Koj tau txheeb xyuas tias cov khoom tau tsim raws li qhov kev qhia tshwj xeeb. Tam sim no xyuas kom tseeb tias koj ua cov kauj ruam los tiv thaiv cov khoom no hauv ib puag ncig uas koj cov neeg siv khoom xav tau. #base
Kev siv tshuaj passivation tseem yog ib kauj ruam tseem ceeb hauv kev ua kom qhov kev tiv thaiv xeb ntawm cov khoom thiab cov khoom sib dhos ua los ntawm cov hlau tsis xeb zoo tshaj plaws. Qhov no tuaj yeem ua qhov sib txawv ntawm kev ua tau zoo thiab kev ua tsis tiav ua ntej lub sijhawm. Kev siv tshuaj passivation tsis raug tuaj yeem ua rau xeb.
Kev siv passivation yog ib txoj kev siv tom qab ua tiav uas ua kom cov hlau stainless hlau uas ua los ntawm cov khoom siv no tsis xeb heev. Qhov no tsis yog kev tshem cov av nplaum lossis pleev xim.
Tsis muaj kev pom zoo txog qhov tseeb ntawm txoj kev ua haujlwm ntawm passivation. Tab sis nws paub tseeb tias muaj ib daim zaj duab xis oxide tiv thaiv rau ntawm qhov chaw ntawm cov hlau tsis xeb uas tau passivated. Daim zaj duab xis tsis pom no tau hais tias nyias heev, tsawg dua 0.0000001 nti tuab, uas yog li ntawm 1/100,000th ntawm qhov tuab ntawm tib neeg cov plaub hau!
Ib feem ntawm cov hlau tsis xeb uas huv si, tshiab, txhuam, lossis pickled yuav tau txais cov zaj duab xis oxide no vim muaj cov pa oxygen hauv huab cua. Nyob rau hauv qhov xwm txheej zoo tshaj plaws, cov txheej oxide tiv thaiv no npog tag nrho cov nto ntawm qhov khoom.
Txawm li cas los xij, hauv kev xyaum ua, cov khoom tsis huv xws li cov av hauv Hoobkas lossis cov hlau me me los ntawm cov cuab yeej txiav tuaj yeem nkag mus rau ntawm qhov chaw ntawm cov khoom siv hlau tsis xeb thaum lub sijhawm ua haujlwm. Yog tias tsis tshem tawm, cov khoom txawv teb chaws no yuav txo qhov ua tau zoo ntawm cov zaj duab xis tiv thaiv qub.
Thaum lub sijhawm ua haujlwm, cov hlau dawb tuaj yeem raug tshem tawm ntawm lub cuab yeej thiab xa mus rau saum npoo ntawm cov hlau tsis xeb. Qee zaum, ib txheej nyias ntawm xeb yuav tshwm sim ntawm qhov. Qhov tseeb, qhov no yog qhov xeb ntawm cov hlau cuab yeej, tsis yog cov hlau hauv paus. Qee zaum cov kab nrib pleb los ntawm cov hlau me me uas nkag los ntawm cov cuab yeej txiav lossis lawv cov khoom xeb tuaj yeem ua rau qhov chaw ntawd nws tus kheej lwj.
Ib yam li ntawd, cov khoom me me ntawm cov av ferrous metallurgical tuaj yeem lo rau ntawm qhov chaw ntawm qhov khoom. Txawm hais tias cov hlau yuav zoo li ci ntsa iab thaum nws tiav lawm, tom qab raug cua, cov khoom me me uas tsis pom ntawm cov hlau dawb tuaj yeem ua rau xeb ntawm qhov chaw.
Cov sulfides uas raug tso tawm kuj tuaj yeem ua teeb meem. Lawv yog ua los ntawm kev ntxiv sulfur rau hauv cov hlau tsis xeb kom txhim kho kev siv tshuab. Sulfides ua rau lub peev xwm ntawm cov hlau sib xyaw ua rau cov chips thaum lub sijhawm siv tshuab, uas tuaj yeem tshem tawm tag nrho ntawm cov cuab yeej txiav. Yog tias cov khoom tsis raug passivated kom zoo, sulfides tuaj yeem dhau los ua qhov pib rau kev xeb ntawm cov khoom lag luam.
Hauv ob qho tib si, passivation yog qhov yuav tsum tau ua kom cov hlau tsis xeb tsis xeb zoo tshaj plaws. Nws tshem tawm cov khoom tsis huv ntawm qhov chaw xws li cov hlau me me thiab cov hlau me me hauv cov cuab yeej txiav uas tuaj yeem ua xeb lossis ua qhov pib rau xeb. Passivation kuj tshem tawm cov sulphides uas pom ntawm qhov chaw ntawm cov hlau tsis xeb qhib.
