What is a Chromium Metal?

Chromium Metal

Chrome is a shiny, brittle hard metal. Its color is silver-gray and it can be polished to a mirror finish. It does not tarnish in the air; when it is heated, it arises and forms the green chromium oxide. Chromium is unstable in oxygen, it immediately creates a thin oxide layer that is impermeable to oxygen and protects the metal below.

Chromium metal is a chemical element by the symbol Cr and atomic number 24. It is the first element in group 6.

Chromium is the principal additive in stainless steel, to which it adds anti-corrosive properties. Chromium is also highly valued as a metal that is capable to be highly polished while resisting tarnishing.

Polished chromium represents approximately 70% of the visible spectrum, with approximately 90% of infrared light reflected. The name of the element is derived from the Greek word ‘chroma’, a Greek word meaning color, due to its ability to produce vivid, colorful compounds, such as chrome oxide.

Who Discovered Chromium?

Chromium metal was discovered by the French chemist Louis-Nicolas Vauquelin in Paris 1797, while experimenting with a material known as Siberian red lead, also known as the mineral crocoite (lead chromate).

How was chromium discovered?

Chromium metal was discovered by the French chemist Louis-Nicolas Vauquelin in Paris 1797, while experimenting with a material known as Siberian red lead, also known as the mineral crocoite (lead chromate).

They boiled crushed carbonate with potassium carbonate, producing a yellow potassium salt solution of lead carbonate and chromic acid. Vauquelin was influenced by further experiments on the solution that he had found a new metal.

In 1781 he succeeded in isolating the metal. Initially, he switched the lead from the mineral sample by precipitation with hydrochloric acid. The vauquelin then obtained the oxide by evaporation and finally separated the chromium by heating the oxide in a charcoal oven. He also identified small amounts of chromium in ruby and emerald stones.

While chromium compounds have been used in dyes and paints for thousands of years, it was not until chromium used in metal use began to develop after the discovery of Voegelin. In the late 19th and early 20th centuries, metallurgists in Europe were actively experimenting with metal alloys, trying to produce stronger and more durable steel.

In 1912, while working at Firth Brown Laboratories in the UK, metallurgist Harry Brearley was tasked with finding a more resilient metal for gun barrels. They added chromium, a higher melting point to traditional carbon steel, which previously produced stainless steel.

However, at about the same time, others, including Elwood Haynes in the US and engineers at Krupp in Germany, were also developing chromium containing steel alloys. With the development of the electric arc furnace, large-scale production of stainless steel followed shortly after that.

During the same period, research was also being done on electro-plating metals, which allowed cheaper metals, such as iron and nickel, to adopt onto their exterior chromium’s resistance to abrasion and corrosion, as well as its aesthetic qualities. The first chrome feature appeared on cars and high-end watches in the late 1920s.

Chromium

Properties of Chromium

Physical Properties of Chromium

Chromium is a hard, steel-gray, shiny, metal that cracks easily. It has a melting point of 1,900°C (3,450°F) and a boiling point of 2,642°C (4,788°F). The density is 7.1 grams per cubic centimeter. One important property is that chromium can be polished to a high shine.

Chemical properties of Chromium

Chromium metal is a chemical element by the symbol Cr and atomic number 24. It is the first element in group 6. Chromium is a fairly active metal. It does not react with water but reacts with most acids. It combines with oxygen at room temperature to form chromium oxide (Cr 2 O 3). Chromium oxide forms a thin layer on the metal surface, protecting it from further corrosion.

Chromium Processing

Industrial chromium products include chromium metals, ferrochrome, chromium chemicals, and foundry sand. In recent years, there has been a trend towards greater vertical integration in chromium material production. That is, more companies are involved in the mining of chromite ore are also processing it into chromium metal, ferrochrome, and, ultimately, stainless steel.

The primary mineral extracted for chromium production in 2010 was 25 million tons in the global production of chromite ore (FeCr2O4). Production of ferrochrome was around 7 million tons, while chromium metal production was about 40,000 tons.

Pheochromium is produced using fully electric arc furnaces, while chromium metal can be produced through electrolytic, silico-thermic, and aluminothermic methods.

During the production of ferrochrome, the heat created by electric arc furnaces, which reaches 5070°F (2800°C), causes coal and coke to reduce chromium ore through a carbothermic reaction. Once sufficient material has been smelted in the furnace hearth, the molten metal is drained out and solidified in large castings before being crushed.

Aluminithmic production of high purity chromium metal exceeds 95% chromium metal produced today. The first step in this process requires that the chromite ore is roasted with soda and lime in the air at 2000°F (1000°C), which creates sodium chromate containing calcine. It can be removed from the waste material and then reduced to chromic oxide (Cr2O3).

The chromic oxide is then mixed with powdered aluminum and put into a large clay crucible. Barium peroxide and magnesium powder are then spread onto the mixture, and the crucible is surrounded by sand (which acts as insulation).

The mixture is ignited, resulting in the oxygen from the chromic oxide reacting with the aluminum to produce aluminum oxide and, thereby, liberating molten chromium metal that is 97-99% pure.

