Hlau yog hom khoom siv uas tib neeg tau siv txij thaum ub los. Cov pab pawg no muaj ntau heev, tab sis lawv txhua tus muaj cov yam ntxwv ntawm lub cev, uas feem ntau hu ua metallic zog.
Qhov nyuaj ntawm lawv yog ib txwm, tab sis tsis txiav txim siab. Ntau qhov tshwj xeeb yog lwm tus uas cov hlau softest muaj. Cov khoom no yog txiav txim siab los ntawm peculiarities ntawm lawv cov qauv ntawm qib molecular.
Khoom ntawm cov hlau
Hlau thiab nws cov alloys (steel, cam khwb cia hlau), tooj liab, txhuas… Txhua yam ntawm cov hlau no muaj cov yam ntxwv uas muab nws tus nqi tsim nyog. Cov yam ntxwv zoo ib yam rau lawv yog cov thermal thiab hluav taws xob conductivity, plasticity - lub peev xwm los tswj kev ncaj ncees thaum lub sij hawm deformation, metallic luster.
Damask hniav uas txiav los ntawm cov hlau armor thiab cov hlau softest, uas cov kab nyob ntawm qhov cuam tshuam me ntsis, muaj cov qauv zoo sib xws. Nws yog raws li ib tug siv lead ua lattice, ntawm cov nodes uas yog atoms nrogtus nqi zoo thiab nruab nrab, ntawm qhov uas muaj "electron gas" - cov khoom uas tau tawm ntawm lub plhaub sab nraud ntawm cov atoms vim qhov tsis muaj zog ntawm daim ntawv cog lus nrog cov nucleus. Ib qho tshwj xeeb ntawm cov hlau nplaum ntawm qhov zoo ions nyob rau ntawm cov pob txha siv lead ua lattice yog ua los ntawm kev txaus nyiam zog uas tshwm sim hauv "electron gas". Lub hardness, ntom, melting point ntawm cov hlau nyob ntawm seb qhov concentration ntawm "gas".
Kev ntsuas ntsuas
Cov lus teb rau lo lus nug ntawm cov hlau twg yog qhov softest yuav ib txwm yog cov ntsiab lus ntawm kev sib tham, tshwj tsis yog cov kev ntsuam xyuas tau pom zoo thiab lub tswv yim ntawm softness yog txhais. Kev xav txog cov yam ntxwv ntawm cov khoom siv no yuav txawv rau cov kws tshaj lij hauv kev lag luam sib txawv. Tus kws tshuaj metallurgist tuaj yeem nkag siab qhov muag muag raws li kev ua kom zoo dua qub, nyiam lees txais deformation los ntawm cov khoom siv abrasive, thiab lwm yam.
Rau cov kws tshawb fawb cov ntaub ntawv, nws yog ib qho tseem ceeb uas yuav tsum muaj peev xwm sib piv cov yam ntxwv sib txawv ntawm cov khoom. Softness kuj tseem yuav tau txais kev ntsuam xyuas feem ntau. Cov hlau softest nyob rau hauv lub ntiaj teb no yuav tsum muaj feem ntau lees paub cov cim ua pov thawj nws "cov ntaub ntawv" cov yam ntxwv. Muaj ntau txoj hauv kev los ntsuas qhov softness ntawm cov khoom sib txawv.
ntsuas ntsuas
Feem ntau ntawm cov ntawv pov thawj rau kev ntsuas qhov nyuaj yog ua raws li kev sib cuag ntawm cov khoom hauv kev sim, ntsuas nrog cov cuab yeej precision, los ntawm lub cev nyuaj hu ua indenter. Nyob ntawm seb hom indenter thiab nyob rau hauv txoj kev ntsuas, muaj ob peb lub ntsiabmethod:
- Brinell txoj kev. Qhov txoj kab uas hla ntawm lub imprint tshuav los ntawm ib lub pob hlau thaum nias rau saum npoo ntawm cov tshuaj ntsuam xyuas yog txiav txim siab.
- Rockwell method. Qhov tob ntawm indentation rau saum npoo ntawm lub pob lossis pob zeb diamond cone yog ntsuas.
- Vickers method. Qhov chaw ntawm lub imprint tshuav los ntawm lub pob zeb diamond tetrahedral pyramid yog txiav txim siab.
- Ntug hardness. Muaj cov nplais rau cov ntaub ntawv nyuaj thiab mos heev - qhov tob ntawm kev tso rau ntawm ib rab koob tshwj xeeb lossis qhov siab ntawm qhov rov qab los ntawm qhov chaw ntawm tus ntaus tshwj xeeb yog ntsuas.
