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Thermite
Thermite () is a pyrotechnic composition of powder metallurgy, metal powder and metal oxide. When ignited by heat or chemical reaction, thermite undergoes an exothermic redox, reduction-oxidation (redox) reaction. Most varieties are not explosive, but can create brief bursts of heat and high temperature in a small area. Its form of action is similar to that of other fuel-oxidizer mixtures, such as gunpowder, black powder. Thermites have diverse compositions. Fuels include aluminium, aluminum, magnesium, titanium, zinc, silicon, and boron. Aluminum is common because of its high boiling point and low cost. Oxidizers include bismuth(III) oxide, boron(III) oxide, silicon(IV) oxide, chromium(III) oxide, manganese(IV) oxide, iron(III) oxide, iron(II,III) oxide, copper(II) oxide, and lead(II,IV) oxide. In a thermochemical survey comprising twenty-five metals and thirty-two metal oxides, 288 out of 800 binary combinations were characterized by adiabatic temperatures greater than 2000 K ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermite Mix
Thermite () is a pyrotechnic composition of metal powder and metal oxide. When ignited by heat or chemical reaction, thermite undergoes an exothermic reduction-oxidation (redox) reaction. Most varieties are not explosive, but can create brief bursts of heat and high temperature in a small area. Its form of action is similar to that of other fuel-oxidizer mixtures, such as black powder. Thermites have diverse compositions. Fuels include aluminum, magnesium, titanium, zinc, silicon, and boron. Aluminum is common because of its high boiling point and low cost. Oxidizers include bismuth(III) oxide, boron(III) oxide, silicon(IV) oxide, chromium(III) oxide, manganese(IV) oxide, iron(III) oxide, iron(II,III) oxide, copper(II) oxide, and lead(II,IV) oxide. In a thermochemical survey comprising twenty-five metals and thirty-two metal oxides, 288 out of 800 binary combinations were characterized by adiabatic temperatures greater than 2000 K. Combinations like these, which possess th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exothermic Welding
Exothermic welding, also known as exothermic bonding, thermite welding (TW), and thermit welding, is a welding process that employs molten metal to permanently join the conductors. The process employs an exothermic reaction of a thermite composition to heat the metal, and requires no external source of heat or current. The chemical reaction that produces the heat is an aluminothermic reaction between aluminium powder and a metal oxide. Overview In exothermic welding, aluminium dust reduces the oxide of another metal, most commonly iron oxide, because aluminium is highly reactive. Iron(III) oxide is commonly used: :\mathrm The products are aluminium oxide, free elemental iron, and a large amount of heat. The reactants are commonly powdered and mixed with a binder to keep the material solid and prevent separation. Commonly the reacting composition is five parts iron oxide red (rust) powder and three parts aluminium powder by weight, ignited at high temperatures. A strongly e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyrotechnic Composition
A pyrotechnic composition is a substance or mixture of substances designed to produce an effect by heat, light, sound, gas/smoke or a combination of these, as a result of non-detonative self-sustaining exothermic reaction, exothermic chemical reactions. Pyrotechnic substances do not rely on oxygen from external sources to sustain the reaction. Types Basic types of pyrotechnic compositions are: * flash powder – burns very fast, produces explosions and/or bright flashes of light * gunpowder – burns slower than flash powder, produces large amount of gases * solid propellants – produce large amount of hot gases, used as sources of kinetic energy for rockets and projectiles * pyrotechnic initiators – produce large amount of heat, flames, and/or hot sparks, used to ignite other compositions * gas generators – produce large amount of gas, either high volume at short time (for actuators and ejection charges, often using solid propellants) or controlled flow rate (e.g. chemical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Incendiary Device
Incendiary weapons, incendiary devices, incendiary munitions, or incendiary bombs are weapons designed to start fires. They may destroy structures or sensitive equipment using fire, and sometimes operate as anti-personnel weapon, anti-personnel weaponry. Incendiaries utilize materials such as napalm, thermite, magnesium, magnesium powder, chlorine trifluoride, or white phosphorus munitions, white phosphorus. Though colloquially often called "bombs", they are not explosives but in fact operate to slow the process of chemical reactions and use Combustion, ignition rather than detonation to start or maintain the reaction. Napalm, for example, is petroleum especially thickened with certain chemicals into a gel to slow, but not stop, combustion, releasing energy over a longer time than an explosive device. In the case of napalm, the gel adheres to surfaces and resists suppression. Pre-modern history A range of early thermal weapons were utilized by Ancient history, ancient, Middle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hans Goldschmidt
Johannes Wilhelm "Hans" Goldschmidt (18 January 1861 – 21 May 1923) was a German chemist notable as the discoverer of the Thermite reaction. He was also co-owner of the Chemische Fabrik Th. Goldschmidt, as of 1911 Th. Goldschmidt AG (later to become part of Evonik Industries) and its most important chemist. The reaction, also called the Goldschmidt process, is used for thermite welding, often used to join railway tracks. Thermites have also been used in metal refining, disabling munitions, and in incendiary weapons. Some thermite-like mixtures are used as pyrotechnic initiators in fireworks. His grave is preserved in the Protestant ''Friedhof I der Jerusalems- und Neuen Kirchengemeinde'' (Cemetery No. I of the congregations of Jerusalem's Church and New Church) in Berlin-Kreuzberg, south of Hallesches Tor. Biography He was born in Berlin on 18 January 1861. He was a student of Robert Bunsen. His father, Theodor Goldschmidt, was the founder of the chemical company ''Chemis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Railway Track
