Hauv cov txheej txheem loj hlob ntawm silicon carbide ib leeg siv lead ua ke, kev thauj mus los ntawm lub cev yog txoj kev lag luam tam sim no. Rau txoj kev loj hlob PVT,silicon carbide hmoovmuaj kev cuam tshuam loj heev rau txoj kev loj hlob. Txhua yam kev ntsuas ntawmsilicon carbide hmoovncaj qha cuam tshuam rau qhov zoo ntawm kev loj hlob ntawm cov siv lead ua ke thiab cov khoom siv hluav taws xob. Hauv cov ntawv thov kev lag luam tam sim no, feem ntau sivsilicon carbide hmoovCov txheej txheem synthesis yog tus kheej-propagating high-temperature synthesis txoj kev.
Txoj kev tsim cov tshuaj uas siv qhov kub siab los ntawm tus kheej siv qhov kub siab los muab cov tshuaj reactants pib cua sov kom pib cov tshuaj tiv thaiv, thiab tom qab ntawd siv nws cov cua sov los ua kom cov tshuaj tsis muaj zog txuas ntxiv ua kom tiav cov tshuaj tiv thaiv. Txawm li cas los xij, txij li thaum cov tshuaj tiv thaiv ntawm Si thiab C tso tawm cua sov tsawg dua, lwm cov tshuaj reactants yuav tsum tau ntxiv los tswj cov tshuaj tiv thaiv. Yog li ntawd, ntau tus kws tshawb fawb tau tawm tswv yim txog txoj kev tsim cov tshuaj uas siv tus kheej zoo dua los ntawm qhov no, qhia txog tus neeg ua haujlwm. Txoj kev tsim cov tshuaj uas siv tus kheej yooj yim heev rau kev siv, thiab ntau yam kev tsim cov tshuaj yooj yim rau kev tswj hwm ruaj khov. Kev tsim cov tshuaj loj ua tau raws li qhov xav tau ntawm kev lag luam.
Txij li xyoo 1999, Bridgeport tau siv txoj kev tsim cov khoom siv kub siab uas nthuav dav los ua kom sib xyaw ua ke.SiC hmoov, tab sis nws siv ethoxysilane thiab phenol resin ua cov khoom siv raw, uas kim heev. Gao Pan thiab lwm tus siv cov hmoov Si-purity siab thiab C hmoov ua cov khoom siv raw los ua keSiC hmoovlos ntawm kev kub siab hauv huab cua argon. Ning Lina tau npaj cov khoom lojSiC hmoovlos ntawm kev sib xyaw ua ke theem ob.
Lub cub tawg cua sov induction nruab nrab uas tsim los ntawm Lub Tsev Kawm Ntawv Tshawb Fawb Thib Ob ntawm Tuam Tshoj Electronics Technology Group Corporation sib tov cov hmoov silicon thiab cov hmoov carbon sib npaug hauv qee qhov sib piv stoichiometric thiab muab tso rau hauv graphite crucible.graphite crucibletau muab tso rau hauv lub cub tawg induction cua sov nruab nrab rau cua sov, thiab qhov hloov pauv kub yog siv los ua ke thiab hloov pauv qhov kub qis thiab kub siab silicon carbide feem. Txij li thaum qhov kub ntawm β-SiC synthesis reaction hauv qhov kub qis qis dua qhov kub volatilization ntawm Si, kev tsim cov β-SiC hauv qab lub tshuab nqus tsev siab tuaj yeem ua kom muaj kev nthuav dav tus kheej. Txoj kev qhia txog argon, hydrogen thiab HCl roj hauv kev tsim cov α-SiC tiv thaiv kev lwj ntawmSiC hmoovnyob rau theem kub siab, thiab tuaj yeem txo cov ntsiab lus nitrogen hauv α-SiC hmoov.
Shandong Tianyue tau tsim lub cub tawg ua los ntawm cov khoom siv silane ua cov khoom siv silicon thiab cov hmoov carbon ua cov khoom siv carbon. Cov roj ntawm cov khoom siv raw tau hloov kho los ntawm ob kauj ruam ntawm kev tsim cov khoom siv, thiab qhov loj me ntawm cov khoom siv silicon carbide kawg yog ntawm 50 thiab 5 000 um.
