Electroplating is the process of plating a thin layer of other metals or alloys on the surface of certain metals using the principle of electrolysis. It is a process that uses electrolysis to make a metal film on the surface of a metal or other material to prevent it. Metal oxidation (such as rust), improve the wear resistance, electrical conductivity, light reflectivity, corrosion resistance (the coating metal is mostly corrosion-resistant metal) and improve the appearance and so on.
Electroplating requires a low-voltage, high-current power supply to the plating tank, and an electrolytic device composed of a plating solution, a part to be plated (cathode), and an anode. The electroplating process is a process in which metal ions in a plating solution are reduced to metal atoms by an electrode reaction under the action of an external electric field, and metal deposition is performed on a cathode.
02 Applicable materials
The coatings are mostly single metals or alloys, such as titanium palladium, zinc, cadmium, gold or brass, bronze, etc .; there are also diffusion layers, such as nickel-silicon carbide, nickel-fluorinated graphite, etc .; and coatings, such as steel Copper-nickel-chromium layer, silver-indium layer on steel, etc. In addition to iron-based cast iron, steel, and stainless steel, electroplated substrate materials also include non-ferrous metals, or ABS plastic, polypropylene, polysulfone, and phenolic plastics. However, plastics must undergo special activation and sensitization treatments before plating.
03 Different plating effects
1) Copper plating: used for priming to improve the adhesion and corrosion resistance of the plating layer. (Copper is easily oxidized. After oxidation, patina is no longer conductive, so copper-plated products must be protected by copper).
2) Nickel plating: Nickel plating has a wide range of applications and can be used as a protective decorative coating. On the surface of steel, zinc die castings, aluminum alloys and copper alloys, it protects the base material from corrosion or bright decoration; it is also often used as The middle plating layer of other plating layers, and then plating it with a thin layer of chromium or a layer of imitation gold, has better corrosion resistance and more beautiful appearance.
3) Gold plating: Improve the conductive contact resistance and signal transmission (gold is the most stable and the most expensive), and it is also a very common decoration process.
4) Palladium-nickel plating: improve the conductive contact resistance, improve signal transmission, and have higher wear resistance than gold.
5) Tin-lead plating: to improve the soldering ability and be quickly replaced by other substitutes (because most of the lead content is now changed to bright tin and matte tin).
6) Silver plating: Improve the conductive contact resistance and signal transmission. (Silver has the best performance, is easy to oxidize, and conducts electricity after oxidation)
Electroplating colors are classified according to their preciousness 1) precious metal plating: such as platinum, gold, palladium, and silver; 2) general metal plating: such as imitation platinum, black gun, nickel-free tin-cobalt, ancient bronze, ancient copper, ancient silver, ancient Tin etc. According to the complexity of the process, 1) general plating: platinum, gold, palladium, silver, imitation platinum, black gun, nickel-free tin-cobalt, pearl nickel, black plating; 2) special plating: antique plating (including oiled patina) , Antique color, parabolic antique color), two-color, sandblasted plating, brushed plating and so on. 01 Platinum
Belongs to expensive rare metals. The color is silvery white. It has stable properties, good abrasion resistance, high hardness, and long color retention period. It is one of the best plating surface colors. The thickness is above 0.03 micrometers. Generally, palladium is used as the bottom layer for good synergy. It can be sealed for more than 5 years.
02 imitation platinum
The electroplated metal is copper-tin alloy (Cu / Zn), which is also called white copper tin. The color is very close to that of platinum, a little yellow compared to platinum. The material is soft and lively, and the surface coating is easy to discolor. If it is closed, it can be placed for half a year.
Gold (Au) is a precious metal. Common decorative coatings. Different composition ratios, different colors: 24K, 18K, 14K. And in this order from yellow to blue, there will be some differences in color between different thicknesses. Stable in nature, the hardness is generally 1 / 4-1 / 6 of platinum. Its abrasion resistance is average. Therefore, its color retention period is average. Rose gold, made of gold-copper alloy, according to the ratio, the color is between golden yellow and red. Compared with other gold, it is more lively, the color control is difficult, and there are often color differences. The color retention period is not as good as other golden colors, and it is easy to change color.
Silver (Ag) is a white metal, which is very lively. Silver encounters sulfides and chlorides in the air and easily discolors. Silver plating is generally protected by electrolytic protection and electrophoresis to ensure the color life. Among them, the life of electrophoretic protection is longer than that of electrolysis, but it is a bit yellowish, and the glossy products will have some small pinholes, and the cost will increase. Electrophoresis is formed at 150 ° C. Products protected by electrophoresis are not easy to be reworked and are often discarded. After silver electrophoresis, it can be stored for more than 1 year without changing color.
05 Black Gun
Metal material nickel / zinc alloy (Ni / Zn), also known as gun black or black nickel. The plating color is black and slightly gray. The surface stability is good, but it is easy to be colored at a low position. This plating color itself contains nickel and cannot be nickel-free. The plating is not easy to rework and reform.
Nickel (Ni) is off-white and is a metal with excellent compactness and hardness. Generally used as a plating sealing layer to improve the plating life. It has good purification ability in the atmosphere and can resist atmospheric corrosion. Nickel is relatively hard and brittle, so it is not suitable for deformation products due to electroplating. When the nickel-plated product is deformed, the plating layer may peel. Nickel may cause skin irritation in some people.
07 Nickel-free tin-cobalt plating
The material is tin-cobalt alloy (Sn / Co). The color is black, close to the black gun (slightly grayer than the black gun), and it is a nickel-free black coating. The surface is relatively stable, and the plating is easy to make color. The plating is not easy to rework and reform.
08 pearl nickel
Its material is nickel, also called sand nickel. Generally used as a pre-plated base layer for the haze process. The color is gray, non-glossy mirror, and has a soft misty appearance, like the feeling of satin. The degree of atomization is unstable. In the absence of special protection, due to the influence of sand-forming materials, discoloration may occur under skin contact.
09 fog color
It is based on pearl nickel to increase the surface color. It has a fogging effect and is matte. Its plating method is pre-plated pearl nickel. Due to the difficulty in controlling the effect of pearl nickel atomization, the surface color is inconsistent and easy to have color difference. This plating color cannot be nickel-free electroplating and post-plating inclusions. This plating is easy to be oxidized. Pay special attention to protection.
10 brush line plating
After copper plating, brush the lines on the copper, and then add the surface color. There is a sense of line. The appearance color is basically the same as the general plating color, except that there are lines on the surface. Brushed wire cannot be nickel-free, because its life is not guaranteed because of nickel-free plating.
Sand blasting is also one of the plating haze methods. It is electroplated after sandblasting on copper plating. The matte surface is sandy, and the same fog color is more obvious than the sandy effect. Like brush plating, nickel-free plating cannot be done.