Plating
Plating is a finishing process in which a
finish.There are several plating methods, and many variations. In one method, a solid surface is covered with a metal sheet, and then heat and pressure are applied to fuse them (a version of this is
Electroplating
In electroplating, an
Electroless Deposition
Specific cases
Gold plating
Gold plating is a method of depositing a thin layer of gold on the surface of glass or metal, most often copper or silver.
Gold plating is often used in electronics, to provide a
Metals and glass may also be coated with gold for ornamental purposes, using a number of different processes usually referred to as gilding.
Sapphires, plastics, and carbon fiber are some other materials that are able to be plated using advance plating techniques. The substrates that can be used are almost limitless.[2]
Silver plating
Silver plating has been used since the 18th century to provide cheaper versions of household items that would otherwise be made of solid silver, including cutlery, vessels of various kinds, and candlesticks. In the UK the assay offices, and silver dealers and collectors, use the term "silver plate" for items made from solid silver, derived long before silver plating was invented from the Spanish word for silver "plata", seizures of silver from Spanish ships carrying silver from America being a large source of silver at the time. This can cause confusion when talking about silver items; plate or plated. In the UK it is illegal to describe silver-plated items as "silver". It is not illegal to describe silver-plated items as "silver plate", although this is ungrammatical.
The earliest form of silver plating was
Another method that can be used to apply a thin layer of silver to objects such as glass, is to place Tollens' reagent in a glass, add glucose/dextrose, and shake the bottle to promote the reaction.
For applications in electronics, silver is sometimes used for plating copper, as its
Care should be used for parts exposed to high humidity environments because in such environments, when the silver layer is porous or contains cracks, the underlying copper undergoes rapid galvanic corrosion, flaking off the plating and exposing the copper itself; a process known as red plague. Silver plated copper maintained in a moisture-free environment will not undergo this type of corrosion.
Copper plating
Copper plating is the process of electrolytically forming a layer of copper on the surface of an item. It is commonly used as an even cheaper alternative to silver plating as it is much cheaper than silver.
Rhodium plating
Rhodium plating is occasionally used on white gold, silver or copper and its alloys. A barrier layer of nickel is usually deposited on silver first, though in this case it is not to prevent migration of silver through rhodium, but to prevent contamination of the rhodium bath with silver and copper, which slightly dissolve in the sulfuric acid usually present in the bath composition.[4]
Chrome plating
Chrome plating is a finishing treatment using the
The traditional solution used for industrial hard chrome plating is made up of about 250 g/L of CrO3 and about 2.5 g/L of SO4−. In solution, the chrome exists as chromic acid, known as hexavalent chromium. A high current is used, in part to stabilize a thin layer of chromium(+2) at the surface of the plated work. Acid chrome has poor throwing power, fine details or holes are further away and receive less current resulting in poor plating.
Zinc plating
Zinc-nickel plating
Zinc-nickel plating is one of the best corrosion resistant finishes available offering over 5 times the protection of conventional zinc plating and up to 1,500 hours of neutral salt spray test performance. This plating is a combination of a high-nickel zinc-nickel alloy (10–15% nickel) and some variation of chromate. The most common mixed chromates include hexavalent iridescent, trivalent or black trivalent chromate. Used to protect steel, cast iron, brass, copper, and other materials, this acidic plating is an environmentally safe option.[6] Hexavalent chromate has been classified as a human carcinogen by the EPA and OSHA.[7][8]
Tin plating
The
Tin is also widely used in the
Alloy plating
In some cases, it is desirable to co-deposit two or more metals resulting in an electroplated alloy deposit. Depending on the alloy system, an electroplated alloy may be
Composite plating
Cadmium plating
Cadmium plating is under scrutiny because of the environmental toxicity of the cadmium metal. Cadmium plating is widely used in some applications in the aerospace, military, and aviation fields. However, it is being phased out due to its toxicity.[9] Military and Aerospace components manufacturers, such as Amphenol Aerospace, have recently been exploring drop-in electroplating replacements for use with currently fielded equipment in order to support the phaseout of the dangerous finish.[10]
Cadmium plating (or cad. plating) offers a long list of technical advantages such as excellent corrosion resistance even at relatively low thickness and in salt atmospheres, softness and
If environmental concerns matter, in most aspects cadmium plating can be directly replaced with gold plating as it shares most of the material properties, but gold is more expensive and cannot serve as a paint base.
Nickel plating
Nickel is electroplated by using a
Electroless nickel plating
This article appears to contradict the article Electroless nickel plating. and do not remove this message until the contradictions are resolved. (June 2010) |
Electroless nickel plating is self-catalyzing process, the resultant nickel layer is NiP compound, with 7–11% phosphorus content. Properties of the resultant layer hardness and wear resistance are greatly altered with bath composition and deposition temperature, which should be regulated with 1 °C precision, typically at 91 °C.
During bath circulation, any particles in it will become also nickel-plated; this effect is used to advantage in processes which deposit plating with particles like silicon carbide (SiC) or polytetrafluoroethylene (PTFE). While superior compared to many other plating processes, it is expensive because the process is complex. Moreover, the process is lengthy even for thin layers. When only corrosion resistance or surface treatment is of concern, very strict bath composition and temperature control is not required and the process is used for plating many tons in one bath at once.
Electroless nickel plating layers are known to provide extreme surface adhesion when plated properly. Electroless nickel plating is non-magnetic and amorphous. Electroless nickel plating layers are not easily solderable, nor do they seize with other metals or another electroless nickel-plated workpiece under pressure. This effect benefits electroless nickel-plated screws made out of malleable materials like titanium. Electrical resistance is higher compared to pure metal plating.
See also
- Anodization
- Mechanical plating
- Organic solderability preservative plating
References
- .
- ^ "Plating on Plastics". Epner Technology, Inc. Archived from the original on 2013-11-01. Retrieved 2013-10-30.
- ^ Clint DeBoer (2009-07-23). "Silver Saboteurs - Are Silver Audio Cables Better?". Audioholics. Archived from the original on 2012-01-30. Retrieved 2011-12-11.
- .
- ^ a b "Cadmium vs. Zinc vs. Nickel Plating Comparison Archived 2009-05-15 at the Wayback Machine" Finishing.com
- ^ Inc., Gatto Industrial Platers. "Zinc Nickel Plating - Zinc Nickel Electroplating - Gatto Industrial Platers, Inc". www.gattoplaters.com. Archived from the original on 2016-02-07.
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:|last=
has generic name (help) - ^ "Health Effects Notebook for Hazardous Air Pollutants". EPA.gov. 25 April 2016. Retrieved 2020-03-03.
- ^ "Chemical Sampling Information - Chromium (VI) (Hexavalent Chromium) - Occupational Safety and Health Administration". www.osha.gov. Archived from the original on 2016-03-05.
- ^ Why use cadmium plated fasteners in the aeronautical field Archived 2008-07-02 at the Wayback Machine. finishing.com
- ^ "Summary of Cadmium's Compatibility with Dissimilar Metal Finishes".
- ^ Cadmium plating Archived 2008-10-01 at the Wayback Machine. Erie Plating Company
- ^ "Watts Nickel Bath: Basis for Modern Nickel Plating". Asterion Inc. Retrieved 6 July 2022.
- ^ Kanigen Archived 2011-07-20 at the Wayback Machine. schnarr.eu