If the steel is left as it is, it will be corroded immediately and red rust will be generated. This corrosion gradually penetrates from the surface to the inside, leaving it in a state where it does not retain its original shape.
Not only steel but also other metals such as copper, copper alloys and aluminum alloys are oxidized, corroded and discolored. Plating is the process of coating the base metal with a metal film that is resistant to corrosion and discoloration in order to keep the surface of various metals beautiful forever.
Plating not only protects against corrosion, but also gives it a design that enhances the value of the product, and hardens the surface to prevent wear.
There are various plating methods, but the most typical one is "electroplating". This is a method of plating using electrolysis.
Other plating methods include electroless plating that does not use current, hot-dip plating in which an item is placed in molten metal and plated, and vacuum plating in which a vacuum is placed in a container.
Generally, processing the surface of an item like plating or painting is called "surface treatment".
Plating greatly contributes to resource conservation by significantly extending the life of metal products.
History of plating
The word plating is a word that originated in Japan and is expressed as plating in English.
In Kanji, it is written as "plating", but since there is no "plating" in common kanji, it is now correct to write "plating".
Originally, the expression is correct with hiragana plating, but since katakana plating is generally widely used, we use plating.
The etymology of plating is that "painting" has changed from "gold" to "mining" to "plating", and "plating" has become established as "plating".
Also, with the introduction of Western technology, the terms "electroplating" and "electroplating" were also used, but they are not often used nowadays, but both are terms that describe plating.
It is said that electroplating was first performed in Japan around 1836, and it is said that the Kagoshima feudal lord Shimazu Nariakira tried it for the first time.
Shimazu Nariakira, who built Japan's first warship Shohei Maru in the first year of Ansei and is famous for holding the Hinomaru flag, built a new Western-style factory on the coast of Sakurajima Bay and started making iron. We made industrial products and applied gold and silver electroplating to the metal fittings of armor and helmets.
The current electroplating was introduced in Japan under the name of galvanic plating, and after the Meiji era, plating of nickel, iron, brass, bronze, etc. in addition to gold, silver, and copper began to be performed. It gradually became industrialized and developed rapidly.
As for electroplating technology, gold, silver, and copper plating has already been actively performed in Western Europe since the middle of the 19th century, but nickel plating started around 1870, zinc plating and brass plating started around 1900, and chrome. Plating began around 1920, and cadmium plating began around 1924.
In addition, tungsten-molybdenum plating began around 1922, and rhenium plating was announced in 1934. Lead and tin plating have also been studied for a long time, and rhodium, platinum, iridium, and palladium plating have come to be performed.
In particular, the progress of plating technology after World War II is remarkable, such as the progress of gloss plating with various brighteners, the development of high-efficiency baths, the improvement of plating effect by changing the current waveform, the spread of chemical plating methods, and the automation of equipment. Problem has been resolved.
Applications for plating
Plating has been used for decorative purposes and for anticorrosion purposes that protect the base metal from corrosion, but in recent years the demand for plating has increased for functional applications such as electronic components.
As decorative plating, copper-nickel-chrome plating and double (W) nickel-chrome plating were applied to automobiles, bicycles, motorcycles, etc., but due to the influence of material changes and the adoption of painting, decorative plating The amount of processing of is greatly reduced.
Recently, alloy plating with a new appearance has been used.
Zinc plating is often used for anticorrosion applications.
The corrosion resistance required for zinc plating is becoming stricter year by year, and the proportion of colored chromate treatment, which has better corrosion resistance than gloss chromate treatment, has increased.
Recently, as the corrosion resistance for automobile applications has become more severe, alloy plating such as zinc-iron alloy plating, zinc-nickel alloy plating, and tin-zinc alloy plating is also being used.
Functional plating is mainly industrial chrome plating and plating on electronic parts, which have been used conventionally.
Industrial chrome plating is used for parts with severe wear such as various rolls and cylinders.
In addition, the demand for electronic components is increasing with the remarkable development of the information industry in recent years, and the spread of personal computers and mobile phones is particularly remarkable, and the functional plating applications related to these electronic components will further expand in the future, and surface treatment in Japan. It will become the center of industry.
List of plating treatments used in electronic components, etc.
Trends and trends in decorative plating
Decorative plating is applied to products in all fields of life, from daily necessities to acoustic parts, automobile exterior parts, automobile parts, interior intellectuals, lighting fixtures, and accessories.
The purpose and environment of use of the product are various, and the required decorative characteristics (luxury, metallic feeling, pollution prevention, corrosion resistance, light reflection, etc.) are also various.
For decorative plating, copper plating → nickel plating → chrome plating or nickel plating → chrome plating is widely used on metal and plastic substrates.
Most of the decorative chrome-plated products are finished with a mirror-glossy appearance, and when it comes to plated products, the image of glittering and shiny "shining things" is widely transmitted.
