Hom thiab kev ua haujlwm ntawm DIspersANTs rau refractory castables

Dispersants yog dav siv nyob rau hauv refractory castables. Feem ntau, kev tsim kho hom ntawm refractory castables muaj xws li kev co molding thiab phom molding. Los ntawm kev txhim kho rheological zog ntawm refractory castable, lub sij hawm tsim kho ntawm refractory castable thiab kev siv zog ntawm cov neeg ua haujlwm yuav raug txo kom tsawg. Txoj hauv kev ncaj ncees tshaj plaws thiab ua tau zoo los txhim kho cov khoom rheological ntawm cov castable thiab txo cov dej xav tau ntawm cov castable yog xaiv cov dispersant tsim nyog nyob rau hauv lub refractory castable ntawm cov coj system.
Daim ntawv thov ntawm dispersants nyob rau hauv refractory castables yog pib raws li kev paub nyob rau hauv lub teb ntawm pob zeb. Hauv xyoo 1950, lignosulfonate thiab sodium polyphosphate dej txo cov neeg ua haujlwm tau pib siv rau hauv cov khoom siv hluav taws xob rau kev co. 10% ~ 15 feem pua. Txij xyoo 1960 mus txog rau xyoo 1980, cov tshuaj polysulfonate tau pib siv los ua cov dej thib ob uas txo cov neeg ua haujlwm hauv nws tus kheej ntws castables, thiab cov dej txo qis tuaj yeem ncav cuag 20 feem pua ​​-25 feem pua. Lub cim thib peb ntawm cov superplasticizers tshwj xeeb yog cov tshuaj polycarboxylate, uas tuaj yeem ua rau cov dej txo qis mus txog 20 feem pua ​​-30 feem pua ​​​​los ntawm cov nyhuv steric hindrance tom qab raug adsorbed rau saum npoo ntawm cov khoom. Wang et al. Kawm txog cov teebmeem ntawm peb cov dispersants, naphthalene sulfonate, sodium tripolyphosphate, thiab acrylic polymer, ntawm hydrate morphology thiab castable zog ntawm CMA cement.
Nws pom tias dispersants nyob rau hauv cement-bonded castables tsis tau tsuas yog disperse cement hais, tab sis kuj cuam tshuam rau cov morphology ntawm cement hydration cov khoom, yog li cuam tshuam rau cov neeg kho tshuab zog ntawm castables. Lopes et al. siv sodium polyphosphate thiab citric acid ua dispersants los npaj nws tus kheej ntws phosphoric acid ua ke castables. Nws ntseeg hais tias hydrolysis ntawm me me molecule ntev chains ntawm phosphates nyob rau hauv sodium polyphosphate yuav ceev thiab txhim kho tus kheej-ntws tus nqi ntawm cov castable. Badie thiab Otroj et al. sim txhim kho nws cov khoom rheological los ntawm kev tswj cov ntsiab lus ntawm silica sol hauv castable. Cov txiaj ntsig tau pom tias ntxiv 9 feem pua ​​-11 feem pua ​​​​ntawm qhov loj ntawm silica sol tuaj yeem txhim kho tus kheej tus nqi ntws ntawm cov castable los ntawm 80-110 feem pua ​​. Anjos et al. kawm txog cov nyhuv ntawm cov dispersants sib txawv (polyethylene glycol-raws li polymer, citric acid (CA), thiab sodium tripolyphosphate (STPP)) ntawm rheological zog ntawm castables rau txhuas-silica sol systems. Nws pom tias plaub cov dispersants Tag nrho cov additives yuav txo tau cov viscosity ntawm lub system; thiab los ntawm kev ntsuas kev poob siab, nws pom tau tias tsuas yog FS10 tuaj yeem txo qhov kev cia khoom thiab poob modulus ntawm lub kaw lus, yog li txhim kho kev tsim kho ntawm cov qauv. Zhu et al. ntseeg hais tias lub sol-combined castable kuj tsis tas yuav siv ib tug dispersant. Ntawm pH=10, cov silica sol tuaj yeem ua raws li cov khoom tawg mus rau cov khoom alumina los ntawm kev ua electrostatic los ua tus cwj pwm ntawm Newtonian kua.
