Aluminium Ion nyhuv ntawm PFA Durability
Phosphoric acid da dej siv rau sealing anodized aluminium Cheebtsam ua haujlwm ntawm 85℃txog 95℃nrog 5% mus rau 10% H₃PO₄ concentration. Thaum lub sijhawm ua haujlwm tas mus li, yaj aluminium ions sib sau los ntawm qhov chaw anodized, ncav cuag 20 txog 30 g / L Al³⁺. Cov ions no cuam tshuam nrog PFA lub tshuab cua sov saum npoo, hloov kho nws tus cwj pwm thiab tsis kam mus rau microcracking. Cov ntaub ntawv teb los ntawm 31 anodizing kab qhia tau hais tias PFA cov cua sov hauv da dej nrog Al³⁺ concentration saum 25 g / L pom 60% tsawg dua microcracks tom qab 5000 teev piv rau cov cua sov zoo tib yam hauv cov kua qaub tshiab nrog Al³⁺ qis dua 5 g / L. Cov aluminium ions hloov pauv cov polymer-acid interface los ntawm ionic crosslinking thiab txo cov phosphoric acid ua haujlwm.
Ion{0}}Mediated Surface Passivation Mechanism
Dissolved aluminium ions nyob rau hauv kub phosphoric acid daim ntawv complexes nrog phosphate hom, tsim ib tug dynamic AlPO₄- nplua nuj txheej ntawm PFA nto. X-ray photoelectron spectroscopy ntawm PFA cov qauv tom qab 3000 teev nyob rau hauv 10% H₃PO₄ nrog 25 g/L Al³⁺ qhia tau hais tias ib qho txhuas- muaj cov zaj duab xis nto 50 txog 100 nanometers tuab. Cov yeeb yaj kiab no ua rau lub cev tsis muaj zog uas txo cov kua qaub ntxiv rau hauv cov cheeb tsam amorphous ntawm PFA. Hauv cov kua qaub tshiab uas tsis muaj txhuas, qhov permeation ntawm H₃PO₄ txog 2.0mm PFA yog 0.08 mg / cm²·hnub ntawm 90 degree. Nrog 25 g / L Al³⁺, tus nqi permeation poob rau 0.03 mg / cm²·hnub, 63% txo. Lower acid permeation txhais tau hais tias tsawg plasticization thiab o, txo cov kev ntxhov siab sab hauv uas tsav microcrack tsim.
Microcracking Resistance Txhim Kho Lub Sijhawm
Cov nyhuv tiv thaiv ntawm aluminium ions nce nrog lub sij hawm raug raws li cov zaj duab xis nto thickens. Kev ntsuas kev laus nrawm ntawm 95℃hauv 10% H₃PO₄ nrog kev tswj hwm Al³⁺ qib qhia tias microcrack ntom (kav ib cm², ntsuas los ntawm optical microscopy ntawm 100 × magnification) tom qab 5000 teev yog nyob ntawm ion concentration. PFA cov qauv hauv cov kua qaub tshiab tsim 12 mus rau 18 microcracks ib cm², feem ntau ntawm thaj tsam spherulite. Cov qauv hauv cov kua qaub nrog 15 g / L Al³⁺ qhia 5 txog 8 microcracks ib cm². Nrog 30 g / L Al³⁺, microcrack ntom ntog mus rau 2 mus rau 4 ib cm², thiab cov kab nrib pleb nyob qis (< 50 microns deep) rather than propagating through the wall. The mechanism involves the aluminum-phosphate layer filling microscopic surface defects that would otherwise serve as crack initiation sites.
Phab ntsa Thickness thiab Aluminium Ion Interaction
Cov txiaj ntsig kev tiv thaiv ntawm aluminium ions txo qhov xav tau PFA phab ntsa tuab rau lub neej kev pabcuam. Hauv cov phosphoric acid tshiab uas tsis muaj Al³⁺ tsub zuj zuj, phab ntsa 2.5 hli raug pom zoo rau 5000-teev microcrack- pabcuam dawb. Hauv cov da dej ua haujlwm tas li nrog Al³⁺ khaws cia siab tshaj 20 g / L (ib txwm ntawm cov kab ntim siab anodizing), 2.0mm phab ntsa ua tiav qhov sib npaug 5000-teev kev ua tau zoo, nrog microcrack ntom hauv qab 5 ib cm². Rau cov da dej nrog lub sijhawm da dej pov tseg qhov twg Al³⁺ cycles ntawm 5 thiab 25 g / L, qhia 2.2 hli phab ntsa kom haum rau kev tiv thaiv sib txawv. Cov nyhuv txhuas ion tso cai rau cov phab ntsa nyias nyias, txhim kho cov cua sov hloov (18℃qis sab hauv hlau kub ntawm 15 W / cm²) thiab txo cov nqi khoom.
