Kev paub ntawm kev faib tawm thiab kev siv cov pob zeb me (ceramic)

Ceramic fiber porous rwb thaiv tsev cov ntaub ntawv tuaj yeem ua tus qauv ruaj khov nrog tsuas yog qee qhov me me ntawm cov khoom (fiber ntau). Piv nrog ceramic pore rwb thaiv tsev cov khoom, ceramic fiber rwb thaiv tsev cov khoom yog lub teeb, ntxeem tau, qis hauv thermal conductivity thiab muaj peev xwm kub muaj peev xwm. Cov nta loj thiab tuaj yeem tiv taus lub siab heev.Qhov khoom siv no tau siv rau hauv ntau qhov chaw xws li kev sib cais, kev rwb thaiv tsev thermal, biomedicine, thiab cov ntaub ntawv sib xyaw. Cov txheej txheem rov tiv thaiv thermal tiv thaiv cov sawv cev los ntawm cov khoom siv fiber ntau cov khoom siv dav siv hauv kev tiv thaiv thermal ntawm ntau cov kev tshaj tawm huab cua hauv tsev thiab txawv teb chaws, thiab muaj cov ntawv thov tseem ceeb thiab kev txhim kho kev cia siab.

Cov xaim xim fiber ntau tuaj yeem faib ua ob pawg: cov hlau tsis muaj oxide tej hub (xws li SiC fibers, C fibers) thiab oxide (suav nrog oxide puas) ceramic fiber (xws li txhuas silicate fibers, Al2O3 fibers).

1. Tsis-oxide ceramic fiber ntau

2. Silicon carbide fiber ntau. Silicon Carbide (SiC), feem ntau hu ua silicon carbide thiab carbon silica, yog cov khoom sib txuas ua ke uas yog covalently sib khi. Nws tuaj yeem npaj los ntawm cov tshuaj vapor deposition, carbothermal txo, hmoov sintering thiab kev sib hloov ua ntej. Cov ntshiab silicon carbide tsis muaj xim thiab pob tshab, thiab silicon carbide siv rau hauv kev lag luam feem ntau yog lub teeb ntsuab lossis dub vim tias nws muaj cov hlau dawb, silicon, carbon thiab lwm yam tsis txaus.

   Vim tias silicon carbide muaj cov yam ntxwv kub zoo, xws li oxidation tsis kam, siab kub lub zog thiab ruaj khov, zoo thermal conductivity, tsis ntom ntom, nthuav dav coefficient, thiab qis nkag, nws tuaj yeem siv ua cov khoom sib txuas rau qhov kub siab roj turbines. Lub ntsuas kub tsis muaj qhov zoo, lub tshuab hluav taws xob, thiab lwm yam Vim nws lub siab thermal conductivity thiab lub zog zoo rwb thaiv tsev, silicon carbide tuaj yeem siv cov khoom siv hluav taws xob kub ua kom sov hauv metallurgical muaj cov qhov cub, nrog rau cov substrates thiab cov khoom ntim rau cov kev sib txig sib xyaw loj. Cov. Nrog nws cov hardness siab, hnav tsis kam thiab cov kua qaub thiab alkali corrosion tsis kam, cov khoom siv ntim khoom siv sib khi xws li zawv zawg kabmob, lub valve pob, kiv cua tshuab thiab cov kav dej xeb tuaj yeem npaj rau hauv kev kho tshuab thiab tshuaj lom neeg.

   Silicon carbide tsis tsuas yog lub cev zoo, tab sis kuj muaj cov tshuaj lom neeg zoo. Nyob rau hauv qhov chaw tsis muaj pa oxygen, tsuas yog 5% ntawm silicon tau muaj nyob hauv theem roj nyob rau saum npoo ntawm silicon carbide ntawm 2300℃Cov. Txawm li cas los xij, thaum silicon carbide tau nthuav tawm cov pa oxygen ntawm 1000 tauj℃, nplaim pib oxidize, tab sis silicon carbide tuaj yeem tsim SiO2 tiv thaiv zaj duab xis kom tiv thaiv qhov cuam tshuam oxidation los txuas ntxiv.

