Tungsten yog cov khoom siv tshuaj lom neeg uas nws tus lej atomic yog 74. Cov hlau hnyav no los ntawm steel-grey mus rau xim dawb yog qhov ruaj khov heev, uas ua rau nws yooj yim hloov tsis tau ntau zaus. Nws cov ntsiab lus melting yog siab dua li ntawm lwm cov hlau, thiab yog li ntawd nws yog siv los ua filaments nyob rau hauv incandescent teeb thiab cua sov ntsiab nyob rau hauv hluav taws xob furnaces (piv txwv li, zirconium-tungsten alloy). Chemistry ntawm lub caij tso cai rau nws siv los ua ib qho catalyst. Nws qhov tshwj xeeb hardness ua rau nws haum rau siv nyob rau hauv "kev kub ceev steels" uas tso cai rau cov ntaub ntawv txiav nyob rau hauv high speeds tshaj carbon steels thiab kub alloys. Tungsten carbide, ib qho kev sib xyaw ntawm cov khoom siv nrog cov pa roj carbon, yog ib qho nyuaj tshaj plaws uas paub thiab siv los ua milling thiab tig cov cuab yeej. Calcium thiab magnesium tungstates tau siv dav hauv cov teeb fluorescent, thiab tungsten oxides tau siv dav hauv cov xim thiab cov iav glazes.
Discovery keeb kwm
Lub neej ntawm cov tshuaj no tau pom thawj zaug hauv xyoo 1779 los ntawm Peter Woolf, thaum nws tshawb xyuas cov ntxhia wolframite thiab tuaj rauqhov xaus tias nws yuav tsum muaj cov khoom tshiab. Xyoo 1781, Carl Wilhelm Scheele tau tsim cov kua qaub tshiab tuaj yeem tau los ntawm tungstenite. Scheele thiab Thorburn Bergman tau thov kom xav txog qhov muaj peev xwm tau txais cov hlau tshiab los ntawm kev txo cov kua qaub no, hu ua tungsthenic acid. Xyoo 1783, ob tug kwv tij, José thiab Fausto Elguiar, pom cov kua qaub hauv wolframite uas zoo ib yam rau tungsthenic acid. Nyob rau hauv tib lub xyoo, cov kwv tij tswj cais tungsten los ntawm nws siv charcoal.
Thaum Tsov Rog Ntiaj Teb Zaum Ob, cov tshuaj no tau ua lub luag haujlwm loj. Qhov kev tiv thaiv ntawm cov hlau mus rau qhov kub thiab txias, nrog rau lub zog loj ntawm nws cov alloys, ua tungsten cov khoom tseem ceeb tshaj plaws rau kev lag luam tub rog. Cov belligerents tso siab rau Portugal raws li lub hauv paus ntawm wolframite nyob rau hauv Teb chaws Europe.
Nyob hauv ntuj
Nyob hauv qhov xwm txheej tshwm sim hauv wolframite (FeWO 4/MnWO4), scheelite (CaWO 4), ferberite thiab hübnerite. Cov deposits tseem ceeb ntawm cov zaub mov no muaj nyob rau hauv Teb Chaws Asmeskas hauv California thiab Colorado, hauv Bolivia, Tuam Tshoj, Kaus Lim Qab Teb, Russia thiab Portugal. Txog 75% ntawm lub ntiaj teb tungsten ntau lawm yog concentrated nyob rau hauv Suav teb. Cov hlau yog tau los ntawm kev txo nws cov oxide nrog hydrogen lossis carbon.
ntiaj teb cov khoom khaws cia yog kwv yees li ntawm 7 lab tons. Nws yog kwv yees tias 30% ntawm lawv yog deposits ntawm wolframite thiab 70% ntawm scheelite. Tam sim no, lawv txoj kev loj hlob tsis yog kev lag luam. Nyob rau theem tam sim no ntawm kev noj, cov nyiaj khaws cia no tsuas yog 140 xyoo. Lwm qhov chaw muaj txiaj ntsigtungsten yog cov khoom siv rov ua dua tshiab.
Key Features
Tungsten yog cov khoom siv tshuaj lom neeg uas tau muab cais ua cov hlau hloov pauv. Nws lub cim W los ntawm lo lus Latin wolframium. Nyob rau hauv lub sij hawm lub sij hawm, nws yog nyob rau hauv pawg VI ntawm tantalum thiab rhenium.
Nyob rau hauv nws daim ntawv purest, tungsten yog ib yam khoom nyuaj xws li xim ntawm steel grey mus rau pewter dawb. Nrog impurities, cov hlau ua nkig thiab nyuaj rau kev ua haujlwm nrog, tab sis yog tias lawv tsis tuaj, ces nws tuaj yeem txiav nrog lub hacksaw. Tsis tas li ntawd, nws tuaj yeem raug forged, dov thiab kos.
Tungsten yog cov khoom siv tshuaj uas nws lub ntsiab lus melting yog qhov siab tshaj plaws ntawm tag nrho cov hlau (3422 ° C). Nws kuj muaj qhov qis tshaj plaws vapor siab. Nws kuj muaj lub zog tensile siab tshaj plaws ntawm T> 1650 ° C. Lub ntsiab yog tsis tshua muaj resistant rau corrosion thiab tsuas yog me ntsis tawm tsam los ntawm ntxhia acids. Thaum sib cuag nrog huab cua, ib txheej tiv thaiv oxide tsim rau ntawm cov hlau nto, tab sis tungsten yog oxidized tag nrho ntawm qhov kub thiab txias. Thaum nws ntxiv me me rau cov hlau, nws qhov hardness nce ntau heev.