1. Kev faib cov dispersants
Muaj ntau txoj kev faib tawm ntawm cov dispersants, ntawm cov uas, raws li hom hydrophilic pawg, lawv tuaj yeem muab faib ua tsib hom: anionic dispersants, cationic dispersants, zwitterionic dispersants, nonionic dispersants, thiab sib xyaw dispersants.
Anionic dispersants tsuas yog tso siab rau lawv tus kheej cov nqi tsis zoo los muab cov teebmeem electrostatic. Cov pawg ion dissociated yog adsorbed rau ntawm qhov chaw ntawm cov khoom them nqi, hloov lawv cov txheej txheem hluav taws xob ob npaug, ua rau zeta muaj peev xwm tus nqi ntawm cov khoom colloidal, thiab thaum kawg txhim kho kev ruaj ntseg ntawm cov tshuaj. Piv txwv li, sodium tripolyphosphate (STPP), citric acid (CA), carboxylates thiab sodium naphthalene sulfonate formaldehyde condensate (FDN).
Sodium tripolyphosphate:
STPP yog ib qho inorganic anionic dispersant nrog qhov ntom ntawm 03-0.9g/cm3 thiab cov tshuaj formula ntawm Na5P3O10. Ob qhov kawg raug txiav los ntawm Na2PO4. Cov qauv ntawm tag nrho cov dispersant yog linear. Nws solubility yog loj, pH tus nqi ntawm cov aqueous tov yog nyob nruab nrab ntawm 8-10, thiab nws yog yooj yim hydrolyzed, thiab cov khoom hydrolyzed yog sodium pyrophosphate, sodium monohydrogen phosphate, sodium dihydrogen phosphate thiab sodium phosphate.
b Citric acid:
CA yog ib tug tricarboxylic acid compound, cov tshuaj formula yog H3C6H5O7, muaj peb H ntxiv uas yuav ua tau ionized, thiab nws muaj ib tug molecule ntawm siv lead ua dej. Citric acid kuj muaj zog.
Polycarboxylate yog ib hom dispersant nrog "comb" qauv tsim los ntawm kev tsim qauv molecular. Nyob rau hauv cov saw tseem ceeb ntawm polycarboxylate, muaj ntau cov ceg ntoo nrog qee qhov ntev thiab nruj, thiab qee pawg sulfonate tuaj yeem them cov khoom. Nws tsuas yog ua tiav cov nyhuv dispersion ntawm cov castable los ntawm kev ua rau cov steric hindrance nyhuv ntawm cov hais. Qhov kom zoo dua ntawm kev siv polycarboxylate ua ib qho dispersant yog tias cov dej-txo cov nyhuv yog pom tseeb, thiab cov nyhuv txo cov dej muaj zog.
Cov khoom ntshiab ntawm FDN yog cov hmoov dawb, uas tau txais los ntawm sulfonation ntawm naphthalene thiab neutralization salting tawm ntawm sodium hydroxide. Cov mis mos molecular yog C10H7SO3Na, thiab qhov hnyav molecular yog 230.22. Nyob rau hauv sib piv rau anionic dispersants. Tom qab dissociating hauv dej, cationic dispersants tuaj yeem tsim cov pab pawg muaj txiaj ntsig zoo nrog kev ua haujlwm muaj zog. Ob pawg hauv amphoteric dispersant yog ob pawg hydrophilic, ib qho ntawm lawv raug them zoo (amino pawg) thiab lwm tus raug them tsis zoo (carboxyl lossis sulfonic acid pawg), vim tias cov pab pawg sib txawv ntawm pH sib txawv. Nws muaj nyob rau hauv cov ntaub ntawv sib txawv ionic ntawm tus nqi qis, yog li muaj ib qho isoelectric point rau hom active neeg sawv cev. Non-ionic dispersants tsis dissociate nyob rau hauv aqueous tov, cov hydrophilic pab pawg neeg feem ntau yog polyethylene glycol pawg, thiab lub polarity ntawm cov active neeg sawv cev yog tswj los ntawm tus naj npawb ntawm hydrophilic pawg.