1 Cov yam ntxwv tswj hwm ntawm cov txheej txheem tsim hmoov
1.1 Cov nyhuv ntawm qhov loj ntawm cov hmoov me me rau kev loj hlob ntawm cov siv lead ua
Qhov loj ntawm cov hmoov silicon carbide muaj feem cuam tshuam tseem ceeb heev rau kev loj hlob ntawm cov siv lead ua ib leeg tom qab. Kev loj hlob ntawm SiC ib leeg siv lead ua los ntawm PVT txoj kev feem ntau yog ua tiav los ntawm kev hloov pauv qhov piv ntawm silicon thiab carbon hauv cov roj theem, thiab qhov piv ntawm silicon thiab carbon hauv cov roj theem muaj feem cuam tshuam rau qhov loj ntawm cov hmoov silicon carbide. Tag nrho cov siab thiab silicon-carbon piv ntawm qhov system loj hlob nce nrog qhov txo qis ntawm qhov loj ntawm cov khoom. Thaum qhov loj ntawm cov khoom txo qis los ntawm 2-3 hli mus rau 0.06 hli, qhov piv ntawm silicon-carbon nce los ntawm 1.3 mus rau 4.0. Thaum cov khoom me me mus rau qee qhov, qhov siab ntawm Si ib nrab nce, thiab ib txheej ntawm Si zaj duab xis tau tsim rau ntawm qhov chaw ntawm cov siv lead ua loj hlob, ua rau muaj roj-kua-khoom loj hlob, uas cuam tshuam rau polymorphism, cov ntsiab lus tsis zoo thiab cov kab tsis zoo hauv cov siv lead ua. Yog li ntawd, qhov loj ntawm cov khoom ntawm cov hmoov silicon carbide siab-purity yuav tsum tau tswj hwm zoo.
Ntxiv mus, thaum qhov loj ntawm SiC hmoov me me, cov hmoov yuav lwj sai dua, ua rau SiC cov siv lead ua ke loj hlob ntau dhau. Ntawm ib sab tes, nyob rau hauv qhov kub siab ntawm SiC cov siv lead ua ke loj hlob, ob txoj kev tsim thiab rhuav tshem tau ua tiav tib lub sijhawm. Silicon carbide hmoov yuav lwj thiab tsim cov pa roj carbon hauv cov roj theem thiab cov khoom khov kho xws li Si, Si2C, SiC2, ua rau muaj carbonization hnyav ntawm cov hmoov polycrystalline thiab tsim cov pa roj carbon hauv cov siv lead ua ke; ntawm qhov tod tes, thaum qhov nrawm rhuav tshem ntawm cov hmoov yog qhov ceev, cov qauv siv lead ua ke ntawm SiC cov siv lead ua ke loj hlob sai, ua rau nws nyuaj rau tswj qhov zoo ntawm SiC cov siv lead ua ke loj hlob.
1.2 Cov nyhuv ntawm cov hmoov siv lead ua rau kev loj hlob ntawm cov siv lead ua
Kev loj hlob ntawm SiC ib leeg siv lead ua los ntawm PVT txoj kev yog ib qho txheej txheem sublimation-recrystallization ntawm qhov kub siab. Cov khoom siv lead ua ntawm SiC raw khoom muaj qhov cuam tshuam tseem ceeb rau kev loj hlob ntawm siv lead ua. Hauv cov txheej txheem ntawm kev tsim hmoov, theem qis-kub synthesis (β-SiC) nrog lub qauv cubic ntawm lub cell thiab theem siab-kub synthesis (α-SiC) nrog lub qauv hexagonal ntawm lub cell yuav raug tsim tawm feem ntau. Muaj ntau cov qauv siv lead ua silicon carbide thiab qhov ntsuas kub nqaim. Piv txwv li, 3C-SiC yuav hloov mus rau hauv hexagonal silicon carbide polymorph, piv txwv li 4H / 6H-SiC, ntawm qhov kub siab dua 1900 ° C.
