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Calcium is one of a group of metals called the alkaline-earth metals. They form alkaline solutions with water and are found in many natural substances. Calcium is an important constituent of bones, making them hard and stable. Magnesium is found in chlorophyll, the green part of plants that can make energy from sunlight by photosynthesis. Alkaline-earth metals form the second group of the periodic table.

The chemical element Calcium (Ca), atomic number 20, is the fifth element and the third most abundant metal in the earth’s crust. The metal is trimorphic, harder than sodium, but softer than aluminium. A well as beryllium and aluminium, and unlike the alkaline metals, it doesn’t cause skin-burns. It is less chemically reactive than alkaline metals and then the other alkaline-earth metals.

Calcium ions solved in water form deposits in pipes and boilers and when the water is hard, that is, when it contains too much calcium or magnesium. This can be avoided with the water softeners. In the industry, metallic calcium is separated from the melted calcium chloride by electrolysis. This is obtained by treatment of carbonated minerals with chlorhydric acid, or like a sub product of the carbonates Solvay process.

In contact with air, calcium develops an oxide and nitride coating, which protects it from further corrosion. It burns in the air at a high temperature to produce nitride. The commercially produced metal reacts easily with water and acids and it produces hydrogen which contains remarkable amounts of ammonia and hydrocarbides as impurities.

The metal is used in aluminium alloys for bearings, as a helper in the bismuth removal form lead, as well as in controlling graphitic carbon in melted iron. It is also used as a deoxidizer in the manufacture of many steels; as a reducing agent in the preparation of metals as chromium, thorium, zirconium and uranium, and as separating material for gaseous mixtures of nitrogen and argon. Calcium is an alloying used in the production of aluminium, beryllium, copper, lead and magnesium alloys. It is also used in making cements and mortar that are used in buildings.

The calcium oxide, CaO, is produced by thermal decomposition of carbonated minerals in furnaces, applying a continuous bed process. The oxide is used in high intensity light arcs (lime light) for its unusual spectral characteristics and as dehydrating industrial agent. The metallurgic industry extensively uses the oxide during the reduction of ferrous alloys.

The pure calcium carbonate occurs in two crystalline forms: calcite, hexagonal shaped, which possesses birrefringent properties, and aragonite, rhombohedric. The natural carbonates are the most abundant calcium minerals. The Iceland spar and the calcite are essentially pure carbonate forms, whilst the marble is impure and much more compact, reason why it can be polished. It’s very demanded as construction material. Although the calcium carbonate is very little soluble in water, it is quite soluble if the water contains dissolved carbon dioxide, for in these solutions it forms bicarbonate when dissolving. This fact explains the cave formation, where the lime stone deposits have been in contact with acid waters.

Calcium is the fifth element and the third most abundant metal in the earth’s crust. The calcium compounds account for 3.64% of the earth’s crust. The distribution of calcium is very wide; it is found in almost every terrestrial area in the world. This element is essential for the life of plants and an animal, for it is present in the animal’s skeleton, in tooth, in the egg’s shell, in the coral and in many soils. Seawater contains 0.15% of calcium chloride. Calcium cannot be found alone in nature. Calcium is found mostly as limestone, gypsum and fluorite. Stalagmites and stalactites contain calcium carbonate.

Calcium is always present in every plant, as it is essential for its growth. It is contained in the soft tissue, in fluids within the tissue and in the structure of every animal’s skeleton. The vertebrate’s bones contain calcium in the form of calcium fluoride, calcium carbonate and calcium phosphate.

Some metals corrode badly on contact with air and water. This means that the surface of the metal reacts with oxygen to form an oxide. The metal loses its shine as a layer of oxide covers it. This is sometimes known as tarnishing. When a bowl covered with silver is cleaned, for example, what is really happening is that the layer of tarnish is being rubbed away. Over a long period of time, all the silver may be rubbed off. Iron corrodes in air and water to produce rust. Non-reactive metals are less likely to corrode than reactive ones.

Corrosion is a natural process that involves the deterioration of metal components. According to NACE International, corrosion is “the destruction of a substance (usually a metal) or its properties because of a reaction with its environment.” This ultimately causes potentially severe damage to your building or application and can become very costly to repair.

Corrosion is an electrochemical reaction that appears in several forms, such as chemical corrosion and atmospheric corrosion, the latter of which is the most common form. When acidic substances (including water) come in contact with metals, such as iron and/or steel, rust begins to form. Rust is the result of corroding steel after the iron (Fe) particles have been exposed to oxygen and moisture (e.g., humidity, vapor, and immersion). When steel is exposed to water, the iron particles are lost to the water’s acidic electrolytes. The iron particles then become oxidized, which results in the formation of Fe??. When Fe?? is formed, two electrons are released and flow through the steel to another area of the steel known as the cathodic area.

Oxygen causes these electrons to rise up and form hydroxyl ions (OH). The hydroxyl ions react with the FE?? to form hydrous iron oxide (FeOH), better known as rust. Where the affected iron particles were, has now become a corrosion pit, and where they are now, is called the corrosion product (rust). Corrosion can happen at any rate, depending on the environment that the metal is in. However, since atmospheric corrosion is so widespread, it is recommended to take effective precautionary measures when it comes to corrosion prevention.

Depending on the situation and application, you may be able to treat the area that has corroded. If the affected area is small and treatable, you may require some tools and products to remove it. Begin by removing the rust from the metal using tools such as a grinding wheel or needle gun.  Be careful not to cause any additional damage to the metal. For large corroded areas, you may want to consider a permanent protective coating, such as CSL’s SI-COAT Anti-Corrosion Protective Coating. You will also want to take this time to look at the application as a whole for other premature signs of corrosion.

The Golden Gate Bridge in San Francisco needs to be painted regularly to stop it from corroding.

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