Dab tsi yog cov yam ntxwv ntawm mullite? Yuav siv li cas hauv aluminium silicon silicon carbide refractory khoom?
Mullite yog cov ntxhia tsim los ntawm aluminosilicates ntawm qhov kub thiab txias. Nws yog tsim thaum aluminosilicates yog cov khoom cua sov thiab feem ntau siv los tsim cov khoom kub kub refractory.Cov tshuaj formula ntawm nws yog 3Al2O3·2SiO2. Raws li txoj cai, Al2O3 cov ntsiab lus hauv cov ntshiab mullite yog li 71.8%. Raws li ib txwm muaj siab, Nws yog tib qho chaw uas tuaj yeem nyob ruaj khov hauv Al2O3-SiO2 binary theem daim duab. Cov qauv siv lead ua ntawm mullite yog ib qho siv lead ua orthorhombic. Cov qauv nruab nrab yog tsim los ntawm octahedral sib koom npoo txuas rau hauv cov saw txuas mus rau C axis. Nws yog nyob rau ntawm plaub vertices thiab nruab nrab ntawm lub dav hlau projection ntawm lub tsev unit cell. Ntawm Z= ntawm txhua lub cell Lub octahedral saw ntawm 1/2 txuas nrog [SiO4] thiab [AlO4] tetrahedrons, thiab cov tetrahedrons tsim ob txoj saw txuas mus rau c-axis.
Mullite yog ib txoj hlua zoo li kev sib txuas ntawm rab koob zoo li lossis columnar crystals txuas nrog c-axis. Cov koob zoo li los yog columnar crystals cuam tshuam nrog ib leeg los tsim ib qho kev sib txuas thiab cov qauv sib txuas. Qhov no feature muab cov khoom mullites Relative zoo heev. Nws muaj cov khoom nram qab no: nws hardness siab, txog 6.7 (Mohs hardness), nws melting point yuav ncav cuag 1870 degree, nws thermal conductivity yog 13.8KJ / m·h·K, thiab nws linear expansion yog me me, piv txwv li, ntawm 20 ~ 1000 degree Qhov linear expansion tus nqi ntawm mullites yog 5.3 × 10-6/K, thiab elastic modulus yog qis, nruab nrab ntawm 160-200Gpa, uas yog ib nrab ntawm Al2O3 thiab SiC.
Mullite muaj cov khoom zoo ntawm lub cev thiab tshuaj lom neeg, xws li siab refractoriness, zoo thermal shock stability thiab creep kuj, siab load softening kub, zoo ntim stability thiab corrosion kuj. Lwm tus yam ntxwv ntawm nws yog tias nws qhov kub thiab txias zog thiab cov khoom tawg yuav nce ntxiv nrog qhov kub thiab txias thiab yuav tsis txo qis. Piv txwv li, nws lub zog ntawm qhov kub thiab txias ntawm 1300 degree yog 1.7 npaug ntawm chav tsev kub. Thaum qhov kub nce siab tshaj 1800 degree, cov kab ntawm cov kua theem pib tsim hauv cov mullite. Thaum qhov kub nce mus txog 1850 degree, lub mullite yaj tag. Yog li ntawd, mullite yog dav siv nyob rau hauv kev lag luam xws li cement, iav, ceramics, metallurgy, chemistry, hluav taws xob fais fab, tiv thaiv lub teb chaws thiab roj, dhau los ua cov khoom siv refractory siab heev uas ua tau raws li kev siv.
Nyob rau hauv aluminium silicon silicon carbide refractory cov ntaub ntawv, columnar thiab koob-zoo li tus mullite crystals yog interspersed nrog rau ib leeg los tsim ib tug staggered network qauv. Cov qauv network no tuaj yeem tsim kev sib xyaw nruj nrog cov khoom nyob ib puag ncig, yog li ua rau cov khoom siv refractory kuj muaj zog. Lub xub ntiag ntawm mullite tuaj yeem txhim kho lub thermal shock stability thiab load softening kub ntawm cov khoom, tso cai rau cov khoom siv aluminium silicon carbide refractory siv nyob rau hauv qhov chaw uas muaj qhov kub thiab txias ntau zaus.