Thaum lub sijhawm ua cov txheej txheem loj hlob ntawm cov siv lead ua ib leeg, thaum siv β-SiC hmoov los cog cov siv lead ua, qhov sib piv ntawm silicon-carbon molar ntau dua 5.5, thaum siv α-SiC hmoov los cog cov siv lead ua, qhov sib piv ntawm silicon-carbon molar yog 1.2. Thaum qhov kub nce siab, kev hloov pauv theem tshwm sim hauv lub crucible. Lub sijhawm no, qhov sib piv ntawm molar hauv theem roj loj dua, uas tsis zoo rau kev loj hlob ntawm cov siv lead ua. Tsis tas li ntawd, lwm yam khoom tsis huv ntawm theem roj, suav nrog carbon, silicon, thiab silicon dioxide, yooj yim tsim thaum lub sijhawm hloov pauv theem. Qhov muaj cov khoom tsis huv no ua rau cov siv lead ua rau cov microtubes thiab cov voids. Yog li ntawd, cov hmoov siv lead ua yuav tsum tau tswj hwm kom meej.
1.3 Cov nyhuv ntawm cov hmoov tsis huv rau kev loj hlob ntawm cov siv lead ua
Cov ntsiab lus tsis huv hauv SiC hmoov cuam tshuam rau qhov kev tsim nucleation thaum lub sijhawm siv lead ua kom loj hlob. Qhov siab dua ntawm cov ntsiab lus tsis huv, qhov tsawg dua rau cov siv lead ua kom nucleate. Rau SiC, cov hlau tsis huv tseem ceeb suav nrog B, Al, V, thiab Ni, uas yuav raug qhia los ntawm cov cuab yeej ua haujlwm thaum lub sijhawm ua cov hmoov silicon thiab cov hmoov carbon. Ntawm lawv, B thiab Al yog cov khoom tsis huv ntawm qib zog qis hauv SiC, ua rau SiC resistivity txo qis. Lwm cov hlau tsis huv yuav qhia ntau qib zog, ua rau cov khoom siv hluav taws xob tsis ruaj khov ntawm SiC ib leeg siv lead ua ntawm qhov kub siab, thiab muaj kev cuam tshuam ntau dua rau cov khoom siv hluav taws xob ntawm cov khoom siv hluav taws xob semi-insulating ib leeg siv lead ua, tshwj xeeb tshaj yog qhov resistivity. Yog li ntawd, cov hmoov silicon carbide uas muaj kev huv siab yuav tsum tau tsim ntau li ntau tau.
1.4 Cov nyhuv ntawm cov ntsiab lus nitrogen hauv cov hmoov rau kev loj hlob ntawm cov siv lead ua
Qib ntawm cov nitrogen txiav txim siab qhov resistivity ntawm ib lub substrate siv lead ua ke. Cov chaw tsim khoom loj yuav tsum tau kho qhov nitrogen doping concentration hauv cov khoom siv hluavtaws raws li cov txheej txheem loj hlob ntawm cov siv lead ua ke thaum lub sijhawm ua hmoov. Cov khoom siv silicon carbide semi-insulating high-purity yog cov khoom siv cog lus tshaj plaws rau cov khoom siv hluav taws xob tub rog. Txhawm rau kom loj hlob cov khoom siv silicon carbide semi-insulating high-purity nrog cov resistivity siab thiab cov khoom siv hluav taws xob zoo heev, cov ntsiab lus ntawm cov nitrogen impurity tseem ceeb hauv lub substrate yuav tsum tau tswj hwm ntawm qib qis. Cov khoom siv conductive ib lub substrates xav tau cov ntsiab lus nitrogen kom raug tswj hwm ntawm qhov concentration siab.
2. Kev siv tshuab tswj hwm tseem ceeb rau kev tsim cov hmoov
Vim yog qhov chaw siv sib txawv ntawm cov khoom siv silicon carbide, cov thev naus laus zis tsim rau cov hmoov loj hlob kuj muaj cov txheej txheem sib txawv. Rau N-hom conductive ib leeg siv lead ua hmoov loj hlob, qhov huv siab thiab ib theem yog qhov yuav tsum tau ua; thaum rau semi-insulating ib leeg siv lead ua hmoov loj hlob, kev tswj hwm nruj ntawm cov ntsiab lus nitrogen yog qhov yuav tsum tau ua.
