There are many types of chrome plating processes, which can be categorized according to their use as follows.
Author: Anna
There are many types of chrome plating processes, which can be categorized according to their use as follows.
① Protective a decorative chrome plating: Protective a decorative chrome plating is commonly known as decorative chrome, with a thin, bright and beautiful coating, usually as the outermost layer of multi-layer plating. In order to achieve the purpose of protection, a sufficiently thick intermediate layer must be plated on zinc or steel substrates, and then a thin layer of chrome with a thickness of 0.25 to 0.5 μm is plated on the bright intermediate layer. Commonly used processes are Cu/Ni/Cr, Ni/Cu/Ni/Cr, Cu-Sn/Cr and so on. After the polished products surface plated with decorative chromium, you can get a silver-blue mirror luster. It does not change color for a long time in the atmosphere. This kind of plating is widely used for the protection and decoration of parts and components of automobile, bicycle, sewing machine, clock, instrument and meter, daily-use hardware and so on. The polished decorative chrome layer has high reflective ability to light and can be used as reflector. In the multi-layer nickel plating microporous or microcracked chromium, is to reduce the total thickness of the plating layer, to obtain high corrosion resistance protection a decorative system is an important way, but also the direction of the development of modern plating process.
② Hard chrome plating (wear-resistant chrome) coating: has a very high hardness and wear resistance, can extend the service life of the workpiece, such as cutting and drawing tools, various materials of the press mold and casting molds, bearings, shafts, gauges, gears, etc., but also can be used to repair the dimensional tolerances of the parts being abraded. The thickness of hard chrome plating is generally 5～50μm, or as required, some as high as 200～800μm. hard chrome plating on steel parts does not require intermediate plating, such as special requirements for corrosion resistance, different intermediate plating can also be used.
③Milky chrome plated chrome layer: Milky white, low gloss, good toughness, low porosity, soft color, lower hardness than hard chrome and decorative chrome, but high corrosion resistance, so it is commonly used in gauges and instrument panels. In order to improve its hardness, a layer of hard chromium can be plated on the surface of the milky white layer, which is called double-layer chromium plating, both milky white chromium plating layer and hard chromium plating, mostly used for plating both wear-resistant and corrosion-resistant parts.
④ Loose hole chromium plating (porous chromium): It is the use of the chromium layer itself has the characteristics of detailed cracks, in the hard chromium plating and then mechanical, chemical or electrochemical loose hole treatment, so that the crack network to further deepen, widen. The surface of the chromium layer is covered with wide grooves, which not only has the characteristics of wear-resistant chromium, but also can effectively store lubricating medium, prevent lubrication-free operation, and improve the friction and wear resistance of the workpiece surface. It is commonly used for plating the surface of sliding friction parts subject to heavy pressure, such as the inner cavity of cylinder barrel of internal combustion engine and piston ring.
⑤ Black chromium plating black chromium plating: black color, with uniform luster, good decorative properties, good matting properties; high hardness (130~350HV), abrasion resistance under the same thickness is 2~3 times higher than bright nickel; its corrosion resistance is the same as that of ordinary chromium plating, which is mainly dependent on the thickness of the intermediate layer. It has good heat resistance and will not change color below 300℃. Black chrome layer can be directly plated on the surface of iron, copper, nickel and stainless steel, in order to improve corrosion resistance and decorative effect, can also be used for copper, nickel or copper-tin alloy as a substrate, on the surface of the black chrome plating. Black chrome plating is often used to coat parts of aviation instruments and optical instruments, solar absorber panels and daily necessities for protection and decoration.