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82-503: Phase I of the program started in February 1986 when development contracts were placed with six companies: AAI Corporation , Ares Incorporated , Colt's Manufacturing Company , Heckler & Koch (H&K), McDonnell Douglas Helicopter Systems (MDHS), and Steyr Mannlicher . Two weapons were cut from the list before Phase II started. The companies started an appeals process and were eventually re-instated, but too late to see testing before

164-425: A body-centered cubic structure and is the more stable form. The structure of the β phase is called A15 cubic ; it is metastable , but can coexist with the α phase at ambient conditions owing to non-equilibrium synthesis or stabilization by impurities. Contrary to the α phase which crystallizes in isometric grains, the β form exhibits a columnar habit . The α phase has one third of the electrical resistivity and

246-437: A sextuple bond between tungsten atoms — the highest known bond order among stable atoms. In 1781, Carl Wilhelm Scheele discovered that a new acid , tungstic acid , could be made from scheelite (at the time called tungsten). Scheele and Torbern Bergman suggested that it might be possible to obtain a new metal by reducing this acid. In 1783, José and Fausto Elhuyar found an acid made from wolframite that

328-496: A US court rejected General Electric 's attempt to patent it, overturning U.S. patent 1,082,933 granted in 1913 to William D. Coolidge . It is suggested that remnants of wolfram have been found in what may have been the garden of the astronomer/alchemist Tycho Brahe The name tungsten (which means ' heavy stone ' in Swedish and was the old Swedish name for the mineral scheelite and other minerals of similar density)

410-568: A colorless gas. At around 250 °C it will react with chlorine or bromine, and under certain hot conditions will react with iodine. Finely divided tungsten is pyrophoric . The most common formal oxidation state of tungsten is +6, but it exhibits all oxidation states from −2 to +6. Tungsten typically combines with oxygen to form the yellow tungstic oxide , WO 3 , which dissolves in aqueous alkaline solutions to form tungstate ions, WO 4 . Tungsten carbides (W 2 C and WC) are produced by heating powdered tungsten with carbon. W 2 C

492-426: A different atom such as phosphorus in place of the two central hydrogens in metatungstate produces a wide variety of heteropoly acids, such as phosphotungstic acid H 3 PW 12 O 40 . Tungsten trioxide can form intercalation compounds with alkali metals. These are known as bronzes ; an example is sodium tungsten bronze . In gaseous form, tungsten forms the diatomic species W 2 . These molecules feature

574-422: A half-life of (1.8 ± 0.2) × 10 years; on average, this yields about two alpha decays of W per gram of natural tungsten per year. This rate is equivalent to a specific activity of roughly 63 micro- becquerel per kilogram. This rate of decay is orders of magnitude lower than that observed in carbon or potassium as found on earth, which likewise contain small amounts of long-lived radioactive isotopes. Bismuth

656-459: A highly realistic simulated environment utilizing an interactive 3-D virtual aircraft environment. This realistic, 3-D virtual vehicle environment, as well as 2-D panels and displays allow students to navigate throughout the F-35 aircraft during maintenance training and select the virtual support equipment and tools required. A real F-35 portable maintenance aid is connected at each student station, allowing

738-638: A much lower superconducting transition temperature T C relative to the β phase: ca. 0.015 K vs. 1–4 K; mixing the two phases allows obtaining intermediate T C values. The T C value can also be raised by alloying tungsten with another metal (e.g. 7.9 K for W- Tc ). Such tungsten alloys are sometimes used in low-temperature superconducting circuits. Naturally occurring tungsten consists of four stable isotopes ( W, W, W, and W) and one very long-lived radioisotope, W. Theoretically, all five can decay into isotopes of element 72 ( hafnium ) by alpha emission , but only W has been observed to do so, with

820-508: A plastic-cased cartridge they called a chiclet due to its box-like profile. Their first loads used duplex or triplex loads of normal projectiles, but the recoil was too high, so these were replaced with flechettes , first with five of them in a 11-millimetre (.42 in) round, eventually three in an 8.6-millimetre (.338 in) round. Phase III began in August 1989, when AAI, Colt, HK, and Steyr entered weapon testing. AAI Corporation entered

