1. Crystal Structure thiab Polytypism ntawm Silicon Carbide
1.1 Cubic thiab Hexagonal Polytypes: Los ntawm 3C mus rau 6H thiab dhau los
(Silicon Carbide Ceramics)
Silicon carbide (SiC) yog covalently adhered ceramic muaj li ntawm silicon thiab carbon atoms teem nyob rau hauv ib tug tetrahedral sychronisation, tsim ib qho ntawm cov txheej txheem nyuaj tshaj plaws ntawm polytypism hauv cov ntaub ntawv tshawb fawb.
Tsis zoo li ntau cov ceramics nrog ib leeg khov kho crystal moj khaum, SiC muaj nyob rau hauv dhau 250 paub zoo polytypes– Qhov sib txawv piling sequences ntawm kaw-packed Si-C bilayers raws c-axis– sib txawv ntawm cubic 3C-SiC (tseem hu ua β-SiC) rau hexagonal 6H-SiC thiab rhombohedral 15R-SiC.
Ib qho ntawm feem ntau cov polytypes siv hauv kev tsim daim ntawv thov yog 3C (kub), 4H, thiab 6 H (ob lub hexagonal), txhua qhov qhia me ntsis ntau yam khoom siv hluav taws xob thiab cov thermal conductivity.
3C-SiC, nrog nws cov zinc blende moj khaum, muaj qhov nqaim bandgap (~ 2.3 eV) thiab feem ntau yog nthuav dav ntawm silicon substrates rau cov cuab yeej semiconductor, thaum 4H-SiC muab cov khoom siv hluav taws xob zoo tshaj plaws thiab tau txais txiaj ntsig zoo rau cov khoom siv hluav taws xob muaj zog.
Cov khoom sib txuas sib txuas thiab kev taw qhia ntawm Si– C bond confer exceptional solidity, thermal kev ruaj ntseg, thiab tiv thaiv plam thiab tshuaj lom neeg ua phem, ua SiC zoo tagnrho rau kev siv ib puag ncig huab cua.
1.2 Teeb meem, Doping, thiab Digital Residence
Txawm hais tias nws cov qauv intricacy, SiC tuaj yeem doped kom muaj ob hom n-hom thiab p-hom conductivity, tso cai rau nws siv hauv cov khoom siv semiconductor.
Nitrogen thiab phosphorus ua haujlwm ua pa phem, qhia electrons txoj cai mus rau hauv lub kis tau tus mob band, thaum lub teeb yuag aluminium thiab boron ua haujlwm raws li kev lees paub, ua qhov nyob rau hauv lub valence band.
Txawm li cas los xij, p-hom doping efficiency yog txwv los ntawm siab ua kom muaj zog, tshwj xeeb tshaj yog nyob rau hauv 4H-SiC, uas poses obstacles rau bipolar cuab tam layout.
Native defects xws li ntsia hlau misplacements, micropipes, thiab piling yuam kev tuaj yeem ua rau cov cuab yeej ua haujlwm tsis muaj zog los ntawm kev ua raws li cov khoom siv rov ua dua lossis cov chav kawm xau, xav tau sab saum toj notch ib leeg-crystal txoj kev loj hlob rau kev siv hluav taws xob.
Bandgap loj heev (2.3– 3.3 eV nyob ntawm polytype), siab tsis ua hauj lwm hluav taws xob cheeb tsam (~ 3 MV/cm), thiab zoo heev thermal conductivity (~ 3– 4 W/m · K rau 4H-SiC) Ua SiC ntau dua li silicon hauv qhov kub thiab txias, high-voltage, thiab high-frequency hwj chim electronics.
2. Kov thiab Microstructural Design
( Silicon Carbide Ceramics)
2.1 Sintering thiab Densification Techniques
Silicon carbide yog ib txwm nyuaj rau densify vim nws muaj zog covalent bonding thiab txo tus kheej diffusion coefficients., xav tau cov txheej txheem kev ua haujlwm tshiab kom ua tiav qhov ntom ntom yam tsis muaj tshuaj ntxiv lossis nrog kev pab sintering tsawg heev.