2.1 Kev tswj qhov loj ntawm cov hmoov av
2.1.1 Qhov kub ntawm kev sib xyaw ua ke
Tsis txhob hloov pauv lwm yam txheej txheem, cov hmoov SiC tsim tawm ntawm qhov kub ntawm 1900 ℃, 2000 ℃, 2100 ℃, thiab 2200 ℃ tau kuaj thiab tshuaj xyuas. Raws li pom hauv Daim Duab 1, nws tuaj yeem pom tias qhov loj me ntawm cov khoom me me yog 250 ~ 600 μm ntawm 1900 ℃, thiab qhov loj me ntawm cov khoom me me nce mus txog 600 ~ 850 μm ntawm 2000 ℃, thiab qhov loj me ntawm cov khoom me me hloov pauv ntau heev. Thaum qhov kub txuas ntxiv mus txog 2100 ℃, qhov loj me ntawm cov hmoov SiC yog 850 ~ 2360 μm, thiab qhov nce ntxiv feem ntau maj mam. Qhov loj me ntawm cov khoom me me ntawm SiC ntawm 2200 ℃ ruaj khov ntawm kwv yees li 2360 μm. Qhov nce ntawm qhov kub ntawm cov khoom me me los ntawm 1900 ℃ muaj qhov cuam tshuam zoo rau qhov loj me ntawm cov khoom me me SiC. Thaum qhov kub ntawm cov khoom me me txuas ntxiv mus txog 2100 ℃, qhov loj me ntawm cov khoom me me tsis hloov pauv ntau lawm. Yog li ntawd, thaum qhov kub ntawm kev tsim khoom raug teeb tsa rau 2100 ℃, qhov loj dua ntawm cov khoom me me tuaj yeem tsim tau ntawm kev siv hluav taws xob qis dua.
2.1.2 Lub sijhawm sib xyaw ua ke
Lwm cov txheej txheem tseem tsis tau hloov pauv, thiab lub sijhawm tsim khoom tau teeb tsa rau 4 teev, 8 teev, thiab 12 teev raws li. Kev tshuaj xyuas cov hmoov SiC uas tau tsim tawm tau pom hauv Daim Duab 2. Nws pom tias lub sijhawm tsim khoom muaj qhov cuam tshuam loj rau qhov loj ntawm SiC. Thaum lub sijhawm tsim khoom yog 4 teev, qhov loj ntawm cov khoom feem ntau yog faib ntawm 200 μm; thaum lub sijhawm tsim khoom yog 8 teev, qhov loj ntawm cov khoom tsim khoom nce ntxiv, feem ntau faib ntawm kwv yees li 1 000 μm; thaum lub sijhawm tsim khoom txuas ntxiv nce ntxiv, qhov loj ntawm cov khoom nce ntxiv, feem ntau faib ntawm kwv yees li 2 000 μm.
2.1.3 Kev cuam tshuam ntawm qhov loj ntawm cov khoom siv raw
Raws li cov saw hlau tsim cov khoom siv silicon hauv tsev tau maj mam txhim kho, qhov huv ntawm cov khoom siv silicon kuj tau txhim kho ntxiv. Tam sim no, cov khoom siv silicon siv rau hauv kev tsim khoom feem ntau yog muab faib ua cov silicon granular thiab cov silicon hmoov, raws li qhia hauv Daim Duab 3.