Due to the diversification of lifestyles in recent years, users have come to demand sensibility from products, and various appearances (glossiness / patterns) and various color tones are beginning to be required for decorative plating.
It has changed to a more subdued appearance than a glaring luster, and a preference for black and astringent neutrals over a single chrome color.
Therefore, by processing the substrate or using a special nickel plating for the underlying nickel plating, it is possible to obtain a wide variety of surface conditions such as satin finish (matte), velvety tone, and pearl tone.
In addition, in the conventional plating method, most of the color tones are single colors, but attempts are being made to express new color tones by various types of alloy plating.
In this way, the appearance and color tone are extremely diversified due to the base processing, the use of base nickel plating, and the application of alloy plating.
On the other hand, gold plating and copper-zinc alloy plating (brass plating) are widely used along with decorative chrome plating as gold-finished plating.
Decorative plating is called a dwarf finish, and there is a method of adding a shade of black to copper plating or brass plating to give it a unique color tone.
Trends and trends in anticorrosion plating
As a plating method to prevent corrosion of the base metal, there are a barrier type plating method in which the base metal is coated with a base metal, and a sacrificial anticorrosion type plating method in which the base metal is covered with a base metal.
Zinc plating, which is inexpensive and has an excellent sacrificial anticorrosion effect on iron, is often used as anticorrosion plating. However, white rust (zinc hydroxide or basic zinc carbonate) is formed on the galvanized surface in the air, so chromate treatment is performed as a post-treatment.
Other anti-corrosion plating uses cadmium plating for the purpose of preventing corrosion and hydrogen embrittlement of high-strength copper parts of aircraft.
Cadmium plating is partly used for aircraft parts because it has excellent corrosion resistance in salt water environments, but from the viewpoint of environmental issues, plating treatment on aircraft parts has excellent corrosion resistance and hydrogen embrittlement. We are shifting to cadmium-titanium alloy plating, which has excellent resistance.
In the automobile industry, rust prevention measures for automobile bodies and parts are strongly required.
This is because in the United States, Canada, and Scandinavian countries, corrosion of automobile bodies due to an increase in the amount of rock salt sprayed to prevent road freezing in winter has become a social problem, and legal regulations on automobile body rust prevention standards have been enforced. It's in the background.
In addition, the rust prevention targets set out by the Nordic Code and the three major automobile manufacturers in the United States in 1983 include rust prevention guarantees for not only the car body but also automobile parts.
Japanese automobile manufacturers, which export half of their automobile production to these regions, are naturally subject to these regulations, and as a countermeasure, the material of automobile bodies is shifting from steel sheets to galvanized steel sheets.
However, in response to the proposition of galvanizing, which has excellent corrosion resistance and coating adhesion without impairing the workability and weldability required for rust-proof steel sheets for automobile bodies, conventional single galvanizing meets these needs. Since it is not possible to handle it, mainly steel makers, zinc-iron alloy plating, zinc-nickel alloy plating, zinc-iron double layer alloy plating, zinc-iron-zinc-nickelni layer alloy plating, zinc-alumina composite plating, zinc -Nickel / silica composite plating Research and development such as hot-dip galvanization has been energetically promoted, and some of them have been put into practical use.
On the other hand, in order to improve the anticorrosion performance of the small automobile sector such as bolts, nuts, springs, oil seal fuel pipes, zinc-nickel, zinc-iron, tin-zinc alloy plating, which is premised on chromate treatment, is used. It is being put to practical use.
Trends and trends in functional plating
The plating process that gives the desired functionality (film hardness, insulation, wear resistance, slidability, etc.) by plating is called "functional plating" (Fanctional Plating, Engineering Plating).
Functional plating includes industrial chrome plating for wear resistance and mold releasability, tin plating for soldering, lead alloy plating for bearings, and gold plating for laser beam reflection. Is used.
The widespread interest in "functional plating" is due to the rapid development of the electronics industry in recent years.
In recent years, the development of electronics has been remarkable, and various related industries centered on the electronics industry have been rapidly developing, and even in the plating process, which is one of the related industries, the demand for the plating film has changed drastically and at the same time, it has become diversified. I am.
New functional characteristics, which are different from the decoration and anticorrosion plating that were synonymous with plating, have been attracting attention, and they are being used for new applications according to those characteristics.
Looking back on our daily lives, there are an extremely large number of products that involve functional plating, and for the electrical wiring inside most electrical products such as televisions and videos, we use copper-plated printed wiring boards and semiconductor parts such as IC chips. Functional plating is also widely used in parts such as gold-plated, silver-plated, high-end cameras, automobiles, air conditioners, personal computers, facsimiles, and calculators.
Connection Co., Ltd.
Please feel free to contact us for plating, coating, polishing, heat treatment, etc.
Consultations and quotations are free.
4-202-5 Shizugaoka, Fukui City, Fukui Prefecture 910-3635 (Japan)