Microcracking Resistance los ntawm Al³⁺ Concentration thiab Phab Ntsa Thickness
| Kev Ua Haujlwm Zoo & Qib Al³⁺ | Yam tsawg kawg nkaus PFA Phab Ntsa Thickness rau 5000-teev Kev Pabcuam | Predicted Microcrack Ceev ntawm 5000 Teev (kawg / cm²) | Dominant Failure Hom yog Thinner Phab Ntsa Siv |
|---|---|---|---|
| Cov kua qaub tshiab, Al³⁺ <5 g / L, nruam | 2.5 hli | 2 rau 5 | Permeation -tsav tawg |
| Accumulated da dej, Al³⁺ 10-15 g / L | 2.2 hli | 3 rau 6 | Nto pitting nrog txwv propagation |
| Steady-lub xeev da dej, Al³⁺ 20-25 g/L | 2.0 hli | 4 rau 7 | Microcracks nyob twj ywm, tsis dhau - phab ntsa tawg |
| Kev sib sau siab, Al³⁺> 30 g / L | 1.8mm ib | 5 rau 9 | Txais tau 5000h nrog Al³⁺ tiv thaiv |
| Cycling da dej (5-25 g / L), pov tseg txhua lub lim tiam | 2.2 hli | 4 rau 8 | Kev tiv thaiv tsis sib xws yuav tsum muaj phab ntsa tuab |
Temperature Sensitivity ntawm cov txheej txheem tiv thaiv
Aluminium -phosphate txheej txheej ua tau zoo tshaj plaws ntawm qhov kub siab tshaj 85℃. Hauv qab 80 degree, nag lossis daus kinetics qeeb qeeb, thiab kev tiv thaiv cov txiaj ntsig ntawm Al³⁺ raug txo los ntawm 50% mus rau 60%. Rau phosphoric acid da dej ua haujlwm ntawm 75℃rau cov ntawv thov tshwj xeeb anodizing, cov nyhuv txhuas ion tseem tshwm sim tab sis yuav tsum muaj ntau dua (txog 30 g / L) kom ua tiav tib lub microcracking txo li 20 g / L ntawm 95 degree. Hloov pauv, ntawm 100 degree, cov txheej txheem tiv thaiv tau nrawm dua, tab sis qhov kev pheej hmoo ntawm cov chaw kub thiab cov polymer degradation nce. Qhov ntsuas kub zoo tshaj plaws rau kev ua kom muaj txiaj ntsig zoo tshaj plaws ntawm txhuas ion yog 88℃txog 92 degree, qhov twg AlPO₄ txheej txheej txheej tsis sib xws tsis muaj kev ntxhov siab ntau dhau ntawm PFA.
Da Dej Lim thiab Aluminium Ion Muaj
Nruam pom ntawm phosphoric acid da dej tshem tawm cov txhuas phosphate particulates tab sis tsis txo cov yaj Al³⁺ concentration. Txawm li cas los xij, kev pom uas hnyav dhau (sub-micron absolute ratings) tuaj yeem tshem tawm cov kab mob colloidal uas koom nrog hauv kev tsim cov yeeb yaj kiab saum npoo. Kev soj ntsuam hauv cheeb tsam qhia tau hais tias da dej siv 5-micron nominal pom ua tiav cov txiaj ntsig microcracking txo cov txiaj ntsig ntawm cov khoom siv txhuas, thaum da dej siv 0.5-micron pom tseeb pom pom 30% kev tiv thaiv tsawg dua vim tias cov khoom zoo colloidal txhuas raug tshem tawm. Rau cov kab anodizing nrhiav ob qho tib si da dej clarity thiab PFA kev tiv thaiv, 1-micron rau 3-micron nominal filtration muab qhov zoo tshaj plaws sib npaug.
Kev taw qhia Specification rau Anodizing Kab Heaters
Rau phosphoric acid sealing da dej nrog cov khoom siv txhuas txhuas (20-25 g / L tom qab stabilization), qhia PFA cov cua sov nrog 2.0mm txog 2.2mm phab ntsa thickness, nkag siab tias txhuas ions yuav muab ntxiv microcracking tsis kam dhau ntawm cov khoom siv polymer. Thaum ua haujlwm da dej tshiab lossis tom qab ua tiav cov pob tseg, ua haujlwm nrog lub zog ntau dua (txog 18 W / cm²) thawj 200 teev kom nrawm Al³⁺ tawg ntawm qhov chaw anodized, tsim cov txheej txheem tiv thaiv sai dua. Rau cov da dej uas tau muab pov tseg txhua lub lim tiam (tsawg Al³⁺), tsis quav ntsej cov txiaj ntsig ntawm txhuas thiab qhia 2.5 hli phab ntsa zoo li cov kua qaub tshiab. Thov los ntawm PFA tus neeg muag khoom microcracking cov ntaub ntawv kuaj hauv phosphoric acid nrog Al³⁺ qib sib piv cov tshuaj da dej tshwj xeeb, raws li kev ntsuas nrawm hauv cov kua qaub ntshiab tsis pom qhov ua tau zoo hauv ntiaj teb. Thaum lub sij hawm ntsuas cua sov ntawm 5000-teev ib ntus, ntsuas microcrack ntom ntawm cov cua sov tshem tawm; Yog tias cov kab nrib pleb ntau dua 10 ib cm² lossis ib qho kev tawg qhov tob tshaj 0.3 hli, nce cov phab ntsa tuab ntawm 0.2 hli rau qhov kev yuav khoom tom ntej, tsis hais Al³⁺ concentration. Rau cov kab anodizing uas tuav Al³⁺ siab tshaj 30 g / L los ntawm kev tswj cov da dej laus, 1.8mm PFA phab ntsa tau pom 8000-teev kev pab cuam lub neej nrog microcracking, uas sawv cev rau 25% cov khoom txuag thiab 15% kev txhim kho nyob rau hauv tshav kub hloov efficiency piv rau cov qauv 2.5mm specifications.
