Cov pa roj pyrolytic uas loj hlob los ntawm cov roj los ntawm kev tso cov pa tshuaj lom neeg

Pyrolytic carbon yog ib yam khoom uas hloov pauv tau yooj yim—nruab nrab ntawm graphite thiab amorphous carbon—uas loj hlob ntawm qhov chaw substrate los ntawm cov txheej txheem tso pa tshuaj lom neeg uas muaj cov pa roj carbon (feem ntau yog hydrocarbons) nyob rau hauv qhov kub siab. (Thermodynamically, graphite yog cov khoom siv carbon khov kho nrog lub zog Gibbs qis tshaj plaws.)

Ⅰ. Cov Pa roj carbon pyrolytic thiab cov pa tshuaj lom neeg tso tawm

Cov txheej txheem uas cov tshuaj precursor dhau los ua cov tshuaj lom neeg nyob rau hauv cov txheej txheem tshwj xeeb thiab tso rau ntawm qhov chaw ntawm lub substrate los tsim cov txheej txheem khov kho hu ua cov tshuaj lom neeg vapor deposition. Daim duab qhia txog cov kauj ruam tseem ceeb hauv cov txheej txheem tshuaj lom neeg vapor deposition tau qhia nyob rau hauv Daim Duab 1 [2]:

(1) Cov precursor nkag mus rau hauv thaj chaw ua tshuaj tiv thaiv;

(2) Cov precursors dhau los ua cov tshuaj tiv thaiv roj-theem los tsim cov khoom nruab nrab;

a) Thaum qhov kub thiab txias hauv thaj chaw ua tshuaj tiv thaiv siab lossis nyob rau thaj chaw deb ntawm lub substrate, cov khoom nruab nrab txuas ntxiv ua tshuaj tiv thaiv hauv theem roj, tsim cov hmoov khov thiab cov khoom lag luam volatile. Cov hmoov khov khov kho rau ntawm qhov chaw substrate, tej zaum yuav ua haujlwm ua qhov chaw nucleation rau kev tso dej ntawm qhov chaw, thaum cov khoom lag luam volatile kis tawm ntawm thaj chaw ua tshuaj tiv thaiv;

b) Thaum qhov kub thiab txias hauv thaj chaw ua tshuaj tiv thaiv qis dua lossis nyob rau thaj chaw ze rau lub substrate deposition, cov khoom nruab nrab kis mus rau ntawm qhov chaw substrate, qhov twg cov kauj ruam hauv qab no tshwm sim:

(3) Cov khoom nruab nrab adsorb rau ntawm qhov chaw substrate thiab dhau los ua cov tshuaj tiv thaiv heterogeneous, tsim cov khoom tso tawm nquag thiab cov khoom lag luam;

(4) Cov khoom tso tawm nquag kis thoob plaws qhov chaw ntawm lub substrate thiab sib sau ua ke los ua ib txheej txheej tas mus li;

(5) Cov khoom siv roj tawm hauv thaj chaw ze ntawm cov khoom siv tso dej;

(6) Cov pa roj uas tsis tau ua haujlwm thiab cov khoom seem ntawm cov tshuaj tiv thaiv tawm hauv thaj chaw ua haujlwm.

Daim Duab 1: Daim duab qhia txog cov kauj ruam tseem ceeb ntawm cov txheej txheem tso pa tshuaj lom neeg

Kev tsim cov pa roj carbon pyrolytic yog ib qho txheej txheem uas tsis tuaj yeem hloov pauv entropy-decreasing uas cov pa roj carbon atoms hloov pauv los ntawm qhov tsis sib haum xeeb mus rau qhov xwm txheej thiab los ntawm cov pa roj mus rau qhov khoom khov kho ntawm qhov kub siab. Nws yog tswj hwm los ntawm qhov kev taw qhia kawg ntawm cov tshuaj thermodynamics thaum khaws cia cov qauv tsis sib npaug los ntawm txoj kev kinetic. Kev nkag siab tob txog cov txheej txheem no tsis yog tsuas yog tso lub hauv paus khoom siv rau cov pa roj carbon-carbon composites, cov txheej txheem kub siab, thiab cov roj nuclear cladding tab sis kuj muab ob qho kev sim thiab kev xav rau qhov muaj nyob ntawm carbon nyob rau hauv cov xwm txheej hnyav.