Railway track ( and UIC terminology) or railroad track (), also known as permanent way () or "P way" ( and Indian English), is the structure on a railway or railroad consisting of the rails, fasteners, sleepers ( railroad ties in American English) and ballast (or slab track), plus the underlying subgrade. It enables trains to move by providing a dependable, low-friction surface on which steel wheels can roll. Early tracks were constructed with wooden or cast-iron rails, and wooden or stone sleepers. Since the 1870s, rails have almost universally been made from steel. Historical development The first railway in Britain was the Wollaton wagonway, built in 1603 between Wollaton and Strelley in Nottinghamshire. It used wooden rails and was the first of about 50 wooden-railed tramways built over the subsequent 164 years. These early wooden tramways typically used rails of oak or beech, attached to wooden sleepers with iron or wooden nails. Gravel or small stones were pa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Reaction
A chemical reaction is a process that leads to the chemistry, chemical transformation of one set of chemical substances to another. When chemical reactions occur, the atoms are rearranged and the reaction is accompanied by an Gibbs free energy, energy change as new products are generated. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking of chemical bonds between atoms, with no change to the Atomic nucleus, nuclei (no change to the elements present), and can often be described by a chemical equation. Nuclear chemistry is a sub-discipline of chemistry that involves the chemical reactions of unstable and radioactive Chemical element, elements where both electronic and nuclear changes can occur. The substance (or substances) initially involved in a chemical reaction are called reagent, reactants or reagents. Chemical reactions are usually characterized by a chemical change, and they yield one or more Product (c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exothermic
In thermodynamics, an exothermic process () is a thermodynamic process or reaction that releases energy from the system to its surroundings, usually in the form of heat, but also in a form of light (e.g. a spark, flame, or flash), electricity (e.g. a battery), or sound (e.g. explosion heard when burning hydrogen). The term ''exothermic'' was first coined by 19th-century French chemist Marcellin Berthelot. The opposite of an exothermic process is an endothermic process, one that absorbs energy, usually in the form of heat. The concept is frequently applied in the physical sciences to chemical reactions where chemical bond energy is converted to thermal energy (heat). Two types of chemical reactions Exothermic and endothermic describe two types of chemical reactions or systems found in nature, as follows: Exothermic An exothermic reaction occurs when heat is released to the surroundings. According to the IUPAC, an exothermic reaction is "a reaction for which the overall stand ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromium(III) Oxide
Chromium(III) oxide (or chromia) is an inorganic compound with the formula . It is one of the principal oxides of chromium and is used as a pigment. In nature, it occurs as the rare mineral eskolaite. Structure and properties has the corundum structure, consisting of a hexagonal close packed array of oxide anions with two thirds of the octahedral holes occupied by chromium. Similar to corundum, is a hard, brittle material (Mohs hardness 8 to 8.5). It is antiferromagnetic up to , the Néel temperature. It is not readily attacked by acids. Occurrence occurs naturally as the mineral eskolaite, which is found in chromium-rich tremolite skarns, metaquartzites, and chlorite veins. Eskolaite is also a rare component of chondrite meteorites. The mineral is named after Finnish geologist Pentti Eskola. Production The Parisians Pannetier and Binet first prepared the transparent hydrated form of in 1838 via a secret process, sold as a pigment. It is derived from the mineral chromi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Copper(II) Oxide
Copper(II) oxide or cupric oxide is an inorganic compound with the formula CuO. A black solid, it is one of the two stable oxides of copper, the other being Cu2O or copper(I) oxide (cuprous oxide). As a mineral, it is known as tenorite, or sometimes black copper. It is a product of copper mining and the precursor to many other copper-containing products and chemical compounds. Production It is produced on a large scale by pyrometallurgy, as one stage in extracting copper from its ores. The ores are treated with an aqueous mixture of ammonium carbonate, ammonia, and oxygen to ultimately give copper(II) ammine complex carbonates, such as . After extraction from the residues and after separation from iron, lead, etc. impurities, the carbonate salt is decomposed with steam to give CuO. It can be formed by heating copper in air at around 300–800 °C: : For laboratory uses, copper(II) oxide is conveniently prepared by pyrolysis of copper(II) nitrate or basic copper(I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnesium
Magnesium is a chemical element; it has Symbol (chemistry), symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic table), it occurs naturally only in combination with other elements and almost always has an oxidation state of +2. It reacts readily with air to form a thin Passivation (chemistry), passivation coating of magnesium oxide that inhibits further corrosion of the metal. The free metal burns with a brilliant-white light. The metal is obtained mainly by electrolysis of magnesium Salt (chemistry), salts obtained from brine. It is less dense than aluminium and is used primarily as a component in strong and lightweight magnesium alloy, alloys that contain aluminium. In the cosmos, magnesium is produced in large, aging stars by the sequential addition of three Helium nucleus, helium nuclei to a carbon nucleus. When such stars explo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iron(III) Oxide
Iron(III) oxide or ferric oxide is the inorganic compound with the formula . It occurs in nature as the mineral hematite, which serves as the primary source of iron for the steel industry. It is also known as red iron oxide, especially when used in pigments. It is one of the three main oxides of iron, the other two being iron(II) oxide (FeO), which is rare; and iron(II,III) oxide (), which also occurs naturally as the mineral magnetite. Iron(III) oxide is often called rust, since rust shares several properties and has a similar composition; however, in chemistry, rust is considered an ill-defined material, described as hydrous ferric oxide. Ferric oxide is readily attacked by even weak acids. It is a weak oxidising agent, most famously when reduced by aluminium in the thermite reaction. Structure can be obtained in various polymorphs. In the primary polymorph, α, iron adopts octahedral coordination geometry. That is, each Fe center is bound to six oxygen ligands. In t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
