Tus txheej txheem ntawm passivation yog dab tsi?

Oct 07, 2024

Tso lus

Ⅰ Introduction to Passivation

Passivation yog cov txheej txheem tseem ceeb uas siv feem ntau hauv kev kho cov hlau tsis huv thiab lwm yam hlau los txhim kho lawv cov kev tiv thaiv corrosion. Nws suav nrog kev tshem tawm cov hlau dawb los ntawm cov hlau qhov chaw, uas, yog tias tsis kho, tuaj yeem cuam tshuam nrog ib puag ncig thiab ua rau xeb. Los ntawm passivation, txheej txheej tiv thaiv oxide tsim rau ntawm qhov chaw, tiv thaiv cov hlau hauv qab los ntawm cov khoom corrosive.

Keeb kwm, passivation tau hloov zuj zus nrog kev nce qib hauv kev ua haujlwm hlau, dhau los ua cov kauj ruam tseem ceeb hauv kev lag luam uas xav tau kev ua haujlwm siab thiab tsis kam tiv thaiv ib puag ncig, xws li aerospace, kev kho mob, thiab automotive sectors.

Stainless steel components undergoing passivation in an industrial setting

▲ Stainless hlau Cheebtsam raug passivation nyob rau hauv ib qho chaw muaj

Ⅱ Kev Tshawb Fawb Tom Qab Passivation

Ntawm nws cov tub ntxhais, passivation yog cov txheej txheem tshuaj lom neeg uas hloov cov nplaim ntawm cov hlau. Cov txheej txheem cuam tshuam nrog kev siv cov kua qaub, feem ntau nitric lossis citric acid, uas dissolves cov hlau dawb thiab lwm yam kab mob los ntawm qhov chaw. Qhov kev kho no tsis yog tsuas yog ntxuav lub ntsej muag xwb tab sis kuj txhawb kev tsim cov txheej nyias, tsis tau muaj zog, oxide txheej.

Cov txheej no yog feem ntau chromium oxide nyob rau hauv cov ntaub ntawv ntawm stainless hlau, uas ib txwm resists corrosion. Cov kev tshawb fawb tom qab passivation tso siab rau cov hlau muaj peev xwm kho tus kheej; yog tias cov oxide txheej yog khawb, nws tuaj yeem hloov kho nyob rau hauv lub xub ntiag ntawm oxygen, tsis tu ncua tiv thaiv cov hlau hauv qab.

Chemical process of passivation on a microscopic level, showing the formation of a protective oxide layer

▲ Cov txheej txheem tshuaj ntawm passivation ntawm qib microscopic, qhia txog kev tsim cov txheej txheem oxide tiv thaiv

Metallurgically, txoj kev vam meej ntawm passivation nyob ntawm tej yam xws li cov hlau muaj pes tsawg leeg, qhov chaw nyob, thiab qhov chaw tshwj xeeb nws yuav raug. Lub xub ntiag ntawm cov ntsiab lus xws li chromium, npib tsib xee, thiab molybdenum nyob rau hauv stainless hlau txhim khu nws lub peev xwm los tsim ib tug passive txheej, ua rau cov alloys tshwj xeeb tshaj yog haum rau passivation.

Ⅲ Tus txheej txheem ntawm Passivation

Cov txheej txheem passivation muaj ob peb kauj ruam tseem ceeb kom ntseeg tau tias cov hlau raug kho kom zoo:

Ntxuav:Cov hlau saum npoo yuav tsum tsis muaj roj, roj, thiab lwm yam kab mob ua ntej passivation. Qhov no tuaj yeem koom nrog degreasing, ntxuav ultrasonic, lossis lwm yam kev npaj.
Kev Kho Acid:Tom qab ntawd cov hlau ntxuav tau muab tso rau hauv cov kua qaub da dej, feem ntau siv nitric lossis citric acid. Nitric acid yog ib txwm siv ntau dua thiab muaj txiaj ntsig thoob plaws ntau yam ntawm cov hlau tsis muaj steel, thaum citric acid yog qhov kev nyab xeeb dua, kev xaiv ib puag ncig zoo dua uas tau loj hlob hauv cov koob npe.
Yaug:Tom qab kev kho cov kua qaub, cov hlau yuav tsum tau yaug nrog dej deionized kom tshem tawm cov kua qaub uas tseem tshuav thiab yaj cov kab mob.
Kev ziab:Thaum kawg, cov hlau yog qhuav nyob rau hauv ib puag ncig tswj kom tsis txhob muaj recontamination. Cov kauj ruam no yog qhov tseem ceeb los tswj kev ncaj ncees ntawm qhov chaw passivated.