Ⅱ. Cov Txheej Txheem Npaj thiab Kev Siv Pyrolytic Carbon

Cov pa roj pyrolytic yog tsim los ntawm kev ua kom cov hydrocarbons kub ntawm 1200–1400 ° C hauv ib puag ncig uas tsis muaj oxygen. Siv lub tshuab ua kom lub txaj fluidized ntsug, cov txheej txheem no tau ua tiav los ntawm cov kauj ruam hauv qab no: cov roj inert (nitrogen lossis helium) raug tso tawm los ntawm hauv qab ntawm lub raj tshuaj tiv thaiv kom ua rau cov khoom refractory fluidize; lub kauj induction sab nraud ua kom cov ntsiab lus ntawm lub raj tshuaj tiv thaiv sov; thiab cov roj hydrocarbon raug tso tawm los pib cov tshuaj tiv thaiv pyrolysis.

Daim Duab 2: Daim duab qhia txog lub txaj fluidized rau kev npaj pyrolytic carbon [3]

Ⅲ. Cov Tshuaj Tiv Thaiv Kub Siab Pyrolytic Carbon

Daim Duab 3: Cov qauv thermal hauv Czochralski crystal furnace [4]

Silicon, raws li feem ntau Cov khoom siv semiconductor , yog siv dav hauv cov khoom siv hluav taws xob thiab photovoltaics, tshwj xeeb tshaj yog nyob rau hauv daim ntawv ntawm crystalline silicon hauv lub hnub ci cell. Nws cov kev hloov pauv photovoltaic siab ua rau nws yog ib qho tseem ceeb hauv kev lag luam photovoltaic. Kev npaj ntawm monocrystalline silicon feem ntau siv Czochralski txoj kev, uas yog siv dav hauv monocrystalline silicon ntau lawm hauv tsev thiab thoob ntiaj teb vim nws cov txiaj ntsig zoo ntawm kev tsim khoom, cov txheej txheem loj hlob tswj tau, thiab kev tswj hwm doping meej. Txawm li cas los xij, thaum qhov loj me ntawm crystal nce ntxiv, tus nqi ntawm graphite thermal teb kuj nce ntxiv, tshwj xeeb tshaj yog nyob rau hauv silicon vapor ib puag ncig qhov twg graphite Cheebtsam yooj yim rau xeb, ua rau lub neej luv luv ntawm cov khoom siv. Txhawm rau daws cov teeb meem no, cov kws tshawb fawb tau tsim cov txheej txheem tiv thaiv corrosion rau cov khoom siv carbon, xws li pyrolytic carbon (PyC), silicon carbide (SiC), thiab tantalum carbide (TaC) coatings, los txhim kho lub neej ua haujlwm ntawm cov khoom siv carbon hauv cov chaw kub siab corrosive.

Cao et al. tau tshawb nrhiav qhov xeb ntawm silicification ntawm graphite (G330 graphite thiab AC200C/C composite materials) siv rau hauv monocrystalline silicon furnaces. Lawv tau hais tias qhov qhib pores txuas ntxiv los ntawm sab hauv ntawm graphite mus rau qhov chaw muab txoj hauv kev rau kev xeb thiab kev sib kis ntawm molten silicon, yog li ua kom cov txheej txheem silicification ntawm cov ntaub ntawv carbon nrawm dua.

