Ua ib hom khoom siv tshauv volcanic, metakaolin yog ib qho khoom siv hloov zoo heev rau cement vim nws siv hluav taws xob tsawg thiab tsis muaj kuab paug rau ib puag ncig thaum lub sijhawm calcination, thiab nws lub peev xwm los txhim kho qee yam khoom ntawm Portland cement, xws li lub zog thiab kev ruaj khov, thaum ua rau hauv cov cement sib xyaw. Nyob rau hauv xyoo tas los no, ntau tus kws tshawb fawb tau mob siab rau kev kawm txog kev ua haujlwm ntawm tshauv volcanic ntawm kaolin. Tsab xov xwm no piav qhia txog qhov kub thiab sijhawm calcination zoo tshaj plaws ntawm kaolin, cov yam ntxwv cuam tshuam rau nws cov haujlwm, thiab cov txheej txheem rau kev ntes cov khoom thiab kev ua haujlwm ntawm kaolin. Cov kev tshawb fawb yav dhau los tau qhia tias qhov kub thiab sijhawm calcination zoo tshaj plaws rau kaolin yog cuam tshuam los ntawm cov yam ntxwv xws li cov khoom siv hauv av, crystallinity, thiab cov ntsiab lus kaolin, ntawm cov crystallinity ntawm cov qauv kaolin muaj qhov cuam tshuam loj tshaj plaws rau nws cov haujlwm tom qab calcination. XRD, TG-DTA, IR thiab lwm txoj hauv kev tau siv los tshuaj xyuas cov khoom ntawm cov hlau nyoos. Kev ua haujlwm ntawm kaolin tau txiav txim siab los ntawm cov txheej txheem xws li Frantini xeem, conductivity xeem, thiab lub zog ua haujlwm index. Cov txheej txheem raug tshaj plaws yog Frantini xeem thiab lub zog ua haujlwm index xeem.
Metakaolin (hu ua MK) yog ib qho anhydrous txhuas silicate (Al2O3 • 2SiO2, AS2) tsim los ntawm kev qhuav kaolin (Al2O3 • 2SiO2 • 2 H2O, AS2H2) ntawm qhov kub tsim nyog (600-900 ℃). Kaolin koom nrog cov qauv silicate txheej, thiab cov txheej raug sib txuas los ntawm van der Waals bonds, nrog OH - ions khi ruaj khov hauv nws. Thaum kaolin raug cua sov hauv huab cua, nws dhau los ntawm ntau qhov kev hloov pauv ntawm cov qauv. Thaum cua sov txog li 600 ℃, cov qauv txheej ntawm kaolin raug rhuav tshem vim kev qhuav dej, tsim cov theem hloov pauv nrog crystallinity tsis zoo - metakaolin.
Vim yog qhov kev teeb tsa tsis sib xws ntawm metakaolin, nws ua rau pom tias muaj lub xeev thermodynamic metastable thiab ua rau pom cov khoom cementitious nyob rau hauv qhov kev txhawb nqa tsim nyog. Metakaolin yog cov khoom siv hluav taws xob ua los ntawm cov tshauv volcanic uas muaj zog heev uas tuaj yeem ua rau muaj kev cuam tshuam nrog Ca (OH) 2 (CH3) thiab dej los tsim cov khoom hydration zoo ib yam li cement. Los ntawm kev siv qhov tshwj xeeb no, thaum siv los ua cov khoom sib xyaw rau cement, nws tuaj yeem ua rau muaj kev cuam tshuam nrog CH3 tsim thaum lub sijhawm ua cov cement hydration, uas tuaj yeem txhim kho qee yam khoom ntawm cement.
Metakaolin (MK) yog ib yam khoom tsim los ntawm kev qhuav dej ntawm kaolin ntawm qhov kub siab, thiab qhov kub calcination tuaj yeem cuam tshuam rau kev ua haujlwm ntawm cov khoom.
Thaum qhov kub nce siab tshaj 950 ℃, cov khoom pib crystallize thiab hloov mus ua mullite thiab cristobalite,
Nws yuav poob nws cov dej num.
Cov kaolin calcined yog cov khoom siv inorganic filler feem ntau siv hauv kev lag luam tsim cov khoom siv polymer xws li roj hmab, yas, thiab cov txheej txheem. Nws tuaj yeem txo tus nqi ntawm cov khoom no, tshwj xeeb tshaj yog txhim kho cov khoom siv lub cev thiab tshuaj lom neeg ntawm cov ntaub ntawv.