Kev ua tiav qhov kub thiab txias siab tshaj 300℃hauv silicone foam boards muaj teeb meem loj, raws li cov khoom siv silicone feem ntau ua haujlwm nyob rau hauv -60℃txog 200℃ntau lub sijhawm ntev - siv, nrog rau lub sij hawm luv luv qhov kub thiab txias muaj peev xwm ncav cuag 250℃. Thaum qhov kub thiab txias tshaj qhov pib, cov pob txha polymer pib degrade, ua rau cov khoom brittleness, poob ntawm elasticity, thiab thaum kawg pulverization.
Yuav kom ua tiav qhov kub thiab txias ntawm ntau tshaj 300 degree, nws yog ib qho tsim nyog yuav tsum tau ua tiav cov qauv tsim thiab kev ua kom zoo los ntawm cov khoom siv yooj yim, kev txhawb zog, cov cua sov- tiv taus cov khoom ntxiv, cov txheej txheem foaming thiab cov qauv tsim.
Cov txheej txheem tseem ceeb thiab kev txiav txim siab rau kev ua tiav lub hom phiaj no yog raws li hauv qab no:
I. Kev xaiv thiab ua kom zoo ntawm cov khoom siv tseem ceeb
Qhov no yog cov kauj ruam tseem ceeb tshaj plaws.
Siv high phenyl silicone roj hmab:
Lub hauv paus ntsiab lus: Ordinary silicone roj hmab (methyl vinyl silicone roj hmab) muaj qhov kub tsis kam. Kev taw qhia ntawm phenyl pawg (tshwj xeeb tshaj yog cov ntsiab lus siab ntawm diphenylsiloxane saw ntu) hauv siloxane cov saw tseem ceeb tuaj yeem txhim kho cov cua sov ntawm cov khoom.
Kev ua haujlwm: Cov qauv loj ntawm lub nplhaib benzene thiab nws cov nyhuv conjugation tuaj yeem tiv thaiv tau zoo thiab ruaj khov ntawm cov cua sov-sensitive Si-O daim ntawv cog lus, yog li inhibiting thermal cyclization degradation thiab oxidative cleavage ntawm polymer saw. High-phenyl silicone roj hmab tuaj yeem tiv taus ntev -lub sijhawm kub txog 250-300℃thiab lub sijhawm luv luv tshaj 350℃.
Siv fumed silica li reinforcing muab tub lim:
Yam yuav tsum tau muaj: Unreinforced silica gel muaj lub zog qis heev. Fumed silica (nanoscale silica) yog tib lub zog muab tub lim uas tuaj yeem muab lub zog xav tau los ntawm silica gel.
Yuav tsum muaj: Yuav tsum siv siab -purity fumed silica nrog kev kho tshwj xeeb, me me me me thiab qhov loj ntawm qhov chaw. Nws tuaj yeem tsim muaj zog nano- cov qauv sib txuas hauv silica matrix thiab tuav qee yam khoom siv txawm tias kub.
II. Thaum tshav kub kub resistant additive system
Nws tsis txaus los tso siab rau cov ntaub ntawv yooj yim ib leeg, thiab cov cua sov tshwj xeeb -cov tshuaj tiv thaiv yuav tsum tau ntxiv rau "tiv thaiv thiab escort".
Thaum tshav kub kub stabilizer:
1) Hlau oxide (Fe₂O₃): Qhov no yog cov khoom siv hluav taws xob zoo tshaj plaws thiab muaj txiaj ntsig zoo- cov tshuaj tiv thaiv. Cov xim liab -xim av -Fe₂O₃ feem ntau yog siv. Nws ntes cov dawb radicals uas tawm tsam cov pob txha siloxane ntawm qhov kub thiab txias thiab catalyzes tsim cov siloxane ruaj khov dua - cov qauv carbon, yog li inhibiting pob txha degradation. Qhov ntau npaum li cas ntawm 0.5 mus rau 3 feem.
2) Cerium oxide (CeO₂) yog lub ntiaj teb tsis tshua muaj txiaj ntsig zoo -raws li cua sov- tiv thaiv stabilizer, tshwj xeeb tshaj yog thaum ua ke nrog Fe₂O₃. Nws zoo inhibits condensation thiab oxidation ntawm silanol pawg.
