Aluminium ntawv ci thiab ntawv tiv thaiv corrosion vim hais tias ib tug compact oxide zaj duab xis ob peb nanometers tuab re-forms nyob rau hauv milliseconds ntawm raug huab cua. Tus kheej- rov ua zaj duab xis piav qhia tias vim li cas cov ntawv ci liab qab muaj sia nyob tau ntau xyoo ntawm kev pabcuam sab hauv tsev, thiab nws cov kev txwv piav qhia tias vim li cas tib cov khoom tsis tuaj yeem sab nraum zoov lossis hauv cov nroj tsuag tshuaj. Kev nkag siab txog lub hauv paus ntawm electrochemical ua rau kev xaiv ntawm anodising, txheej los yog kev sib koom ua ke tsim kom deb li deb tau.
Vim li cas Aluminium Corrodes: Electrochemical Baseline
Nyob rau hauv galvanic series txhuas yog muaj zog anodic thiab zaum tsis zoo tshaj li feem ntau cov qauv hlau sib nrug los ntawm magnesium thiab zinc. Thaum txhuas yog txuas rau hlau, stainless hlau los yog tooj liab nyob rau hauv lub xub ntiag ntawm ib tug electrolyte, lub txhuas ua lub sacrificial anode thiab lub noble hlau tsav nws dissolution.
Cov oxide ib txwm muaj kuj yog amphoteric: nws ruaj khov nyob rau thaj tsam ntawm pH 4 txog pH 9 thiab yaj sai sai hauv cov kua qaub lossis alkalis. Cov dej nag, cov tshuaj ntxuav tes tsis huv thiab cov roj hydrocarbon feem ntau yog li ua rau muaj kev puas tsuaj me me, thaum lub acidic descaler los yog caustic ntxuav tuaj yeem strip lub teeb meem hauv feeb. Txhua qhov kev tiv thaiv kev ntsuas tau tham hauv qab no yog ua kom cov kab mob no ua rau muaj zog, ua kom nws ruaj khov, lossis tshem tawm cov xwm txheej uas ua rau nws tawg.
Yuav Ua Li Cas Cov Ntawv Tseem Ceeb Corrosion Tsim
Kev ua tsis tiav ntawm cov ntawv ci, ntawv thiab extrusion ua raws li qhov sib txawv, thiab lawv yuav tsum tau muab cais ua ntej xaiv txoj kev tiv thaiv.
| Corrosion daim ntawv | Ua rau | Qhov twg nws tshwm | Tswv yim tawm tsam |
|---|---|---|---|
| Pitting | Chloride ions nkag mus rau cov ntsiab lus tsis muaj zog hauv oxide zaj duab xis | Foil nto, coil stock, marine los yog ntug hiav txwv raug | Txwv cov tshuaj chloride tiv tauj, qhia meej anodised lossis coated nto |
| Intergranular | Sensitized grain ciam teb nyob rau hauv Al-Mg 5xxx alloys tuav saum 65 degree | Weld tshav kub- thaj chaw cuam tshuam thiab tshav kub- phaj phaj | Tswj cov thermal raug, xaiv qis -sensitisation tempers |
| Crevice | Stagnant electrolyte hauv qhov khoob, pH qis dua 4 lossis siab dua 9 | Lap sib koom tes, gasket rooj, fastener interfaces | Foob pob qij txha, tsis txhob nqus cov gaskets, tsim rau cov kua dej |
| Galvanic | Sib cuag nrog cov hlau zoo dua qub ntxiv rau tus choj electrolyte | Mixed- hlau ncej, fasteners, bracketry | Insulate qhov sib koom ua ke, tswj thaj tsam piv, tsho tiv no ob lub hlau |
| Exfoliation | Sensitized microstructure ua ke nrog kev ntxhib los mos | Rolled los yog extruded npoo ntawm tuab seem | Tswj kev kub ntxhov thiab kev kho cua sov, kaw cov npoo npog |
Surface Engineering rau siab dua Corrosion Resistance
Kev kho saum npoo yog qhov ncaj tshaj plaws qib. Txhua tus txheej txheem hauv qab no ua lag luam tus nqi, thickness thiab tsos txawv, yog li cov lus qhia yuav tsum ua raws li cov chav kawm raug ntau dua li qhov rov qab.
Anodizingtsim kom muaj 5-150 µm oxide txheej nrog cov qauv columnar pore; sealing cov pores kaw lub ntsiab chloride txoj kev thiab tuaj yeem ua ke nrog cov xim.
Kev hloov pauv txheejkeeb kwm cia siab rau hexavalent chromium inhibitors uas ua rau tus kheej - kho nyhuv. Vim tias Cr(VI) raug txwv, trivalent chromium thiab chromium -dawb titanium los yog zirconium conversion coatings yog tam sim no ib txwm specification.
Plasma electrolytic oxidationtsim ceramic alumina coatings mus txog 300 µm tuab nrog hardness ncav cuag 2000 HV, haum qhov twg puas thiab corrosion ua ua ke.
Sol-gel txheejuse zirconia nanoparticle dispersions to form a dense chemical barrier that bonds covalently to the oxide.
Laser nto meltingrefines ze ntawm -surface microstructure thiab dissolves intermetallic hais tias yuav ua lwm yam raws li pitting pib qhov chaw.
Tsim Cov Cai Uas Tiv Thaiv Galvanic thiab Crevice Attack
Geometry nquag txiav txim siab kev ua haujlwm corrosion ntau dua li kev xaiv alloy. Cov cai hauv qab no yog pheej yig nyob rau theem kev kos duab thiab raug nqi rau retrofit.
cais cov hlau tsis sib xws nrog dielectric washers, lub tes tsho lossis gaskets; ib tug 0.1 hli standoff yog txaus los ua txhaum txoj kev conductive.
