Chrome Plating Glossary
Nickel/Chromium
Bright Chromium does not exist in its own right. A deposit of nickel is required prior to any chromium application. If used without the combination of nickel, an extremely heavy deposit of chromium would need to be applied in order to achieve only a slight degree of protection against corrosion and wear.
Experience has shown over the years that a nickel/chromium finish provides the best protection against abrasion, and corrosion, whilst providing a finish that is visually appealing. Essentially the nickel deposit gives protection to the basis metal, and is itself preserved from surface oxidation by the relatively thin bright chromium deposit. This type of finish is well suited to the automotive, medical, security and shop fitting industries.
The thickness of the nickel/chromium deposit will vary according to customer requirements or the relevant BS or aerospace spec.
Black Chrome
EIC Finishing Services can also offer black chromium plating as an unusual alternative to bright chromium.
Black chromium deposits have a high degree of micro-porosity which produces better corrosion resistance than standard bright chromium. The same micro-porosity gives the coating the ability to absorb and retain oil and paint films which makes it useful for machine tools.
Hard Chrome
Hard chromium deposits are extensively used on components such as cutting tools, hydraulic rams, machine parts, moulds and printing applications which requires a hard and abrasion resistant wearing surface.
Hard chrome is also very useful for undersized and worn parts which require building up.
The hard chrome deposit is generally applied directly to the base metal and is many times thicker than bright chromium plating. Hard chrome can deposit a protective coating onto a variety of components.
The deposit gives excellent adhesion on a variety of surfaces whether ground, finely turned or highly polished.
A general thickness of 0.13mm (0.005”) is ample for most plating applications, and in many cases thin deposits of 12 to 50 microns (0.0005 to 0.002) are sufficient to give good wear resistance. The maximum deposit of hard chrome for normal purposes is between 0.3mm and 0.4mm (0.012 to 0.015”), greater thicknesses can however be applied if required.
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