902-530: A range of oxidation states. Notable examples include the trigonal prismatic W(CH 3 ) 6 and octahedral W(CO) 6 . The world's reserves of tungsten are 3,200,000 tonnes; they are mostly located in China (1,800,000 t), Canada (290,000 t), Russia (160,000 t), Vietnam (95,000 t) and Bolivia . As of 2017, China, Vietnam and Russia are the leading suppliers with 79,000, 7,200 and 3,100 tonnes, respectively. Canada had ceased production in late 2015 due to

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984-480: A sharp blow. The hardness and heat resistance of tungsten can contribute to useful alloys . A good example is high-speed steel , which can contain as much as 18% tungsten. Tungsten's high melting point makes tungsten a good material for applications like rocket nozzles , for example in the UGM-27 Polaris submarine-launched ballistic missile . Tungsten alloys are used in a wide range of applications, including

1066-481: A shortage of tungsten used in the shell core, caused in part by the Wolfram Crisis , limited their use. Tungsten has also been used in dense inert metal explosives , which use it as dense powder to reduce collateral damage while increasing the lethality of explosives within a small radius. Tungsten(IV) sulfide is a high temperature lubricant and is a component of catalysts for hydrodesulfurization . MoS 2

1148-499: A tungsten bar with gold, which has been observed since the 1980s, or taking an existing gold bar, drilling holes, and replacing the removed gold with tungsten rods. The densities are not exactly the same, and other properties of gold and tungsten differ, but gold-plated tungsten will pass superficial tests. Gold-plated tungsten is available commercially from China (the main source of tungsten), both in jewelry and as bars. Because it retains its strength at high temperatures and has

1230-729: A wide variety of operational systems. The Logistics & Technical Services business unit also provides depot maintenance equipment and services to domestic and international military aviation customers. AAI's test systems are used by every branch of the U.S. military. The Joint Systems Electronic Combat Systems Tester is part of the DoD's family of testers and currently supports flight-line electronic warfare testing for several U.S. military aircraft. The company's Advanced Boresight Equipment systems are used to align avionics and weapons systems onboard military aircraft and helicopters. AAI also produces radar simulators that simulate varied threat signals to test

1312-414: Is hypoallergenic , and is harder than gold alloys (though not as hard as tungsten carbide), making it useful for rings that will resist scratching, especially in designs with a brushed finish . Because the density is so similar to that of gold (tungsten is only 0.36% less dense), and its price of the order of one-thousandth, tungsten can also be used in counterfeiting of gold bars , such as by plating

1394-475: Is selective laser melting , which is a form of 3D printing and allows creating complex three-dimensional shapes. Tungsten is mainly used in the production of hard materials based on tungsten carbide (WC), one of the hardest carbides . WC is an efficient electrical conductor , but W 2 C is less so. WC is used to make wear-resistant abrasives , and "carbide" cutting tools such as knives, drills, circular saws , dies , milling and turning tools used by

1476-696: Is an aerospace and defense development and manufacturing firm, located in Hunt Valley, Maryland , US. Formerly a wholly owned subsidiary of United Industrial Corporation, AAI was acquired by Textron in 2007. It currently operates as a unit of Textron Systems and employs more than 2,000. AAI's products and services include unmanned aircraft and ground control technologies; training and simulation systems; automated aerospace test and maintenance equipment; armament systems; and logistical, engineering, supply chain and operational support services, multi-turreted tracked ground combat vehicles . The company's customers include

1558-522: Is currently working on the U.S. Army's Lightweight Small Arms Technologies project. It has also developed the PDCue Gunshot Detection System and TDCue acoustic detection systems for the U.S. Army and Marine Corps. Tungsten Tungsten (also called wolfram ) is a chemical element ; it has symbol W and atomic number 74. It is a rare metal found naturally on Earth almost exclusively as compounds with other elements. It

1640-476: Is heated with hydrogen or carbon to produce powdered tungsten. Because of tungsten's high melting point, it is not commercially feasible to cast tungsten ingots . Instead, powdered tungsten is mixed with small amounts of powdered nickel or other metals, and sintered . During the sintering process, the nickel diffuses into the tungsten, producing an alloy. Tungsten can also be extracted by hydrogen reduction of WF 6 : or pyrolytic decomposition : Tungsten