3. Cov carbon fiber. Cov pa roj carbon fiber hais txog cov khoom siv carbon fiber uas tau kho kom sov mus txog 1000°C lossis siab dua los ntawm cov organic fiber hauv qhov roj inert los tsim cov khoom siv carbon fiber muaj cov ntsiab lus carbon 90% lossis ntau dua. Cov pa roj carbon fiber yog ib yam tshiab ntawm cov khoom siv nrog lub cev ntom ntom ntawm 1.5-2g / cm3, uas yog 1/4 ntawm qhov ntom ntawm cov hlau, 1/2 ntawm qhov ntom ntawm aluminium alloy, thiab 4 zaug txog 5 zaug muaj zog dua li cov hlau. Cov thermal expansion coefficient yog qhov me me, thiab lub thermal poob siab zoo yog qhov zoo. Nws dheev poob los ntawm qhov kub ntawm ob peb txhiab degrees Celsius mus rau qhov kub thiab txias thiab tsis tawg, thiab muaj zoo lubricity thiab hluav taws xob conductivity. Cov pa roj carbon fiber muaj tshuaj zoo ib yam li carbon, yog inert rau cov kev suav nrog, thiab tsis txhob yaj ntawm cov kua nitrogen txias. Nyob hauv ib qho chaw uas tsis muaj cua oxygen, txawm hais tias ntawm qhov ntsuas kub ntawm 3000℃, nws tsis yaj, tab sis nyob rau hauv huab cua huab cua, thaum qhov kub siab tshaj 400℃, cuam tshuam los ntawm oxidation tshwm sim, thiab CO thiab CO 2 yog tsim tawm. Yog li no, carbon fiber ntau tuaj yeem txo qhov hnyav ntawm qhov teeb meem ntawm cov feem thiab txhim kho cov txuj ci kev ua haujlwm, ua rau nws siv dav hauv cov tsheb aerospace.

   Ua raws li cov ntaub ntawv raw siv, carbon fiber tuaj yeem muab faib ua polyacrylonitrile-based carbon fiber, pitch-based carbon fiber, cellulose-based carbon fiber, thiab phenolic-based carbon fiber. Cov pa roj carbon fiber ntau siv yog polyacrylonitrile carbon fiber thiab pitch carbon fiber.

4. Oxide tej hub fiber

5. Aluminium silicate fiber. Cov duab thiab xim ntawm txhuas silicate fiber yog zoo li cov paj rwb. Nws yog amorphous ceramic fiber feem ntau ua los ntawm alumina thiab silica, thiab qee zaum muaj qee qhov me me ntawm cov hlau oxide, titanium dioxide, calcium oxide thiab lwm yam. Raws li kev sib xyaw ua ke ntawm cov tshuaj thiab cov ntsiab lus, nws tuaj yeem muab faib ua plaub pawg: tus qauv (zoo tib yam) aluminium silicate fiber, siab-ntshiab aluminium silicate fiber, siab-purity aluminium-muaj aluminium silicate fiber thiab siab-purity zirconium aluminosilicate fiber Cov. Cov ntsiab lus ntawm cov feem tau qhia hauv Table 1-2.

   Aluminium silicate fiber muaj ib txoj kab uas hla ntawm 1-10μm thiab ntev li 5-25cm. Nws muaj qhov kub tsis kam tiv taus zoo, rwb thaiv tsev kub thiab nqus suab, thiab muaj cov tsis muaj cua sov cia, tsis tshua muaj thermal conductivity thiab muaj zog tiv taus cov neeg kho tshuab kev co. Qhov kev pabcuam kub tau ncav cuag 1200 ° C. Qhov ntom tsuas yog 0.096-0.128g / cm3. Tom qab sib ntxiv ntawm CrO2, txij li CrO2 tiv thaiv cov siv lead ua dej nag thiab kev loj hlob ntawm qhov sib chwv ntawm cov kab nrig, qhov kub siab kom tsis tuaj yeem tiv thaiv ntawm cov fiber ntau tuaj yeem txhim kho, thiab kev siv kub tau mus txog 1400 ° C. Aluminium silicate fiber fiber puas khoom tuaj yeem ua tus qauv ntaub pua plag, muaj kev xav, ntawv thiab phaj. Nws tau dav siv hauv lub tshuab ua hluav taws xob thermal thermal ntawm cov khoom siv hluav taws xob xws li kev lag luam chemical thiab tshuab, thiab txheej txheej thermal rwb thaiv tsev ntawm pob zeb cav qhov chaw.

