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Native Iron
Telluric iron, also called native iron, is iron that originated on Earth, and is found in a metallic form rather than as an ore. Telluric iron is extremely rare, with only one known major deposit in the world, located in Greenland. Introduction With the exception of its molten core, nearly all elemental iron on Earth is found as iron ores. All metallic iron was thought to have been transformed into iron oxides during the Great Oxidation Event, beginning roughly 2 billion years ago, among other theories. Until the late 1800s, iron as a native metal was only a matter of speculation, outside of isolated Greenland. The only known, terrestrial iron in metallic form was found as meteorites, which were deposited onto the Earth from outer space. Telluric iron is so named after the Latin word ''Tellus'', meaning "Earth" (the planet, as opposed to ''terra'' meaning "earth": the land, ground or soil), combined with the suffix ''-ic'' meaning "of" or "born from", differentiating it fr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Basalt
Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial planet, rocky planet or natural satellite, moon. More than 90% of all volcanic rock on Earth is basalt. Rapid-cooling, fine-grained basalt is chemically equivalent to slow-cooling, coarse-grained gabbro. The eruption of basalt lava is observed by geologists at about 20 volcanoes per year. Basalt is also an important rock type on other planetary bodies in the Solar System. For example, the bulk of the plains of volcanism on Venus, Venus, which cover ~80% of the surface, are basaltic; the lunar mare, lunar maria are plains of flood-basaltic lava flows; and basalt is a common rock on the surface of Mars. Molten basalt lava has a low viscosity due to its relatively low silica content (between 45% and 52%), resulting in rapidly moving lava flo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbon
Carbon () is a chemical element; it has chemical symbol, symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—meaning that its atoms are able to form up to four covalent bonds due to its valence shell exhibiting 4 electrons. It belongs to group 14 of the periodic table. Carbon makes up about 0.025 percent of Earth's crust. Three Isotopes of carbon, isotopes occur naturally, carbon-12, C and carbon-13, C being stable, while carbon-14, C is a radionuclide, decaying with a half-life of 5,700 years. Carbon is one of the timeline of chemical element discoveries#Pre-modern and early modern discoveries, few elements known since antiquity. Carbon is the 15th abundance of elements in Earth's crust, most abundant element in the Earth's crust, and the abundance of the chemical elements, fourth most abundant element in the universe by mass after hydrogen, helium, and oxygen. Carbon's abundance, its unique diversity of organic compounds, and its unusual abi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cohenite
Cohenite is a naturally occurring iron carbide mineral with the chemical structure ( Fe, Ni, Co)3 C. This forms a hard, shiny, silver mineral which was named by E. Weinschenk in 1889 after the German mineralogist Emil Cohen, who first described and analysed material from the Magura meteorite found near Slanica, Žilina Region, Slovakia. Cohenite is found in rod-like crystals in iron meteorites.Vagn F. Buchwald, ''Handbook of Iron Meteorites,'' University of California Press, 1975 On Earth cohenite is stable only in rocks which formed in a strongly reducing environment and contain native iron deposits. Such conditions existed in some places where molten magmas invaded coal deposits, e.g. on Disko Island in Greenland, or at the Bühl near Kassel in Germany. Associated minerals include native iron, schreibersite, troilite and wüstite. Similar iron carbides occur also in technical iron alloys and are called cementite. See also * Edscottite * Glossary of meteoritics *List ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cementite
Cementite (or iron carbide) is a compound of iron and carbon, more precisely an intermediate transition metal carbide with the formula Fe3C. By weight, it is 6.67% carbon and 93.3% iron. It has an orthorhombic crystal structure. It is a hard, brittle material, normally classified as a ceramic in its pure form, and is a frequently found and important constituent in ferrous metallurgy. While cementite is present in most steels and cast irons, it is produced as a raw material in the iron carbide process, which belongs to the family of alternative ironmaking technologies. The name ''cementite'' originated from the theory of Floris Osmond and J. Werth, in which the structure of solidified steel consists of a kind of cellular tissue, with ferrite as the nucleus and Fe3C the envelope of the cells. The carbide therefore ''cemented'' the iron. Metallurgy In the iron–carbon system (i.e. plain-carbon steels and cast irons) it is a common constituent because ferrite can contain at m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pearlite
Pearlite is a two-phased, lamellar (or layered) structure composed of alternating layers of ferrite (87.5 wt%) and cementite (12.5 wt%) that occurs in some steels and cast irons. During slow cooling of an iron-carbon alloy, pearlite forms by a eutectoid reaction as austenite cools below (the eutectoid temperature). Pearlite is a microstructure occurring in many common grades of steels. Composition The eutectoid composition of austenite is approximately 0.8% carbon; steel with less carbon content ( hypoeutectoid steel) will contain a corresponding proportion of relatively pure ferrite crystallites that do not participate in the eutectoid reaction and cannot transform into pearlite. Likewise steels with higher carbon content ( hypereutectoid steels) will form cementite before reaching the eutectoid point. The proportion of ferrite and cementite forming above the eutectoid point can be calculated from the iron/iron—carbide equilibrium phase diagram using the lever ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cold Working
In metallurgy, cold forming or cold working is any metalworking process in which metal is shaped below its recrystallization temperature, usually at the ambient temperature at or near room temperature. Such processes are contrasted with hot working techniques like hot rolling, forging, welding, etc. The same or similar terms are used in glassmaking for the equivalents; for example cut glass is made by "cold work", cutting or grinding a formed object. Cold forming techniques are usually classified into four major groups: squeezing, bending, drawing, and shearing. They generally have the advantage of being simpler to carry out than hot working techniques. Unlike hot working, cold working causes the crystal grains and inclusions to distort following the flow of the metal; which may cause work hardening and anisotropic material properties. Work hardening makes the metal harder, stiffer, and stronger, but less plastic, and may cause cracks of the piece. The possible us ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eutectoid
