Lub PTFE sheath ntawm lub rhaub yog ib qho tshuaj tiv thaiv, tab sis nws tsis yog ib qho tsis muaj tseeb, impermeable phab ntsa. Ntau lub hlis lossis xyoo ntawm kev pabcuam hauv qhov kub, muaj zog acid ib puag ncig, cov kua qaub me me tuaj yeem maj mam diffuse los ntawm fluoropolymer matrix. Cov txheej txheem sab nrauv yuav nyob twj ywm tsis pom kev hloov pauv, tab sis cov txheej txheem chemical uas ntsiag to tuaj yeem pib hauv qab nws. Lub polymer nws tus kheej tsis yog tam sim ntawd degraded, tab sis tom ntej no defensive txheej nyob rau hauv lub rhaub ua rau qhov tseeb cov tshuaj tiv thaiv cheeb tsam. Sij hawm dhau mus, cov txheej txheem qeeb neutralization yog pib nyob rau hauv lub rwb thaiv tsev, qhov twg hluav taws xob ncaj ncees yog maj mam undermined.
Acid Permeation Los ntawm PTFE Sheath hauv Thermal Ib puag ncig
Lub phenomenon tau piav raws liacid permeation PTFE sheath MgO rwb thaiv tsevyog tswj los ntawm diffusion kinetics los ntawm fluoropolymer. Txawm hais tias PTFE nthuav tawm cov tshuaj tiv thaiv tsis tshua muaj siab, nws tsis yog tag nrho impermeable. Thaum qhov kub thiab txias, molecular mobility nce, thiab permeation tus nqi nce exponentially. Qhov kev cia siab ntawm qhov ntsuas kub no txhais tau hais tias qhov nce me me hauv kev khiav hauj lwm kub tuaj yeem ua kom cov kua qaub nkag mus.
Thaum cov kab mob acidic xws li hydrochloric acid (HCl) lossis sulfuric acid (H₂SO₄) pib diffuse los ntawm sheath, qhov kev tawm tsam tsis cuam tshuam rau cov qauv polymer tam sim ntawd. Hloov chaw, cov kua qaub nkag mus rau sab hauv kom txog rau thaum nws ntsib cov txheej txheem rwb thaiv tsev uas muaj magnesium oxide (MgO). Cov kua qaub nkag los ntawm PTFE, tsuas yog kom tau raws li qhov qhuav, alkaline foe uas nws maj mam hloov mus rau hauv tus neeg xyuas pib ...
Tshuaj Reaction ntawm Acid thiab Magnesium Oxide
Magnesium oxide yog dav siv los ua ib qho hluav taws xob sab hauv hluav taws xob hauv sheathed cua sov cov ntsiab lus vim nws lub zog dielectric siab thiab thermal stability. Nws tus cwj pwm insulating yog txuas nrog rau nws cov alkaline xwm thiab nws qhuav, compact hmoov qauv.
Thaum cov kab mob acidic nkag mus rau hauv lub plhaub, cov tshuaj tiv thaiv neutralization tshwm sim hauv MgO txaj:
HCl reacts los tsim magnesium chloride (MgCl₂)
H₂SO₄ reacts tsim magnesium sulfate (MgSO₄)
Ob qho khoom siv tshuaj tiv thaiv yog qhov ua tau zoo dua li thawj MgO. Qhov kev hloov pauv no tseem ceeb heev vim nws hloov cov rwb thaiv tsev sab hauv los ntawm qhov siab -tsis kam dielectric mus rau qhov nruab nrab ib nrab.
Raws li cov tshuaj tiv thaiv zoo zuj zus, cov hmoov dawb thiab qhuav MgO yuav maj mam ua ntub dej, compacted, thiab greyish nyob rau hauv tsos. Txawm hais tias qhov kev hloov pauv no tsis pom sab nraud, qhov cuam tshuam hluav taws xob yog qhov tseem ceeb.
Hluav taws xob degradation thiab rwb thaiv tsev tsis kam
MgO muaj nuj nqis rau kev tuav cov rwb thaiv tsev nyob rau hauv gigaohm ntau yam nyob rau hauv ib txwm muaj mob. Txawm li cas los xij, ib zaug cov ntsev ntsev tau tsim, txoj hauv kev ionic pib tsim nyob rau hauv cov hmoov matrix. Cov txheej txheem no txo qhov kev tiv thaiv thiab qhia cov kab hluav taws xob hauv cheeb tsam ntawm cov cua sov hlau thiab cov hlau nplaum.
Nyob rau tib lub sij hawm, rwb thaiv tsev tsis kam yog nce degraded. Cov txheej txheem yog irreversible vim hais tias tsim ntawm magnesium chloride thiab magnesium sulfate mus tas li hloov cov tshuaj muaj pes tsawg leeg ntawm rwb thaiv tsev txaj. Txawm hais tias cov av noo tom qab raug tshem tawm, cov kua ntsev tseem nyob hauv cov qauv.