6. Quartz fiber ntau. Quartz fiber ntau hais txog qib siab purity tshwj xeeb silica iav fiber ntau nrog cov ntawv xov xwm tsawg dua 0.1% thiab cov duab fiber ntau ntawm 0.7-15 μm. Nws muaj lub siab kub ua haujlwm siab, lub sijhawm ntev siv ruaj khov kub txog 1050 ° C, thiab kev kub ntxhov tam sim li 1700 ° C. Tsis tas li, quartz fiber ntau muaj kev txhim kho corrosion, siab zog khaws cia ntawm qhov kub, dim seem, zoo thermal poob siab. , siab stability tshuaj lom neeg, thiab zoo heev hluav taws xob rwb thaiv tsev zog, dielectric tas mus li thiab dielectric poob. Cov coefficient yog qhov zoo tshaj plaws ntawm txhua qhov ntawm cov ntxhia pob zeb thiab yog qhov ntau pheej yig los tsim dua li cov roj nplua nyeem silicon carbide. Yog li no, quartz fiber ntau muaj kev siv tseem ceeb hauv kev tiv thaiv kev lag luam tub rog thiab aerospace thiab tuaj yeem siv los tsim cov tshuab tiv thaiv aerospace thermal.

   Quartz fiber ntau tau muab faib ua cov ntu txuas iav quartz iav thiab quartz iav ntaub plaub. Nruam quartz iav fiber ntau hais txog lub fiber ntau ntev tau los ntawm kev kos ib qho kev quab yuam sab nraud tom qab quartz iav tau yaj. Feem ntau, txoj kab uas hla ntawm monofilament yog 3-10 μm, thiab nws tuaj yeem ua tiav rau hauv quartz iav fiber ntau yarn, daim ntaub, thiab lwm yam. Quartz iav ntaub plaub yog hais txog ib hom ntev thiab luv luv quartz iav fiber ntau tau los ntawm tshuab lub quartz iav yaj los ntawm lub tshuab cua siab, thiab nws cov duab yog nplaim, zoo ib yam li paj rwb ntaub plaub. Feem ntau, cov paj rwb ultrafine, uas muaj cov xov fiber ntau dua 3 μm, yog hu ua cov paj rwb zoo uas muaj qhov ntev txog 3-5 μm.

7. Mullite fiber ntau. Mullite tsuas yog qhov binary compound uas tuaj yeem pom stably thaum kub thiab lub siab nyob rau hauv binary system ntawm silica thiab alumina. Tus qauv tshuaj lom neeg yog 3Al2O3·2SiO2, thiab nws cov duab daim duab ntu muaj raws li pom hauv daim duab 1.

