Category Archives: Facts

Calcium Carbide

Calcium carbide is a chemical compound with the chemical formula of CaC2. Its main use industrially is in the production of acetylene and calcium cyanamide.

The pure material is colorless, however pieces of technical-grade calcium carbide are grey or brown and consist of about 80–85% of CaC2 (the rest is CaO (calcium oxide), Ca3P2 (calcium phosphide), CaS (calcium sulfide), Ca3N2 (calcium nitride), SiC (silicon carbide), etc.). In the presence of trace moisture, technical-grade calcium carbide emits an unpleasant odor reminiscent of garlic.

Applications of calcium carbide include manufacture of acetylene gas, and for generation of acetylene in carbide lamps; manufacture of chemicals for fertilizer; and in steelmaking.

In the artificial ripening of fruit, calcium carbide is sometimes used as source of acetylene gas, which is a ripening agent similar to ethylene. However, this is illegal in some countries because consumption of fruits artificially ripened using calcium carbide can cause serious health problems in those who partake them.

Calcium carbide is used in toy cannons such as the Big-Bang Cannon, as well as in bamboo cannons.

Calcium carbide, together with calcium phosphide, is used in floating, self-igniting naval signal flares, such as those produced by the Holmes’ Marine Life Protection Association.

Silicon Carbide

Silicon carbide, also known as carborundum, is a compound of silicon and carbon with chemical formula SiC. It occurs in nature as the extremely rare mineral moissanite. Silicon carbide powder has been mass-produced since 1893 for use as an abrasive. Grains of silicon carbide can be bonded together by sintering to form very hard ceramics that are widely used in applications requiring high endurance, such as car brakes, car clutches and ceramic plates in bulletproof vests. Electronic applications of silicon carbide as light-emitting diodes (LEDs) and detectors in early radios were first demonstrated around 1907, and today SiC is widely used in high-temperature/high-voltage semiconductor electronics. Large single crystals of silicon carbide can be grown by the Lely method; they can be cut into gems known as synthetic moissanite. Silicon carbide with high surface area can be produced from SiO2 contained in plant material.

It is used in Abrasive and cutting tools, Structural material, Automobile parts, Electric systems, Electronic circuit elements(Power electronic devices, LEDs), Astronomy, Thin filament pyrometry, Heating elements, Nuclear fuel particles, Nuclear fuel cladding, Jewelry, Steel production, Catalyst support, Carborundum printmaking and Graphene production.

Boron Carbide

Boron carbide is an extremely hard boron–carbon ceramic material used in tank armor, bulletproof vests, engine sabotage powders,as well as numerous industrial applications. With a Mohs hardness of about 9.497, it is one of the hardest materials known, behind cubic boron nitride and diamond.

Boron carbide was discovered in 19th century as a by-product of reactions involving metal borides, however, its chemical formula was unknown. It was not until the 1930s that the chemical composition was estimated as B4C. There remained, however, controversy as to whether or not the material had this exact 4:1 stoichiometry, as in practice the material is always slightly carbon-deficient with regard to this formula, and X-ray crystallography shows that its structure is highly complex, with a mixture of C-B-C chains and B12 icosahedra. These features argued against a very simple exact B4C empirical formula. Because of the B12 structural unit, the chemical formula of “ideal” boron carbide is often written not as B4C, but as B12C3, and the carbon deficiency of boron carbide described in terms of a combination of the B12C3 and B12CBC units.

The ability of boron carbide to absorb neutrons without forming long lived radionuclides makes it attractive as an absorbent for neutron radiation arising in nuclear power plants. Nuclear applications of boron carbide include shielding, control rod and shut down pellets. Within control rods, boron carbide is often powdered, to increase its surface area.

Boron carbide is known as a robust material having high hardness, high cross section for absorption of neutrons (i.e. good shielding properties against neutrons), stability to ionizing radiation and most chemicals. Its Vickers hardness (38 GPa), Elastic Modulus (460 GPa) and fracture toughness (3.5 MPa·m1/2) approach the corresponding values for diamond (115 GPa and 5.3 MPa·m1/2).

