1. Cov Carbon Nanotubes "loj" li cas?
Cov pa roj carbon nanotubes tsis yog mined los ntawm hauv av; lawv yog "loj" nyob rau hauv lub chaw soj nstuam. Carbon atoms rearrange nyob rau hauv ib txoj kev, curling mus rau hauv hollow tubular qauv- ib tug txheej txheem zoo li dov ib daim ntawv ntawm graphene ntawv rau hauv ib lub straw.
Txij li thaum lawv nrhiav tau nyob rau hauv 1991, cov kws tshawb fawb tau tsim ntau txoj hauv kev los npaj cov "super material." Ntawm lawv, txoj kev tawm arc, txoj kev laser ablation, thiab tshuaj vapor deposition (CVD) txoj kev yog peb txoj hauv kev loj tshaj plaws. Kab lus no tham txog qhov tshwj xeeb ntawm txhua txoj hauv kev- lawv ua haujlwm li cas, lawv qhov zoo thiab qhov tsis zoo, thiab qhov twg yog qhov tsim nyog rau kev tsim khoom lag luam.
2. Kev piav qhia ntxaws txog peb txoj kev npaj ua ntej
2.1 Arc Discharge Method: Txoj Kev "Feem ntau tshaj plaws".
Txoj kev tawm arc yog thawj txoj kev siv los tshawb pom CNTs thiab tuaj yeem suav tias yog "tus qub tub rog" thev naus laus zis.
Nws ua haujlwm li cas?
Ib qho roj inert (feem ntau helium lossis argon) tau nkag mus rau hauv lub reactor, thiab ob lub graphite rods yog siv los ua anode thiab cathode. Thaum siv ncaj qha tam sim no, cov graphite ntawm lub anode yog vaporized los ntawm qhov kub thiab txias, thiab carbon atoms rearrange rau CNTs, depositing li "soot" ntawm lub cathode nto thiab reactor phab ntsa.
Qhov sib txawv ntawm cov khoom:
Ntau -walled CNTs:Nws tuaj yeem ua ke siv cov ntshiab graphite electrodes ncaj qha.
Ib -walled CNTs:Yuav tsum tau ntxiv cov hlau catalysts xws li hlau, cobalt, los yog npib tsib xee rau lub anode.
Qhov zoo:
Cov khoom lag luam siab crystallinity thiab cov qauv zoo meej- ob peb phab ntsa tsis xws luag, qib siab ntawm graphitization.
Cov cuab yeej siv tau zoo, cov cuab yeej siv yooj yim.
Cov khoom zoo tshaj plaws ntawm peb txoj kev.
Qhov tsis zoo:
Kev siv hluav taws xob siab, xav tau lub tshuab nqus tsev siab thiab cov xwm txheej kub tshwj xeeb.
Tsawg tawm los; nyuaj rau scale nce economic.
Cov khoom yog sib xyaw nrog ntau ntawm amorphous carbon, fullerenes, thiab lwm yam impurities, yuav tsum tau 繁琐 purification cov kauj ruam.
Cov hlau thiab semiconducting CNTs sib xyaw ua ke thiab tsis tuaj yeem sib cais.
Yuav tsum tau hloov lub sij hawm ntawm electrodes thiab lub hom phiaj.
Cov ntsiab lus:Zoo zoo, tab sis tsis tshua muaj tawm los thiab siab impurities; tsis haum rau kev lag luam loj - nplai ntau lawm.
2.2 Laser Ablation Method: Siab precision, qis tshaj tawm
Txoj kev laser ablation tau tshaj tawm thawj zaug los ntawm Guo thiab cov npoj yaig hauv xyoo 1995 thiab tuaj yeem suav tias yog "kev hloov kho tshiab" ntawm txoj kev tawm arc.
Nws ua haujlwm li cas?
Nyob rau hauv qhov siab -kub (800–1500 degree) inert cua, siab -lub zog laser beam pulse bombards ib lub hom phiaj graphite mounted rau hauv ib lub raj quartz, vaporizing nws. Cov pa roj carbon atoms rov sib sau ua ke rau hauv CNTs, uas tom qab ntawd sau ua cov pa roj carbon-raws li cov kua qaub hauv lub tshuab.
