タングステン 化学特性,用途語,生産方法
外観
無色澄明の液体
溶解性
水と混和。アルコールに可溶。水及びエタノールと任意の割合で混和する。
解説
タングステン，原子番号74の元素．電子配置[Xe]4f 145d46s2の周期表6族遷移金属元素．原子量183.84(1)．天然同位体存在比は 180W 0.12(1)％，182W 26.50(16)％，183W 14.31(4)％，184W 30.64(2)％，186W 28.43(19)％．質量数158～190までの30種の放射性核種がつくられている．純粋な金属は灰白色で軟らかい．密度19.3 g cm－3．融点3410 ℃ で最高，沸点5700 ℃．第一イオン化エネルギー733.2 kJ mol－1(7.60 eV)．金属は白熱電球，蛍光灯のフィラメント，電子管，ブラウン管の電極，X線管のターゲットなどに用いられる．鋼との合金や炭化タングステンは超硬合金として高速切削用工具，強力・耐蝕合金ハステロイはNi，Cr，Moとの合金，タングステン酸カルシウムは蛍光灯用の蛍光体，硫化タングステンは高温用の潤滑剤に用いられる
森北出版「化学辞典（第2版）
主な性質
- タングステンは灰白色金属である。
- 純粋なタングステンはかなり柔らかい。（不純物が入ると、硬く脆くなる）
- タングステン密度は鉄の２.５倍弱で、非常に重い。
- 全ての金属の中で最も融点が高く、蒸気圧が低い。
- 極めて細い線にも加工出来るので、白熱電球のフィラメントに利用。
- 鉄鋼にタングステンを添加すると著しく硬度が増す。炭素との化合物はダイヤモンド、炭化ホウ素に次いで硬い。（切削工具に利用される）
用途
原子吸光分析、ICP発光分析、比色分析等によるタングステン定量用標準液。
主な用途
含W特殊鋼部品（高速度鋼、耐熱鋼、工具鋼など機械、切削工具）
超硬合金（切削工具、耐磨耗工具、鉱山工具）
金属タングステン製品（フィラメント、電子レンジのマグネトロン、Ｘ線の陰極、自動車部品）
ターゲット（Ｘ線フィルム蛍光体、磁気ディスク）
化成品（各種触媒、顔料）
反応
高温で酸素と反応して三酸化物WO3になる．フッ素と室温で反応して六フッ化物WF6をつくる．塩素とも容易に反応して六塩化物となる．酸化数1～6．通常の酸，希アルカリ水溶液には侵されない．常温で水と反応しない．
使用上の注意
保証期限をラベルに表示。
説明
Tungsten was recognized as a distinct element in 1779 by
Peter Woulfe, but not isolated until 1783, by Jose and Fausto
d’Elhuyar. The average tungsten concentration in the earth’s
crust is ~0.006%. Tungsten occurs naturally as tungstate,
mainly in compounds such as wolframites and scheelites.
化学的特性
Tungsten is a hard, brittle, steel-gray to tinwhite
metal or fine powder.
物理的性質
Extremely pure samples of tungsten are rather soft and can be cut easily with a simple saw.Pure tungsten can be drawn into fine wires (ductile). On the other hand, if there are even a fewimpurities in the sample, the metal becomes very hard and brittle. It is a very dense metal witha whitish-to-silvery-grayish color when freshly cut. It has the highest melting point of all metalsat 3,422°C, making it a useful metal where high temperatures are required. Incidentally,the transition metals on both sides of it in period 6 (
73Ta and
75Re) have the second- and thirdhighestmelting points. Tungsten’s boiling point is also high at 5,927°C.
同位体
There are 36 isotopes of tungsten. Five are naturally stable and therefore contributeproportionally to tungsten’s existence on Earth, as follows: W-180 = 0.12%, W-182 = 26.50%, W-183 = 14.31%, W-184 = 30.64%, and W-186 = 28.43%. The other31 isotopes are man-made in nuclear reactors and particle accelerators and have halflivesranging from fractions of a second to many days.
名前の由来
Tungsten was originally named “Wolfram” by German scientists, after
the mineral in which it was found, Wolframite—thus, its symbol “W.” Later, Swedish scientists
named it tung sten, which means “heavy stone,” but it retained its original symbol
of “W.”
