- Mar 20, 2018 -
There are many types of chrome plated processes, which can be classified as follows according to their use.
① Protective a decorative chromium plating shield a decorative chromium plating commonly known decorative chromium plating thin, bright beautiful, generally as the outermost layer of the multilayer plating, to achieve the protective purposes, on the zinc-based or steel substrates must be coated thick enough The middle layer is then plated with a thin layer of 0.25-0.5 μm chromium on the bright interlayer. Commonly used processes include Cu/Ni/Cr, Ni/Cu/Ni/Cr, and Cu-Sn/Cr. After the surface of the polished product is plated with decorative chrome, a silver-blue specular gloss can be obtained. Prolonged non-discoloration in the atmosphere. This kind of coating is widely used in the protection and decoration of parts and components such as automobiles, bicycles, sewing machines, watches, instruments, and daily-use hardware. The polished decorative chrome layer is highly reflective of light and can be used as a mirror. Plating micro-holes or micro-cracks of chromium on multi-layer nickel is an important way to reduce the total thickness of the coating and obtain a high corrosion resistance protection system, and is also the development direction of modern electroplating process.
② Hard chrome plating (wear-resistant chrome) The coating has extremely high hardness and wear resistance, which can prolong the service life of the workpiece, such as cutting and drawing tools, pressing dies and molds for various materials, bearings, shafts, gauges, gears, etc. It can also be used to repair dimensional tolerances of worn parts. The thickness of hard chrome plating is generally 5 ~ 50μm, and can also be determined according to needs, some up to 200 ~ 800μm. Hard chrome plating of steel parts does not require intermediate plating. For special requirements on corrosion resistance, different intermediate platings may be used.
③ Plating white chromium plating layer is milky white, low gloss, good toughness, low porosity, soft color, hardness than hard chrome and decorative chrome, but corrosion resistance is high, it is often used in measuring instruments and instrument panel. In order to increase its hardness, a layer of hard chrome can be plated on the surface of the milky white plating layer, which is a so-called double-layer chrome plating layer. It has the characteristics of a milky white chrome plating layer and a hard chrome plating layer. It is used for plating and requires both wear resistance and corrosion resistance.
④ Pore-plated chromium (porous chromium) is characterized by the fine cracking of the chromium layer itself. After the hard chromium plating, mechanical, chemical or electrochemical loose hole treatment is performed to further deepen and widen the crack network. The surface of the chromium layer is covered with a wide groove, not only has the characteristics of wear-resistant chromium, but also can effectively store the lubricating medium, prevent non-lubrication operation, improve the surface friction and wear resistance of the workpiece. It is commonly used for the plating of sliding friction surfaces on heavy pressure, such as internal combustion engine cylinder bore, piston rings and so on.
⑤ Black chrome plated Black chrome plated color black has a uniform gloss, good decorative, good extinction; high hardness (130 ~ 350HV), wear resistance at the same thickness is 2 to 3 times higher than bright nickel; its resistance Etching properties are the same as ordinary chrome plating, depending on the thickness of the intermediate layer. Good heat resistance, no discoloration below 300°C. The black chromium layer can be directly plated on the surface of iron, copper, nickel and stainless steel. In order to improve the corrosion resistance and decorative effect, copper, nickel or copper-tin alloy can also be used as the bottom layer, and a black chromium plating layer is plated on the surface thereof. Black chrome plating is commonly used for the protection and decoration of parts and components of solar aviation instruments and optical instruments, solar absorption panels and daily necessities.