Qhov zoo:
Synthesized CNTs muaj cov qauv zoo meej.
Yuav tsim SWCNTs yam tsis muaj MWCNT impurities.
Muaj peev xwm tswj kev tsim cov chiralities tshwj xeeb (piv txwv li, (10,10) CNTs).
Ua kom tsawg amorphous carbon impurities.
Qhov tsis zoo:
Cov khoom siv nyuaj thiab kim; tus nqi laser siab.
Tsis tshua muaj txiaj ntsig - tsuas yog milligram kom muaj nuj nqis rau ib qho kev npaj.
Kev siv hluav taws xob siab; yuav tsum muaj qhov kub thiab txias siab.
Kuj muaj teeb meem impurity yuav tsum tau purification.
Muaj feem cuam tshuam:Cov tshuaj muaj pes tsawg leeg ntawm lub hom phiaj, lub zog laser thiab wavelength, thiab qhov kev ncua deb ntawm lub substrate thiab lub hom phiaj tag nrho cuam tshuam cov khoom yield thiab zoo.
Cov ntsiab lus:Siab precision thiab purity, tab sis tawm los yog pitifully tsawg; tsuas yog tsim nyog rau kev tshawb fawb mechanistic hauv chav kuaj.
2.3 Chemical Vapor Deposition (CVD): "Cov Neeg Ua Haujlwm" ntawm Industrialization
CVD txoj kev tam sim no yog qhov kev xaiv tseem ceeb rau kev tsim khoom lag luam thiab yog txoj hauv kev zoo tshaj plaws rau kev ua tiav cov khoom loj -.
Nws ua haujlwm li cas?
Hydrocarbons lossis carbon-muaj oxides (xws li, methane, acetylene, ethylene) tau nkag mus rau hauv qhov kub siab -kub tube rauv uas muaj hlau catalysts (hlau, cobalt, nickel, thiab lwm yam). Cov pa roj decomposes ntawm qhov chaw catalyst, thiab cov pa roj carbon atoms rov ua dua los ua CNTs.
Hom khoom siv:Kab rov tav reactors, fluidized txaj reactors, ntsug reactors, thiab lwm yam.
Vim li cas CVD tau dhau los ua qhov tseem ceeb?
Qhov kub thiab txias:Cov tshuaj tiv thaiv kub (600-1000 degree) qis dua li ntawm arc tawm thiab laser txoj kev (tshaj 3000 degree).
Kev tsim khoom tsis tu ncua:Gas tsis tu ncua qhia, CNTs tsis tu ncua loj hlob, tso cai rau kev ua haujlwm tsis tu ncua.
High yield:Lub peev xwm ntau lawm ntawm ib lub reactor deb tshaj li ntawm ob txoj kev.
Zoo controllability:Los ntawm kev kho qhov tsis xws li catalyst, kub, thiab roj ntws tus nqi, txoj kab uas hla, qhov ntev, thiab cov qauv ntawm CNTs tuaj yeem tswj tau.
Qhov tsis zoo:
Cov khoom lag luam muaj ntau yam tsis xws luag; cov℃ntawm graphitization tsis siab npaum li nrog rau txoj kev tawm arc.
Tej zaum yuav khaws cov catalyst hlau impurities, yuav tsum tau kho purification.
Kev xaiv catalyst yog qhov tseem ceeb - cov catalyst ncaj qha txiav txim siab cov khoom zoo thiab cov txiaj ntsig.
Cov ntsiab lus:CVD txoj kev yog qhov kev xaiv zoo tshaj plaws rau kev tsim khoom lag luam-txawm tias qhov purity yog me ntsis qis dua thawj ob txoj hauv kev, nws muaj qhov zoo ntawm cov txiaj ntsig, nqi, thiab kev tswj hwm.