3) Lwm yam tsawg hauv ntiaj teb oxides, xws li lanthanum oxide (La₂O₃), kuj qhia tau zoo thermal stability.
Xaiv qhov tsim nyog vulcanization system:
1) Peroxide vulcanization: Rau cov ntaub ntawv foaming, peroxides (xws li bis (2,5-tertiary) peroxide) feem ntau yog siv cov tshuaj vulcanizing. Nws yog ib qho tseem ceeb uas yuav tsum xaiv cov peroxides nrog cov khoom lag luam ruaj khov thiab cov khoom tsis muaj corrosive, thaum ua kom tiav vulcanization kom tsis txhob muaj cov khoom seem ntawm degrading nyob rau hauv qhov kub thiab txias.
2) Platinum sulfide (ntxiv sulfide) yog qhov kev xaiv zoo tshaj plaws thaum ua npuas dej - tsim cov txheej txheem tso cai. Nws tus ntoo khaub lig-txuas Si-C qauv pom zoo thermal kuj piv rau C-C bonds hauv peroxide-raws li systems, tsis muaj decomposition residues. Txawm li cas los xij, platinum-raws li cov tshuab xav tau cov txheej txheem nruj thiab kev tswj hwm ib puag ncig thiab ua rau muaj tshuaj lom.
III. Kev sib tw ntawm cov txheej txheem foaming
Thaum nrhiav kev kub siab ua haujlwm, nws tseem yuav tsum ua kom tau raws li cov qauv tsim thiab ruaj khov foaming.
Tshuaj foaming tus neeg sawv cev: Lub decomposition kub yuav tsum sib npaug rau vulcanization kub, thiab cov khoom decomposition yuav tsum yog ib tug inert gas (xws li nitrogen). Lub decomposition residue yuav tsum tsis catalyze degradation ntawm silica gel matrix.
Lub cev foaming: Cov thev naus laus zis xws li supercritical fluid foaming tuaj yeem zam qhov teeb meem ntawm cov tshuaj foaming residue, tab sis cov cuab yeej siv tau loj thiab cov txheej txheem nyuaj.
Cov ntsiab lus tseem ceeb: Txawm tias siv cov txheej txheem foaming dab tsi, nws yog ib qho tsim nyog los xyuas kom meej tias cov qauv ntawm tes ruaj khov thiab cov phab ntsa ntawm tes yog ntom. Cov qauv qhib ntawm tes lossis phab ntsa ntawm tes tsis muaj zog yuav tawg lossis tawg sai ntawm qhov kub thiab txias, ua rau muaj kev poob qis hauv thermal rwb thaiv tsev.
IV. Structure thiab Post-Kev Tsim Qauv
Ua kom qhov ntom ntom / Txo cov npuas: Ntawm qhov chaw ua kom tau raws li qhov hnyav thiab qhov xav tau, tsim kom muaj qhov ntom ntom ntawm cov npuas dej (uas yog, txo qhov foaming piv) tuaj yeem tau thicker thiab kub dua -cov phab ntsa resistant, yog li kev txhim kho tag nrho cov kub tsis kam thiab txhua yam muaj zog.
Cov qauv sib xyaw: Xav txog kev tsim "sandwich" qauv, piv txwv li, nrog ob sab ua los ntawm siab - kub resistant non- ntxeem tau silicone zaj duab xis los yog iav fiber ntau daim ntaub sib xyaw, thiab ib txheej foamed nyob rau hauv nruab nrab. Qhov no tuaj yeem tiv thaiv cov qauv ntxeem tau yooj yim los ntawm kev raug ncaj qha mus rau qhov kub thiab txias ib puag ncig.
Tom qab- kub vulcanization: Lub rooj tsavxwm tsim ua npuas ncauj yuav tsum tau ua kom tiav tag nrho- kub vulcanized (xws li ci rau ob peb teev ntawm 200-}250 degree) kom tshem tawm cov tsis tshua muaj molecular volatiles thiab stabilize lub crosslinking network, uas yog ib qho tseem ceeb rau kev siv lub sij hawm ntev kub.