Cov khoom siv silicon sib txawv tau siv los ua cov kev sim ua silicon carbide synthesis. Kev sib piv ntawm cov khoom tsim tau pom hauv Daim Duab 4. Kev tshuaj xyuas qhia tau tias thaum siv cov khoom siv silicon block, muaj ntau cov ntsiab lus Si nyob hauv cov khoom. Tom qab lub silicon block raug tsoo rau lub sijhawm thib ob, cov ntsiab lus Si hauv cov khoom tsim tau txo qis, tab sis nws tseem muaj. Thaum kawg, hmoov silicon yog siv rau kev tsim, thiab tsuas yog SiC xwb nyob hauv cov khoom. Qhov no yog vim tias nyob rau hauv cov txheej txheem ntau lawm, cov silicon loj loj yuav tsum tau dhau los ntawm kev ua haujlwm ntawm qhov chaw ua ntej, thiab silicon carbide yog synthesized rau ntawm qhov chaw, uas tiv thaiv cov hmoov Si sab hauv los ntawm kev sib xyaw nrog C hmoov. Yog li ntawd, yog tias block silicon yog siv ua cov khoom siv raw, nws yuav tsum tau tsoo thiab tom qab ntawd raug rau cov txheej txheem tsim theem ob kom tau txais cov hmoov silicon carbide rau kev loj hlob ntawm cov siv lead ua.
2.2 Kev tswj cov hmoov siv lead ua hmoov
2.2.1 Kev cuam tshuam ntawm qhov kub ntawm kev tsim khoom
Yog tias tswj hwm lwm yam txheej txheem tsis hloov pauv, qhov kub ntawm kev tsim khoom yog 1500 ℃, 1700 ℃, 1900 ℃, thiab 2100 ℃, thiab cov hmoov SiC uas tsim tawm raug kuaj thiab tshuaj xyuas. Raws li pom hauv Daim Duab 5, β-SiC yog xim av daj, thiab α-SiC yog xim sib dua. Los ntawm kev soj ntsuam cov xim thiab morphology ntawm cov hmoov tsim tawm, nws tuaj yeem txiav txim siab tias cov khoom tsim tawm yog β-SiC ntawm qhov kub ntawm 1500 ℃ thiab 1700 ℃. Ntawm 1900 ℃, cov xim yuav sib dua, thiab cov khoom me me tshwm sim, qhia tias tom qab qhov kub nce mus txog 1900 ℃, kev hloov pauv theem tshwm sim, thiab ib feem ntawm β-SiC raug hloov mus rau α-SiC; thaum qhov kub txuas ntxiv nce mus txog 2100 ℃, nws pom tias cov khoom me me yog pob tshab, thiab α-SiC tau hloov pauv lawm.
2.2.2 Cov nyhuv ntawm lub sijhawm tsim khoom
Lwm cov txheej txheem tseem tsis tau hloov pauv, thiab lub sijhawm tsim khoom yog teem rau 4h, 8h, thiab 12h, raws li. Cov hmoov SiC uas tsim tawm raug kuaj thiab tshuaj xyuas los ntawm diffractometer (XRD). Cov txiaj ntsig tau pom hauv Daim Duab 6. Lub sijhawm tsim khoom muaj qee yam cuam tshuam rau cov khoom tsim los ntawm SiC hmoov. Thaum lub sijhawm tsim khoom yog 4 h thiab 8 h, cov khoom tsim khoom feem ntau yog 6H-SiC; thaum lub sijhawm tsim khoom yog 12 h, 15R-SiC tshwm sim hauv cov khoom.
2.2.3 Kev cuam tshuam ntawm cov khoom siv raw piv
Lwm cov txheej txheem tseem tsis tau hloov pauv, qhov ntau ntawm cov tshuaj silicon-carbon raug tshuaj xyuas, thiab qhov sib piv yog 1.00, 1.05, 1.10 thiab 1.15 rau kev sim ua ke. Cov txiaj ntsig tau qhia hauv Daim Duab 7.
Los ntawm XRD spectrum, nws tuaj yeem pom tias thaum qhov sib piv ntawm silicon-carbon ntau dua 1.05, qhov ntau dhau Si tshwm sim hauv cov khoom, thiab thaum qhov sib piv ntawm silicon-carbon tsawg dua 1.05, qhov ntau dhau C tshwm sim. Thaum qhov sib piv ntawm silicon-carbon yog 1.05, cov pa roj carbon dawb hauv cov khoom tsim tawm raug tshem tawm, thiab tsis muaj silicon dawb tshwm sim. Yog li ntawd, qhov sib piv ntawm silicon-carbon yuav tsum yog 1.05 los tsim cov SiC ntshiab.