Uses of Chromium

The following area where Uses of Chromium:

  • Chromium surfaces are formed by electrochemical and chroming on other metals.
  • There are two types of electroplating: decorative and “hard.” The decorative plate varies between 0.000254 and 0.000508 millimeters (0.00001 and 0.00002 inches) in thickness and is usually deposited over nickel.
  • “Hard” plating is used because of its wear resistance and low coefficient of friction. For this type of plating, a solution of chromic acid (CrO3) is used.
  • Chromium is added to cobalt alloys in quantities of up to 25 percent to obtain corrosion resistance and hardness. Cobalt – chromium – tungsten alloys are used for cutting tools and hard facing.
  • Nickel-chromium superalloys with up to 60 percent chromium and sometimes a little iron are used for high-temperature applications. Chromium is also added to aluminum alloys in amounts up to 0.5 percent to improve their strength and corrosion resistance.
  • The metal is also widely used as a catalyst in the dyeing and tanning of leather
  • Chromium compounds are used as industrial catalysts and pigments (in bright green, yellow, red, and orange colors). Rubies get their red color from chromium, and glass treated with chromium has an emerald green color.
  • To manufacture molds for the firing of bricks
  • Chromium is a required trace element for humans because it helps us to use glucose. However, it is poisonous in excess. We take in about 1 milligram a day. Foods such as brewer’s yeast, wheat germ, and kidney are rich in chromium.

Chromium Element uses

Chromium element have many different uses. Some include:

  • chromic fluoride (CrF 3): printing, dyeing, and mothproofing woolen cloth
  • chromic oxide (Cr 2 O 3): a green pigment (coloring agent) in paint, asphalt roofing, and ceramic materials; refractory bricks; abrasive
  • chromic sulfate (Cr 2 (SO 4) 3): a green pigment in paint, ceramics, glazes, varnishes, and inks; chrome plating
  • chromium boride (CrB): refractory; a high-temperature electrical conductor
  • chromium dioxide (CrO 2): covering for magnetic tapes (“chromium” tapes)
  • chromium hexacarbonyl (Cr (CO) 6): catalyst; gasoline additive

Side Effects of Chromium

People can be exposed to chromium through breathing, eating or drinking, and skin contact with chromium or chromium compounds. Chromium levels in air and water are usually low. In drinking water, the level of chromium is usually low as well, but contaminated well water may contain the dangerous hexavalent chromium.

For most people eating food that contains chromium is the main route of chromium uptake, as chromium occurs naturally in many vegetables, fruits, meats, yeasts, and grains. Different methods of food products and storage can change the chromium content of the food. Food may increase when stores in steel tanks or compartment chromium concentrations.

Chromium is an essential nutrient for humans and shortages may cause heart conditions, disruptions of metabolisms, and diabetes. But the uptake of too much chromium can cause health effects as well, for instance, skin rashes.

chromium is a threat to human health, mainly to people who work in the steel and textile industries. People who consume tobacco are more likely to be exposed to chromium.

Chromium is known to cause various health effects. When it is a compound in leather products, it can cause allergic effects, such as skin rashes. After breathing it in chromium can cause nose irritations and nosebleeds.

Other health problems that are caused by chromium are:

  • Skin rashes
  • Upset stomachs and ulcers
  • Respiratory problems
  • Weakened immune systems
  • Kidney and liver damage
  • Alteration of genetic material
  • Lung cancer
  • Death

The health hazards of exposure to chromium depend on its oxidation status. The metal form (chromium as present in this product) is of low toxicity. The hexavalent form is toxic. Adverse effects of the hexavalent form on the skin may include ulcerations, dermatitis, and allergic skin reactions.

Inhalation of hexavalent chromium compounds can occur as a result of ulceration and perforation of the mucous membrane of the nasal septum, pharyngeal and laryngeal irritation, bronchitis, bronchospasm, and edema. Respiratory symptoms may include coughing and wheezing, shortness of breath, and nasal itch.

FAQ

What is chromium metal?


Chromium is a lustrous, brittle, hard metal. Its color is silver-gray and it can be highly polished. It does not tarnish in air, when heated it borns and forms the green chromic oxide. Chromium is unstable in oxygen, it immediately produces a thin oxide layer that is impermeable to oxygen and protects the metal below.

What are the side effects of chromium?


Chromium has been used safely in a small number of studies using doses of 200-1000 mcg daily for up to 2 years. Some people experience side effects such as skin irritation, headaches, dizziness, nausea, mood changes, impaired thinking, judgment, and coordination.

What are the uses of chromium?


A hard, silvery metal with a blue tinge. Chromium is used to harden steel, to manufacture stainless steel (named as it won’t rust), and to produce several alloys. Chromium plating can be used to give a polished mirror finish to steel. Chromium-plated car and lorry parts, such as bumpers, were once very common.

What are the properties of chromium?


Chromium is a lustrous, brittle, hard metal. Its color is silver-gray and it can be highly polished. It does not tarnish in air, when heated it born and forms green chromic oxide. Chromium is unstable in oxygen; it immediately produces a thin oxide layer that is impermeable to oxygen and protects the metal below.

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