PTFE-coated fiberglass fabric na kɔmpɔzit matirial we dɛn mek bay we dɛn impregnate fayv glas klos wit polytetrafluoroethylene (PTFE) dispersion ɛn afta dat dɛn sinter am na ay tɛmpracha. I strɔkchɔ kin sheb to tu pat: di PTFE kɔtin ɛn di fayv glas bays fabrik.
insay kεmikכl kכrosiv envayroment, di strכkchכral chenj dεm dipכnt pan di tכp, kכnsantreshכn, εn tεmprachכ fכ di kכrosiv mεdiכm, εn bak if i fכs fכ atak di kכt כ di sabstεrayt. Lɛ wi chɛk dis layt bay layt frɔm di we aw di wan dɛn we de mek fayv glas we dɛn kɔt wit PTFE de si am:
I. Chenj dεm na di PTFE Kכtin: Ekstrim Stebul in di Vast Majority of Kes dεm
PTFE na wan we pipul dɛn sabi as di 'King of Plastics' bikɔs ɔf in rili strɔng kabɔn-fluorine bɔnd ɛn ɛksepshɔnal ay kemikal inɛtnɛs. Insay kɔmɔn kemikal kɔrosiv ɛnvayrɔmɛnt (inklud bɔyl akwa regia, kɔnsɛntret sɔlfɔrik asid, kɔnsɛntret naytrik asid, ɔrganik sɔlvɛnt, ɛn ɔda tin dɛn), in mɔlikul chen strɔkchɔ nɔ kin chenj kεmikכl. Bɔt ɔnda dɛn kayn bad bad tin ya, di strɔkchɔ go pwɛl:
1. Mɔlt Alkali Mɛtal / Strɔng Alkaline Sɔlwɛshɔn (ɛgz., sɔdiɔm, potashɔm, sɔdiɔm haydroksayd we di tɛmpracha ay) .
- Struktכral Chenj dεm: Alkali mεtal dεm go pul fluorine atכm dεm frכm PTFE, we go mek dihaydrofluorination riakshכn. di -CF2- grup dεm na di mכlikul chen de dεstroy, we de fכm kabכn-kכbכn dכbl bכnd (-C=C-) εn afta dat i de lid to kabכnayzεshכn.
- Makroskopik Manifestation: di kכt de chenj frכm milky wayt/translucent to brawn כ blak, i de lכs fleksibiliti, i de bi brittle, εn pauda. Dis na di tipik kεmikכl dεgradashכn.
- Elemental fluorine (F2), chlorine trifluoride (ClF3), εn di sem kayn ejen dεm kin brok di kabכn-kabכn bakbon, we kin mek di kכt de kכmכt.
- כnda ay tεmprachכ εn prεshכn, sכm Freon-tayp sכlvεnt dεm kin mek PTFE swεla bad bad wan. pan ɔl we kemikal riakshɔn nɔ kin rili apin, di fizik strɔkchɔ de sɔfa frɔm ridyus kristaliniti, volyum ɛkspɛnshɔn, ɛn lɔs trɛnk bikɔs ɔf di mɔlikul chen dɛn we dɛn de fos fɔ apat.
3. Strɔng Ɔksidayz Asid dɛn na Ay Tɛmpratura
- if yu put yu fכ lכng tεm insay fכm naytrik asid כ hot kכnsantreyt sכlfyurik asid i kin כksidayz di PTFE sכfayz sכmtεm, i kin introdכks pכlar grup dεm lεk kabכnayl εn haydroksil grup dεm, εn i kin inkrεs di sכfayz εnεji. Bɔt dɛn nɔ kin si dis na kɔmɔn aplikeshɔn dɛn.
Ki Point: fכ di big mכtalman kεmikכl mεdia, di PTFE kכt insεf na strכkchכral 'unchεnj.' כltu, di prכblεm bכku tεm de insay di fכt se i nכ de absoliutli impermeable, εn bak insay in fyzikal mכfכlכji.
II. Chenj dɛn na di Fayba Glas Bes Fabrik: Di Wik Link fɔ di Ɔl Matirial
Di men tin dɛn we de insay fayv glas na silikon dayɔgzayd (SiO2) ɛn sɔm mɛtal ɔksayd dɛn. Wans dis pat dɔn kɔrod, di ɔl strɔkchɔ fɔ di ay-tɛmpracha fabrik go fɔdɔm.