1722-484: Is in tungsten carbide , a wear-resistant metal used in metalworking , mining , and construction . About 50% of tungsten is used in tungsten carbide, with the remaining major use being alloys and steels: less than 10% is used other compounds. Tungsten is the only metal in the third transition series that is known to occur in biomolecules , being found in a few species of bacteria and archaea . However, tungsten interferes with molybdenum and copper metabolism and

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1804-465: Is more ductile and can be cut with a hard-steel hacksaw . Tungsten occurs in many alloys, which have numerous applications, including incandescent light bulb filaments, X-ray tubes , electrodes in gas tungsten arc welding , superalloys , and radiation shielding . Tungsten's hardness and high density make it suitable for military applications in penetrating projectiles . Tungsten compounds are often used as industrial catalysts . Its largest use

1886-642: Is more commonly used for such applications. Tungsten oxides are used in ceramic glazes and calcium / magnesium tungstates are used widely in fluorescent lighting . Crystal tungstates are used as scintillation detectors in nuclear physics and nuclear medicine . Other salts that contain tungsten are used in the chemical and tanning industries. Tungsten oxide (WO 3 ) is incorporated into selective catalytic reduction (SCR) catalysts found in coal-fired power plants. These catalysts convert nitrogen oxides ( NO x ) to nitrogen (N 2 ) and water (H 2 O) using ammonia (NH 3 ). The tungsten oxide helps with

1968-489: Is not traded as a futures contract and cannot be tracked on exchanges like the London Metal Exchange . The tungsten industry often uses independent pricing references such as Argus Media or Metal Bulletin as a basis for contracts. The prices are usually quoted for tungsten concentrate or WO 3 . Approximately half of the tungsten is consumed for the production of hard materials – namely tungsten carbide – with

2050-658: Is problematic even in depleted form, or where uranium's additional pyrophoric properties are not desired (for example, in ordinary small arms bullets designed to penetrate body armor). Similarly, tungsten alloys have also been used in shells , grenades , and missiles , to create supersonic shrapnel. Germany used tungsten during World War II to produce shells for anti-tank gun designs using the Gerlich squeeze bore principle to achieve very high muzzle velocity and enhanced armor penetration from comparatively small caliber and light weight field artillery. The weapons were highly effective but

2132-426: Is resistant to chemical attack, although it reacts strongly with chlorine to form tungsten hexachloride (WCl 6 ). In aqueous solution, tungstate gives the heteropoly acids and polyoxometalate anions under neutral and acidic conditions. As tungstate is progressively treated with acid, it first yields the soluble, metastable "paratungstate A" anion , W 7 O 24 , which over time converts to

2214-450: Is somewhat toxic to most forms of animal life. In its raw form, tungsten is a hard steel-grey metal that is often brittle and hard to work . Purified, monocrystalline tungsten retains its hardness (which exceeds that of many steels), and becomes malleable enough that it can be worked easily. It is worked by forging , drawing , or extruding but it is more commonly formed by sintering . Of all metals in pure form, tungsten has

2296-529: Is still registered as an active corporation in the State of Maryland under the name, AAI Corporation. AAI is one of a limited number of companies engaged in the design and full-rate production of a successfully fielded, operational unmanned aircraft system (UAS) for the DoD. AAI first began development work on the unmanned systems product line in 1985, winning a competitive fly-off with its Pioneer Remotely Piloted Vehicle. The company's unmanned aircraft systems include

2378-616: Is strictly regulated by the Chinese Government, which fights illegal mining and excessive pollution originating from mining and refining processes. There is a large deposit of tungsten ore on the edge of Dartmoor in the United Kingdom , which was exploited during World War I and World War II as the Hemerdon Mine . Following increases in tungsten prices, this mine was reactivated in 2014, but ceased activities in 2018. Within

2460-623: Is the Aerosonde Mark 4.7 small unmanned aircraft system. In late 2009, AAI conducted a shipboard demonstration of the system aboard the M80 Stiletto ship. In September 2008, AAI announced that it had teamed with Aeronautics Ltd. to provide the Orbiter miniature UAS in selected markets. The company's One System Ground Control Station is fielded as part of the Shadow Tactical UAS, as well as

