Ma castable otsika a simenti okana simenti amayerekezeredwa ndi ma castable achikhalidwe a simenti okana simenti. Kuchuluka kwa simenti kowonjezera ma castable achikhalidwe a simenti okana simenti nthawi zambiri kumakhala 12-20%, ndipo kuchuluka kwa madzi nthawi zambiri kumakhala 9-13%. Chifukwa cha kuchuluka kwa madzi owonjezeredwa, thupi lopangidwa limakhala ndi ma pores ambiri, silili lolimba, ndipo lili ndi mphamvu zochepa; chifukwa cha kuchuluka kwa simenti yowonjezeredwa, ngakhale kuti mphamvu zapamwamba komanso kutentha kochepa zimapezeka, mphamvu zimachepa chifukwa cha kusintha kwa calcium aluminate pa kutentha kwapakati. Mwachionekere, CaO yomwe yayambitsidwa imagwira ntchito ndi SiO2 ndi Al2O3 mu castable kuti ipange zinthu zina zosungunuka pang'ono, zomwe zimapangitsa kuti kutentha kwapamwamba kwa zinthuzo kuwonongeke.
Pamene ukadaulo wa ufa wa ultrafine, zosakaniza zogwira ntchito bwino kwambiri komanso kukula kwa tinthu tasayansi zimagwiritsidwa ntchito, kuchuluka kwa simenti mu castable kumachepetsedwa kufika pa 8% ndipo kuchuluka kwa madzi kumachepetsedwa kufika pa ≤7%, ndipo castable yocheperako ya simenti ikhoza kukonzedwa ndikubweretsedwa mu CaO kuchuluka ndi ≤2.5%, ndipo zizindikiro zake zogwirira ntchito nthawi zambiri zimaposa za aluminate simenti yokana. Mtundu uwu wa castable yokana uli ndi thixotropy yabwino, ndiko kuti, zinthu zosakanikirana zimakhala ndi mawonekedwe enaake ndipo zimayamba kuyenda ndi mphamvu yakunja pang'ono. Mphamvu yakunja ikachotsedwa, imasunga mawonekedwe omwe apezeka. Chifukwa chake, imatchedwanso thixotropic refractory castable. Castable yokana yokha imatchedwanso thixotropic refractory castable. Ili m'gululi. Tanthauzo lenileni la castable yocheperako ya simenti silinafotokozedwe mpaka pano. American Society for Testing and Materials (ASTM) imatanthauzira ndikugawa castable yokana kutengera kuchuluka kwa CaO.
Zokhuthala komanso zolimba kwambiri ndi zinthu zabwino kwambiri zomwe zimapezeka mu castables zotsukira zamtundu wa simenti yochepa. Izi ndi zabwino pakukweza moyo wa ntchito ndi magwiridwe antchito a chinthucho, komanso zimabweretsa mavuto pakuphika musanagwiritse ntchito, ndiko kuti, kuthira kumatha kuchitika mosavuta ngati simusamala mukaphika. Kuphulika kwa thupi kungafunike kutsanulidwanso, kapena kungayike pachiwopsezo chitetezo cha ogwira ntchito ozungulira ngati zinthuzo zitavuta kwambiri. Chifukwa chake, mayiko osiyanasiyana achitanso maphunziro osiyanasiyana pa kuphika castables zotsukira zamtundu wa simenti yochepa. Njira zazikulu zaukadaulo ndi izi: popanga ma curve oyenera a uvuni ndikuyika zinthu zabwino kwambiri zotsutsana ndi kuphulika, ndi zina zotero, izi zingapangitse kuti castables zotsukira zichotsedwe bwino popanda kuyambitsa zotsatira zina zoyipa.
Ukadaulo wa ufa wa ultrafine ndiye ukadaulo wofunikira kwambiri pa zinthu zopopera za simenti yochepa (pakadali pano ufa wambiri wa ultrafine womwe umagwiritsidwa ntchito mu zoumba ndi zinthu zopopera uli pakati pa 0.1 ndi 10m, ndipo umagwira ntchito makamaka ngati zotulutsira mpweya komanso zokulitsa mphamvu ya kapangidwe kake. Woyamba umapangitsa tinthu ta simenti kukhala tofalikira kwambiri popanda kugwedezeka, pomwe womaliza umapangitsa kuti ma micropores omwe ali m'thupi lothira akhale odzaza mokwanira ndikuwonjezera mphamvu.