Isotopes
Hauv qhov xwm txheej, tungsten yog tsim los ntawm tsib lub xov tooj cua isotopes, tab sis lawv muaj lub neej ntev li ib nrab hnub uas lawv tuaj yeem suav tias ruaj khov. Tag nrho cov ntawm lawv lwj mus rau hauv hafnium-72 nrog lub emission ntawm alpha hais (xws li helium-4 nuclei). Alpha lwj tsuas yog pom nyob rau hauv 180 W, qhov lightest thiab rarest ntawm cov noisotopes. Qhov nruab nrab, ob qhov alpha lwj tshwm sim hauv 1 g ntawm ntuj tungsten hauv ib xyoos 180 W.
Ntxiv rau, 27 cov khoom siv hluav taws xob hluav taws xob hluav taws xob ntawm tungsten tau piav qhia. Qhov ruaj khov tshaj plaws ntawm cov no yog 181 W nrog ib nrab lub neej ntawm 121.2 hnub, 185 W (75.1 hnub), 188 W (69, 4 hnub) thiab 178 W (21, 6 hnub). Tag nrho lwm cov isotopes tsim muaj ib nrab ntawm lub neej tsawg dua ib hnub, thiab feem ntau lawv tsawg dua 8 feeb. Tungsten kuj muaj plaub lub xeev "metastable", uas ruaj khov tshaj plaws yog 179m W (6.4 min).
Kev sib txuas
Hauv cov tshuaj lom neeg, tungsten oxidation lub xeev hloov ntawm +2 mus rau +6, ntawm +6 yog qhov ntau tshaj. Lub caij feem ntau khi nrog cov pa oxygen los tsim cov xim daj trioxide (WO 3), uas yaj hauv aqueous alkaline daws raws li tungstate ions (WO42-).
Daim ntawv thov
Vim tias tungsten muaj cov ntsiab lus melting siab heev thiab yog ductile (tuaj yeem kos rau hauv cov hlau), nws yog dav siv los ua cov filament ntawm incandescent teeb thiab lub tshuab nqus tsev teeb, nrog rau cov cua kub ntawm hluav taws xob furnaces. Tsis tas li ntawd, cov khoom siv tiv taus huab cua. Ib qho ntawm nws cov ntawv thov paub yog roj-shielded tungsten arc vuam.
Qhov nyuaj heev, tungsten yog cov khoom siv zoo tagnrho rau cov phom phom hnyav. High ceev yog siv nyob rau hauv kettlebells,counterweights thiab ballast keels rau yachts, nrog rau hauv darts (80-97%). Kev kub ceev hlau, uas tuaj yeem txiav cov khoom ntawm qhov nrawm dua li carbon steel, muaj txog li 18% ntawm cov khoom no. Turbine hniav, hnav qhov chaw thiab txheej siv "superalloys" uas muaj tungsten. Cov no yog cov cua sov-resistant, siab resistant alloys uas ua haujlwm ntawm qhov kub siab.
Lub thermal expansion ntawm cov khoom siv tshuaj zoo ib yam li borosilicate iav, yog li nws yog siv los ua iav-rau-hlau seals. Composites uas muaj tungsten yog ib qho zoo heev hloov cov hlau lead hauv cov mos txwv thiab tua. Nyob rau hauv alloys nrog npib tsib xee, hlau los yog cob alt, cuam tshuam projectiles yog tsim los ntawm nws. Zoo li lub mos txwv, nws lub zog kinetic yog siv los ntaus lub hom phiaj. Hauv kev sib xyaw ua ke, tungsten yog siv los ua kev sib txuas rau transistors. Qee hom suab paj nruag cov hlua yog tsim los ntawm tungsten hlau.
Siv kev sib txuas
Qhov tshwj xeeb hardness ntawm tungsten carbide (W 2 C, WC) ua rau nws cov khoom siv ntau tshaj plaws rau milling thiab tig cov cuab yeej. Nws yog siv rau hauv metallurgical, mining, roj thiab kev tsim kho kev lag luam. Tungsten carbide kuj tseem siv rau hauv cov hniav nyiaj hniav kub ua raws li nws yog hypoallergenic thiab tsis nyiam poob nws cov luster.
Glaze yog tsim los ntawm nws cov oxides. Tungsten "bronze" (yog li hu ua vim cov xim ntawm cov oxides) yog siv nyob rau hauv cov xim. Magnesium thiab calcium tungstates yog siv nyob rau hauv fluorescentteeb. Crystalline tungstate ua hauj lwm raws li ib tug scintillation detector nyob rau hauv nuclear tshuaj thiab physics. Cov ntsev yog siv rau hauv kev lag luam chemical thiab tawv. Tungsten disulfide yog cov roj kub kub uas tuaj yeem tiv taus 500 ° C. Qee cov tebchaw uas muaj tungsten yog siv hauv chemistry ua catalysts.
Properties
Lub cev lub cev tseem ceeb ntawm W yog raws li hauv qab no:
- Atomic naj npawb: 74.
- Atomic mass: 183, 85.
- Melting point: 3410 ° C.
- Boiling point: 5660 °C.
- Density: 19.3 g/cm3 ntawm 20°C.
- Oxidation xeev: +2, +3, +4, +5, +6.
- Electronic Configuration: [Xe]4 f 145 d 46 s 2.