2542-468: Is to be based on the Carter PAV . In 2014, Carter said they bought back the license from AAI and is seeking production partners outside USA. AAI was developing an RQ-7 Shadow , also with a Carter rotor on top for vertical take-off and landing , to fly in 2012. AAI also intends to use this technology as the basis for their proposal to DARPAs "Flying Humvee" Transformer program. In March 2019,

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2624-539: Is used in English, French, and many other languages as the name of the element, but wolfram (or volfram ) is used in most European (especially Germanic and Slavic) languages and is derived from the mineral wolframite , which is the origin of the chemical symbol W . The name wolframite is derived from German wolf rahm ( ' wolf soot, wolf cream ' ), the name given to tungsten by Johan Gottschalk Wallerius in 1747. This, in turn, derives from Latin lupi spuma ,

2706-695: The Carrock mine from the German owned Cumbrian Mining Company and, during World War I , restrict German access elsewhere. In World War II , tungsten played a more significant role in background political dealings. Portugal, as the main European source of the element, was put under pressure from both sides , because of its deposits of wolframite ore at Panasqueira . Tungsten's desirable properties such as resistance to high temperatures, its hardness and density, and its strengthening of alloys made it an important raw material for

2788-579: The EU , the Austrian Felbertal scheelite deposit is one of the few producing tungsten mines. Portugal is one of Europe's main tungsten producers, with 121 kt of contained tungsten in mineral concentrates from 1910 to 2020, accounting for roughly 3.3% of the global production. Tungsten is considered to be a conflict mineral due to the unethical mining practices observed in the Democratic Republic of

2870-475: The United States Department of Defense (DoD) and its prime contractors, allied foreign government ministries of defense, and other United States federal agencies. AAI Corporation originated as Aircraft Armaments, Inc. in August 1950, founded by six aviation and defense industry professionals. It was renamed AAI Corporation in the late 1950s. AAI's parent company, United Industrial Corporation (UIC),

2952-522: The ACR program ended. Eugene Stoner ’s Ares Incorporated also entered their Advanced Individual Weapon System (AIWS), which used a 5mm tracer round, but had to withdraw due to ongoing problems. The AIWS shared some features with the Steyr entry, notably the "rising chamber" action and "telescoped" cartridge. McDonnell Douglas Helicopter Systems, originally Hughes Helicopters , planned to enter their design using

3034-496: The ACR tests held 45 rounds in a single long magazine lying along the top of the barrel, leading to a distinctive and somewhat blocky appearance. The last entry submitted was the Steyr ACR , another fléchette-firing weapon. The Steyr differed from the AAI in the details of the round, which used a plastic shell casing to reduce weight. The firing mechanism was quite complex as a result, moving

3116-448: The ACR trials. The basic idea of the duplex load is to increase the number of projectiles fired, which is the primary determinant of battlefield casualties. However, they significantly reduced accuracy, requiring the user to also carry traditional ammunition for long-range shots. Although all the designs worked well, none managed to meet or even approach the 100% improvement over the M16A2 that

3198-469: The Congo . South Korea's Sangdong mine , one of the world's largest tungsten mines with 7,890,000 tonnes of high-grade tungsten reportedly buried, was closed in 1994 due to low profitability but has since re-registered mining rights and is scheduled to resume activities in 2024. Tungsten is extracted from its ores in several stages. The ore is eventually converted to tungsten(VI) oxide (WO 3 ), which

3280-490: The One System Portable Ground Control Station and One System Remote Video Terminal. On 16 November 2009, AAI entered a 40-year exclusive license agreement with Carter Aviation Technologies concerning a possible autonomous slowed rotor/compound aircraft with potential for increased speed (250 knots) and range (1300 nautical miles) delivering 3000 pounds cargo, compared to traditional rotorcraft. It

3362-556: The Shadow 200 Tactical UAS, which is designated RQ-7B by the U.S. Army, as well as the Shadow 400 and 600 systems. As of July, 2014, Shadow systems had accumulated more than 920,000 flight hours, with more than 90 percent of those hours in support of U.S. and allied combat operations in Iraq and Afghanistan. The company's UAS capabilities expanded with the 2006 acquisition of Australian UAS manufacturer Aerosonde Pty. Ltd. This fleet's newest model