It is used in Padlocks Personal and vehicle anti-ballistic armor plating, Grit blasting nozzles, High-pressure water jet cutter nozzles, Scratch and wear resistant coatings, Cutting tools and dies, Abrasives, Neutron absorber in nuclear reactors, Metal matrix composites, High energy fuel for solid fuel Ramjets, In brake linings of vehicles and Engine Sabotage powder.

Natural Graphite

Graphite is made almost entirely of carbon atoms, and as with diamond, is a semi-metal native element mineral, and an allotrope of carbon. Graphite, meaning “writing stone”, was named by Abraham Gottlob Werner in 1789 from the Ancient Greek γράφω (graphō), “to draw/write”, for its use in pencils, where it is known as lead (not to be confused with the metallic element lead). Graphite is the most stable form of carbon under standard conditions. Therefore, it is used in thermochemistry as the standard state for defining the heat of formation of carbon compounds. Graphite may be considered the highest grade of coal, just above anthracite and alternatively called meta-anthracite, although it is not normally used as fuel because it is difficult to ignite.

Graphite occurs in metamorphic rocks as a result of the reduction of sedimentary carbon compounds during metamorphism. It also occurs in igneous rocks and in meteorites. Minerals associated with graphite include quartz, calcite, micas and tourmaline. In meteorites it occurs with troilite and silicate minerals.Small graphitic crystals in meteoritic iron are called cliftonite.

According to the United States Geological Survey (USGS), world production of natural graphite in 2012 was 1,100 thousand tonnes (kt), of which the following major exporters are: China (750 kt), India (150 kt), Brazil (75 kt), North Korea (30 kt) and Canada (26 kt). Graphite is not mined in the United States, but U.S. production of synthetic graphite in 2010 was 134 kt valued at $1.07 billion.

Natural graphite is mostly consumed for refractories, batteries, steel-making, expanded graphite, brake linings, foundry facings and lubricants.[7] Graphene, which occurs naturally in graphite, has unique physical properties and might be one of the strongest substances known; however, the process of separating it from graphite will require some technological development before it is economically feasible to use it in industrial processes.

Magnesite

Magnesite is a mineral with the chemical formula MgCO3 (magnesium carbonate). Mixed crystals of iron II carbonate and magnesite (mixed crystals known as ankerite) possess a layered structure: monolayers of carbonate groups alternate with magnesium monolayers as well as iron II carbonate monolayers. Manganese, cobalt and nickel may also occur in small amounts.

Magnesite occurs as veins in and an alteration product of ultramafic rocks, serpentinite and other magnesium rich rock types in both contact and regional metamorphic terrains. These magnesites often are cryptocrystalline and contain silica in the form of opal or chert.

Magnesite is also present within the regolith above ultramafic rocks as a secondary carbonate within soil and subsoil, where it is deposited as a consequence of dissolution of magnesium-bearing minerals by carbon dioxide within groundwaters.

Fluorspar

Fluorite (also called fluorspar) is the mineral form of calcium fluoride, CaF2. It belongs to the halide minerals. It crystallizes in isometric cubic habit, although octahedral and more complex isometric forms are not uncommon.

Fluorite is a colorful mineral, both in visible and ultraviolet light, and the stone has ornamental and lapidary uses. Industrially, fluorite is used as a flux for smelting, and in the production of certain glasses and enamels. The purest grades of fluorite are a source of fluoride for hydrofluoric acid manufacture, which is the intermediate source of most fluorine-containing fine chemicals. Optically clear transparent fluorite lenses have low dispersion, so lenses made from it exhibit less chromatic aberration, making them valuable in microscopes and telescopes. Fluorite optics are also usable in the far-ultraviolet range where conventional glasses are too absorbent for use.

Source : http://en.wikipedia.org/wiki/Fluorite