Zikomo polembetsa ndi Physics World Ngati mukufuna kusintha zambiri nthawi iliyonse, chonde pitani ku Akaunti Yanga
Mafilimu a graphite amatha kuteteza zipangizo zamagetsi ku radiation ya electromagnetic (EM), koma njira zamakono zopangira izo zimatenga maola angapo ndipo zimafuna kutentha kwa pafupifupi 3000 ° C. Gulu la ofufuza ochokera ku Shenyang National Laboratory for Materials Science ku Chinese Academy of Sciences tsopano lasonyeza njira ina yopangira mafilimu apamwamba kwambiri a graphite m'masekondi ochepa chabe mwa kuzimitsa zitsulo zotentha za faifi mu ethanol. Kukula kwa mafilimuwa ndi kuwirikiza kawiri kuposa njira zomwe zilipo kale, ndipo mphamvu zamakasitomala zamakanemawa komanso mphamvu zamakina zimafanana ndi za makanema opangidwa pogwiritsa ntchito chemical vapor deposition (CVD).
Zida zonse zamagetsi zimapanga ma radiation a EM. Zida zikamacheperachepera komanso zimagwira ntchito pamafuriji apamwamba kwambiri, kuthekera kwa electromagnetic interference (EMI) kumakula, ndipo kumatha kusokoneza magwiridwe antchito a chipangizocho komanso makina apakompyuta omwe ali pafupi.
Graphite, allotrope ya kaboni yomangidwa kuchokera ku zigawo za graphene zomwe zimagwiridwa ndi mphamvu za van der Waals, zili ndi mphamvu zambiri zamagetsi, zotentha komanso zamakina zomwe zimapangitsa kuti ikhale chishango chogwira ntchito motsutsana ndi EMI. Komabe, ziyenera kukhala mu mawonekedwe a filimu yopyapyala kwambiri kuti ikhale ndi magetsi apamwamba kwambiri, omwe ndi ofunika kwambiri pa ntchito za EMI chifukwa zikutanthauza kuti zinthuzo zimatha kuwonetsera ndi kuyamwa mafunde a EM pamene akugwirizana ndi zonyamulira mkati. izo.
Pakali pano, njira zazikulu zopangira filimu ya graphite zimaphatikizapo kutentha kwapamwamba kwa ma polima onunkhira kapena kuyika graphene (GO) oxide kapena graphene nanosheets wosanjikiza ndi wosanjikiza. Njira zonsezi zimafuna kutentha kwakukulu kwa 3000 ° C ndi nthawi yokonza ola limodzi. Mu CVD, kutentha kofunikira kumakhala kotsika (pakati pa 700 mpaka 1300 ° C), koma zimatengera maola angapo kuti mupange mafilimu amtundu wa nanometre, ngakhale mu vacuum.
Gulu lotsogozedwa ndi Wencai Ren tsopano lapanga filimu yapamwamba kwambiri ya graphite makulidwe a nanometers mkati mwa masekondi pang'ono potenthetsa zojambula za nickel mpaka 1200 °C mumlengalenga wa argon kenako ndikumiza mwachangu zojambulazo mu ethanol pa 0 °C. Ma atomu a carbon omwe amapangidwa kuchokera pakuwonongeka kwa ethanol amafalikira ndikusungunuka mu faifi tambala chifukwa cha kusungunuka kwa carbon kwachitsulo (0.4 wt% pa 1200 °C). Chifukwa kusungunuka kwa kaboni uku kumachepa kwambiri pakatentha kwambiri, maatomu a kaboni amalekanitsa ndikutsika kuchokera pamwamba pa faifi tambala panthawi yozimitsa, ndikupanga filimu yokhuthala ya graphite. Ofufuzawo akuti ntchito yabwino kwambiri ya nickel imathandizanso kupanga ma crystalline graphite.
Pogwiritsa ntchito makina opangidwa ndi ma microscopy apamwamba kwambiri, X-ray diffraction ndi Raman spectroscopy, Ren ndi anzake adapeza kuti graphite yomwe adapanga inali yonyezimira kwambiri m'madera akuluakulu, osanjikiza bwino komanso opanda zolakwika zowonekera. Ma electron conductivity a filimuyi anali okwera kwambiri mpaka 2.6 x 105 S/m, mofanana ndi mafilimu opangidwa ndi CVD kapena njira zotentha kwambiri komanso kukanikiza kwa mafilimu a GO/graphene.
Pofuna kuyesa momwe zinthuzo zingatsekereze ma radiation a EM, gululo linasamutsa mafilimu okhala ndi malo a 600 mm2 pazitsulo zopangidwa ndi polyethylene terephthalate (PET). Kenako anayeza filimuyo EMI shielding performance (SE) mu X-band frequency range, pakati pa 8.2 ndi 12.4 GHz. Anapeza EMI SE yoposa 14.92 dB ya filimu pafupifupi 77 nm thick. Mtengowu umakwera mpaka kupitilira 20 dB (mtengo wochepera wofunikira pazamalonda) mu gulu lonse la X pomwe amawunjikana mafilimu ochulukirapo. Zowonadi, filimu yomwe ili ndi zidutswa zisanu zamakanema a graphite (ozungulira 385 nm makulidwe onse) ili ndi EMI SE ya 28 dB, zomwe zikutanthauza kuti zinthuzo zitha kuletsa 99.84% ya ma radiation omwe adachitika. Ponseponse, gululo linayeza chitetezo cha EMI cha 481,000 dB/cm2/g kudutsa X-band, kupitilira zida zonse zopanga zomwe zidanenedwapo kale.
Ofufuzawa akunena kuti mwakudziwa kwawo, filimu yawo ya graphite ndi yowonda kwambiri pakati pa zipangizo zotetezera zomwe zanenedwa, ndi EMI shielding performance yomwe ingathe kukwaniritsa zofunikira pa malonda. Mawotchi ake ndi abwino. Mphamvu zosweka za zinthuzo za pafupifupi 110 MPa (zochokera ku kupsinjika-kusefukira kwa zinthu zomwe zimayikidwa pa chothandizira cha polycarbonate) ndizokwera kuposa makanema a graphite omwe amapangidwa ndi njira zina. Kanemayo ndi wosinthika, nawonso, ndipo amatha kupindika nthawi za 1000 ndi utali wopindika wa 5 mm osataya katundu wake wotchinga wa EMI. Ndiwokhazikika pa kutentha mpaka 550 ° C. Gululi limakhulupirira kuti zinthu izi ndi zina zikutanthauza kuti zitha kugwiritsidwa ntchito ngati ultrathin, lightweight, flexible and effective EMI shielding material for applications in many areas, as aerospace and electronics and optoelectronics.
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Nthawi yotumiza: May-07-2020