Qhov kev degradation no feem ntau maj mam, ncua lub hlis lossis xyoo ua haujlwm. Txawm li cas los xij, tus nqi ntawm kev hloov pauv nce ntau nyob rau hauv siab - qhov kub thiab txias, qhov twg ob qho tib si diffusion thiab cov tshuaj tiv thaiv kinetics tau nrawm dua.
Internal Arcing thiab hluav taws xob tsis ua hauj lwm tshuab
Raws li conductivity nce nyob rau hauv lub MgO rwb thaiv tsev, localized electric teb concentration yuav tshwm sim. Cov cheeb tsam no dhau los ua cov ntsiab lus tseem ceeb rau kev tso tawm sab hauv lossis arcing.
Thaum ib qho arc sab hauv tau tsim, ib txoj kev conductive yuav raug tsim sai ntawm cov hlau tsis kam thiab cov hlau nplaum. Qhov no tuaj yeem ua rau muaj kev puas tsuaj rau cov rwb thaiv tsev tsis ua haujlwm, suav nrog cov hlua khi lossis hluav taws xob luv.
Lub xub ntiag ntawm cov ntsev conductive ua rau txo qis qhov kev puas tsuaj ntawm cov txheej txheem rwb thaiv tsev. Dab tsi yog qhov siab tshaj - tiv thaiv thermal barrier dhau los ua ib feem ntawm qhov nruab nrab muaj peev xwm ua kom muaj hluav taws xob tawm hauv kev ua haujlwm voltage.
Temperature Dependence thiab Long -Tsev Teeb Meem Acceleration
Qhov permeation tus nqi ntawm cov kua qaub los ntawm PTFE yog qhov kub thiab txias - nyob ntawm thiab ua raws li kev sib raug zoo exponential. Raws li qhov kub thiab txias, cov khoom siv hluav taws xob hloov pauv tau nce ntxiv, tso cai rau kev nthuav dav ntawm cov khoom me me. Cov nyhuv no yog sib xyaw ua ke los ntawm cov tshuaj tiv thaiv kab mob nrawm nrawm hauv MgO txheej.
Kev kub siab - kub ua haujlwm yog li ua raws li cov khoom siv rau ob qho tib si ingress thiab cov tshuaj tiv thaiv. Nyias-cov ntaub thaiv phab ntsa thiab cov tshuaj lom neeg ib puag ncig ua rau muaj zog ntxiv rau cov txheej txheem no, txo cov kev pab cuam lub neej ntawm cov cua sov.
Hauv qhov sib piv, cov phab ntsa PTFE tuab, cov qib crystallinity siab dua, lossis hloov kho fluoropolymers xws li PFA tuaj yeem txo qis permeation thiab ua kom cov txheej txheem degradation tag nrho.
Ntev -Lub Sij Hawm Hloov Khoom Siv Hauv Lub Cuab Yeej
Qhov tseem ceeb tshaj plaws ntawm cov kua qaub ingress tsis yog tam sim ntawd tsis ua hauj lwm, tab sis irreversible khoom transformation. Thaum MgO tau hloov dua siab tshiab rau hauv magnesium ntsev, cov khoom qub insulating tsis tuaj yeem rov qab los. Cov qauv sab hauv tau raug hloov kho rau hauv ib feem ntawm cov khoom siv hluav taws xob.
Cov txheej txheem no yog qhov tsis txaus ntseeg tshwj xeeb vim tias cov ntsuas sab nraud tuaj yeem tsis tuaj txog thaum lig - theem tsis ua haujlwm tshwm sim. Cov hluav taws xob xau, tsis tu ncua tsis tu ncua, lossis kev tawg tam sim ntawd yuav tshwm sim yam tsis pom kev puas tsuaj.
Xaus
Acid permeation los ntawm fluoropolymer sheaths sawv cev rau qeeb, zais degradation mechanism hauv siab -kub cua sov tshuab. Nyob rau tib lub sijhawm, permeated acid PTFE sheath MgO rwb thaiv tsev sib cuam tshuam tuaj yeem hloov cov rwb thaiv tsev ceramic rau hauv ib feem ntawm cov ntsev sib txuas, txo qis cov rwb thaiv tsev tiv thaiv thiab ua rau muaj kev pheej hmoo ntawm sab hauv arcing.
Hom kev ua tsis tiav no yog qhov zoo tshaj plaws los txo qis los ntawm kev siv cov thicker lossis ntau crystalline fluoropolymer teeb meem, tshwj xeeb tshaj yog nyob rau hauv siab heev -kub acid ib puag ncig. Thaum kawg, cov txheej txheem degradation txaus ntshai tshaj plaws hauv cov tshuab cua sov tsis yog ib txwm pom sab nraud, tab sis tshwm sim sab hauv, ntsiag to hloov rwb thaiv tsev mus rau hauv txoj kev coj mus ua haujlwm ntev.