Steps of the passivation process, including cleaning, acid treatment, rinsing, and drying

▲ Cov kauj ruam ntawm cov txheej txheem passivation, suav nrog kev ntxuav, kho kua qaub, rinsing, thiab ziab

Kev npaj nto yog qhov tseem ceeb los ua kom cov txheej txheem passivation ua haujlwm zoo. Txhua yam kab mob seem ntawm qhov chaw tuaj yeem cuam tshuam nrog kev tsim cov oxide txheej, ua rau muaj kev tiv thaiv tsis tiav.

Ⅳ Hom Stainless Hlau thiab Lawv Passivation Xav Tau

Cov qib sib txawv ntawm stainless hlau yuav tsum tau txiav txim siab tshwj xeeb thaum lub sij hawm passivation:

Austenitic Stainless hlau:Cov hlau no, xws li 304 thiab 316, yog cov feem ntau passivated. Lawv muaj cov qib siab ntawm chromium thiab npib tsib xee, uas pab txhawb kev tsim cov txheej txheem passive zoo.
Martensitic Stainless hlau:Cov no nyuaj thiab muaj zog dua tab sis tsis tshua muaj corrosion-resistant piv rau qib austenitic. Lawv yuav tsum tau ceev faj passivation los xyuas kom meej cov ntaub ntawv oxide ruaj khov.
Ferritic Stainless hlau:Cov no muaj cov ntsiab lus chromium qis dua thiab tsis muaj nickel, ua rau lawv nyuaj rau passivate. Kev saib xyuas tshwj xeeb yog xav tau thaum lub sijhawm ua haujlwm kom ntseeg tau tias muaj txiaj ntsig zoo.
Duplex Stainless Hlau:Ua ke cov yam ntxwv ntawm ob qho tib si austenitic thiab ferritic stainless hlau, duplex steels yuav tsum tau ua kom haum rau kev ua kom dhau los vim lawv cov microstructure sib xyaw.

Stainless steel samples before and after passivation

▲ Stainless hlau kuaj ua ntej thiab tom qab passivation

Txhua yam ntawm cov hlau stainless no yuav xav tau cov kua qaub sib txawv, qhov kub thiab txias, thiab lub sijhawm ua haujlwm kom ua tiav qhov kev pom zoo passivation.

Ⅴ Passivation Standards thiab Specifications

Txhawm rau kom muaj txiaj ntsig zoo thiab muaj txiaj ntsig zoo, ntau cov qauv kev lag luam tau tsim:

ASTM A967 Khoom: Qhov no yog ib qho ntawm cov qauv kev lees paub ntau tshaj plaws rau kev ua haujlwm ntawm cov hlau tsis muaj steel, nthuav dav cov txheej txheem thiab cov kev sim uas yuav tsum tau ua kom tiav passivation.
ASTM A380 Txuj:Cov qauv no suav nrog kev tu, descaling, thiab passivation ntawm stainless hlau qhov chaw, muab cov lus qhia ntxaws txog cov txheej txheem.
TSI 2700:Cov txheej txheem aerospace no qhia txog qhov yuav tsum tau ua rau kev tiv thaiv corrosion-resistant steels, nrog rau qhov tseem ceeb ntawm cov txiaj ntsig zoo tsim nyog rau cov khoom siv hauv aerospace.

Ua raws li cov qauv no yog qhov tseem ceeb rau cov tuam txhab tsim khoom, tshwj xeeb tshaj yog nyob rau hauv kev tswj hwm kev lag luam xws li aerospace thiab kev tsim khoom siv kho mob, qhov khoom ua tau zoo thiab kev nyab xeeb yog qhov tseem ceeb.