Pressureless sintering ntawm submicron SiC hmoov yog ua tau nrog kev txhim kho ntawm boron thiab carbon, uas txhawb nqa densification los ntawm kev tshem tawm cov oxide txheej thiab txhim kho solid-state diffusion.
Kev sib tw sov yog siv uniaxial siab thaum cua sov hauv tsev, tso cai rau tag nrho densification ntawm txo qhov kub thiab txias (~ 1800 Nws– 2000 ° C )thiab tsim cov nplua-grained, high-strength Cheebtsam zoo tagnrho rau txo cov khoom siv thiab muab tso rau ntawm qhov chaw.
Rau cov duab loj lossis nyuaj, kev sib txuas lus teb yog siv, qhov twg porous carbon preforms nkag mus nrog molten silicon ntawm ~ 1600 ° C, tsim β-SiC hauv situ nrog marginal shrinkage.
Txawm li cas los xij, residual nqi-dawb silicon (~ 5– 10%) tseem nyob hauv microstructure, limiting high-temperature efficiency thiab oxidation kuj saum toj no 1300 ° C.
2.2 Additive Production thiab Ze-Net-Shape Manufacture
Tam sim no breakthroughs nyob rau hauv additive manufacturing (AM), tshwj xeeb binder jetting thiab stereolithography siv SiC hmoov los yog preceramic polymers, tso cai rau fabrication ntawm intricate geometry yav tas los unattainable nrog pa mus kom ze.
Nyob rau hauv polymer-derived ceramic (PDC) txoj kev, Cov kua dej SiC forerunners yog tsim los ntawm 3D luam ntawv thiab tom qab ntawd pyrolyzed ntawm heats los tsim amorphous lossis nanocrystalline SiC, feem ntau xav tau densification.
Cov txheej txheem no txo tus nqi machining thiab cov khoom pov tseg, ua SiC muaj ntau yam ntxiv rau aerospace, nuclear, thiab sov exchanger daim ntaub ntawv uas complex layouts txhim khu kev ua tau zoo.
Tom qab ua haujlwm xws li tshuaj vapor infiltration (CVI) los yog kua dej silicon seepage (LSI) Qee zaum siv los txhim kho qhov ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom.
3. Neeg kho tshuab, Kub, thiab Environmental Efficiency
3.1 Lub zog, Hardness, thiab siv Resistance
Silicon carbide qeb ntawm cov khoom lag luam nyuaj tshaj plaws, nrog Mohs solidity ntawm ~ 9.5 thiab Vickers firmness surpassing 25 Qib nruab nrab, ua rau nws tiv thaiv kev puas tsuaj, kev tawg, thiab scraping.
Nws lub zog flexural feem ntau yog los ntawm 300 rau 600 MPa, vam khom mus kom ze thiab grain loj, thiab nws khaws toughness ntawm qhov kub thiab txias mus txog 1400 ° C nyob rau hauv inert ambiences.
Lub zog tawg, thaum me ntsis (~ 3– 4 MPa · m 1ST/TWO), yog txaus rau ntau daim ntawv thov architectural, tshwj xeeb tshaj yog thaum kev koom ua ke nrog kev txhawb nqa fiber ntau hauv ceramic matrix composites (CMCs).
SiC-raws li CMCs yog siv nyob rau hauv turbine hniav, combustor linings, thiab nres systems, qhov twg lawv muab qhov hnyav tus nqi txuag, gas efficiency, thiab ntev kev pab cuam lub neej tshaj metallic sib npaug.
Nws tshwj xeeb hnav tsis kam ua rau SiC zoo meej rau cov ntsaws ruaj ruaj, bearings, twj tso kua mis, thiab ballistic ntaub thaiv npog, qhov twg sturdiness nyob rau hauv heev mechanical loading yog ib qho tseem ceeb.
