Puas yog Zinc Zoo nrog Aluminium?
Cov lus nug ntawm seb zinc puas yog "zoo" nrog txhuas yog kev dag ntxias yooj yim. Nyob rau hauv lub ntiaj teb no ntawm cov ntaub ntawv science thiab engineering, tshwj xeeb tshaj yog nyob rau hauv daim ntawv thov uas muaj kev tiv thaiv corrosion, galvanic coupling, thiab txheej technologies, kev sib raug zoo ntawm zinc thiab txhuas tsis yog ib qho yooj yim kev phooj ywg los yog antagonism. Hloov chaw, nws yog ib qho kev sib koom ua ke uas tswj hwm los ntawm cov hauv paus ntsiab lus ntawm electrochemical. Cov lus teb luv luv yog: nws nyob ntawm cov ntsiab lus thiab daim ntawv thov. Hauv ntau qhov xwm txheej, zinc yog qhov tshwj xeeb zoo rau kev tiv thaiv txhuas, thaum nyob rau hauv ncaj qha, txuas hluav taws xob txuas mus rau hauv ib puag ncig corrosive, nws tuaj yeem ua rau muaj kev pheej hmoo.
Lub Electrochemical Foundation: Galvanic Series
Yuav kom nkag siab txog kev sib cuam tshuam, ib tus yuav tsum xub nkag siab txog cov galvanic series. Qhov no yog ib daim ntawv teev cov hlau thiab alloys txheej txheem raws li lawv tus qauv electrode muaj peev xwm nyob rau hauv ib tug muab electrolyte (xws li seawater). Ib txoj cai tseem ceeb: thaum ob lub hlau sib txawv yog hluav taws xob sib txuas thiab raug rau ib qho electrolyte, qhov ntau "active" los yog "anodic" hlau yuav corrode nyiam, txi nws tus kheej los tiv thaiv ntau "noble" los yog "cathodic" hlau.
Peb ob lub hlau nyob qhov twg?
· Zinc yog anodic heev. Nws tus qauv electrode muaj peev xwm yog kwv yees li -0.76 V.
· Aluminium kuj yog anodic, tab sis tsawg tshaj li zinc, muaj peev xwm nyob ib ncig ntawm -0.71 txog -0.74 V rau ntau alloys (qhov no yuav txawv me ntsis). Nyob rau hauv cov tswv yim galvanic series nyob rau hauv seawater, aluminium alloys feem ntau poob ntawm cov anodic zinc / magnesium thiab ntau noble hlau xws li hlau los yog tooj liab.
Tseem ceeb heev, nyob rau hauv feem ntau standardized galvanic series rau seawater, zinc yog ntau anodic tshaj txhuas. Qhov no txhais tau hais tias nyob rau hauv ib tug ua ke system, zinc yuav ua raws li lub anode thiab corrode, thaum txhuas ua lub cathode thiab tiv thaiv. Qhov no yog lub hauv paus ntsiab lus tom qab ib qho ntawm zinc lub luag haujlwm tseem ceeb tshaj plaws nrog txhuas: kev tiv thaiv kev txi.
Qhov twg Zinc yog "Zoo" rau Aluminium: Kev Tiv Thaiv Kev Tiv Thaiv
1. Galvanic (Xib Fwb) Kev Tiv Thaiv:
Qhov no yog qhov txiaj ntsig ncaj qha tshaj plaws. Yog tias koj txuas ib daim zinc (lossis zinc anode) rau cov qauv txhuas-zoo li txhuas- lub nkoj nkoj, lub nkoj tawm sab nrauv, lossis lub tank hauv av- zinc yuav corrode maj mam, xa cov tiv thaiv tam sim no rau txhuas thiab tiv thaiv nws cov oxidation. Qhov no yog txoj kev dav thiab muaj txiaj ntsig zoo tiv thaiv corrosion.
2. Zinc-Raws li txheej txheej:
· Galvanizing (ntawm Steel) Nyob ze Aluminium: Ib qho xwm txheej tshwm sim yog thaumgalvanized hlau(steel coated nrog ib txheej ntawm zinc) yog nyob rau hauv kev sib cuag nrog txhuas. Ntawm no, zinc txheej sacrificially tiv thaiv tsis tau tsuas yog lub hauv paus hlau, tab sis kuj, rau ib tug npaum li cas, cov nyob ib sab aluminium. Cov zinc corrodes ua ntej ntawm qhov sib txuas, ncua kev xeb ntawm ob lub hlau. Kev tsim kom zoo nrog cov khoom siv insulating los yog txheej txheej ntawm qhov chaw sib cuag tseem pom zoo rau kev ua haujlwm ntev -.