1. Di Fatal Atak we Haydrofluorik Asid (HF) de du .
- Struktכral Chenj dεm: HF de כndago wan spεsifi k riakshכn wit SiO2: SiO2 + 4HF → SiF4↑ + 2H2O. Di fayv glas skel de sɔlv dairekt wan ɛn i nɔ de igen.
- Makroskopik Manifestation: di fabrik sεf de lכs trεnk kwik kwik wan, i de bi lεk sכft skin wit כnli di kכt we de rεst, i de tear izi wan we yu pul, wit big skel separeshכn bitwin di kכt εn di sabstεrayt. Dis na di kemikal kɔrɛshɔn we pipul dɛn kin fred pas ɔl fɔ mek tin dɛn we dɛn mek wit glas fayba. As lɔng as pinhol dɛn de na di kɔtin ɔ di ed dɛn we de na do, di damej kin rili bad.
- Struktכral Chenj dεm: OH− ayכn dεm de brok di siloksan bכnd dεm (-Si-O-Si-) na di glas nεtwכk, we de fכm sכlubul silikayt dεm. di fayv sεf de chenj frכm smol to rכf, wit etch pit εn krak krak de apia, di fayv dayamita de tכn, εn leta i de brok.
- Makroskopik Manifestɔ: di trɛnk de kɔntinyu fɔ dכn, di klos de brok, εn we i bεn, di fayv dεm we brok de kכmכt tru di kכt, we de mek di kכt krak εn pul.
3. Asid Midia (eksept haydrofluorik asid) .
- Struktכral Chenj dεm: di kכmכn asid dεm (haydroklorik asid, sכlfyurik asid, εtk) dεn kin fכs fכ lich di kכmכpכnεnt dεm we nכ de fכ silika (lεk aluminiכm, kalsiכm oksayd, εtk) frכm di fayv glas, we de lεf mכst di silika skel. dis prכsεs dεn kכmכn fכ kכl am 'liching,' we de fכm wan maykroporous strכkchכ pan di fayv sεf.
- Makroskopik Manifestɔ: di klos kin at ɛn brit, wit chenj dɛn na di shrinkage, pan ɔl we dɛn kin kip di ɔvala fɔm. Strεngth de dכn biכs fכ strεs kכnsantreshכn.
III. Chenj dɛn na di Kɔmpɔzit Intafɛs: Hidden Failure
bכku tεm di kεmikכl envayroment dεm nכ de atak ed-on bכt insted dεn de pεnεtra frכm di ed dεm כ tru maykro-difεkt dεm.
- Pεnεtreshכn εn Delaminεshכn: כrganik sכlvεnt כ asid sכlushכn dεm de pεnεtrashכn tru pinhol, maykro-krak, כ kכt ed dεm na di PTFE kכt, we de atak di fayv glas. riakshכn prodakt כ pεnεtrayt likwid dεm de akכmyuleyt na di intafεys, we de jεnarεt osmotik prεshכn, we de mek di PTFE kכt de blista εn delaminate frכm di fayv glas sabstεrayt pan big skel.
- Stress Corrosion Cracking: Di fabrik we gɛt ay tɛmpracha de ɔnda tɛnsiɔn we dɛn de yuz am. di kכroshכn fכ di fayv glas bay kεmikכl midia (especially strכng alkali dεm) de akt sinagεstik wit mεkanikal strεs, we de mek krak krak dεm fכ prכpagεt kwik kwik wan along di fayv raydial dεyshכn, we de mek di fabrik frakshכn wan wan wit wan klin britl-frakshכn mכfכlכji na di brεk.
insay kεmikכl kכrosiv envayroment, dεn kin sכmariz di strכkchכral chenj dεm fכ PTFE-kכt fayv glas fכbכk lεk: di 'King of Plastics' kכt de stil kכlכsכl lεk mכunt, we di fayv glas bays fכbrik—wan tεm we i pεnεtrat כ atak—de bi di Akilis in il, we de mek di skel dεm sכlushכn, intafεys dεlaminεshכn, εn di כl mεtirial de kolכp frɔm insay to do.