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3444-512: The U.S. Army selected Martin UAV and AAI Corporation to "provide unmanned aircraft systems for platoons to try out as candidates to replace the Shadow tactical UAS ." The companies signed a contract for delivery over a three-year period. They will deliver systems to six platoons in order to evaluate them during combat and training rotations. The Army seeks better acoustics and runway independence as compared to

3526-417: The aerospace and automotive industries and radiation shielding. Superalloys containing tungsten, such as Hastelloy and Stellite , are used in turbine blades and wear-resistant parts and coatings. Tungsten's heat resistance makes it useful in arc welding applications when combined with another highly-conductive metal such as silver or copper. The silver or copper provides the necessary conductivity and

3608-422: The arms industry, both as a constituent of weapons and equipment and employed in production itself, e.g., in tungsten carbide cutting tools for machining steel. Now tungsten is used in many more applications such as aircraft and motorsport ballast weights, darts, anti-vibration tooling, and sporting equipment. Tungsten is unique amongst the elements in that it has been the subject of patent proceedings. In 1928,

3690-448: The closure of its sole tungsten mine. Meanwhile, Vietnam had significantly increased its output in the 2010s, owing to the major optimization of its domestic refining operations, and overtook Russia and Bolivia. China remains the world's leader not only in production, but also in export and consumption of tungsten products. Tungsten production is gradually increasing outside China because of the rising demand. Meanwhile, its supply by China

3772-404: The density, tungsten is seen as an alternative (albeit more expensive) to lead fishing sinkers . Depleted uranium is also used for these purposes, due to similarly high density. Seventy-five-kg blocks of tungsten were used as "cruise balance mass devices" on the entry vehicle portion of the 2012 Mars Science Laboratory spacecraft. It is an ideal material to use as a dolly for riveting , where

3854-727: The design, production, and sustainment of maintenance training devices such as the C-17 Globemaster , the F-22 Raptor , and most recently, the F-35 Lightning II Joint Strike Fighter. AAI modified and produced state-of-the-art, simulation-based maintenance training devices for the F-22 Raptor providing students with instruction in ground maintenance, aircraft servicing, and munitions loading. The armament training device provides hands-on skill development pertaining to

3936-488: The element tungsten is not ferromagnetic (but iron is), when it is present in steel in these proportions, it stabilizes the martensite phase, which has greater ferromagnetism than the ferrite (iron) phase due to its greater resistance to magnetic domain wall motion . Tungsten, usually alloyed with nickel , iron , or cobalt to form heavy alloys, is used in kinetic energy penetrators as an alternative to depleted uranium , in applications where uranium's radioactivity

4018-403: The entire chamber as opposed to just the bolt. When fired, the chamber would move down where a new round would be pushed in from the rear, forcing the spent cartridge case forward out of the chamber where it would drop out through an ejection port behind the pistol grip. The chamber would then move back into firing position on a spring, where it would lock in front of a fixed breechblock. On firing,

4100-515: The existing M16A2. Modifications were the addition of a new optical sighting system, a hydraulic buffer to smooth out recoil during automatic fire, and a collapsing butt stock similar to the one already in use on the carbine versions of the M16. The key design change was the use of "duplex rounds", a single cartridge with two smaller bullets in it. Olin Corporation produced three different rounds for testing,

4182-420: The first consisting of two tungsten projectiles in a long-necked case, the second used a standard-length case with two 1.7 grams (27 gr), 4.0-millimetre (0.158 in) tungsten projectiles, and the final entry was another standard-length case with two 5.7-millimetre (0.224 in) projectiles, one 2.3 grams (35 gr), the other 2.1 g (33 gr). The latter was eventually selected for submission to

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4264-530: The functionality of radar warning receivers and cockpit displays and controls. AAI acquired ESL Defence Limited in 2005. Based in the UK, ESL designs and manufactures electro-optical, infrared, and ultraviolet test and simulation/stimulation products for use on flight lines, in aircraft maintenance facilities, and at military test and evaluation ranges. AAI also provides functional automated test equipment for satellite, electronic and other systems. AAI has capabilities in