   Daim duab 1 Mullite cov khoom ntu theem daim duab

   Mullite fiber ntau yog polycrystalline fiber ntau nrog lub ntsiab siv lead ua ntu ntawm mullite crystallites. Nws yog tus tsuas yog theem ruaj khov nyob rau hauv binary system ntawm silica thiab alumina. Nws cov haujlwm yog tsawg thiab nws qhov peev xwm recrystallization tsis zoo. Cov pob zeb fiber tau muaj qhov kub zoo ua haujlwm siab thiab tuaj yeem siv tau ntev li 1500℃Cov. Txawm li cas los xij, thaum kub siab tshaj 1500℃, cov noob yuav loj hlob thiab poob nws qhov siab kub txhua yam zog. Thaum kub txog kwv yees li 1830℃, Yuav sai sai decompose rau hauv alumina thiab kua theem. Cov kab mob mullite nthuav dav tusyees thaum rhaub, muaj zoo thermal poob siab ua hauj stability, tsis tshua muaj thermal conductivity, tsis yooj yim rau nkag ntawm qhov kub thiab txias, thiab tuaj yeem tsis tsuas yog tswj tau zoo elasticity, tab sis kuj muaj shrinkage me me, thiab cov khoom nws tus kheej muaj cov tshuaj lom neeg zoo. Cov. Nws tsis raug rau xeb, yog li nws yog siv dav hauv ntau yam khoom kub thiab lub tshuab tiv thaiv thermal ua cov khoom siv tshiab ultra-light high-temperature heat-resistant fiber ntau. Txawm li cas los xij, qhov kub tsis zoo lub tshuab hloov kho ntawm mullite fiber tsis zoo, uas tau dhau los ua txoj kev cuam tshuam loj rau kev siv cov khoom siv.

8. Alumina fiber ntau. Alumina fiber ntau yog hom polycrystalline ceramic fiber, uas muaj ntau hom xws li ntev fiber, luv fiber ntau thiab whisker. Nws feem ntau muaj Al2O3, thiab qee zaum muaj qee tus nqi ntawm cov khoom sib ntxiv xws li silica, boron nitride, zirconia, iron oxide, magnesium oxide thiab lwm yam. Lub alumina fiber muaj lub zog ntawm 10-20 μm thiab lub ntom ntawm 2.7-4.2 g / cm3, thiab muaj cov cuab yeej siab, lub zog ntawm 1.4-2.45 GPa, thiab tensile modulus ntawm 190-385 GPa.

   Nws muaj cov tshuaj lom neeg zoo, kev tiv thaiv oxidation, siab kub kuj, tshuaj lom neeg ruaj khov thiab tsis tshua muaj coefficient ntawm thermal expansion, melting kis ntawm 2050 ° C, tuaj yeem siv tau ntawm 1500 ° C rau lub sijhawm ntev.

Alumina luv luv fiber ntau yog siv rau cov khoom siv rwb thaiv tsev kub, cov xov paj ntev yog siv rau kev ntxiv cov ntaub ntawv zoo, thiab cov nplaws hluav taws xob muaj lub zog siab thiab qee cov tshwj xeeb sib nqus, hluav taws xob thiab kho qhov muag, uas yog siv hauv cov khoom ua haujlwm. Alumina fiber ntau muaj cov haujlwm zoo saum npoo av thiab yog ib qho yooj yim kom muaj kev sib xyaw nrog cov khoom siv hauv paus xws li hlau thiab ceramics. Ua ke nrog nws cov kub siv siab, nws tau siv dav hauv kev lag luam dav dav thiab cov chaw siab. Nws tuaj yeem siv rau hauv qhov cub sov qhov kub thiab cov tshuab hluav taws xob thermal. Cov cuab yeej siv, tshuaj tiv thaiv nuclear thiab cov khoom thaiv rwb thaiv tsev rau lub chaw shuttle. Tebchaws Asmeskas siv cov roj carbon alumina ua cov rwb thaiv tsev ntawm qhov chaw sib thawb Columbia. Thaum qhov chaw shuttle ya mus rau hauv cov cua hauv, cov rwb thaiv tsev thaiv kom tsis txhob nkag los ntawm tshav kub los ntawm kev tiv thaiv tshav kub los ntawm qhov sib txawv nruab nrab ntawm cov rwb thaiv tsev. Alumina fiber muaj lub ntsiab lus tseem ceeb tseem ceeb thiab kev lag luam muaj txiaj ntsig hauv kev ua tub rog thiab aerospace, nyiam ntau lub teb chaws los nqis peev ntau tus neeg ua haujlwm, cov khoom siv dag zog thiab peev nyiaj txiag rau kev tshawb fawb thiab kev tsim kho thiab siv. Txawm li cas los xij, alumina fiber muaj qhov ntom ntom ntom thiab siab thermal conductivity, uas txwv nws cov ntawv thov ntxiv.