Mohs hardness scale
Qhov ntsuas no rau kev txiav txim siab qhov sib txheeb ntawm cov ntxhia thiab cov hlau tau npaj rau thaum pib ntawm lub xyoo pua 19th los ntawm German Friedrich Moos. Nws yog ua raws li txoj kev khawb, qhov twg cov qauv nyuaj tawm ib qho cim ntawm ib qho softer, thiab nws yooj yim heev rau kev nrhiav seb cov hlau twg yog qhov softest. Nyob rau hauv kev sib raug zoo rau 10 siv minerals, uas tau muab ib tug conditional hardness index, ib qho chaw nyob rau hauv lub teev thiab ib tug digital index yog txiav txim rau cov tshuaj ntsuam xyuas. Lub softest siv ntxhia yog talc. Nws muaj Mohs hardness ntawm 1, thiab qhov nyuaj tshaj plaws, pob zeb diamond, yog 10.
Kev ntsuas qhov nyuaj ntawm Mohs nplai yog raws li lub hauv paus ntsiab lus "softer - harder". Nws tuaj yeem txiav txim siab raws nraim pes tsawg zaus, piv txwv li, txhuas, uas muaj qhov ntsuas ntawm Mohs nplai ntawm 2.75, yog softer dua tungsten (6.0), tsuas yog nrog kev ntsuas ntsuas raws li lwm txoj hauv kev. Tab sis txhawm rau txiav txim siab cov hlau softest nyob rau hauv lub sij hawm, lub rooj no txaus.
Qhov softest yog alkali hlau
Los ntawm Mohs mineralogical nplai, nws tuaj yeem pom tau tias cov softest yog cov tshuaj muaj feem xyuam rau cov hlau alkali. Txawm tias mercury, paub txog ntau yam ntawm cov kua los ntawm tus pas ntsuas kub, muaj qhov hardness Performance index ntawm 1.5. softer tshaj nws yog ob peb yam khoom uas zoo sib xws ntawm lub cev, txhua yam thiab tshuaj muaj zog: lithium (0.6 ntawm Mohs scale), sodium (0.5), poov tshuaj. (0, 4), rubidium (0, 3). Cov hlau softest yog cesium, uas muaj Mohs hardness nplai ntawm 0.2.
Lub cev thiab tshuaj lom neeg ntawm alkali hlau yog txiav txim siab los ntawm lawv cov kev teeb tsa hluav taws xob. Nws txawv me ntsis ntawm cov qauv ntawm inert gases. Ib qho hluav taws xob nyob rau ntawm lub zog sab nraud muaj kev txav mus los, uas txiav txim siab txog kev ua haujlwm siab. Cov hlau softest yog qhov tshwj xeeb volatility, lawv nyuaj rau kuv thiab khaws cia tsis hloov. Lawv muaj kev sib cuam tshuam tshuaj lom neeg nrog huab cua, dej, oxygen.
khoom 55
Lub npe "cesium" los ntawm Latin caesius - "lub ntuj xiav": nyob rau hauv lub spectrum emission los ntawm ib yam khoom kub heev, ob kaj xiav kab txaij pom nyob rau hauv lub infrared ntau yam. Nyob rau hauv nws daim ntawv ntshiab, nws pom lub teeb zoo, zoo li lub teeb kub thiab muaj xim silvery-daj. Cesium yog cov hlau softest nyob rau hauv lub ntiaj teb no, nrog Brinell hardness Performance index ntawm 0.15 MN / m 2 (0.015 kgf / cm 2). Melting point: +28.5 ° C, yog li nyob rau hauv ib txwm muaj mob, ntawm chav tsev kub, cesium yog nyob rau hauv ib tug semi-kua xeev.
Nws tsis tshua muajkim thiab heev reactive hlau. Hauv electronics, xov tooj cua engineering thiab high-tech chemical kev lag luam, cesium thiab alloys raws li nws tau siv ntau zuj zus thiab qhov kev xav tau ntawm nws yuav loj hlob tas li. Nws cov tshuaj lom neeg kev ua si, muaj peev xwm tsim cov tebchaw nrog lub siab tshaj plaws hluav taws xob conductivity yog nyob rau hauv kev thov. Cesium yog ib qho tseem ceeb hauv kev tsim cov khoom siv kho qhov muag tshwj xeeb, lub teeb nrog cov khoom tshwj xeeb thiab lwm yam khoom siv high-tech. Nyob rau tib lub sijhawm, softness tsis yog nws qhov zoo tshaj plaws nrhiav-tom qab zoo.