Zhao thiab lwm tus tau tso ib qho Cov pa roj carbon pyrolytic (PyC) txheej ntawm qhov chaw graphite los ntawm kev siv tshuaj lom neeg vapor deposition (CVD). Cov txheej PyC uas tshwm sim tau npog tag nrho cov graphite substrate thiab pom ib qho qauv ntom ntom uas tsis muaj qhov pom tseeb lossis cov kab nrib pleb me me. Tom qab kho cov khoom siv graphite coated hauv ib puag ncig silicon vapor corrosion ntawm 1600 ° C rau 2 teev, cov qauv morphology ntawm cov txheej thiab cov txiaj ntsig ntawm EDX tau pom hauv Daim Duab 4. Raws li tau pom hauv Daim Duab 4a, txawm tias tom qab silicon etching, cov txheej tseem nyob ruaj khov rau ntawm qhov chaw substrate yam tsis muaj qhov tawg pom. Kev tshuaj xyuas ntawm cov khoom faib ntawm carbon thiab silicon qhia txog yuav luag tsis muaj silicon faib hauv qab cov txheej pyrolytic carbon, qhia tias nws muab kev tiv thaiv zoo heev rau cov graphite substrate [5].

Daim Duab 4: Cov duab ntawm PyC coated graphite tom qab silicide etching

Ⅳ. Cov noob roj nuclear uas muaj cov pa roj carbon pyrolytic

Daim Duab 5 qhia txog daim duab qhia txog cov txheej txheem txheej rau cov roj pellets uas tau txheej rau lub tshuab hluav taws xob txias kub 10 MW (HTR-10), tsim los ntawm Lub Tsev Kawm Ntawv ntawm Nuclear Energy Technology Design ntawm Tsinghua University. Raws li ib feem tseem ceeb ntawm cov tshuab hluav taws xob txias kub kub, kev ua haujlwm ntawm cov roj pellets uas tau txheej ncaj qha cuam tshuam rau kev ua haujlwm zoo ntawm lub tshuab hluav taws xob. Lub Tsev Kawm Ntawv ntawm Nuclear Energy Technology Design ntawm Tsinghua University tau ua tiav tsim cov roj pellets uas tau txheej TRISO uas ua tau raws li cov qauv tsim siv cov thev naus laus zis chemical vapor deposition (CVD) hauv lub tshuab hluav taws xob fluidized txaj [3].

Cov roj pellets uas muaj txheej txheej TRISO muaj plaub txheej, teeb tsa los ntawm sab hauv mus rau sab nraud raws li nram no:

Lub hauv paus roj: Uranium dioxide microspheres nrog txoj kab uas hla ntawm kwv yees li 500 μm;

Cov pa roj carbon pyrolytic xoob (PyC): qhov ceev ≤ 1.10 g/cm³, tuab 90 ± 18 μm;

Cov txheej carbon pyrolytic sab hauv tuab: qhov ceev 1.9 ± 0.1 g/cm³, tuab 40 ± 10 μm;

Silicon carbide (SiC) txheej: qhov ceev > 3.18 g/cm³, tuab 35 ± 5 μm;

Txheej txheej carbon pyrolytic sab nraud tuab: qhov ceev 1.9 ± 0.1 g/cm³, tuab 40 ± 10 μm;

Txhua txheej muaj ib txoj haujlwm uas tau txhais meej meej:

Cov txheej pyrolytic carbon xoob: muab qhov chaw cia rau cov khoom fission thiab pab txhawb kev nthuav dav ntawm cov roj core

Cov txheej txheem carbon pyrolytic ntom ntom: ua haujlwm ua lub plhaub siab los thaiv kev tso tawm ntawm cov khoom fission

Txheej silicon carbide: Muaj peev xwm tiv thaiv tau zoo, tshwj xeeb tshaj yog tiv thaiv cov khoom siv fission xws li Cs, Sr, thiab Ba

Daim Duab 5: Daim duab qhia txog txheej uas muaj cov khoom me me ntawm cov roj nuclear nyob hauv.

Cov kev tshawb fawb no tsis yog tsuas yog daws cov teeb meem tseem ceeb rau cov roj hauv Tuam Tshoj thawj lub tshuab hluav taws xob txias roj kub siab xwb tab sis kuj tau tsim lub hauv paus tseem ceeb rau kev txhim kho yav tom ntej ntawm cov thev naus laus zis txias roj kub siab. Los ntawm kev tswj hwm cov txheej txheem tso dej ntawm txhua txheej, cov roj pellets coated nrog cov qauv microstructures thiab cov khoom zoo tagnrho tau tsim tau zoo, ua kom muaj kev nyab xeeb thiab ruaj khov ntawm lub tshuab hluav taws xob.

