![]() Magnesium/Teflon/Viton is another pyrolant of this type. Fluoropolymers can be used in special formulations, Teflon with magnesium or aluminium being a relatively common example. All of these examples use aluminium as the reactive metal. Other oxides are occasionally used, such as MnO 2 in manganese thermite, Cr 2O 3 in chromium thermite, SiO 2 (quartz) in silicon thermite, or copper(II) oxide in copper thermite, but only for specialized purposes. Black iron(II,III) oxide (Fe 3O 4, magnetite) also works. Red iron(III) oxide (Fe 2O 3, commonly known as rust) is the most common iron oxide used in thermite. Types Ī thermite reaction taking place on a cast iron skillet The first commercial application of thermite was the welding of tram tracks in Essen in 1899. Goldschmidt was originally interested in producing very pure metals by avoiding the use of carbon in smelting, but he soon discovered the value of thermite in welding. Consequently, the reaction is sometimes called the "Goldschmidt reaction" or "Goldschmidt process". The thermite ( thermit) reaction was discovered in 1893 and patented in 1895 by German chemist Hans Goldschmidt. Thermites with nanosized particles are described by a variety of terms, such as metastable intermolecular composites, super-thermite, nano-thermite, and nanocomposite energetic materials. For example, a copper thermite reaction using copper oxide and elemental aluminium can be used for creating electric joints in a process called cadwelding, that produces elemental copper (it may react violently): Other metal oxides can be used, such as chromium oxide, to generate the given metal in its elemental form. The reactants are commonly powdered and mixed with a binder to keep the material solid and prevent separation. ![]() The products are aluminium oxide, elemental iron, and a large amount of heat. In the following example, elemental aluminium reduces the oxide of another metal, in this common example iron oxide, because aluminium forms stronger and more stable bonds with oxygen than iron: The sparks flying outwards are globules of molten iron trailing smoke in their wake. Some thermite-like mixtures are used as pyrotechnic initiators in fireworks.Ī thermite reaction using iron(III) oxide. Thermites have also been used in metal refining, disabling munitions, and in incendiary weapons. The reaction, also called the Goldschmidt process, is used for thermite welding, often used to join railway tracks. 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. Aluminium is common because of its high boiling point and low cost. Fuels include aluminium, magnesium, titanium, zinc, silicon, and boron. Its form of action is similar to that of other fuel-oxidizer mixtures, such as black powder. Most varieties are not explosive, but can create brief bursts of heat and high temperature in a small area. When ignited by heat or chemical reaction, thermite undergoes an exothermic reduction-oxidation (redox) reaction. Thermite ( / ˈ θ ɜːr m aɪ t/) is a pyrotechnic composition of metal powder and metal oxide. A thermite mixture using iron (III) oxide
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