· Zinc-Primers nplua nuj: Aluminium nto, tshwj xeeb tshaj yog nyob rau hauv kev xav tau ib puag ncig zoo li txuas hniav, aircraft, los yog cov khoom siv hauv hiav txwv, feem ntau yog pleev xim rau zinc- nplua nuj primers. Cov xim no muaj cov khoom hnyav zinc plua plav. Thaum cov xim zaj duab xis yog khawb los yog puas, cov zinc particles tsim ib tug galvanic cell nrog cov raug txhuas substrate, muab sacrificial tiv thaiv ntawm qhov chaw tsis xws luag thiab tiv thaiv underfilm corrosion creep-ib qho tseem ceeb kom zoo dua tsis yog -galvanic primers.
·Zinc Platingntawm Fasteners: Nws yog ib qho kev xyaum siv zinc-plated steel fasteners (ntsia hlau, rivets, bolts) nrog txhuas sib dhos. Zinc plating ua hauj lwm raws li ib tug sacrificial txheej. Thaum pib, cov zinc corrodes los tiv thaiv ob lub steel fastener thiab aluminium qhov. Thaum cov zinc depleted, qhov tsawg dua -noble steel yuav corrode, uas tseem tuaj yeem nyiam rau cov txhuas corroding, nyob ntawm seb qhov tsim ua ntej.
3. Zinc nyob rau hauv Aluminium Alloys (Raws li Alloying Element):
Qhov no yog kev sib txawv tab sis tseem ceeb heev. Zinc yog ib qho tseem ceeb alloying nyob rau hauv lub siab tshaj plaws - zog aluminium alloys, tshwj xeeb tshaj yog cov 7xxx series (xws li, 7075, siv nyob rau hauv aerospace thav duab). Nyob rau hauv cov alloys no, zinc (nrog rau magnesium thiab tooj liab) ua rau tsim cov nplua precipitates thaum tshav kub kub kho ( nag lossis daus hardening), muab cov txhuas tshwj xeeb lub zog - rau - hnyav piv. Hauv cov ntsiab lus no, zinc tsis yog "zoo" xwb tab sis tseem ceeb hauv cov hlau matrix.
Qhov twg Zinc tuaj yeem ua "tsis zoo" rau Aluminium: Qhov Kev pheej hmoo thiab Kev txo qis
Qhov kev tiv thaiv flips yog aluminium yog txuas rau ib lub hlau zoo tshaj li nws tus kheej. Yog hais tias cov zinc txheej los yog txheej yog depleted, thiab lub hauv paus hlau (xws li hlau) raug, ces cov galvanic ob peb ua hlau (cathode) thiab txhuas (anode). Hauv qhov no, aluminium yuav corrode sai heev.
Cov kev pheej hmoo tseem ceeb yog:
1. Galvanic Corrosion nyob rau hauv Aggressive Environments: Nyob rau hauv lub xub ntiag ntawm ib tug persistent electrolyte (kua ntsev, condensation tas li, muaj chemicals), ncaj hlau - mus rau -hlau sib cuag ntawm zinc thiab txhuas tau, nyob rau hauv ib co tej yam kev mob raws li qhov tseeb alloys, ua rau kom ceev noj cov zinc. Qhov tseem ceeb tshaj, yog tias cov zinc tsis tau khaws cia thiab tau noj tag nrho, qhov tshwm sim ntawm ntau cov cathodic substrate (xws li steel) yuav tawm tsam cov txhuas. Qhov chaw txheeb ze yog qhov tseem ceeb: ib qho me me anode (aluminium) txuas nrog lub cathode loj (zinc-coated steel)yuav yog ib tug txaus ntshai tsim, raws li cov anode corrodes intensely.
2. Dissimilar Hlau Corrosion nyob rau hauv Assemblies: Qhov no yog classic engineering kev sib tw. Lub zinc-plated steel bolt nyob rau hauv ib lub phaj txhuas, nyob rau hauv ib qho chaw ntub dej, tsim ib lub cell galvanic. Zinc plating yog qhov muaj txiaj ntsig zoo, tab sis tus qauv tsim yuav tsum xyuas kom meej tias qhov sib koom ua ke raug kaw kom zoo, rwb thaiv tsev (nrog tsis yog -cov tshuab ntxhua khaub ncaws lossis txheej txheej), lossis tsim kom yooj yim txij nkawm thiab tshuaj xyuas.