Mitundu ya ufa wa ultrafine yomwe imagwiritsidwa ntchito kwambiri masiku ano ndi SiO2, α-Al2O3, Cr2O3, ndi zina zotero. Malo enieni a ufa wa SiO2 ndi pafupifupi 20m2/g, ndipo kukula kwa tinthu tating'onoting'ono ndi pafupifupi 1/100 ya kukula kwa tinthu ta simenti, kotero imakhala ndi makhalidwe abwino odzaza. Kuphatikiza apo, ufa wa SiO2, Al2O3, Cr2O3, ndi zina zotero zimatha kupanga tinthu ta colloidal m'madzi. Pamene chotulutsira madzi chilipo, gawo lamagetsi lolumikizana limapangidwa pamwamba pa tinthu kuti lipange mphamvu ya electrostatic, yomwe imagonjetsa mphamvu ya van der Waals pakati pa tinthu ndikuchepetsa mphamvu yolumikizirana. Zimaletsa kulowetsedwa ndi kugwedezeka pakati pa tinthu; nthawi yomweyo, chotulutsira madzi chimalowetsedwa mozungulira tinthu kuti chipange gawo losungunulira, lomwe limawonjezeranso kusuntha kwa chotulutsira madzi. Ichi ndi chimodzi mwa njira za ufa wa ultrafine, ndiko kuti, kuwonjezera ufa wa ultrafine ndi zotulutsira madzi zoyenera kungachepetse kugwiritsa ntchito madzi kwa zotulutsira madzi zosasinthika ndikuwonjezera kusuntha kwa madzi.
Kukhazikika ndi kuuma kwa ma castable osakhala ndi simenti yotsika kumachitika chifukwa cha kuphatikizana kwa hydration bonding ndi cohesion bonding. Kuuma ndi kuuma kwa simenti ya calcium aluminate makamaka ndi hydration ya hydraulic phases CA ndi CA2 komanso njira yokulira ya kristalo ya ma hydrate awo, ndiko kuti, amachitapo kanthu ndi madzi kuti apange hexagonal flake kapena singano-shaped CAH10, C2AH8 ndi Hydration products monga cubic C3AH6 crystals ndi Al2O3аq gels kenako amapanga connectivity condensation-crystallization network structure panthawi ya crying ndi heating processes. Agglomeration ndi bonding zimachitika chifukwa cha active SiO2 ultrafine powder kupanga colloidal particles pamene ikumana ndi madzi, ndipo imakumana ndi ma ion pang'onopang'ono olekanitsidwa ndi chowonjezera chowonjezera (monga electrolyte substance). Chifukwa chakuti pamwamba pa awiriwa pali ma charges osiyana, ndiko kuti, pamwamba pa colloid pali ma counter ions obzalidwa, zomwe zimapangitsa kuti £2 The potential ichepe ndipo condensation imachitika pamene adsorption ifika pa "isoelectric point". Mwanjira ina, pamene mphamvu ya electrostatic repulsion pamwamba pa tinthu ta colloidal ili yochepa kuposa kukopa kwake, mgwirizano wogwirizana umachitika mothandizidwa ndi mphamvu ya van der Waals. Pambuyo poti refractory castable yosakanizidwa ndi ufa wa silica yafupika, magulu a Si-OH omwe amapangidwa pamwamba pa SiO2 amauma ndikusungunuka kuti agwirizane, ndikupanga kapangidwe ka netiweki ya siloxane (Si-O-Si), motero amalimba. Mu kapangidwe ka netiweki ya siloxane, maubwenzi pakati pa silicon ndi oxygen samachepa pamene kutentha kukukwera, kotero mphamvu imapitilirabe kuwonjezeka. Nthawi yomweyo, kutentha kwambiri, kapangidwe ka netiweki ya SiO2 kamachitapo kanthu ndi Al2O3 yokulungidwamo kuti ipange mullite, yomwe imatha kukulitsa mphamvu pa kutentha kwapakati komanso kwakukulu.
Nthawi yotumizira: Feb-28-2024
