Black Chrome Plating
Black has a sense of solemnity and is known as a color tone with permanent charm. Compared with black nickel coating, black chromium coating has better corrosion resistance, durability, and selective absorption of solar energy.
Author: Marisa
Black has a sense of solemnity and is known as a color tone with permanent charm. Compared with black nickel coating, black chromium coating has better corrosion resistance, durability, and selective absorption of solar energy. Although the hardness of black chromium coating is low, ranging from HVl30 to 350, its wear resistance is similar to that of ordinary chromium coatings. The black chromium coating is not pure metallic chromium, but amorphous oxide crystals. According to analysis, its metallic chromium content only accounts for about 50% to 75% of the coating, while the rest is chromium oxide, which mainly exists in the form of chromium trioxide hydrate (Cr203 · xH2O). There is an example in the literature analyzing the chemical composition of black chromium coatings, and the result is:
Chromium (Cr) 56.1%, nitrogen (N) 0.4%, carbon (c) 0.1%, hydrogen (H) 1.25%, oxygen (O)>26.0%
The black chromium coating has loose crystals and a dendritic structure, so it can completely absorb light waves and appear black. It has been proven that with the utilization and development of solar energy, black chromium coating is the most excellent selective absorption among all black electroplating coatings and coatings. The ratio of absorption rate a and reflectivity y of black chromium coating can be greater than 10, so it is widely used in solar absorbers, weapons, optical instruments, and cameras; Due to its dignified appearance, black has been increasingly used in decorative parts for automobiles and daily light industrial products.
The black chrome plating has good adhesion to other commonly used base metals except for aluminum. The black chromium coating has high thermal stability and does not change in appearance when heated to 480 ℃. Although the corrosion resistance of black chromium coating is better than that of ordinary chromium coating, this coating generally requires a base coating of the substrate. Although black chromium can be directly plated on copper and brass substrates, it is indeed done in this way; It is unreasonable for us to avoid electrochemical corrosion even from a physical perspective; Due to the significant difference in thermal expansion coefficient between black chromium coating and copper or brass, if a base coating is not used, the black chromium coating will crack over time and detach from the substrate. Therefore, the corrosion resistance of black chromium mainly depends on the quality of the substrate coating, and the more reasonable and commonly used bottom coating is the nickel plating layer. There is also a lot of black chromium plating on stainless steel, but due to the severe dullness of the surface, black chromium plating on stainless steel should be done first in a nickel plating bath with high chloride content. If the black chromium layer still has a requirement for a brighter appearance, an additional layer of bright nickel should be plated, and then black chromium should be plated on top of the bright nickel coating.
There are many formulas for black chromium plating, including sodium nitrate type, acetic acid type, fluoride type, and vanadate type. In recent years, there have been some product additives, most of which are combination types that are easy to add and have good stability.
Black chromium electroplating is an electroplating process that covers the surface of a workpiece with a black coating composed of chromium and its oxides. The coating has a dignified and elegant appearance, which is wear-resistant, corrosion-resistant, and heat-resistant. It is suitable for cameras, optical instruments, weapons, and solar collectors. Using chromic acid plating solution, using acetic acid, fluoride, or nitrate as catalysts. There is also a trivalent chromium compound plating process that can reduce environmental pollution, and the main salt in the plating solution is chromium chloride or chromium sulfate.
Based on the electroplating method, CTP Plate can mainly be divided into rack plating, barrel plating, electroless plating/chemical plating, continuous plating, and annular vertical plating, among others.
Ruisite customizes equipment according to various factors such as the customer's production rhythm, capacity, and plating requirements. Plating production lines can be fully automatic, semi-automatic, or manually operated. Multiple sets of programs are integrated into the main electrical cabinet with a touchscreen, catering to specific operational needs as per customer requirements.
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