Ib lub pellet roj nuclear me me yog lub cim ntawm kev siv zog tsis muaj zog ntawm ntau pab pawg tshawb fawb, thaum ib txheej nyias nyias ua rau lub zog ntawm lub chaw tsim hluav taws xob nuclear ua haujlwm zoo thiab lub teb chaws lub zog ruaj ntseg - zoo li cov pa roj carbon sib txuas tes ua ib lub pob zeb diamond ci ntsa iab, lossis 1.4 billion tus xeeb ntxwv ntawm Zaj ua haujlwm ua ke los txhawb nqa lub neej yav tom ntej ci ntsa iab ntawm kev rov ua dua tshiab ntawm lub teb chaws Suav.

Liufang Technology tau mob siab rau kev tshawb fawb thiab kev tsim cov khoom tiv thaiv rau cov chaw kub siab - xws li silicon carbide thiab tantalum carbide - siv cov txheej txheem chemical vapor deposition (CVD), nrog rau kev kawm txog cov txheej txheem txheej. Tsis ntev los no, lub tuam txhab tau ua kev tshawb fawb txog cov khoom txheej pyrolytic carbon los muab cov kev daws teeb meem ib zaug rau cov neeg siv khoom uas muaj kev xav tau txheej tiv thaiv thoob plaws ntau yam kev ua haujlwm.

Yog tias cov khoom siv semiconductor uas koj lub luag haujlwm yuav tsum ua haujlwm hauv qhov chaw inert, kub siab, xav tau kev tsis muaj tshuaj lom neeg thiab kev tswj hwm cov khoom me me, tab sis koj muaj teeb meem vim tias Cov txheej txheem SiC tsis tuaj yeem tiv taus qhov kub thiab txias lossis xeb - xav txog pyrolytic carbon. Qhov tseeb, pyrolytic carbon yog ib qho "pure carbon armor" uas tsis tuaj yeem hloov pauv tau hauv kev tsim cov txheej txheem semiconductor kub siab.

Xav paub ntxiv txog cov txheej txheem thev naus laus zis pyrolytic carbon, lossis tau txais cov ntsiab lus hais txog SiC / pyrolytic carbon composite solutions? Thov hu rau peb kom paub ntxiv.

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References:

1. Zhang, Weigang. Kev Tso Pa Tshuaj Lom Zem - Los ntawm Cov Pa Hydrocarbon mus rau Cov Pa Khoom Khov. Science Press, Tshooj 1.

2. Hu, Chunxia. Kev Siv Tshuab Ua Pa Methane Rau Kev Tso Pa. Daim Ntawv Kawm Tiav Doctoral, Northwestern Polytechnical University.

3. Zhu, Junguo. Yang, Bing. Zhang, Bingzhong. Huang, Jintao. Xu, Shijiang. Kev Tso Pa Tshuaj Lom Zem ntawm Cov Khoom Siv Roj Uas Tau Txheej Hauv Cov Reactors Uas Muaj Gas Txias Kub. Phau Ntawv Xov Xwm ntawm Tsinghua University (Natural Science Edition). Vol. 36, No. 11, 1996. 65-71.

4. Jianxin Tu, Kui Hao, Caixia Huo, Ziyuan Guo, Jianhao Wang, Aijun Li, Ruicheng Bai, Zhihao Ji. Kev Tshawb Fawb Kev Txhim Kho ntawm Corrosion-Resistant Coatings ntawm Carbon-Based Materials rau Semiconductor Field. Kev nce qib hauv Materials Science. 1-13.

5. Wei Zhao, Bo Zhu, Weiwei Cao. Kev Npaj thiab Cov Khoom ntawm Pyrolytic Carbon Txheej rau Cov Khoom Siv Carbon Siv hauv Czochraski Ib Leeg Crystal Silicon Rauv. Applied Mechanics thiab Cov Khoom Siv, Vol. 597, 2014, 170-174;

6. Robert More, J. Sines, Ling Ma, Jack Bokros, Pyrolytic carbon.