3. Kev sib piv cov ntsiab lus ntawm peb txoj kev
| Sib piv Dimension | Arc tso tawm | Laser Ablation | Chemical Vapor Deposition (CVD) |
|---|---|---|---|
| Qhov kub thiab txias | ~ 4000 degree | 800-1500 degree | 600-1000 degree |
| Khoom Purity | Siab (tab sis muaj impurities) | Siab heev | Nruab nrab (yuav tsum tau purification) |
| Cov qauv zoo meej | Siab | Siab heev | Nruab nrab (muaj qhov tsis xws luag) |
| Yield | Tsawg | Tsawg heev | Siab |
| Kev siv hluav taws xob | Siab | Siab heev | Tsawg heev |
| Khoom siv | Nruab nrab | Siab heev | Nruab nrab |
| Controllability | pluag | Nruab nrab | Zoo |
| Kev Tsim Nyog | Tsis muaj | Tsis muaj | Yog lawm |
| Muaj peev xwm Industrialization | Tsawg | Tsawg heev | Siab |
Cov ntsiab lus tseem ceeb:Cov txheej txheem arc tawm thiab laser ablation yog tsim nyog rau kev npaj siab -cov qauv zoo nyob rau hauv lub chaw soj nstuam; CVD txoj kev tsuas yog kev xaiv rau kev lag luam loj - nplai ntau lawm.
4. Advanced CVD Technology: Los ntawm Chav Ua Haujlwm mus rau Kaum-Tub-Ton Scale
CVD thev naus laus zis nws tus kheej tsis tu ncua. Ntxiv rau cov txheej txheem thermal CVD, cov txheej txheem qib siab xws li ntshav- txhim kho CVD (PECVD) thiab microwave plasma CVD tau tsim. Cov no tuaj yeem loj hlob CNTs ntawm qhov kub qis dua thiab muab kev tswj xyuas meej dua ntawm cov raj sib dhos thiab kev taw qhia.
Kev tawg hauv CVD industrialization los ntawm Suav tuam txhab:
Shandong Tanfeng yog ib qho ntawm ob peb lub tuam txhab hauv tsev uas tau paub txog cov thev naus laus zis tseem ceeb rau kev tsim cov pa roj carbon nanomaterials ntawm cov pa roj- theem txheej txheem. Siv tag nrho automated tswj, cov khoom yield tau nce mus rau ntau tshaj 99%. Muaj peev xwm tsim tau tam sim no tau nthuav dav rau 2,000 tons hauv ib xyoos, ua rau nws yog ib lub hauv paus loj tshaj plaws CNT ntau lawm hauv ntiaj teb.
5. Qhov zoo ntawm cov neeg tsim khoom: Ua CVD Technology los ntawm "muaj peev xwm" mus rau "Siv yooj yim"
Raws li cov chaw tsim khoom CNT, peb tau xaiv txoj hauv kev siv tshuab CVD thiab tau ua ntau yam ua tiav ntawm qib kev lag luam:
Mastering thev naus laus zis tseem ceeb ntawm catalyst tsim thiab npaj.Hauv CVD txoj kev, tus catalyst yog "tus ntsuj plig" - nws ncaj qha txiav txim siab txoj kab uas hla, tus naj npawb ntawm phab ntsa, thiab tawm los ntawm CNTs. Los ntawm peb tus kheej tsim cov txheej txheem catalyst, peb tau ua tiav kev tswj hwm ntawm cov khoom tsim, nrog rau txoj kab uas hla nqaim thiab cov khoom zoo - mus rau -batch sib xws.
Ua txhaum ntawm lub fwj ntawm lub reactor scaling -up.Traditional CVD reactors muaj tsawg tsawg -unit peev xwm. Tsim kom muaj kaum- txhiab- tuj cog yuav xav tau ntau lub tsev ua haujlwm sib luag, suav nrog kev nqis peev siab thiab kev tswj hwm nyuaj. Peb tau txais ib qho thib peb - tiam loj - nplai reactor tsim, qhov twg lub peev xwm ntawm ib chav tsev yog ob peb zaug ntawm cov khoom siv ib txwm siv, txo qis kev siv hluav taws xob thiab nqi zog.
Tam sim no, peb cov khoom CNT tau siv dav hauv lithium roj teeb conductive additives rau tsheb tshiab zog, siab heev polymer composites, elastomers, aerospace, tsheb thauj mus los, cua zog, thiab lwm yam teb. Los ntawm raw cov ntaub ntawv mus rau reactors, los ntawm catalysts mus rau purification thiab dispersion, peb tau mastered tag nrho cov saw ntawm technology rau CVD zus tau tej cov CNTs, cog lus los nqa no "super khoom" rau ntau txhiab industries.