3.2 Thermal Conductivity thiab Oxidation Security
Ib qho ntawm SiC cov khoom siv tau zoo tshaj plaws hauv tsev lossis kev lag luam yog nws cov thermal conductivity– kwv yees 490 W/m · K rau ib leeg-crystal 4H-SiC thiab ~ 30– 120 W/m · K rau hom polycrystalline– mus dhau qhov ntau ntawm cov hlau thiab ua rau nws ua tau rau kev ua kom sov zoo.
Cov vaj tsev nyob no yog qhov tseem ceeb hauv hluav taws xob hluav taws xob, qhov twg SiC cov cuab yeej tsim hluav taws xob tsawg dua thiab tuaj yeem khiav ntawm lub zog ntau dua li cov khoom siv silicon.
Nyob rau theem kub nce hauv oxidizing ib puag ncig, SiC tsim kev tiv thaiv silica (SiO ₂) txheej uas txo cov oxidation ntxiv, muab zoo ecological sturdiness ntau npaum li ~ 1600 ° C.
Txawm li cas los xij, nyob rau hauv cov dej vapor-nplua nuj cua, txheej no tuaj yeem volatilize li Si(OH)₄, ua rau kom ceev degradation– ib qho kev sib tw tseem ceeb hauv kev siv roj turbine.
4. Advanced Applications hauv Zog, Electronic Devices, thiab Aerospace
4.1 Fais fab Electronic Devices thiab Semiconductor Gadgets
Silicon carbide tau hloov hluav taws xob hluav taws xob los ntawm kev ua rau nws ua tau rau cov khoom siv xws li Schottky diodes, MOSFETs, thiab JFETs uas ua haujlwm ntawm qhov hluav taws xob siab dua, zaus, thiab kub tshaj qhov sib piv ntawm silicon.
Cov cuab yeej no txo qis zog poob hauv tsheb hluav taws xob, renewable zog inverter, thiab kev lag luam hluav taws xob tsav tsheb, ntxiv rau lub ntiaj teb no lub zog efficiency enhancements.
Muaj peev xwm khiav ntawm qhov sib txuas kub ntau dhau 200 ° C tso cai rau cov tshuab ua kom txias thiab txhim kho kev ntseeg tau.
Tsis tas li ntawd, SiC wafers yog siv los ua substratums rau gallium nitride (GaN) epitaxy nyob rau hauv high-electron-mobility transistors (HEMTs), integrating qhov zoo ntawm ob qhov dav-bandgap semiconductors.
4.2 Nuclear, Aerospace, thiab Optical Equipments
Hauv atomic fais fab nroj tsuag, SiC yog lub hauv paus tseem ceeb ntawm kev sib tsoo-tiv taus roj cladding, qhov twg nws txo neutron absorption cross-section, hluav taws xob tsis kam, thiab high-temperature toughness txhim khu kev ruaj ntseg thiab kev ruaj ntseg thiab efficiency.
Hauv aerospace, SiC fiber-reinforced composites yog siv nyob rau hauv dav hlau cav thiab hypersonic tsheb rau lawv lub teeb yuag thiab thermal stability..
Tsis tas li ntawd, Cov tsom iav ultra-smooth SiC tau siv ua ntej telescopes vim lawv qhov kev sib tw siab-rau-qhov sib npaug., thermal stability, thiab polishability rau sub-nanometer roughness.
Hauv cov ntsiab lus, silicon carbide ceramics sawv ntsug rau lub pob zeb tseem ceeb ntawm cov khoom siv niaj hnub no, combining zoo heev mechanical, thermal, thiab cov khoom siv digital.
Nrog kev tswj tshwj xeeb ntawm polytype, microstructure, thiab tuav, SiC tseem ua kom muaj kev tsim kho thev naus laus zis hauv lub zog, thauj, thiab kev teeb tsa tshwj xeeb engineering.
5. Tus neeg muab khoom
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Cim npe: silicon carbide ceramic,silicon carbide ceramic khoom, kev lag luam ceramic
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