alloy as an example, the process flow is as follows:
Chemical degreasing→hot water washing→water washing→electric de-oiling→hot water washing→water washing→strong corrosion→water washing→electroplating zinc-iron alloy→water washing→water washing→lighting→passivation→water washing→drying.
2. Electroplating zinc plating solution preparation
Preparation of plating solution (taking lL as an example):
(1) Firstly add 1/3 volume of purified water in the plating tank;
(2) Dissolve sodium hydroxide with 1/3 of pure water (heating when dissolved, care must be taken);
(3) Adjust the zinc oxide into a paste with a small amount of water, then add more pure water and stir well. The stirred zinc oxide is slowly added to the dissolved sodium hydroxide solution, stirred while being added, and fully complexed and added to the plating tank;
(4) After the bath temperature drops below 30~C, add 85g of Baser and stir well;
(5) Dissolving 15 mL of BaseF in 15 g of BaseR, and then adding the mixture to the plating tank;
(6) Add 4 mL of H-O624, stir well; add water to the volume;
(7) Add brighteners ZF-105A, ZF-105B; stir well.
Black passivation process: water washing → light discharge → water washing → black passivation → water washing → post-treatment → drying.
3. Factors affecting electroplating
(1) Effect of zinc content
The zinc content is too high, the brightness range is narrow, and it is easy to obtain a thick plating layer, and the iron content in the plating layer is lowered; the zinc content is too low, the brightness range is wide, and it takes a long time to reach the required thickness, and the iron content in the plating layer is high.
(2) The effect of sodium hydroxide
When the sodium hydroxide content is too high, the high temperature operation is easy to burn; when the sodium hydroxide content is too low, the dispersibility is poor.
(3) The effect of iron content
The iron content is too high, the iron content in the coating is high, the passivation film is not bright; the iron content is too low, the iron content in the coating is low, the corrosion resistance is lowered, and the color is olive-colored.
(4) The effect of brightener
ZF-IOOA is too high, the coating is brittle; too low, no plating in the low current area, uneven passivation color; ZF-100B is too high, the coating is brittle; too low, the entire coating is not bright.
(5) The effect of temperature
The temperature is too high, the dispersing ability is lowered, the iron content in the coating is high, the corrosion resistance is lowered, the passivation film is not uniform in color, and the hair is smear; the temperature is too low, the high current density region is burnt, the plating layer is brittle, and the deposition speed is slow.
(6) Influence of cathode movement
Cathodic movement must be used. Moving too fast, the coating in the high current density region is rough; too slow, it may generate airflow, and there is no plating at all.
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Metal silicon, also known as Crystalline Silicon or Industrial Silicon, is mainly used as an additive to non-ferrous based alloys. Metal silicon is a product made of quartz and coke in an electric furnace. The content of silicon in the main component is about 98% (in recent years, 99.99% of Si is also contained in metal silicon), and the remaining impurities are iron and aluminum. , calcium, etc.
Silicon Metal,Metallic Silicon,Crystalline Silicon,Industrial Silicon
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