4346-492: The high wear resistance and thermal conductivity of tungsten carbide improves the printing of abrasive filaments. Some string instrument strings incorporates tungsten. Tungsten is used as an absorber on the electron telescope on the Cosmic Ray System of the two Voyager spacecraft . Its density, similar to that of gold, allows tungsten to be used in jewelry as an alternative to gold or platinum . Metallic tungsten

4428-423: The highest boiling point , at 5,930 °C (10,706 °F; 6,203 K). Its density is 19.254 g/cm , 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 into metal . However, pure single-crystalline tungsten

4510-515: The highest melting point (3,422 °C, 6,192 °F), lowest vapor pressure (at temperatures above 1,650 °C, 3,000 °F), and the highest tensile strength . Although carbon remains solid at higher temperatures than tungsten, carbon sublimes at atmospheric pressure instead of melting, so it has no melting point. Moreover, tungsten's most stable crystal phase does not exhibit any high-pressure-induced structural transformations for pressures up to at least 364 gigapascals. Tungsten has

4592-689: The landing gear systems, environmental control systems, hydraulics, and electrical and electronic warfare systems. The device supports nose and right main landing gear operation, and an operational arresting hook. The aft fuselage training device is a mock-up of the left side wing, horizontal stabilizer, vertical stabilizer, engine bay, forward engine bay door, and aft engine bay door, as well as numerous light systems and engine bay area components for removal and installation task training. The F-35 Lightning II aircraft system maintenance trainer provides student maintainers comprehensive training on ground operation, maintenance, fault isolation, and testing procedures in

4674-408: The latest variant of their long line of experimental fléchette rifles. Their entry used a standard 5.56×45mm NATO cartridge case firing a 1.6×41.27mm fléchette of 0.66 grams at 1402 m/s. One of the biggest complaints about their earlier efforts was the loud muzzle blast, a problem that is hard to avoid with a sabotted round. As a result, AAI added a flash hider/sound suppressor that reduced

4756-476: The less soluble "paratungstate B" anion, H 2 W 12 O 42 . Further acidification produces the very soluble metatungstate anion, H 2 W 12 O 40 , after which equilibrium is reached. The metatungstate ion exists as a symmetric cluster of twelve tungsten- oxygen octahedra known as the Keggin anion. Many other polyoxometalate anions exist as metastable species. The inclusion of

4838-402: The lowest coefficient of thermal expansion of any pure metal. The low thermal expansion and high melting point and tensile strength of tungsten originate from strong covalent bonds formed between tungsten atoms by the 5d electrons. Alloying small quantities of tungsten with steel greatly increases its toughness . Tungsten exists in two major crystalline forms: α and β. The former has

4920-454: The main reasons for using a fléchette is its low recoil. This particular design was less complex than some of their earlier models, which could switch between fléchette ammunition for rapid fire and standard 5.56 NATO rounds for long-range semi-automatic fire. The Heckler & Koch G11 series used caseless ammunition where the propellant was molded onto the bullet itself, making the round smaller and much lighter. The new K2 version used in

5002-535: The mass necessary for good results can be achieved in a compact bar. High-density alloys of tungsten with nickel, copper or iron are used in high-quality darts (to allow for a smaller diameter and thus tighter groupings) or for artificial flies (tungsten beads allow the fly to sink rapidly). Tungsten is also used as a heavy bolt to lower the rate of fire of the SWD M11/9 sub-machine gun from 1300 RPM to 700 RPM. Tungsten has seen use recently in nozzles for 3D printing ;

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5084-431: The metal matrix in place of cobalt because it takes a higher luster when polished. Sometimes manufacturers or retailers refer to tungsten carbide as a metal, but it is a ceramic . Because of tungsten carbide's hardness, rings made of this material are extremely abrasion resistant, and will hold a burnished finish longer than rings made of metallic tungsten. Tungsten carbide rings are brittle, however, and may crack under

5166-535: The metalworking, woodworking, mining , petroleum and construction industries. Carbide tooling is actually a ceramic/metal composite, where metallic cobalt acts as a binding (matrix) material to hold the WC particles in place. This type of industrial use accounts for about 60% of current tungsten consumption. The jewelry industry makes rings of sintered tungsten carbide , tungsten carbide/metal composites, and also metallic tungsten. WC/metal composite rings use nickel as

