Roj Hmab auxiliary seals yog cov khoom siv ntau tshaj plaws ntawm cov ntsaws ruaj ruaj. Cov khoom siv roj hmab feem ntau yog cov roj hmab nitrile, fluoroelastomer silicone roj hmab, neoprene roj hmab thiab lwm yam.
(1) Nitrile roj hmab NBR Nitrile roj hmab yog hom roj hmab feem ntau siv. Nws yog copolymer ntawm butadiene thiab acrylonitrile. Raws li tus nqi ntawm cov ntsiab lus acrylonitrile tau muab faib ua ntau hom: qis acrylonitrile (NBR-18), nruab nrab acrylonitrile (NBR-26) thiab siab acrylonitrile (NBR-40). Qhov siab dua cov ntsiab lus ntawm acrylonitrile, qhov zoo dua cov roj kuj, qhov siab dua lub zog tensile, hardness thiab abrasion tsis kam, siab dua cov dej tsis kam, thiab qis permeability. Yog li ntawd, nws solubility nyob rau hauv polar solvents nce thiab nws corrosion kuj raug cuam tshuam. Elasticity thiab txias tsis kam kuj deteriorate. NBR tsis tiv taus flexing, thiab kua muag kuj tsis zoo. Feem ntau cov ntsiab lus acrylonitrile hauv NBR cov ntsaws ruaj ruaj yog 26% ~ 50%. NBR muaj kev tiv thaiv zoo heev rau cov roj ntxhia, tsiaj thiab zaub rog thiab roj, aliphatic hydrocarbons, thiab siv dav hauv cov khoom siv hauv kev sib cuag nrog roj av thiab lwm yam roj. Nws tuaj yeem tiv taus alkali thiab tsis-oxidising dilute acid corrosion, tab sis tsis oxidising acid (xws li nitric acid, chromic acid, thiab lwm yam), muaj ntxhiab hydrocarbons, roj, ketone, ether, halogenated hydrocarbons thiab lwm yam corrosion. Tsis ntev los no, hydrogenated nitrile butadiene roj hmab (HNBR) tau tsim, thiab nws cov kev ua tau zoo dua li cov roj hmab nitrile. Kev siv qhov kub ntawm -40 ~ 150 degree, roj kuj zoo dua li cov roj hmab nitrile, hydrogen sulfide kuj zoo dua fluoroelastomer, siv nyob rau hauv 200 degree chav yog thib ob tsuas yog ethylene propylene roj hmab.
(2) Fluoroelastomer FPM fluoroelastomer muaj qhov zoo ntawm qhov kub thiab txias tsis kam, roj tsis kam, tshuaj tiv thaiv corrosion. Nyob rau hauv concentrated sulfuric acid, nitric acid, phosphoric acid, caustic soda thiab lwm yam xov xwm yuav siv tau. Tab sis raws li qhov kub nce nws cov corrosion kuj txo qis, qhov siab tshaj plaws ua haujlwm kub ntawm 200 degree. Feem ntau siv fluoroelastomers hauv tsev yog fluorinated olefin copolymer, feem ntau yog fluorine-23 thiab fluorine-26. 23-hom fluoroelastomers los ntawm vinylidene fluoride thiab chlorotrifluoroethylene ntawm chav tsev kub thiab txog 3.3MPa siab los ntawm kev ncua polymerisation ntawm ib hom amorphous rubbery copolymer. 23- hom fluoroelastomers yog sib npaug rau txawv teb chaws Kel-F fluoroelastomers, uas tuaj yeem siv rau hauv cov kua qaub muaj zog. 26- hom fluoroelastomers muaj ob hom: Viton-26, uas yog ua los ntawm vinylidene fluoride thiab hexafluorocarbon. Muaj ob hom fluoroelastomers: fluoroelastomer-26, ib qho emulsion copolymer ntawm vinylidene fluoride thiab hexafluoropropylene, uas yog sib npaug rau txawv teb chaws Viton fluoroelastomers; fluoroelastomer-246, terpolymer ntawm vinylidene fluoride, hexafluoropropylene thiab tetrafluoroethylene. Nyob rau hauv xyoo tas los no, kev txhim kho ntawm perfluoroelastomer (FFKM perfluoropolymer elastomer), sib npaug rau txawv teb chaws Kalrez perfluoroelastomer. Nws muaj cov khoom zoo los tiv thaiv kev laus, tsis muaj qhov tshwm sim tseem ceeb ntawm kev laus tom qab 112 hnub ntawm kev siv ntawm 260 degree. Lub zog tensile tseem tshuav 90% ntawm lub zog qub. Lub zog tensile tseem tuav txog 90% ntawm qhov qub, tuaj yeem siv tsis tu ncua ntawm 288 degree, 310 degree rau lub sijhawm luv luv. Nws cov roj tsis kam, ua kom tsis haum thiab tsis kam rau cov organic corrosion kuj zoo, tab sis nws cov coefficient ntawm kev nthuav dav yog ze li ob npaug ntawm cov roj hmab nitrile (320 * 10-6/K), thiab nws tsis haum rau kev siv hauv qab no. xoom degrees.