2.3 Kev tswj cov ntsiab lus nitrogen tsawg hauv cov hmoov
2.3.1 Cov khoom siv ua los ntawm cov khoom siv hluavtaws
Cov khoom siv raw siv rau hauv qhov kev sim no yog cov hmoov carbon uas muaj purity siab thiab cov hmoov silicon uas muaj purity siab nrog lub cheeb tsam nruab nrab ntawm 20 μm. Vim lawv qhov me me thiab thaj chaw loj, lawv yooj yim nqus N2 hauv huab cua. Thaum synthesizing cov hmoov, nws yuav raug coj mus rau hauv daim ntawv siv lead ua ntawm cov hmoov. Rau kev loj hlob ntawm N-hom siv lead ua, qhov tsis sib xws ntawm N2 hauv cov hmoov ua rau tsis sib xws ntawm cov siv lead ua thiab txawm tias hloov pauv hauv daim ntawv siv lead ua. Cov ntsiab lus nitrogen ntawm cov hmoov synthesized tom qab hydrogen tau qhia yog qis heev. Qhov no yog vim tias qhov ntim ntawm cov hydrogen molecules yog me me. Thaum N2 adsorbed hauv cov hmoov carbon thiab silicon hmoov raug cua sov thiab decomposed ntawm qhov chaw, H2 diffuses tag nrho rau hauv qhov sib txawv ntawm cov hmoov nrog nws qhov me me, hloov qhov chaw ntawm N2, thiab N2 dim ntawm crucible thaum lub sijhawm nqus tsev, ua tiav lub hom phiaj ntawm kev tshem tawm cov ntsiab lus nitrogen.
2.3.2 Cov txheej txheem sib xyaw ua ke
Thaum lub sijhawm tsim cov hmoov silicon carbide, vim tias lub vojvoog ntawm cov pa roj carbon thiab cov pa nitrogen zoo sib xws, nitrogen yuav hloov cov pa roj carbon hauv silicon carbide, yog li ua rau cov pa nitrogen ntau ntxiv. Cov txheej txheem sim no siv txoj kev qhia H2, thiab H2 cuam tshuam nrog cov pa roj carbon thiab silicon hauv cov khoom siv sib xyaw ua ke los tsim cov pa roj C2H2, C2H, thiab SiH. Cov ntsiab lus ntawm cov pa roj carbon nce ntxiv los ntawm kev sib kis ntawm cov pa roj, yog li txo cov pa roj carbon. Lub hom phiaj ntawm kev tshem tawm nitrogen tau ua tiav.
2.3.3 Kev tswj cov ntsiab lus nitrogen tom qab txheej txheem
Cov khoom siv graphite crucibles uas muaj porosity loj siv tau ua cov khoom siv C ntxiv los nqus cov pa Si hauv cov khoom siv theem roj, txo Si hauv cov khoom siv theem roj, thiab yog li ua rau C/Si nce ntxiv. Tib lub sijhawm, cov khoom siv graphite crucibles kuj tseem tuaj yeem ua rau Si huab cua tsim Si2C, SiC2 thiab SiC, uas sib npaug rau Si huab cua coj C qhov chaw los ntawm graphite crucible mus rau hauv huab cua loj hlob, ua rau C piv ntau dua, thiab tseem ua rau carbon-silicon piv ntau dua. Yog li ntawd, carbon-silicon piv tuaj yeem nce ntxiv los ntawm kev siv cov khoom siv graphite crucibles uas muaj porosity loj, txo cov pa carbon, thiab ua tiav lub hom phiaj ntawm kev tshem tawm nitrogen.
