Filimu ya graphite yomwe imakula mwachangu imaletsa kuwala kwa magetsi

Zikomo polembetsa ku Physics World Ngati mukufuna kusintha zambiri zanu nthawi iliyonse, chonde pitani ku akaunti yanga

Makanema a graphite amatha kuteteza zida zamagetsi ku ma electromagnetic radiation (EM), koma njira zamakono zopangira izi 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 lawonetsa njira ina yopangira makanema apamwamba a graphite m'masekondi ochepa pongotseka zingwe zotentha za nickel foil mu ethanol. Kukula kwa mafilimu awa ndi kwakukulu kuposa njira zomwe zilipo, ndipo mphamvu zamagetsi ndi makina a mafilimuwa ndizofanana ndi za mafilimu opangidwa pogwiritsa ntchito chemical vapour deposition (CVD).

Zipangizo zonse zamagetsi zimapanga kuwala kwa EM. Pamene zipangizo zikuchepa kwambiri ndikugwira ntchito pafupipafupi kwambiri, kuthekera kwa kusokoneza kwa electromagnetic (EMI) kumakula, ndipo kungakhudze kwambiri magwiridwe antchito a chipangizocho komanso machitidwe amagetsi apafupi.

Graphite, yomwe ndi allotrope ya kaboni yopangidwa kuchokera ku zigawo za graphene zomwe zimagwirizanitsidwa ndi mphamvu za van der Waals, ili ndi mphamvu zambiri zamagetsi, kutentha ndi makina zomwe zimapangitsa kuti ikhale chishango chothandiza ku EMI. Komabe, iyenera kukhala ngati filimu yopyapyala kwambiri kuti ikhale ndi mphamvu zamagetsi zambiri, zomwe ndizofunikira pakugwiritsa ntchito EMI chifukwa zikutanthauza kuti zinthuzo zimatha kuwunikira ndikuyamwa mafunde a EM pamene akugwirizana ndi zonyamulira zamagetsi mkati mwake.

Pakadali pano, njira zazikulu zopangira filimu ya graphite zimaphatikizapo pyrolysis ya ma polima a aromatic omwe amatentha kwambiri kapena kuyika graphene (GO) oxide kapena graphene nanosheets pagawo lililonse. Njira zonsezi zimafuna kutentha kwambiri kwa pafupifupi 3000 °C ndi nthawi yokonza ya ola limodzi. Mu CVD, kutentha kofunikira kumakhala kotsika (pakati pa 700 mpaka 1300 °C), koma zimatenga maola angapo kupanga mafilimu okhuthala ngati nanometer, ngakhale mu vacuum.

Gulu lotsogozedwa ndi Wencai Ren tsopano lapanga filimu yapamwamba kwambiri ya graphite yokhuthala kwambiri mkati mwa masekondi ochepa potenthetsa nickel foil kufika pa 1200 °C mumlengalenga wa argon kenako n’kumiza foil iyi mwachangu mu ethanol pa 0 °C. Maatomu a kaboni omwe amapangidwa kuchokera ku kuwonongeka kwa ethanol amafalikira ndikusungunuka mu nickel chifukwa cha kusungunuka kwa kaboni kwambiri kwa chitsulocho (0.4 wt% pa 1200 °C). Chifukwa kusungunuka kwa kaboni kumeneku kumachepa kwambiri kutentha kochepa, maatomu a kaboni pambuyo pake amalekanitsa ndikutuluka kuchokera pamwamba pa nickel panthawi yozimitsa, ndikupanga filimu yokhuthala ya graphite. Ofufuzawo anena kuti ntchito yabwino kwambiri yothandiza ya nickel imathandizanso kupanga graphite yolimba kwambiri.

Pogwiritsa ntchito makina ojambulira maginito ojambulira maginito apamwamba, ma diffraction a X-ray ndi ma Raman spectroscopy, Ren ndi anzake adapeza kuti graphite yomwe adapanga inali yonyezimira kwambiri m'malo akuluakulu, yokhala ndi zigawo zabwino komanso yopanda zilema zooneka. Mphamvu ya ma elekitironi ya filimuyi inali yokwera kufika pa 2.6 x 105 S/m, yofanana ndi mafilimu omwe amakula pogwiritsa ntchito njira za CVD kapena kutentha kwambiri komanso kukanikiza mafilimu a GO/graphene.

Pofuna kuyesa momwe zinthuzo zingatsekere kuwala kwa EM, gululo linasamutsa mafilimu okhala ndi malo okwana 600 mm2 kupita ku zinthu zopangidwa ndi polyethylene terephthalate (PET). Kenako anayeza mphamvu ya EMI shielding efficiency (SE) ya filimuyi mu X-band frequency range, pakati pa 8.2 ndi 12.4 GHz. Anapeza EMI SE yoposa 14.92 dB ya filimu yokwana pafupifupi 77 nm makulidwe. Mtengo uwu umawonjezeka kufika pa 20 dB (mtengo wocheperako wofunikira pa ntchito zamalonda) mu X-band yonse pamene anasonkhanitsa mafilimu ambiri pamodzi. Zoonadi, filimu yokhala ndi zidutswa zisanu za mafilimu a graphite ophatikizidwa (pafupifupi 385 nm makulidwe onse) ili ndi EMI SE yokwana 28 dB, zomwe zikutanthauza kuti zinthuzo zimatha kuletsa 99.84% ya kuwala kwa ngozi. Ponseponse, gululo linayesa EMI shielding ya 481,000 dB/cm2/g kudutsa X-band, zomwe zimachita bwino kuposa zinthu zonse zopangidwa zomwe zinanenedwa kale.

Ofufuzawo akuti, malinga ndi zomwe akudziwa, filimu yawo ya graphite ndiyo yopyapyala kwambiri pakati pa zipangizo zotetezera zomwe zanenedwa, yokhala ndi magwiridwe antchito a EMI shielding omwe angakwaniritse zofunikira pa ntchito zamalonda. Makhalidwe ake amakina nawonso ndi abwino. Mphamvu ya kusweka kwa chipangizocho ya pafupifupi 110 MPa (yochokera ku ma stress-strain curves a chinthucho chomwe chimayikidwa pa polycarbonate support) ndi yokwera kuposa ya mafilimu a graphite omwe amalimidwa ndi njira zina. Filimuyi nayonso ndi yosinthasintha, ndipo imatha kupindika nthawi 1000 ndi utali wopindika wa 5 mm popanda kutaya mawonekedwe ake a EMI shielding. Imakhazikikanso kutentha mpaka 550 °C. Gululi likukhulupirira kuti izi ndi zina zikutanthauza kuti ingagwiritsidwe ntchito ngati zinthu zotetezera za EMI zoonda kwambiri, zopepuka, zosinthasintha komanso zothandiza pa ntchito m'malo ambiri, kuphatikizapo ndege komanso zamagetsi ndi ma optoelectronics.

Werengani kupita patsogolo kwakukulu komanso kosangalatsa mu sayansi ya zinthu mu magazini yatsopano yotseguka iyi.

Physics World ikuyimira gawo lofunika kwambiri la ntchito ya IOP Publishing yolankhulana ndi kafukufuku wapadziko lonse lapansi komanso zatsopano kwa anthu ambiri momwe angathere. Webusaitiyi ndi gawo la Physics World portfolio, gulu la mautumiki apaintaneti, a digito ndi osindikiza a gulu la asayansi padziko lonse lapansi.