5248-483: The most stable being W ( t 1/2  6.4 minutes). Tungsten is a mostly non-reactive element: it does not react with water, is immune to attack by most acids and bases, and does not react with oxygen or air at room temperature. At elevated temperatures (i.e., when red-hot) it reacts with oxygen to form the trioxide compound tungsten(VI), WO 3 . It will, however, react directly with fluorine (F 2 ) at room temperature to form tungsten(VI) fluoride (WF 6 ),

5330-412: The most stable of which are W with a half-life of 121.2 days, W with a half-life of 75.1 days, W with a half-life of 69.4 days, W with a half-life of 21.6 days, and W with a half-life of 23.72 h. All of the remaining radioactive isotopes have half-lives of less than 3 hours, and most of these have half-lives below 8 minutes. Tungsten also has 11  meta states , with

5412-413: The muzzle blast to just louder than an M16A2. While the standard 5.56×45mm case was used, the rifle was not safe to fire using standard ammunition due to the design of the gas system. A special magazine was used to prevent soldiers loading standard 5.56×45mm NATO ammunition into the magazine, but rounds could still be chambered by hand. The weapon was limited to three-round bursts despite the fact that one of

5494-714: The name Georg Agricola used for the mineral in 1546, which translates into English as ' wolf's froth ' and is a reference to the large amounts of tin consumed by the mineral during its extraction, as though the mineral devoured it like a wolf. This naming follows a tradition of colorful names miners from the Ore Mountains would give various minerals, out of a superstition that certain ones that looked as if they contained then-known valuable metals but when extracted were somehow "hexed". Cobalt (cf. Kobold ), pitchblende (cf. German blenden for ' to blind, to deceive ' ) and nickel (cf. "Old Nick") derive their names from

5576-416: The old Shadow. The Army is expected to decide "over the course of fiscal 2020" whether it will proceed in replacing Shadow. AAI provides a variety of engineering, logistical, maintenance, repair and overhaul services for the company's own platforms as well as those of other original equipment manufacturers. Its customers include the U.S. Army, Air Force, Navy and Marine Corps, for which the company supports

5658-426: The pervasiveness of the chromium(III) compounds. The highest oxidation state is seen in tungsten(VI) oxide (WO 3 ). Tungsten(VI) oxide is soluble in aqueous base , forming tungstate (WO 4 ). This oxyanion condenses at lower pH values, forming polyoxotungstates . The broad range of oxidation states of tungsten is reflected in its various chlorides: Organotungsten compounds are numerous and also span

5740-619: The physical strength of the catalyst and extends catalyst life. Tungsten containing catalysts are promising for epoxidation, oxidation, and hydrogenolysis reactions. Tungsten heteropoly acids are key component of multifunctional catalysts. Tungstates can be used as photocatalyst, while the tungsten sulfide as electrocatalyst. Applications requiring its high density include weights, counterweights , ballast keels for yachts, tail ballast for commercial aircraft, rotor weights for civil and military helicopters, and as ballast in race cars for NASCAR and Formula One . Being slightly less than twice

5822-671: The program demanded. In 1986/7, the United States Army Infantry School had published a report asserting that the rifle, as a weapon, had already reached its peak, and the only way to really improve matters was to use an exploding warhead. This led to the ending of the ACR program in April 1990, and led the way to the Objective Individual Combat Weapon program. The program's total cost was approximately US$ 300 million. AAI Corporation AAI Corporation

5904-402: The remaining major use being in alloys and steels. Less than 10% is used in other chemical compounds . Because of the high ductile-brittle transition temperature of tungsten, its products are conventionally manufactured through powder metallurgy , spark plasma sintering , chemical vapor deposition , hot isostatic pressing , and thermoplastic routes. A more flexible manufacturing alternative

5986-451: The removal, installation, inspection, operation, and checkout tasks of the gun, gun doors, left main weapons bay door system and launchers, left side weapons bay launcher, right wing pylon, partial fuel system, stores management system, and weapons safing system. The trainer uses real aircraft support equipment including munitions and the portable maintenance aid (PMA). The landing gear training device allows instruction on maintenance tasks on

