Kev Taw Qhia Txog Khoom Uas Tsis Tshua Muaj Cement Refractory Castable

Piv rau cov castables refractory uas muaj cement tsawg dua li cov castables refractory aluminate cement ib txwm muaj. Feem ntau, cov cement ntxiv rau cov castables refractory aluminate cement ib txwm muaj yog 12-20%, thiab feem ntau yog 9-13%. Vim muaj dej ntxiv ntau, lub cev cam khwb cia muaj ntau lub qhov hws, tsis ntom, thiab tsis muaj zog; vim muaj cement ntxiv ntau, txawm hais tias muaj zog ntau dua thiab kub tsawg, lub zog txo qis vim yog kev hloov pauv crystalline ntawm calcium aluminate ntawm qhov kub nruab nrab. Nws yog qhov tseeb tias CaO uas tau qhia tawm yuav cuam tshuam nrog SiO2 thiab Al2O3 hauv lub castable los tsim qee cov khoom uas tsis yaj, ua rau cov khoom siv kub kub puas tsuaj.

Thaum siv cov thev naus laus zis hmoov ultrafine, cov khoom sib xyaw ua haujlwm siab thiab kev hloov pauv ntawm cov khoom me me, cov ntsiab lus cement ntawm cov castable raug txo kom tsawg dua 8% thiab cov ntsiab lus dej raug txo kom ≤7%, thiab cov khoom siv refractory castable qis-cement tuaj yeem npaj thiab coj mus rau hauv. Cov ntsiab lus CaO yog ≤2.5%, thiab nws cov ntsuas kev ua tau zoo feem ntau tshaj li cov ntawm aluminate cement refractory castables. Hom refractory castable no muaj thixotropy zoo, uas yog, cov khoom sib xyaw muaj ib qho duab thiab pib ntws nrog lub zog sab nraud me ntsis. Thaum lub zog sab nraud raug tshem tawm, nws tswj cov duab tau txais. Yog li ntawd, nws tseem hu ua thixotropic refractory castable. Tus kheej ntws refractory castable kuj hu ua thixotropic refractory castable. Koom nrog pawg no. Lub ntsiab lus tseeb ntawm cov khoom siv refractory castables qis cement tsis tau txhais txog tam sim no. Lub Koom Haum Asmeskas rau Kev Ntsuas thiab Cov Khoom Siv (ASTM) txhais thiab faib cov khoom siv refractory castables raws li lawv cov ntsiab lus CaO.

Qhov ntom thiab muaj zog yog cov yam ntxwv zoo tshaj plaws ntawm cov khoom siv refractory castables uas tsis tshua muaj cement. Qhov no zoo rau kev txhim kho lub neej ua haujlwm thiab kev ua haujlwm ntawm cov khoom, tab sis nws kuj coj teeb meem rau kev ci ua ntej siv, uas yog, kev nchuav tuaj yeem tshwm sim yooj yim yog tias koj tsis ceev faj thaum ci. Qhov xwm txheej ntawm lub cev tawg yuav xav tau kev nchuav dua tsawg kawg, lossis yuav ua rau muaj kev phom sij rau kev nyab xeeb ntawm cov neeg ua haujlwm nyob ib puag ncig hauv cov xwm txheej hnyav. Yog li ntawd, ntau lub tebchaws kuj tau ua ntau yam kev tshawb fawb txog kev ci cov khoom siv refractory castables uas tsis tshua muaj cement. Cov kev ntsuas tseem ceeb yog: los ntawm kev tsim cov kab nkhaus qhov cub tsim nyog thiab kev qhia cov neeg sawv cev tiv thaiv kev tawg zoo heev, thiab lwm yam, qhov no tuaj yeem ua rau cov khoom siv refractory castables. Dej raug tshem tawm zoo yam tsis ua rau muaj lwm yam kev phiv.

