Mullite yog cov khoom siv zoo refractory. Nws tau xub pom thiab muaj npe nyob rau Isle of Moore hauv Scotland. Cov muaj pes tsawg leeg ntawm txhuas thiab silicon yog ib tug ntau yam, uas muaj peev xwm nyob ruaj khov nyob rau hauv ib txwm kub thiab siab. Ntuj mullite yog qhov tsawg thiab feem ntau yog npaj los ntawm kev kho cua sov-kho aluminium-silicon tebchaw. Nws microstructure yog columnar lossis granular. Vim nws cov refractoriness siab, nws feem ntau yog siv nyob rau hauv high-temperature refractories. Ntxiv rau qhov zoo ntawm qhov kub thiab txias tsis kam, siab zog, thiab thermal conductivity tsawg, nws kuj muaj qhov zoo ntawm thermal shock stability, me me kub siab creep nqi thiab zoo tshuaj corrosion kuj.
Muaj feem ntau hauv qab no 5 txoj hauv kev rau kev npaj cov khoom siv mullite
(1) Khoom theem sintering txoj kev
Txoj kev npaj los ntawm cov txheej txheem sintering khoom tau dhau los ua qhov zoo tshaj plaws kom deb li deb, thiab nws tuaj yeem muab faib ua hom hauv qab no: kev siv tshuab ua kom zoo, ntxiv cov khoom siv sintering tsim nyog, thiab ntxiv rau qee yam ntawm cov noob pob zeb muaju. Txoj kev uas feem ntau yog ntxiv ib qho kev pab sintering tsim nyog los npaj.
Du Jing et al. siv high-purity kaolin thiab industrial alumina maj mam hlawv ntawm 1000 degree raws li raw cov ntaub ntawv, thiab ntxiv ib feem ntawm ZnO, talc thiab zircon xuab zeb ua additives rau synthesize tsawg-nqi, high-purity mullite. Nws cov ntsiab lus txheeb ze yog 97 feem pua, thiab nws qhov ceev yog 2.89g / cm3.
(2) Hydrolysis nag lossis daus txheej txheem
Txoj kev nag lossis daus hydrolytic yog hais txog kev tsim cov nag lossis daus hauv kev daws los ntawm kev ntxiv cov nag lossis daus, thiab tom qab ntawd tsim cov hmoov uas ua tau raws li qhov xav tau tom qab kev kho cua sov. Txoj kev ua dej nag lossis daus tuaj yeem muab faib ua ob hom: txoj kev nag lossis daus thiab ib-theem nag lossis daus.
(3) Hydrothermal crystallization txoj kev
Txoj kev hydrothermal crystallization feem ntau yog siv lub hauv paus ntsiab lus ntawm dissolution-recrystallization. Cov khoom siv raw yog thawj zaug yaj hauv qhov nruab nrab hydrothermal, thiab tom qab ntawd cov ion lossis molecular pawg hauv cov tshuaj raug xa mus rau thaj chaw loj hlob nrog cov noob muaju los ntawm convection, thiab cov muaju yuav raug precipitated tom qab solubility saturated. Cov hmoov npaj los ntawm txoj kev hydrothermal crystallization muaj ntau dua particle purity thiab zoo dispersibility, thiab cov hmoov synthesized feem ntau tsis tas yuav mus rau kev kho cua sov kub.
Xue Rujun thiab lwm tus siv cov thee-series kaolin ua cov khoom siv los ua cov hmoov nplej ultra-fine los ntawm hydrothermal crystallization txoj kev, thiab tshawb xyuas cov teebmeem ntawm kev kho cua sov, hydrothermal crystallization kub, cov kua dej sib piv, alkali concentration thiab lub sij hawm ntawm mullite. Cov nyhuv ntawm pob zeb synthesis thiab nws cov particle loj.
(4) Txoj kev Sol-gel
Txoj kev sol-gel npaj cov gel nrog cov qauv kev sib txuas ntawm peb sab los ntawm kev sib xyaw ua ke ntawm cov khoom siv tsis zoo lossis cov hlau alkoxides ua cov ntaub ntawv ua ntej, tom qab tau txais cov tshuaj tiv thaiv ntawm hydrolysis thiab condensation, thiab tom qab ntawd polymerizing colloidal hais. Tom qab ntawd muab tso rau hauv ib lub thawv kub kom qhuav kom qhuav. Tom qab kev kho cua sov, cov organic Cheebtsam yog oxidized thiab volatilized, thiab thaum kawg tau txais ib qho inorganic non-metallic khoom. Feem ntau hais lus, raws li kev sib xyaw ua ke ntawm gel precursor, mullite gel tuaj yeem muab faib ua ib theem mullite gel (SiO2 thiab Al2O3 yog sib xyaw ntawm qib molecular) thiab ob-theem mullite gel (SiO2 thiab Al2O3 yog tov ntawm nanometer. Qhov sib xyaw degree ntawm mullite gel precursor muaj kev txiav txim siab ntawm cov theem hloov thiab tsim kub ntawm mullite.
Cov txheej txheem tsim ntawm dual-theem gel mullite feem ntau yog ua los ntawm ob txoj hauv kev:
1. Mullite yog ua los ntawm cov tshuaj tiv thaiv ntawm amorphous SiO2 thiab hloov lub xeev Al2O3;
2. Cov gel pib tsim Al-Si spinel theem ntawm ib ncig ntawm 1000 degree, thiab tom qab ntawd reacts nrog amorphous SiO2 los ua mullite ntawm 1200 degree.
Zhao Huizhong thiab lwm tus siv TEOS thiab tshuaj ntsuam xyuas cov ntshiab txhuas isopropoxide (ALP) ua cov ntaub ntawv tseem ceeb los npaj cov tshuaj nano-theem mullite precursor, thiab thaum kawg tau npaj ib qho me me ntawm 30-50nm nrog thaj chaw tshwj xeeb ntawm 30-50nm. 95.81-138.91m2/g mullite khoom.
(5) Gas-solid reaction method
Cov txheej txheem roj-khoom siv tshuaj tiv thaiv yog hais txog cov txheej txheem ntau-theem cov tshuaj tiv thaiv uas cov theem roj thiab cov theem khoom tau koom nrog cov tshuaj tiv thaiv tib lub sijhawm hauv cov tshuaj tiv thaiv. Raws li qhov muaj lossis tsis muaj cov catalyst, nws tuaj yeem muab faib ua cov txheej txheem roj-khoom catalytic cov txheej txheem thiab cov txheej txheem roj-khoom tsis-catalytic. Xu Xiaohong thiab lwm tus siv kaolin nplua hmoov thiab muaj Al (OH) 3 hmoov zoo ua cov ntaub ntawv tseem ceeb, ntxiv rau AlF3 thiab V2O5 ua catalysts, thiab npaj mullite whiskers los ntawm cov txheej txheem roj-cov tshuaj tiv thaiv catalyzed.