(3) Silicone roj hmab MVQ silicone roj hmab kub tsis kam thiab kub tsis kam yog qhov zoo heev, kev nyab xeeb siv qhov kub ntawm -70 ~ 200 degree . Hauv dilute sulfuric acid, hydrochloric acid, acetic acid, caustic soda, ethanol, ntxhia roj thiab lwm yam xov xwm, tsis muaj qhov tshwm sim tseem ceeb corrosion. Silicone roj hmab yog ua los ntawm dimethylsiloxane thiab lwm yam silicone monomers, nyob rau hauv lub xub ntiag ntawm acidic los yog alkaline catalyst polymerised rau hauv ib tug polar polymer. Silicone roj hmab muaj thermal stability, tab sis nws muaj polarity, yooj yim rau ionic cleavage nyob rau hauv qhov kev txiav txim ntawm acids thiab alkalis, yog li cov corrosion kuj tsis zoo. Tsis haum rau roj av kuab tshuaj (xws li benzene, toluene, thiab lwm yam), acetone, ketone, ether thiab lwm yam organic solvents. Silicone roj hmab tsim kua muag lub zog thiab tsim kua muag elongation yog me me (tsuas yog 1/3 ntawm nitrile roj hmab).
Tsis ntev los no, fluorosilicone roj hmab (MFQ) tuaj yeem siv dav hauv cov roj av, roj av thiab cov kuab tshuaj.
(4) Ethylene Propylene Rubber EPM Ethylene Propylene Rubber yog polymerised los ntawm ethylene thiab propylene, muab faib ua binary thiab terpolymer. Nws yog tshwj xeeb tshaj yog tiv taus phosphate ester hydraulic kua, ketones, cawv daws thiab acids thiab alkalis, tab sis kuj resistant rau high-pressure vaporurs, huab cua tsis kam thiab zoo ozone kuj. Tab sis nyob rau hauv cov ntxhia roj thiab cov roj lubricants hauv kev nthuav dav, yog li tsis tuaj yeem siv rau hauv cov xov xwm no.
2, polytetrafluoroethylene PTFE
Polytetrafluoroethylene tshav kub, roj thiab corrosion kuj tshaj li cov roj hmab dav dav, feem ntau yog siv rau hauv cov tshuab foob nws yog ua los ntawm V-shaped nplhaib thiab lub nplhaib nplhaib. Polytetrafluoroethylene yas thiab roj hmab sib piv, nrog ntau dua nruj, qis elasticity thiab txias txaus. Lub coefficient ntawm expansion ntawm polytetrafluoroethylene yog siab, thiab nrog rau qhov kub thiab txias hloov, tshwj xeeb tshaj yog nyob rau hauv chav tsev kub nrog lub ncov, uas tiv thaiv nws los ntawm kev siv nyob rau hauv mechanical seals. Txawm li cas los xij, PTFE muaj ntau yam kev siv (-150 ~ 250 degree), coefficient ntawm kev sib txhuam tsawg heev (hauv qhov qis qis f=0.05 ~ 0.1) thiab nws tus kheej lubricating , non-bonding nto, zoo tshuaj stability, tsis kam mus rau chlorides, fluorine boron trifluoride, high-boiling solvents, ketones, esters, ethers, boiling nitric acid, aqua regia, thiab sodium hydroxide, hydrofluoric acid thiab lwm yam. Tib yam uas yuav tawm tsam PTFE yog cov hlau molten thiab fluorine nyob rau hauv siab. Nyob rau hauv qhov kev txiav txim ntawm load, txhua yam kub creep (xws li, txias txaus), ntau tshaj 8) 83, nws yuav sublimate los tsim cov pa phem.
3, lwm yam ntaub ntawv
Siv los ua lub nplhaib sib khi ntawm lwm cov ntaub ntawv yog hlau, ntim nrog PTFE, nthuav graphite (hloov graphite), asbestos thiab roj hmab-yas cov ntaub ntawv sib xyaw. Cov ntaub ntawv no tsuas yog siv nyob rau hauv lub sijhawm kub.