3 Kev tshuaj xyuas thiab tsim cov txheej txheem tsim cov hmoov siv lead ua ib zaug xwb
3.1 Lub hauv paus ntsiab lus thiab kev tsim qauv ntawm cov txheej txheem synthesis
Los ntawm kev tshawb fawb txog kev tswj hwm qhov loj me ntawm cov khoom me me, cov duab siv lead ua thiab cov ntsiab lus nitrogen ntawm cov hmoov ua ke, cov txheej txheem ua ke tau npaj tseg. Cov hmoov C thiab Si uas muaj cov khoom qab zib siab raug xaiv, thiab lawv tau sib xyaw ua ke thiab thauj mus rau hauv lub graphite crucible raws li qhov sib piv ntawm silicon-carbon ntawm 1.05. Cov kauj ruam ntawm cov txheej txheem feem ntau muab faib ua plaub theem:
1) Cov txheej txheem denitrification kub qis, nqus tsev mus rau 5 × 10-4 Pa, tom qab ntawd qhia hydrogen, ua rau lub chamber siab li 80 kPa, tswj tau 15 feeb, thiab rov ua plaub zaug. Cov txheej txheem no tuaj yeem tshem tawm cov ntsiab lus nitrogen ntawm qhov chaw ntawm cov hmoov carbon thiab cov hmoov silicon.
2) Cov txheej txheem denitrification kub siab, nqus tsev mus rau 5 × 10-4 Pa, tom qab ntawd cua sov mus rau 950 ℃, thiab tom qab ntawd qhia hydrogen, ua rau lub chamber siab txog 80 kPa, tswj hwm rau 15 feeb, thiab rov ua plaub zaug. Cov txheej txheem no tuaj yeem tshem tawm cov ntsiab lus nitrogen ntawm qhov chaw ntawm cov hmoov carbon thiab silicon hmoov, thiab tsav nitrogen hauv thaj chaw kub.
3) Kev tsim cov txheej txheem kub qis, tshem tawm mus rau 5 × 10-4 Pa, tom qab ntawd cua sov rau 1350 ℃, khaws cia rau 12 teev, tom qab ntawd qhia hydrogen kom ua rau lub chamber siab txog 80 kPa, khaws cia rau 1 teev. Cov txheej txheem no tuaj yeem tshem tawm cov nitrogen uas tau yaj thaum lub sijhawm tsim cov txheej txheem.
4) Kev tsim cov txheej txheem kub siab, sau nrog qee qhov piv ntawm cov pa roj ntawm cov pa roj hydrogen thiab argon sib xyaw ua ke, ua kom lub chamber siab txog 80 kPa, nce qhov kub mus rau 2100 ℃, khaws cia rau 10 teev. Cov txheej txheem no ua tiav kev hloov pauv ntawm silicon carbide hmoov los ntawm β-SiC mus rau α-SiC thiab ua tiav kev loj hlob ntawm cov khoom siv lead ua.
Thaum kawg, tos kom qhov kub ntawm chav txias mus rau qhov kub ntawm chav tsev, sau kom txog rau qhov siab ntawm huab cua, thiab muab cov hmoov tawm.
3.2 Cov txheej txheem ua tiav tom qab ua hmoov
Tom qab cov hmoov raug tsim los ntawm cov txheej txheem saum toj no, nws yuav tsum tau ua tiav tom qab kom tshem tawm cov pa roj carbon dawb, silicon thiab lwm yam hlau tsis huv thiab tshuaj xyuas qhov loj me ntawm cov khoom me me. Ua ntej, cov hmoov tsim tau muab tso rau hauv lub tshuab zeb pob rau kev sib tsoo, thiab cov hmoov silicon carbide uas raug tsoo raug muab tso rau hauv lub cub tawg thiab cua sov rau 450 ° C los ntawm oxygen. Cov pa roj carbon dawb hauv cov hmoov raug oxidized los ntawm cua sov los tsim cov pa roj carbon dioxide uas tawm hauv lub chamber, yog li ua tiav kev tshem tawm cov pa roj carbon dawb. Tom qab ntawd, cov kua ntxuav acidic tau npaj thiab muab tso rau hauv lub tshuab ntxuav silicon carbide rau kev ntxuav kom tshem tawm cov pa roj carbon, silicon thiab cov hlau tsis huv uas tsim thaum lub sijhawm ua cov txheej txheem sib xyaw. Tom qab ntawd, cov kua qaub seem raug ntxuav hauv dej ntshiab thiab ziab. Cov hmoov qhuav raug tshuaj xyuas hauv lub vijtsam vibrating rau kev xaiv qhov loj me ntawm cov khoom me me rau kev loj hlob ntawm cov siv lead ua.
Lub sijhawm tshaj tawm: Lub Yim Hli-08-2024