6068-459: The sabot traveled down the barrel with the fléchette and was quickly "stripped" off upon exit. This was found to present a hazard in combat, where the sabots could hit other soldiers or bounce off the ground when being fired prone. Like the AAI weapon, the Steyr was limited to three round bursts. One of the more traditional of the ACR prototypes was the Colt ACR , which was a highly modified version of

6150-1044: The same miners' idiom. Tungsten has thus far not been found in nature in its pure form. Instead, tungsten is found mainly in the minerals wolframite and scheelite . Wolframite is iron – manganese tungstate (Fe,Mn)WO 4 , a solid solution of the two minerals ferberite (FeWO 4 ) and hübnerite (MnWO 4 ), while scheelite is calcium tungstate (CaWO 4 ). Other tungsten minerals range in their level of abundance from moderate to very rare, and have almost no economic value. Tungsten forms chemical compounds in oxidation states from -II to VI. Higher oxidation states, always as oxides, are relevant to its terrestrial occurrence and its biological roles, mid-level oxidation states are often associated with metal clusters , and very low oxidation states are typically associated with CO complexes . The chemistries of tungsten and molybdenum show strong similarities to each other, as well as contrasts with their lighter congener, chromium . The relative rarity of tungsten(III), for example, contrasts with

6232-427: The student to monitor the virtual aircraft functions, run diagnostics, and display technical and task documentation. AAI's training systems are utilized by U.S. and allied international military customers. Products include naval, electronic warfare, air defense, radar, and UAS training systems. AAI's Advanced Systems unit primarily investigates and responds to new and emerging customer needs and markets. The company

6314-441: The tungsten allows the welding rod to withstand the high temperatures of the arc welding environment. Quenched (martensitic) tungsten steel (approx. 5.5% to 7.0% W with 0.5% to 0.7% C) was used for making hard permanent magnets, due to its high remanence and coercivity , as noted by John Hopkinson (1849–1898) as early as 1886. The magnetic properties of a metal or an alloy are very sensitive to microstructure. For example, while

6396-635: Was acquired by AAI. Textron acquired AAI and other subsidiaries of UIC with its purchase of the parent company for approximately $ 1.1 billion in 2007. AAI became part of Textron's helicopter subsidiary, Bell Textron, in the acquisition. Today, AAI owns or occupies more than 1,100,000 square feet (100,000 m ) of office and manufacturing space across Australia, the United Kingdom and the USA. As of May 2014, AAI had been made into three parts: Unmanned Systems, Support Solutions, and Electronic Systems. The company

6478-576: Was founded as Hayes Body Corporation in the early 1900s. Renamed many years later, UIC was admitted into the New York Stock Exchange for trading on December 15, 1964. From 1994 to 2004, AAI partnered with the Czech firm, Škoda , in a joint venture to manufacture trolley buses . The joint venture, named Electric Transit, Inc. , supplied 330 trolley buses to San Francisco and Dayton before being dissolved in 2004. On 22 June 2006 Aerosonde Ltd

6560-481: Was identical to tungstic acid. Later that year, at the Royal Basque Society in the town of Bergara , Spain, the brothers succeeded in isolating tungsten by reduction of this acid with charcoal , and they are credited with the discovery of the element (they called it "wolfram" or "volfram"). The strategic value of tungsten came to notice in the early 20th century. British authorities acted in 1912 to free

6642-401: Was identified as a distinct element in 1781 and first isolated as a metal in 1783. Its important ores include scheelite and wolframite , the latter lending the element its alternative name. The free element is remarkable for its robustness, especially the fact that it has the highest melting point of all known elements, melting at 3,422 °C (6,192 °F; 3,695 K). It also has

6724-585: Was long thought to be non-radioactive, but Bi (its longest lived isotope) actually decays with a half life of 2.01 × 10 years or about a factor 10 slower than W . However, due to naturally occurring bismuth being 100% Bi , its specific activity is actually higher than that of natural tungsten at 3 milli-becquerel per kilogram. The other naturally occurring isotopes of tungsten have not been observed to decay, constraining their half-lives to be at least 4 × 10  years . Another 34 artificial radioisotopes of tungsten have been characterized,

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