PTFE-coated fiberglass fabric hi fiberglass puan chu polytetrafluoroethylene (PTFE) dispersion hmanga impregnate a, temperature sang taka sintering hmanga siam a ni. A structure hi hmun hnih ah then theih a ni a, chungte chu PTFE coating leh fiberglass base fabric te an ni.
Chemical corrosive environment-ah chuan structural changes chu corrosive medium chi, concentration leh temperature-ah a innghat a, chubakah a bul berah chuan coating emaw substrate emaw a bei em tih pawh a innghat bawk. PTFE-coated fiberglass fabric siamtute ngaihdan aangin he layer khat hnu layer khatin han chhui ila:
I. PTFE Coating-a inthlak danglamna: Case tam zawkah chuan a nghet hle
PTFE hi carbon-fluorine bonds chak tak leh chemical inertness sang tak a neih avangin 'King of Plastics' tia hriat a ni. Chemical corrosive environment pangngai (aqua regia boiling, concentrated sulfuric acid, concentrated nitric acid, organic solvents, etc. te pawh tel)-ah chuan a molecular chain structure-ah hian chemical inthlak danglamna a awm lo tak zet a ni. Mahse, a hnuaia boruak khirh tak hnuaiah hian a structure chu a chhe dawn a ni:
1. Alkali Metal hnim / Alkaline Solution chak tak (eg, sodium, potassium, sodium hydroxide temperature sang takah) .
- Structural Changes: Alkali metals hian PTFE atang hian fluorine atom a la chhuak ang a, chu chuan dehydrofluorination reaction a siam ang. Molecular chain chhunga -CF2- group te chu an chhe vek a, carbon-carbon double bonds (-C=C-) an siam a, chu chuan carbonization a thlen leh thin.
- Macroscopic Manifestation: Coating chu milky white/translucent atanga brown emaw black emaw ah a inthlak a, flexibility a hloh a, a brittle a, powder a ni. Hei hi chemical degradation pangngai a ni.
2. Fluorinating Agent chak tak tak leh Halogenated Hydrocarbon thenkhat (temperature leh pressure sang tak hnuaiah) .
- Elemental fluorine (F2), chlorine trifluoride (ClF3), leh a ang chi te hian carbon-carbon backbone a tichhia thei a, chu chuan coating chu a ti chhe thei a ni.
- Temperature leh pressure sang hnuaiah Freon-type solvent thenkhat chuan PTFE hi nasa takin a ti hring thei. Chemical reaction a awm hauh lo thei a, mahse, physical structure hian crystallinity tlahniam, volume expansion, leh molecular chain te chu forced apart avanga chakna hloh te a tuar a ni.
3. Temperature sang takah Oxidizing Acids chak tak
- Fuming nitric acid emaw hot concentrated sulfuric acid emaw-a rei tak inhnim chuan PTFE chunglam chu zawi zawiin a oxidize thei a, polar groups carbonyl leh hydroxyl group te a rawn luh tir thei a, surface energy a tipung thei bawk. Mahse, hei hi hmanraw pangngaiah chuan hmuh tur a awm lo.
Key Point: Chemical media tam zawk tan chuan PTFE coating ngei pawh hi structurally 'unchanged.' a ni a, mahse, buaina chu a luh theih loh tak tak loh vang a ni fo va, chutiang bawkin a physical morphology-ah pawh a awm fo bawk.
II. Fiberglass Base Fabric-a inthlak danglamna: Material pumpui inzawmna chak lo
Fiberglass-a thil awm berte chu silicon dioxide (SiO2) leh metal oxide thenkhat te an ni. He hmun hi a chhe tawh chuan high-temperature fabric structure pum pui chu a chim vek ang.
1. Hydrofluoric Acid (HF)-in a thihpui theihna .
- Structural Changes: HF hian SiO2 nen reaction bik a nei a: SiO2 + 4HF → SiF4↑ + 2H2O. Fiberglass skeleton chu direct-in a hmin a, a bo ta a ni.
- Macroscopic Manifestation: Puan chunglam chu chakna a hloh nghal vat a, vun nêm ang maiin a coating chauh a la awm a, a hrual chuan awlsam takin a chhe thei a, coating leh substrate inkarah hian nasa takin a inthen a ni. Hei hi glass-fiber hmanga siam thil siamna atana chemical corrosion hlauhawm ber a ni. Coating emaw exposed edges emaw-ah pinhole a awm chhung chuan a chhiatna chu a nasa hle.
2. Alkali chak tak (a bik takin hot concentrated alkali) hmanga Slow Etching .
- Structural Changes: OH− ion te hian glass network chhunga siloxane bonds (-Si-O-Si-) te chu a titawp a, soluble silicates a siam thin. Fiber chunglam chu a hrual atanga a hring thlengin a inthlak a, etching pit leh crack a lo lang a, fiber diameter chu a thim a, a tawpah chuan a chhe ta a ni.
- Macroscopic Manifestation: A chakna a tlahniam zel a, puan chu a chhe vek a, a ben chuan fiber chhe tawhte chu coating chhungah a rawn chhuak a, chu chuan coating chu a ti chhe vek a, a peel off thin.
3. Acid Media (hydrofluoric acid tih loh) .
- Structural Changes: Acid tlanglawn (hydrochloric acid, sulfuric acid, etc.) te hian fiberglass atang hian non-silica components (aluminum, calcium oxides, etc.) te chu an leach chhuak duh zawk a, a tam zawk chu silica skeleton a awm ta a ni. Hetiang thil hi 'leaching,' tia hriat a ni tlangpui a, fiber chung lamah microporous structure a siam a ni.
- Macroscopic Manifestation: Puan chu a khauh zawk a, a chhe zawk bawk a, a shrinkage pawh a inthlak danglam a, mahse a form pum pui chu a vawng reng thei tho. Stress concentration vangin chakna a tlahniam.
III. Composite Interface-a inthlak danglamna: Hlawhchhamna thup
Chemical environment hian head-on-in a bei lo fo va, chu ai chuan a sir atang emaw, micro-defects hmangin emaw a lut zawk thin.
- Penetration and Delamination: Organic solvent emaw acid solution emaw chu PTFE coating chhunga pinhole, micro-crack, emaw cut edges hmangin a lut a, fiberglass chu a bei thin. Reaction products emaw penetrating liquids emaw chu interface-ah a pung khawm a, osmotic pressure a siam a, chu chuan PTFE coating chu fiberglass substrate atang hian nasa takin a blister a, a delaminate a ni.
- Stress Corrosion Cracking: Temperature sang tak puan hi hman laiin tension hnuaiah a awm a. Chemical media (a bik takin alkalis chak tak) hmanga fiberglass corrosion hian mechanical stress nen synergistically-in hna a thawk a, chu chuan fiber radial direction-ah crack-te chu rang takin a darh a, chu chuan break-ah brittle-fracture morphology thianghlim tak neiin fabric fracture nghal a thlen a ni.
Chemical corrosive environment-ah chuan PTFE-coated fiberglass fabric-a structural changes chu hetiang hian sawifiah theih a ni: 'King of Plastics' coating chu tlang ang maiin a ding reng a, fiberglass base fabric chu—vawikhat a luhchilh emaw, a beih emaw chuan—Achilles-a kephah a lo ni ta a, chu chuan skeleton dissolution, interface delamination, leh material pumpui a chim vek thung chhung lam atanga pawn lam.
