Electrogalvanizing: Also known as cold galvanizing in the industry, it is a process that uses electrolysis to form a uniform, dense, and well-bonded metal or alloy deposition layer on the surface of the workpiece. Compared with other metals, zinc is a relatively cheap and easy-to-plat metal. It is a low-value anti-corrosion electroplating layer and is widely used to protect steel parts, especially to prevent atmospheric corrosion, and for decoration. Plating technologies include tank plating (or rack plating), barrel plating (suitable for small parts), blue plating, automatic plating and continuous plating (suitable for wires and strips).
Electrogalvanizing classification
●Currently, domestic electroplating solutions can be divided into four categories:
●1. Cyanide zinc plating Since (CN) is highly toxic, environmental protection has put forward strict restrictions on the use of cyanide in electro-galvanizing. The development of electro-zinc plating bath systems that reduce cyanide and replace cyanide is continuously promoted, requiring the use of low-carbon electro-galvanizing solutions. Cyanide (microcyanide) plating solution. After electroplating using this process, the product quality is good, especially color plating, and the color remains good after passivation.
●2. Zincate zinc plating This process evolved from cyanide zinc plating. At present, two major factions have formed in China, namely: a) the "DPE" series of the Wuhan Materials Protection Institute; b) the "DE" series of the Radio, Film and Television Institute. Both are zincate zinc plating with alkaline additives, with a pH value of 12.5~13. Using this process, the coating lattice structure is columnar, has good corrosion resistance, and is suitable for color galvanizing. Note: After the product comes out of the tank, go to the first step -> wash with water - -> get out the light (nitric acid + hydrochloric acid) -> wash with water - -> passivate - -> wash with water one -> wash with one> iron and dry one -> dry one -> aging treatment (80~90°C in the oven.
●3. Chloride zinc plating This process is widely used in the electroplating industry, accounting for up to 40%. After passivation (blue white), zinc can replace chromium (comparable to chrome plating). Especially after adding water-soluble varnish, it is difficult for laymen to distinguish whether it is zinc plating or chromium plating. This process is suitable for white passivation (blue white, silver white).
●4. Sulfate galvanizing This process is suitable for continuous plating (wires, strips, simple, thick and large parts and components), and the cost is low
Electro zinc plating process
1. Preparation of electroplating zinc plating solution Preparation of plating solution (taking IL as an example):
(1) First add 1/3 volume of pure water into the plating tank;
(2) Dissolve sodium hydroxide with 1/3 of pure water (it will generate heat when dissolved, so be careful);
(3) Use a small amount of water to make zinc oxide into a paste, then add more pure water and stir thoroughly. Slowly add the stirred zinc oxide to the dissolved sodium hydroxide solution, stir while adding, until it is fully complexed and then added to the plating tank;
(4) When the temperature of the plating solution drops below 30~C, add 85g of Baser and stir thoroughly;
(5) Dissolve 15mL BaseF in 15g BaseR, and then add the mixture into the plating tank;
(6) Add 4mL of H-0624, stir thoroughly; add water to the required volume;
(7) Add brightener ZF-105A and ZF-105B; stir thoroughly.
Black passivation process flow: water washing ≥ light extraction > water washing → black passivation → water washing → post-processing > drying.