Cov thev naus laus zis hmoov ultrafine yog cov thev naus laus zis tseem ceeb rau cov khoom siv refractory castables uas muaj cov cement tsawg (tam sim no feem ntau ntawm cov hmoov ultrafine siv hauv cov khoom siv ceramics thiab cov khoom siv refractory yog qhov tseeb ntawm 0.1 thiab 10m, thiab lawv feem ntau ua haujlwm ua cov khoom siv dispersion accelerators thiab cov khoom siv densifiers. . Tus thawj ua rau cov cement particles dispersed heev yam tsis muaj flocculation, thaum qhov kawg ua rau cov micropores hauv lub cev pouring puv tag nrho thiab txhim kho lub zog.

Tam sim no cov hmoov ultrafine feem ntau siv suav nrog SiO2, α-Al2O3, Cr2O3, thiab lwm yam. Qhov chaw tshwj xeeb ntawm SiO2 micropowder yog li 20m2 / g, thiab nws qhov loj me yog li 1/100 ntawm qhov loj me ntawm cov cement, yog li nws muaj cov khoom zoo filling. Tsis tas li ntawd, SiO2, Al2O3, Cr2O3 micropowder, thiab lwm yam kuj tuaj yeem tsim cov khoom colloidal hauv dej. Thaum muaj dispersant, ib txheej hluav taws xob ob txheej sib tshooj tau tsim rau ntawm qhov chaw ntawm cov khoom kom tsim cov electrostatic repulsion, uas kov yeej lub zog van der Waals ntawm cov khoom thiab txo qhov interface zog. Nws tiv thaiv kev nqus thiab flocculation ntawm cov khoom; tib lub sijhawm, tus dispersant yog adsorbed nyob ib puag ncig cov khoom los tsim ib txheej solvent, uas kuj ua rau kom muaj kev ntws ntawm castable. Qhov no kuj yog ib qho ntawm cov txheej txheem ntawm ultrafine hmoov, uas yog, ntxiv cov hmoov ultrafine thiab cov dispersants tsim nyog tuaj yeem txo qhov kev siv dej ntawm refractory castables thiab txhim kho kev ntws.

Qhov teeb tsa thiab tawv ntawm cov cement refractory castables qis yog qhov tshwm sim ntawm kev ua ke ntawm kev sib txuas hydration thiab kev sib txuas cohesion. Kev hydration thiab tawv ntawm calcium aluminate cement feem ntau yog hydration ntawm cov hydraulic theem CA thiab CA2 thiab cov txheej txheem loj hlob ntawm lawv cov hydrates, uas yog, lawv react nrog dej los tsim hexagonal flake lossis koob-puab CAH10, C2AH8 thiab Hydration cov khoom xws li cubic C3AH6 crystals thiab Al2O3аq gels ces tsim cov qauv sib txuas condensation-crystallization network thaum lub sijhawm kho thiab cua sov. Qhov agglomeration thiab kev sib txuas yog vim muaj cov hmoov SiO2 ultrafine ua cov khoom colloidal thaum nws ntsib dej, thiab ntsib cov ions maj mam dissociated los ntawm cov khoom ntxiv (piv txwv li electrolyte tshuaj). Vim tias cov nqi ntawm ob qho yog qhov sib txawv, uas yog, qhov chaw colloid tau adsorbed counter ions, ua rau £ 2 Lub peev xwm txo qis thiab condensation tshwm sim thaum adsorption ncav cuag "isoelectric point". Hauv lwm lo lus, thaum lub zog electrostatic repulsion ntawm qhov chaw ntawm cov khoom colloidal tsawg dua nws qhov kev nyiam, kev sib txuas ua ke tshwm sim nrog kev pab los ntawm van der Waals lub zog. Tom qab cov khoom siv refractory sib xyaw nrog silica hmoov raug condensed, Si-OH pawg tsim rau ntawm qhov chaw ntawm SiO2 tau qhuav thiab dehydrated rau choj, tsim cov qauv network siloxane (Si-O-Si), yog li ntawd hardening. Hauv cov qauv network siloxane, cov kev sib txuas ntawm silicon thiab oxygen tsis txo qis thaum qhov kub nce, yog li lub zog kuj tseem nce ntxiv. Tib lub sijhawm, thaum kub siab, SiO2 network qauv yuav cuam tshuam nrog Al2O3 qhwv rau hauv nws los tsim mullite, uas tuaj yeem txhim kho lub zog ntawm qhov kub nruab nrab thiab siab.