Mitigation Strategies:
· Rwb thaiv tsev: Siv cov pa taws tsis zoo, lub tes tsho, lossis cov ntxhua khaub ncaws ua los ntawm cov yas lossis lwm yam insulators kom tawg hluav taws xob txuas ntxiv.
· Barrier Coatings: Siv cov xim, hmoov txheej, los yog cov khoom sib txuas rau ob qho tib si sib txuas ua ntej sib sau ua ke, tshwj xeeb tshaj yog rau cov khoom zoo tshaj plaws (los yog qhov koj tsis xav txi).
· Kev xaiv Anode raug: Rau kev tiv thaiv cathodic, siv anodes tshwj xeeb tsim los rau cov qauv txhuas, xws li txhuas -zinc-indium alloys, uas muaj peev xwm zoo thiab muaj peev xwm.
· Kev xaiv cov khoom siv: Qee zaum, siv cov fasteners ua los ntawm cov hlau ze rau txhuas hauv cov galvanic series, xws li stainless hlau (txawm tias yuav tsum tau ceev faj nrog qee hom) lossis txawm tias aluminium alloys lawv tus kheej, yog qhov zoo dua.
Qhov Tshwj Xeeb Case:Al-Zn Coated Steel(eg, Galvalume)
Ib tug fascinating hybrid technology qhia txog kev sib koom ua ke. Galvalume® yog hlau coated nrog ib tug alloy ntawm kwv yees li 55% txhuas, 43.4% zinc, thiab 1.6% silicon. Cov txheej no ua ke nrog kev tiv thaiv kev tiv thaiv thiab kev ua neej ntev ntawm txhuas nrog galvanic sacrificial tiv thaiv ntawm zinc. Cov zinc-nplua nuj theem nyob rau hauv lub txheej sacrificially tiv thaiv cov npoo thiab khawb, thaum lub txhuas matrix muab zoo heev ntev -lub sij hawm atmospheric corrosion kuj. Ntawm no, zinc- aluminium kev koom tes yog tsim los ntawm qib microstructural rau kev ua tau zoo dua.
Xaus: Kev Koom Tes Zoo Tshaj Plaws
Yog li, zinc puas zoo nrog txhuas? Cov lus teb yog ib qho resounding yog, tab sis nrog kev saib xyuas engineering tseem ceeb.
Zinc yog ib qho kev tiv thaiv ntawm txhuas hauv feem ntau ntawm cov kev siv tswv yim. Nws qhov kev txaus siab rau corrode ua ntej ua rau nws yog ib qho cuab yeej tseem ceeb rau kev khaws cov qauv txhuas los ntawm kev txi anodes, zinc- nplua nuj primers, thiab raws li kev tiv thaiv plating ntawm fasteners. Nws lub luag haujlwm raws li cov khoom siv alloying yog qhov tseem ceeb sib npaug rau kev tsim cov khoom muaj zog, hnav.
Lub peev xwm rau kev puas tsuaj tshwm sim tsis yog los ntawm zinc nws tus kheej, tab sis los ntawm kev tawg ntawm cov zinc txheej tiv thaiv los yog los ntawm kev tsim tsis zoo uas tso cai rau ob peb galvanic aggressively tsim. Kev sib raug zoo yog li ntawd tsis muaj teeb meem tshwm sim; nws yog ib lub cuab yeej muaj zog. Zoo li txhua yam cuab yeej muaj zog, nws yuav tsum tau siv nrog kev nkag siab. Los ntawm kev hwm cov hauv paus ntsiab lus ntawm cov galvanic series, siv cov txheej txheem rwb thaiv tsev kom zoo thiab thaiv cov txheej txheem, thiab xaiv cov ntaub ntawv tsim nyog rau ib puag ncig, engineers thiab cov neeg tsim qauv tuaj yeem siv cov ntaub ntawv tsim nyog.zinc{0}} txhuaskev koom tes los tsim kom muaj kev ruaj ntseg, txhim khu kev qha, thiab ntev - cov khoom siv thiab cov qauv siv tau ntev. Kev sib koom ua ke, thaum ua tau zoo, muaj txiaj ntsig zoo.