Ⅵ Passivation vs. Electropolishing

Passivation thiab electropolishing feem ntau muab piv vim tias ob txoj kev txhim kho corrosion ntawm stainless hlau, tab sis lawv ua tiav qhov no los ntawm kev sib txawv:

Passivation:tsom rau kev tshem tawm cov tshuaj lom neeg ntawm cov hlau saum npoo thiab tsim cov txheej txheem oxide tiv thaiv. Nws yog cov txheej txheem yooj yim dua, raug nqi ntau dua, haum rau feem ntau cov ntawv thov.
Electropolishing:Koom nrog tshem cov txheej nyias ntawm cov hlau los ntawm qhov chaw los ntawm cov txheej txheem electrochemical, uas tsis tsuas yog txhim kho corrosion kuj, tab sis kuj txhim kho qhov chaw tiav los ntawm smoothing tawm microscopic roughness.

Comparison between passivation and electropolishing processes

▲ Kev sib piv ntawm cov txheej txheem passivation thiab electropolishing

Thaum twg los xaiv txhua tus txheej txheem nyob ntawm daim ntawv thov. Electropolishing feem ntau nyiam nyob rau hauv kev lag luam uas qhov chaw ua kom zoo nkauj yog qhov tseem ceeb, xws li hauv cov khoom siv kho mob thiab cov khoom siv ua zaub mov. Passivation feem ntau yog siv rau kev tiv thaiv corrosion nyob rau hauv tsawg dua visually demanding daim ntaub ntawv.

Ⅶ Validation thiab Testing Passivated Parts

Kev ntsuam xyuas yog qhov tseem ceeb kom paub meej tias cov txheej txheem passivation tau ua tiav. Cov kev kuaj pom muaj xws li:

Ntsej Tsuag Test:Tshaj tawm qhov passivated mus rau ib puag ncig saline los ntsuas nws cov kev tiv thaiv corrosion thaum lub sijhawm.
High Humidity Test:Kawm ib feem rau cov av noo siab kom simulate lub ntiaj teb ib puag ncig raug.
Water Immersion Test:Ib feem yog immersed nyob rau hauv dej rau ib lub sij hawm teem, thiab nws tsis kam mus rusting yog pom.

Salt spray test chamber used for testing corrosion resistance of passivated parts

▲ Cov tshuaj tsuag tshuaj ntsev siv rau kev sim tshuaj tiv thaiv corrosion ntawm passivated qhov chaw

Ntxiv rau qhov no, kev txheeb xyuas lub zog yog qhov tseem ceeb rau qee yam kev siv, kom ntseeg tau tias cov hlau khaws nws cov qauv kev ncaj ncees tom qab passivation. Qhov no yog qhov tseem ceeb tshwj xeeb hauv kev lag luam uas qhov kev ua tau zoo ntawm cov hlau tseem ceeb raws li nws qhov kev tiv thaiv corrosion.

Ⅷ Cov Pitfalls hauv Passivation

Thaum passivation yog cov txheej txheem ncaj nraim, ntau yam teeb meem tuaj yeem tshwm sim:

Kev ntxuav tsis tiav:Yog tias qhov chaw tsis raug ntxuav kom zoo ua ntej passivation, cov kab mob tuaj yeem nyob twj ywm, ua rau tsis tiav lossis tsis sib xws.
Tsis yog Acid Concentration: Kev siv qhov tsis ncaj ncees lawm ntawm cov kua qaub tuaj yeem ua rau qis qis (tawm qee cov hlau tom qab) lossis dhau ntawm qhov chaw, ua rau cov khoom puas.
Kev Rinsing tsis txaus:Kev tsis ua kom zoo yaug qhov chaw tom qab kho cov kua qaub tuaj yeem tso cov seem uas yuav ua rau corrosion.

Example of incomplete passivation with areas of rust formation

▲ Piv txwv ntawm kev ua tsis tiav passivation nrog thaj tsam ntawm xeb tsim

Txhawm rau zam cov pitfalls no, ua tib zoo tswj cov txheej txheem tsis tu ncua thiab kev tshuaj xyuas zoo ntawm cov khoom ua ntej thiab tom qab passivation yog tsim nyog.