Khaws cov cathode-rau-anode cheeb tsam piv txwv, hauv qab no txog 1:100 qhov twg cov khoom siv txhuas me me ua tau raws li cov qauv hlau loj.
Siv cov zinc anodes los yog zinc- nplua nuj primers rau submerged thiab marine assemblies.
Tsis txhob nqus cov gaskets thiab qhov muag tsis pom qhov khoob uas tuav electrolyte; muab cov kua dej kom cov dej tsis tuaj yeem zaum hauv qhov chaw.
Sau cov pob qij txha nrog cov khoom siv sib khi kom cov electrolyte tsis ncav cuag cov xov interface.
Kev xeem, Kev Tsim Nyog thiab Hauv -Kev Saib Xyuas Kev Pabcuam
Kev tsim nyog hauv chav kuaj ib txwm pib nrog cov tshuaj ntsev nruab nrab rau ASTM B117 lossis nws qhov sib npaug ISO 9227, 5% sodium chloride pos huab tuav ntawm 35 degree, qhia cov sij hawm rau thawj xim dawb los yog blistering. Cov tshuaj tsuag ntsev ib leeg yog cov cuab yeej tshuaj ntsuam xyuas; ib qho kev pab cuam tag nrho ntxiv cov txheej txheem electrochemical thiab teb.
Electrochemical impedance spectroscopy daws teeb meem kev tiv thaiv thiab txheej txheej capacitance los ntawm qhov sib npaug -circuit fitting, kuaj pom kev degradation ua ntej kev tawm tsam pom.
Cyclic corrosion testing alternates ntsev pos huab, av noo thiab ziab theem kom rov tsim cov kev pabcuam tiag tiag ntau dua li cov tshuaj tsuag tas li.
Hydrogen evolution ntsuas ntsuas ntsuas qhov sib cais ntawm cov kua qaub.
Kev soj ntsuam Kelvin sojntsuam kuaj pom micro- ntsuas qhov sib txawv ntawm qhov ntsuas qhov ntsuas pitting.
Kev saib xyuas teb siv hluav taws xob tiv thaiv kev sojntsuam rau hlau poob, electrochemical suab nrov sensors rau pitting transients, multi-electrode arrays rau localized attack mapping thiab fiber-optic pH sensors embedded nyob rau hauv coatings rau chij qhov chaw tsis xws luag.
Robotic tej zaum daim ntawv qhia txhawb kev soj ntsuam ntawm lub tank loj thiab lub nkoj nto yam tsis muaj scaffolding.
Sib piv cov kev sim ntsuas rau ib puag ncig tiag tiag yog dab tsi ua rau kev txhim kho corrosion credible: chloride-tsav pitting yuav tsum tau ntsev raug, alkaline tiv tauj yuav tsum tau immersion sim, thiab sib tov-hlau sib dhos yuav tsum tau galvanic coupling xeem es tsis yog cais daim coupon xeem.
Cov lus nug nquag
Q: Qhov twg aluminium alloys feem ntau yooj yim rau intergranular corrosion?
Al-Mg 5xxx alloys yog cov ntaub ntawv classic. Thaum lub sensitized microstructure loj hlob nyob rau hauv grain ciam teb tom qab ntev raug tshaj li ntawm 65 degree, cov ciam teb corrode preferentially, yog li tshav kub-paj phaj thiab weld aav yuav tsum tau tsawg -sensitisation tempers.
Q: Puas yog anodising ib txwm zoo dua li kev hloov pauv txheej?
Tsis yog universally. Anodising muab lub thicker, nyuaj thiab ntau abrasion -resistant barrier, thaum lub sij hawm hloov txheej txheej yog thinner, pheej yig dua thiab khaws cia hluav taws xob tiv thaiv zoo dua, uas tseem ceeb rau txoj kev hauv av.
Q: Vim li cas kev ntsuas tshuaj ntsev tsis kwv yees lub neej kev pabcuam ncaj qha?
Cov pos huab tsis tu ncua ua kom lub ntsej muag ntub thiab chloride- nplua nuj, uas dhau - hnyav pitting txheeb ze rau lub voj voog ziab, UV raug thiab kev puas tsuaj. Cyclic regimes thiab fields exposure panels correlated with real services far better.
Q: Yuav ua li cas galvanic corrosion tuaj yeem tswj tau qhov kev sib cais tsis tuaj yeem?
Tswj lub cheeb tsam piv yog li cov txhuas anode yog loj txheeb ze rau cathode, coated lub cathodic hlau, thiab txais kev tswj fij tus cwj pwm qhov twg cov anode yuav hloov nyob rau hauv lub sij hawm npaj.
Q: Dab tsi yog txoj hauv kev ceev tshaj plaws los kuaj xyuas cov txheej txheej hauv daim teb?
Electrochemical impedance spectroscopy thiab luam theej duab Kelvin sojntsuam ob qho tib si kuaj pom qhov poob ntawm kev ua haujlwm tsis zoo ua ntej pom kev xeb, thiab cov khoom siv hluav taws xob tiv thaiv ua rau cov hlau tsis tu ncua - poob qauv ntawm cov cuab tam tseem ceeb.
Q: Puas yog txheej txheej oxide tuab tuaj yeem lav lub neej ntev?
Tsuas yog tias nws tseem nyob ruaj khov thiab kaw. Unsealed pores, machining kev puas tsuaj thiab cov npoo ntse tsim qhov chaw pib, yog li kev tiv thaiv ntug thiab tuav kev qhuab ntuas ntau npaum li nominal txheej thickness.
