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Copper–tungsten
Copper–tungsten (tungsten–copper, CuW, or WCu) is a mixture of copper and tungsten. As copper and tungsten are not mutually soluble, the material is composed of distinct particles of one metal dispersed in a matrix of the other one. The microstructure is therefore rather a metal matrix composite instead of a true alloy. The material combines the properties of both metals, resulting in a material that is heat-resistant, ablation-resistant, highly thermally and electrically conductive, and easy to machine. Parts are made from the CuW composite by pressing the tungsten particles into the desired shape, sintering the compacted part, then infiltrating with molten copper. Sheets, rods, and bars of the composite mixture are available as well. Commonly used copper tungsten mixtures contains 10–50 wt.% of copper, the remaining portion being mostly tungsten. The typical properties is dependent on its composition. The mixture with less wt.% of copper has higher density, higher hardn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Copper
Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orange color. Copper is used as a conductor of heat and electricity, as a building material, and as a constituent of various metal alloys, such as sterling silver used in jewelry, cupronickel used to make marine hardware and coins, and constantan used in strain gauges and thermocouples for temperature measurement. Copper is one of the few metals that can occur in nature in a directly usable metallic form ( native metals). This led to very early human use in several regions, from circa 8000 BC. Thousands of years later, it was the first metal to be smelted from sulfide ores, circa 5000 BC; the first metal to be cast into a shape in a mold, c. 4000 BC; and the first metal to be purposely alloyed with another metal, tin, to create ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chip Carrier
In electronics, a chip carrier is one of several kinds of surface-mount technology packages for integrated circuits (commonly called "chips"). Connections are made on all four edges of a square package; compared to the internal cavity for mounting the integrated circuit, the package overall size is large.Kenneth Jackson, Wolfgang Schroter, (ed), ''Handbook of Semiconductor Technology Volume 2'',Wiley VCH, 2000, ,page 627 Types Chip carriers may have either J-shaped metal leads for connections by solder or by a socket, or may be lead-less with metal pads for connections. If the leads extend beyond the package, the preferred description is " flat pack". Chip carriers can be smaller than dual in-line packages and since they use all four edges of the package they can have a larger pin count. Chip carriers may be made of ceramic or plastic. Some forms of chip carrier package are standardized in dimensions and registered with trade industry associations such as JEDEC. Other forms are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tungsten Compounds
Tungsten, or wolfram, is a chemical element with the symbol W and atomic number 74. Tungsten is a rare metal found naturally on Earth almost exclusively as compounds with other elements. It was identified as a new element in 1781 and first isolated as a metal in 1783. Its important ores include scheelite and wolframite, the latter lending the element its alternate name. The free element is remarkable for its robustness, especially the fact that it has the highest melting point of all known elements barring carbon (which sublimes at normal pressure), melting at . It also has the highest boiling point, at . Its density is , comparable with that of uranium and gold, and much higher (about 1.7 times) than that of lead. Polycrystalline tungsten is an intrinsically brittle and hard material (under standard conditions, when uncombined), making it difficult to work. However, pure single-crystalline tungsten is more ductile and can be cut with a hard-steel hacksaw. Tungsten occurs in many ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Copper Alloys
Copper alloys are metal alloys that have copper as their principal component. They have high resistance against corrosion. The best known traditional types are bronze, where tin is a significant addition, and brass, using zinc instead. Both of these are imprecise terms, having both been commonly referred to as lattens in the past. Today the term ''copper alloy'' tends to be substituted, especially by museums. Composition The similarity in external appearance of the various alloys, along with the different combinations of elements used when making each alloy, can lead to confusion when categorizing the different compositions. There are as many as 400 different copper and copper alloy compositions loosely grouped into the categories: copper, high copper alloy, brasses, bronzes, copper nickels, copper–nickel–zinc (nickel silver), leaded copper, and special alloys. The following table lists the principal alloying element for four of the more common types used in modern i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sulfur Hexafluoride Circuit Breaker
Sulfur hexafluoride circuit breakers protect electrical power stations and distribution systems by interrupting electric currents, when tripped by a protective relay. Instead of oil, air, or a vacuum, a sulfur hexafluoride circuit breaker uses sulfur hexafluoride (SF6) gas to cool and quench the arc on opening a circuit. Advantages over other media include lower operating noise and no emission of hot gases, and relatively low maintenance. Developed in the 1950s and onward, SF6 circuit breakers are widely used in electrical grids at transmission voltages up to 800 kV, as generator circuit breakers, and in distribution systems at voltages up to 35 kV. Sulfur hexafluoride circuit breakers may be used as self-contained apparatus in outdoor air-insulated substations or may be incorporated into gas-insulated switchgear which allows compact installations at high voltages. Operating principle Current interruption in a high-voltage circuit breaker is obtained by separating two contacts ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Graphite
Graphite () is a crystalline form of the element carbon. It consists of stacked layers of graphene. Graphite occurs naturally and is the most stable form of carbon under standard conditions. Synthetic and natural graphite are consumed on large scale (300 kton/year, in 1989) for uses in pencils, lubricants, and electrodes. Under high pressures and temperatures it converts to diamond. It is a weak conductor of heat and electricity. Types and varieties Natural graphite The principal types of natural graphite, each occurring in different types of ore deposits, are * Crystalline small flakes of graphite (or flake graphite) occurs as isolated, flat, plate-like particles with hexagonal edges if unbroken. When broken the edges can be irregular or angular; * Amorphous graphite: very fine flake graphite is sometimes called amorphous; * Lump graphite (or vein graphite) occurs in fissure veins or fractures and appears as massive platy intergrowths of fibrous or acicular crystalline ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oil Well Completion
