Chromium compounds are also used to anodize aluminum, a process which coats aluminum with a thick, protective layer of oxide. Chromite, chromium's primary ore, is used to make molds for the firing of bricks because of its high melting point, moderate thermal expansion and stable crystal structure.
Estimated Crustal Abundance : 1. Number of Stable Isotopes : 3 View all isotope data. Electron Shell Configuration :. Chromium Previous Isotopes Next. Chrome plating is not only used for looks; because the chromium forms a protective oxide layer on the surface, chrome-plated objects resist corrosion, according to Krebs. Stainless steel is an alloy of iron and at least It is highly resistant to corrosion. It is used in kitchen cutlery, appliances and cookware such as stainless steel pans and skillets.
About 90 percent of leather is chrome tanned, according to Emsley. During this process, chromium sulfate is used to treat animal skin and turn it into leather that is resistant to hot water that can cause degradation. Kilns and furnaces use bricks made of chromite ore, which retains strength at high temperatures.
The textile industry uses chromium ions to help adhere dyes to fabric. Chromium's high melting point, moderate thermal expansion and crystalline structure stability make it suitable for these purposes. Though its specific role in humans is unclear, studies have shown that chromium is an essential trace element that is found in RNA and helps the body to use glucose.
As early as the cotton and wool industries were using large amounts of chromium compounds such as potassium bichromate in the dyeing process. Red and green pigments developed from chromium compounds were also used for printing wallpaper during this period.
Local manufacturers soon followed suit and competition drove the price down to 8 pence, about an eighth of the original price. This did not give Kurtz a satisfactory profit, so he began producing other chrome compounds, specifically chrome pigments. His chrome yellow achieved vogue status when the popular Princess Charlotte, daughter of British monarch George IV, had it used to paint her carriage. While chromium chemicals gained commercial importance rapidly in the pigment industries, chromium took longer to make an impression on other sectors.
One of these areas was the metallurgical — metal manufacturing — industry. Beginning in the mids, iron manufacturers discovered that adding chromium to steel produced a harder, more useful metal. Steel is a mixture of iron with a small amount of carbon — around 1 percent. Such mixtures of metals are called alloys.
Iron objects produced this way are only moderately hard, and they can bend in use. But adding carbon to iron changes its microstructure and properties. When this mixture is heated it reaches an extremely ductile stage and can be formed easily. As steel cools it gains strength and rigidity, becoming stronger than iron. This process is called tempering. Different amounts of carbon and the rate of cooling determine the final properties of steel. Adding chromium to this mixture produces a harder steel by delaying the transformation that occurs as steel is cooled, and steels with 3 to 5 percent chromium were produced beginning in It was not until the early s that the corrosion resistant-properties of steels containing percentages of chromium higher than 5 percent were noticed.
At higher percentages, chromium makes steel highly resistant to many corrosive agents and environments. Perhaps the most well known uses of stainless steel are in cutlery and cookware. Today the use of chromium in the production of stainless steel accounts for 60 percent of chromium consumption. Stainless steel utensils and cutlery are found in kitchens throughout the United States. Kitchens contain chromium in another form: electroplated chromium covers sink fixtures and appliances in a mirror-like film.
The ubiquity of electroplated chromium is impressive given that the fundamental principles of chromium electroplating were not discovered until He suggested that chromium could be deposited on surfaces submerged in solutions of chromium chloride and chromium sulfate. In , a Frenchman obtained a patent for a process that made gold adhere to iron with an intermediate chromium plate. Most metals plate from salts chloride and sulfate compounds but chromium is unusual in that it plates best from chromic acids.
Early experimenters tried chromium chloride and sulfate solutions with little success. The correct solution was discovered by chance when a German professor electrolyzed a chromic acid solution and noticed a deposit of chromium. This surprising discovery led to research by Colin G.
Fink and several graduate students from Cornell and Columbia that explicated the process. The first application of chrome plating was in the production of jewelry. Chrome was used to plate solid-platinum wedding rings to protect them from wear. Hailed as a miracle metal that looked like platinum but wore much better, chrome-plated jewelry was soon on the ear and hand of fashionable woman across the United States.
As the plating process became cheaper and more common, plumbing fixtures and household appliances were plated with chrome. The attractive shiny surface and the resistance to corrosion made plated articles aesthetically and functionally desirable. Soon consumers were demanding chrome trim on all their appliances, and car manufacturers began making the chrome bumpers and molding so characteristic of s auto designs.
Industrial applications for chrome plating were being discovered at the same time that decorative chrome plating was making its flashy debut.
Chrome is a very hard metal and has a low coefficient of friction. Manufacturers started plating machine parts such as car cylinders that received a lot of wear with a thick layer of chromium, extending the life of these parts considerably. Chrome was also useful in boiler pipes. Pipes made of steel would build up scale — mineral deposits released by boiling water — and the deposits would flake off the surface of the pipe and clog the system.
Chromium plated pipes, however, did not release the scale. The Acid Etching process on stainless steel and other metals. An explanation of the truly ancient art of engraving, etching and intaglios on copper, mild steel, aluminium, brass and stainless steel by Richard Storer-Adam. An introduction to hard-anodised aluminium coatings, their advantages and environmental implications for architectural cladding. An analysis of the color and corrosion properties of aluminium cladding, its maintenance and waste products.
An exploration of metals, elements and alloys. We look at how these naturally occur on Earth and how they are treated through processes of colouring, plating, etching, anodising and Physical Vapor Deposition to become materials and products used in industry, construction, art, decoration and jewellery. Nitrogen N - part of a series on gases used during the physical vapour deposition PVD process - an innovative method for improving the performance of stainless steel.
Richard Storer-Adam investigates the paradoxical role nitrogen plays in both saving and destroying life as a critical element in the manufacture of explosives, agri-fertilisers and airbags.
Oxygen O - part of a series on gases used during the physical vapour deposition PVD process - an innovative method for improving the performance of stainless steel. Chromium Cr — The discovery of chromium, its origins and wide-ranging industrial and aesthetic applications. Metals added to stainless steel include Chromium Cr. The origins of chromium Chromium is a beautiful and useful element - the name comes from the Greek word for color, chroma.
Chromium in paint Chromium ores were used extensively in the paint industry; for example, the pigment chrome yellow was very popular with artists and the paint industry. Chromite It was recently estimated that there are 11 billion tonnes of minable chrome in the earth's crust, making it the 21st most abundant element on the planet.
In we mined well over 30 million metric tonnes of chromite. Chromium in humans Chromium like lots of other elements is vital for human health.
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