天然物の起源
Tungsten is the 58th most abundant element found on Earth. It is never found in 100%pure form in nature. Its major ore is called wolframite or tungsten tetroxide, (Fe,Mn)WO
4,which is a mixture of iron and manganese and tungsten oxide. During processing, the ore ispulverized and treated with strong alkalis resulting in tungsten trioxide (WO
3), which is thenheated (reduced) with carbon to remove the oxygen. This results in a variety of bright colorchanges and ends up as a rather pure form of tungsten metal: 2WO
3 + 3C → 2WO + 3CO
2.Or, if hydrogen is used as the reducing agent, a more pure form of metal is produced: WO3+ 3H
2 → W + 3H
2O.
Tungsten ores (oxides) are found in Russia, China, South America, Thailand, and Canada.In the United States, the ores are found in Texas, New Mexico, Colorado, California, Arizona,and Nebraska.
特性
Tungsten is considered part of the chromium triad of group six (VIB), which consists of
24Cr,
42Mo, and
74W. These elements share many of the same physical and chemical attributes.Tungsten’s high melting point makes it unique insofar as it can be heated to the point thatit glows with a very bright white light without melting. This makes it ideal as a filamentfor incandescent electric light bulbs. Most metals melt long before they reach the point ofincandescence.
Chemically, tungsten is rather inert, but it will form compounds with several other elementsat high temperatures (e.g., the halogens, carbon, boron, silicon, nitrogen, and oxygen).Tungsten will corrode in seawater.
使用
Tungsten, also known as wolfram, occurs as wolframite (FeWO4). It can be found in the earth’s crust but not in its pure metal form. It combines with other chemicals and compounds within the rocky earth’s crust. It is a transitional hard metal with physicochemical properties and can also be manufactured commercially (Lassner and Schnubert, 1999; Gbaruko and Igwe, 2007; Stefaniak, 2010; Strigul et al., 2010).
Tungsten is most commonly used to increase the hardness of steel. It is available commercially in the form of powder, single crystal, and ultrapure granule grades. It is also used in the manufacturing of alloys, light filaments, and X-ray tubes. A recent use for tungsten is as a lead substitute during the manufacturing of ammunition and sporting good products. Another recent commercial use for tungsten is in the production of wedding bands. It is also used as a catalyst in chemical reactions (Lassner and Schnubert, 1999; Gbaruko and Igwe, 2007; Stefaniak, 2010; Strigul et al., 2010).
To increase hardness, toughness, elasticity, and tensile strength of steel; manufacture of alloys; manufacture of filaments for incandescent lamps and in electron tubes; in contact points for automotive, telegraph, radio and television apparatus; in phonograph needles. Tungsten carbides (W2C, WC) used in rock drills, metal-cutting tools, wire-drawing dies. WC used as catalyst instead of platinum: Bennett et al., Science 184, 563 (1974).
定義
tungsten: Symbol W. A white orgrey metallic transition element(formerly called wolfram); a.n. 74;r.a.m. 183.85; r.d. 19.3; m.p. 3410°C;b.p. 5660°C. It is found in a numberof ores, including the oxides wolframite,(Fe,Mn)WO
4, and scheelite,CaWO4. The ore is heated with concentratedsodium hydroxide solutionto form a soluble tungstate. Theoxide WO
3 is precipitated from thisby adding acid, and is reduced to themetal using hydrogen. It is used invarious alloys, especially high-speedsteels (for cutting tools) and in lampfilaments. Tungsten forms a protectiveoxide in air and can be oxidizedat high temperature. It does not dissolvein dilute acids. It forms compoundsin which the oxidation stateranges from +2 to +6. The metal wasfirst isolated by Juan d’Elhuyer andFausto d’Elhuyer (1755–1833) in1783.
調製方法
Tungsten occurs principally in the minerals wolframite (Fe,Mn)WO4, scheelite (CaWO4), ferberite (FeWO4), and hubnerite (MnWO4). These ores are found in China, Russia, Canada, Austria, Africa, Bolivia, Columbia, and Portugal. Wolframite is the most important oreworldwide; scheelite is the principal domestic U.S. ore. Scheelite, when pure, contains 80.6% WO3, the most common impurity being MoO3. The percentages of FeO and MnO in wolframite vary considerably; hubnerite is the term applied to ore containing more than 20% MnO and ferberite and to ore containing more than 20% FeO. Intermediate samples are called wolframite.