Well completion is the process of making a well ready for production (or injection) after drilling operations. This principally involves preparing the bottom of the hole to the required specifications, running in the production tubing and its associated down hole tools as well as perforating and stimulating as required. Sometimes, the process of running in and cementing the casing is also included. After a well has been drilled, should the drilling fluids be removed, the well would eventually close in upon itself. Casing ensures that this will not happen while also protecting the wellstream from outside incumbents, like water or sand. Lower completion (downhole completion) This refers to the portion of the well across the production or injection zone. The well designer has many tools and options available to design the lower completion (downhole completion) according to the conditions of the reservoir. Typically, the lower completion is set across the productive zone using a liner ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shaped Charge
A shaped charge is an explosive charge shaped to form an explosively formed penetrator (EFP) to focus the effect of the explosive's energy. Different types of shaped charges are used for various purposes such as cutting and forming metal, initiating nuclear weapons, penetrating armor, or perforating wells in the oil and gas industry. A typical modern shaped charge, with a metal liner on the charge cavity, can penetrate armor steel to a depth of seven or more times the diameter of the charge (charge diameters, CD), though greater depths of 10 CD and above have been achieved. Contrary to a misconception (possibly resulting from the acronym for ''high-explosive anti-tank'', HEAT) the shaped charge EFP jet does not depend in any way on heating or melting for its effectiveness; that is, the EFP jet from a shaped charge does not melt its way through armor, as its effect is purely kinetic in nature – however the process does create significant heat and often has a significant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dymalloy
Dymalloy is a metal matrix composite consisting of 20% copper and 80% silver alloy matrix with type I diamond. It has very high thermal conductivity of 420 W/(m·K), and its thermal expansion can be adjusted to match other materials, e.g. silicon and gallium arsenide chips. It is chiefly used in microelectronics as substrate for high power and high density multi-chip modules, where it aids with removal of waste heat. Dymalloy was developed as part of CRADA between Sun Microsystems and Lawrence Livermore National Laboratory. It was first researched for use in space-based electronics for the Brilliant Pebbles project. Dymalloy is prepared from diamond powder of about 25 micrometers size. The grains are coated by physical vapor deposition with 10 nanometers thick layer of alloy of tungsten with 26% rhenium, forming a tungsten carbide layer that assists bonding, then coated with 100 nanometers of copper to avoid carbide oxidation, then compacted in a mold and infiltrated with molt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
AlSiC
AlSiC, pronounced "alsick", is a metal matrix composite consisting of aluminium matrix with silicon carbide particles. It has high thermal conductivity (180–200 W/m K), and its thermal expansion can be adjusted to match other materials, e.g. silicon and gallium arsenide chips and various ceramics. It is chiefly used in microelectronics as substrate for power semiconductor devices and high density multi-chip modules, where it aids with removal of waste heat. Several variants exist: *AlSiC-9, containing 37 vol.% of A 356.2 aluminium alloy and 63 vol.% silicon carbide. Its thermal conductivity is 190–200 W/m K. Its thermal expansion roughly matches gallium arsenide, silicon, indium phosphide, alumina, aluminium nitride, silicon nitride, and Direct Bonded Copper aluminium nitride. It is also compatible with some low temperature co-fired ceramics, e.g. Ferro A6M and A6S, Heraeus CT 2000, and Kyocera GL560. Its density at 25 °C is 3.01 g/cm3. *AlSiC-10, containing 45 vol.% o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ceramic
A ceramic is any of the various hard, brittle, heat-resistant and corrosion-resistant materials made by shaping and then firing an inorganic, nonmetallic material, such as clay, at a high temperature. Common examples are earthenware, porcelain, and brick. The earliest ceramics made by humans were pottery objects (''pots,'' ''vessels or vases'') or figurines made from clay, either by itself or mixed with other materials like silica, hardened and sintered in fire. Later, ceramics were glazed and fired to create smooth, colored surfaces, decreasing porosity through the use of glassy, amorphous ceramic coatings on top of the crystalline ceramic substrates. Ceramics now include domestic, industrial and building products, as well as a wide range of materials developed for use in advanced ceramic engineering, such as in semiconductors. The word "'' ceramic''" comes from the Greek word (), "of pottery" or "for pottery", from (), "potter's clay, tile, pottery". The earliest kno ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gallium Arsenide
Gallium arsenide (GaAs) is a III-V direct band gap semiconductor with a Zincblende (crystal structure), zinc blende crystal structure. Gallium arsenide is used in the manufacture of devices such as microwave frequency integrated circuits, monolithic microwave integrated circuits, infrared light-emitting diodes, laser diodes, solar cells and optical windows. GaAs is often used as a substrate material for the epitaxial growth of other III-V semiconductors, including indium gallium arsenide, aluminum gallium arsenide and others. Preparation and chemistry In the compound, gallium has a +3 oxidation state. Gallium arsenide single crystals can be prepared by three industrial processes: * The vertical gradient freeze (VGF) process. * Crystal growth using a horizontal zone furnace in the Bridgman-Stockbarger technique, in which gallium and arsenic vapors react, and free molecules deposit on a seed crystal at the cooler end of the furnace. * Liquid encapsulated Czochralski process, Czoch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