A eutectic system or eutectic mixture ( ) is a type of a homogeneous mixture that has a melting point lower than those of the constituents. The lowest possible melting point over all of the mixing ratios of the constituents is called the ''eutectic temperature''. On a phase diagram, the eutectic temperature is seen as the eutectic point (see plot on the right). Non-eutectic mixture ratios have different melting temperatures for their different constituents, since one component's lattice will melt at a lower temperature than the other's. Conversely, as a non-eutectic mixture cools down, each of its components solidifies into a lattice at a different temperature, until the entire mass is solid. A non-eutectic mixture thus does not have a single melting/freezing point temperature at which it changes phase, but rather a temperature at which it changes between liquid and slush (known as the liquidus) and a lower temperature at which it changes between slush and solid (the solidus) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alloy
An alloy is a mixture of chemical elements of which in most cases at least one is a metal, metallic element, although it is also sometimes used for mixtures of elements; herein only metallic alloys are described. Metallic alloys often have properties that differ from those of the pure elements from which they are made. The vast majority of metals used for commercial purposes are alloyed to improve their properties or behavior, such as increased strength, hardness or corrosion resistance. Metals may also be alloyed to reduce their overall cost, for instance alloys of gold and Copper(II) sulfate, copper. A typical example of an alloy is SAE 304 stainless steel, 304 grade stainless steel which is commonly used for kitchen utensils, pans, knives and forks. Sometime also known as 18/8, it as an alloy consisting broadly of 74% iron, 18% chromium and 8% nickel. The chromium and nickel alloying elements add strength and hardness to the majority iron element, but their main function is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phase (matter)
In the physical sciences, a phase is a region of material that is chemically uniform, physically distinct, and (often) mechanically separable. In a system consisting of ice and water in a glass jar, the ice cubes are one phase, the water is a second phase, and the humid air is a third phase over the ice and water. The glass of the jar is a different material, in its own separate phase. (See .) More precisely, a phase is a region of space (a thermodynamic system), throughout which all physical properties of a material are essentially uniform. Examples of physical properties include density, index of refraction, magnetization and chemical composition. The term ''phase'' is sometimes used as a synonym for state of matter, but there can be several immiscible phases of the same state of matter (as where oil and water separate into distinct phases, both in the liquid state). Types of phases Distinct phases may be described as different states of matter such as gas, liquid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reducing Environment
A reducing atmosphere is an atmosphere in which oxidation is prevented by the absence of oxygen and other oxidizing gases or vapours, and which may contain actively reductant gases such as hydrogen, carbon monoxide, methane and hydrogen sulfide that would be readily oxidized to remove any free oxygen. Although Early Earth had a reducing prebiotic atmosphere prior to the Proterozoic eon, starting at about 2.5 billion years ago in the late Neoarchaean period, the Earth's atmosphere experienced a significant rise in oxygen and transitioned to an oxidizing atmosphere with a surplus of molecular oxygen (dioxygen, O2) as the primary oxidizing agent. Foundry operations The principal mission of an iron foundry is the conversion of iron oxides (purified iron ores) to iron metal. This reduction is usually effected using a reducing atmosphere consisting of some mixture of natural gas, hydrogen (H2), and carbon monoxide. The byproduct is carbon dioxide. Metal processing In metal pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Smelting
Smelting is a process of applying heat and a chemical reducing agent to an ore to extract a desired base metal product. It is a form of extractive metallurgy that is used to obtain many metals such as iron-making, iron, copper extraction, copper, silver mining#Ore processing, silver, tin, lead smelting, lead and zinc smelting, zinc. Smelting uses heat and a chemical reducing agent to decompose the ore, driving off other elements as gases or slag and leaving the metal behind. The reducing agent is commonly a fossil-fuel source of carbon, such as carbon monoxide from incomplete combustion of coke (fuel), coke—or, in earlier times, of charcoal. The oxygen in the ore binds to carbon at high temperatures, as the Chemical energy, chemical potential energy of the bonds in carbon dioxide () is lower than that of the bonds in the ore. Sulfide ores such as those commonly used to obtain copper, zinc or lead, are roasting (metallurgy), roasted before smelting in order to convert the sulfid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subduction
Subduction is a geological process in which the oceanic lithosphere and some continental lithosphere is recycled into the Earth's mantle at the convergent boundaries between tectonic plates. Where one tectonic plate converges with a second plate, the heavier plate dives beneath the other and sinks into the mantle. A region where this process occurs is known as a subduction zone, and its surface expression is known as an arc-trench complex. The process of subduction has created most of the Earth's continental crust. Rates of subduction are typically measured in centimeters per year, with rates of convergence as high as 11 cm/year. Subduction is possible because the cold and rigid oceanic lithosphere is slightly denser than the underlying asthenosphere, the hot, ductile layer in the upper mantle. Once initiated, stable subduction is driven mostly by the negative buoyancy of the dense subducting lithosphere. The down-going slab sinks into the mantle largely under its own ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