反応プロフィール
Tungsten is stable at room temperature. Very slowly attacked by nitric acid, sulfuric acid, and aqua regia. Dissolved by a mixture of hydrofluoric acid and nitric acid. No reaction with aqueous bases. Attacked rapidly by motlen alkaline melts such as Na2O2 or KNO3/NaOH. Vigorous reactions with bromine trifluoride and chlorine trifluoride. Becomes incandescent upon heating with lead oxide; becomes incandescent in cold fluorine and with iodine pentafluoride. Combustible in the form of finely divided powder and may ignite spontaneously.
危険性
Tungsten dust, powder, and fine particles will explode, sometimes spontaneously, in air.The dust of many of tungsten’s compounds is toxic if inhaled or ingested.
健康ハザード
The soluble compounds of
tungsten are distinctly more toxic than the
insoluble forms.
安全性プロファイル
An inhalation hazard.
Mildly toxic by an unspecified route. An
experimental teratogen. Experimental
reproductive effects. A skin and eye irritant.
Flammable in the form of dust when
exposed to flame. The powdered metal may
ignite on contact with air or oxidants (e.g.,
bromine pentafluoride, bromine, chlorine
trifluoride, potassium perchlorate, potassium
dichromate, nitryl fluoride, fluorine, oxygen
difluoride, iodine pentafluoride, hydrogen
sulfide, sodlum peroxide, lead (IV)oxide).
See also TUNGSTEN COMPOUNDS and
POWDERED METALS.
職業ばく露
Tungsten is used in ferrous and
nonferrous alloys, and for filaments in incandescent lamps.
It has been stated that the principal health hazards from
tungsten and its compounds arise from inhalation of aerosols
during mining and milling operations. The principal
compounds of tungsten to which workers are exposed are
ammonium paratungstate, oxides of tungsten (WO3, W2O5,
WO2); metallic tungsten; and tungsten carbide. In the production
and use of tungsten carbide tools for machining, exposure
to the cobalt used as a binder or cementing substance
may be the most important hazard to the health of the
employees. Since the cemented tungsten carbide industry
uses such other metals as tantalum, titanium, niobium, nickel,
chromium, and vanadium in the manufacturing process, the
occupational exposures are generally to mixed dust.
特性
融点が 3,400℃と高い
強度や弾性に富む
比重が 19.3 と大きい
熱膨張係数がガラスに近い
製法
主要なタングステン鉱石として、鉄マンガン重石（（Fe, Mn）WO4）や灰重石（CaWO4）がある。これらの鉱石は、 アルカリによる分解浸出後、有機相と接触させてタングステンを有機相に抽出し、アンモニア水と接触させてタ ングステンを逆抽出し、APTができる。また、イオン交換樹脂法によっても分解浸出液からAPTを生成すること ができる。APTを加熱すれば三酸化タングステンが得られ、それを水素中で還元したものが金属タングステン （粉）である。
発がん性
Tungsten has been suspected to be involved in the occurrence of childhood leukemia, with the discovery of a cluster of diseases in Fallon, Nevada, associated with elevated levels of tungsten in urine and drinking water. The exact environmental source of exposure to tungsten was not clearly identi?ed and there is little evidence for an etiological role of tungsten in eliciting leukemia.
環境運命予測
Tungsten in the environment largely exists as ions in
compounds and primarily insoluble solids. The potential for
particulate matter to spread is low as wet and dry deposition
removes it from the atmosphere. If released to air, most
tungsten compounds have low vapor pressures and are expected
to exist solely in the particulate phase in the ambient
atmosphere. Volatization is not expected to be an important
fate process.
輸送方法
UN3089 Metal powders, flammable, n.o.s.,
Hazard Class: 4.1; Labels: 4.1-Flammable solid. UN3189
Metal powder, self heating, n.o.s., Hazard Class: 4.2;
Labels: 4.2-Spontaneously combustible material.
純化方法
Clean the solid with conc NaOH solution, rub it with very fine emery paper until its surface is bright, wash it with previously boiled and cooled conductivity water and dry it with filter paper. [Hein & Herzog in Handbook of Preparative Inorganic Chemistry (Ed. Brauer) Academic Press Vol II p 1417 1965.]
不和合性
Tungsten: The finely divided powder is
combustible and may ignite spontaneously in air.
Incompatible with bromine trifluoride; chlorine trifluoride;
fluorine, iodine pentafluoride.
廃棄物の処理
Recovery of tungsten from
sintered metal carbides, scrap and spent catalysts has been
described as an alternative to disposal.
タングステン 上流と下流の製品情報
原材料
準備製品