Ⅸ Kev tuav thiab tu cov khoom Passivated

Txawm tias tom qab ua tiav passivation, cov khoom yuav tsum tau ua thiab khaws cia kom zoo kom lawv cov kev tiv thaiv corrosion:

Kev kho kom raug:Siv cov cuab yeej uas tsis yog abrasive thiab hnav cov hnab looj tes tiv thaiv kev kis kab mob ntawm qhov chaw passivated.
Tswj Cia ib puag ncig:Khaws cov khoom passivated nyob rau hauv qhov chaw qhuav, huv si kom tsis txhob raug ya raws, plua plav, lossis lwm yam kab mob.
Tsis tu ncua:Kev tshuaj xyuas ib ntus thiab kev ntxuav ntawm cov khoom passivated yuav tsum tau ua kom muaj kev tiv thaiv mus ntev, tshwj xeeb tshaj yog nyob rau hauv ib puag ncig hnyav.

Proper handling and storage of passivated stainless steel components

▲ Kev tuav thiab khaws cia ntawm cov khoom siv stainless hlau passivated

Ⅹ Daim ntawv thov ntawm Passivation

Passivation yog siv nyob rau hauv ntau yam kev lag luam vim nws lub peev xwm los txhim kho cov kav ntev thiab ntev ntawm cov khoom hlau:

Cov cuab yeej kho mob:Xyuas kom meej tias cov cuab yeej phais thiab cov khoom cog yog cov resistant rau corrosion, uas yog ib qho tseem ceeb rau cov neeg mob kev nyab xeeb.
Aerospace:Tiv thaiv cov khoom siv dav hlau los ntawm qhov chaw hnyav uas lawv raug, suav nrog qhov sib txawv ntawm qhov kub thiab txias.
Kev ua zaub mov:Ua kom huv huv thiab tiv thaiv corrosion ntawm cov khoom siv los tiv thaiv cov khoom noj, tiv thaiv kev sib kis.

Passivated medical devices and aerospace components

▲ Passivated cov cuab yeej kho mob thiab cov khoom siv dav hlau

Hauv txhua qhov kev lag luam no, passivation tsis yog ib qho kev tiv thaiv xwb tab sis yog qhov tsim nyog kom ua tau raws li kev cai nruj.

Ⅺ Yav Tom Ntej Trends hauv Passivation

Lub neej yav tom ntej ntawm passivation zoo li yuav pom kev nce qib uas tau tsav los ntawm qhov xav tau kom muaj txiaj ntsig zoo dua thiab muaj txiaj ntsig zoo:

Emerging Technologies:Cov txheej txheem tshiab ntawm passivation tau raug tshawb fawb, suav nrog cov txheej txheem plasma-based thiab kev kho laser, uas tuaj yeem muab ntau qhov tseeb thiab ib puag ncig zoo rau lwm txoj hauv kev tshuaj lom neeg passivation.
Sustainability Considerations:Raws li kev lag luam txav mus rau kev coj noj coj ua ntsuab, kev siv citric acid dhau nitric acid tau dhau los ua ntau dua vim nws qhov cuam tshuam ib puag ncig qis. Tsis tas li ntawd, kaw-loop systems rau cov kua qaub da dej yog tsim los txo cov khoom pov tseg.

Ⅻ Cov lus xaus

Passivated stainless steel surfaces with a focus on their enhanced durability and longevity

▲ Passivated stainless hlau nto nrog rau kev tsom mus rau lawv cov kev txhim kho kom ruaj khov thiab ntev

Passivation tseem yog lub hauv paus txheej txheem hauv kev kho cov hlau tsis muaj hlau thiab lwm yam hlau, ua kom lawv cov kav ntev thiab tsis kam tiv thaiv corrosion hauv ntau daim ntawv thov. Los ntawm kev nkag siab txog kev tshawb fawb tom qab passivation, ua raws li cov txheej txheem tsim nyog, thiab ua raws li cov qauv kev lag luam, cov tuam ntxhab tuaj yeem txuas lub neej thiab kev ntseeg siab ntawm lawv cov khoom. Raws li cov thev naus laus zis tau nce mus, kev nkag mus yuav txuas ntxiv mus ntxiv, muab kev tiv thaiv ntau dua thiab kev ruaj khov nyob rau xyoo tom ntej.