Cov txheej txheem ob kauj ruam muab qhov zoo tshaj plaws tiv taus xeb: 1. Kev ntxuav, cov txheej txheem tseem ceeb, tab sis qee zaum tsis quav ntsej 2. Da dej kua qaub lossis passivation.
Kev ntxuav yuav tsum yog qhov tseem ceeb tshaj plaws. Cov chaw yuav tsum tau ntxuav kom huv si ntawm cov roj, cov dej txias lossis lwm yam khib nyiab kom ntseeg tau tias muaj kev tiv thaiv xeb zoo tshaj plaws. Cov khib nyiab ua haujlwm lossis lwm yam av hauv Hoobkas tuaj yeem so maj mam tawm ntawm qhov chaw. Cov tshuaj ntxuav roj lossis cov tshuaj ntxuav lag luam tuaj yeem siv los tshem tawm cov roj ua haujlwm lossis cov dej txias. Tej yam txawv teb chaws xws li cov pa roj thermal oxides yuav tsum tau tshem tawm los ntawm cov txheej txheem xws li kev sib tsoo lossis kev sib xyaw.
Qee zaum tus neeg ua haujlwm tshuab yuav hla dhau qhov kev ntxuav yooj yim, ntseeg yuam kev tias kev ntxuav thiab passivation yuav tshwm sim tib lub sijhawm, tsuas yog muab qhov chaw uas muaj roj tso rau hauv lub dab dej acid. Nws yuav tsis tshwm sim. Ntawm qhov tod tes, cov roj uas muaj kuab paug yuav ua rau cov kua qaub ua rau cov pa npuas. Cov npuas no sib sau ua ke rau ntawm qhov chaw ua haujlwm thiab cuam tshuam rau passivation.
Qhov phem dua, kev ua qias tuaj ntawm cov tshuaj passivation, uas qee zaum muaj cov chlorides ntau, tuaj yeem ua rau "flash". Tsis zoo li kev tsim cov zaj duab xis oxide uas xav tau nrog lub ntsej muag ci ntsa iab, huv si, tiv taus corrosion, flash etching tuaj yeem ua rau muaj kev etching hnyav lossis blackening ntawm qhov chaw - qhov kev puas tsuaj ntawm qhov chaw uas passivation yog tsim los ua kom zoo dua.
Cov khoom siv hlau tsis xeb Martensitic [sib nqus, tiv taus xeb nruab nrab, lub zog tso zis txog li 280 txhiab psi (1930 MPa)] raug quenched ntawm qhov kub siab thiab tom qab ntawd tempered kom muab qhov nyuaj thiab cov khoom siv kho tshuab xav tau. Cov hlau nplaum uas tau los ntawm nag lossis daus (uas muaj lub zog zoo dua thiab tiv taus xeb dua li cov qib martensitic) tuaj yeem kho nrog cov tshuaj, ua ib feem ntawm tshuab, laus ntawm qhov kub qis dua, thiab tom qab ntawd ua tiav.
Hauv qhov no, qhov khoom yuav tsum tau ntxuav kom huv si nrog cov tshuaj degreaser lossis cov tshuaj ntxuav ua ntej kho cua sov kom tshem tawm cov kua txiav. Txwv tsis pub, cov dej txias uas tseem tshuav ntawm qhov khoom yuav ua rau muaj kev oxidation ntau dhau. Qhov xwm txheej no tuaj yeem ua rau muaj qhov dents rau ntawm cov khoom me me tom qab tshem tawm cov av nrog cov kua qaub lossis cov txheej txheem abrasive. Yog tias cov dej txias tseem tshuav rau ntawm cov khoom ci ntsa iab, xws li hauv lub cub tawg lossis hauv huab cua tiv thaiv, qhov chaw carburization tuaj yeem tshwm sim, ua rau poob ntawm kev tiv thaiv corrosion.
Tom qab ntxuav kom huv si, cov khoom ua los ntawm cov hlau tsis xeb tuaj yeem muab tso rau hauv lub dab dej uas muaj kua qaub passivating acid. Peb txoj kev no siv tau - passivation nrog nitric acid, passivation nrog nitric acid nrog sodium dichromate, thiab passivation nrog citric acid. Yuav siv txoj kev twg nyob ntawm qib ntawm cov hlau tsis xeb thiab cov qauv lees txais tshwj xeeb.
Cov qib nickel chromium uas tiv taus xeb ntau dua tuaj yeem raug passivated hauv 20% (v/v) nitric acid da dej (Daim Duab 1). Raws li pom hauv lub rooj, cov hlau tsis xeb uas tsis tiv taus ntau dua tuaj yeem raug passivated los ntawm kev ntxiv sodium dichromate rau hauv da dej ntawm nitric acid kom ua rau cov tshuaj oxidizing ntau dua thiab tuaj yeem tsim cov zaj duab xis passivating ntawm qhov chaw hlau. Lwm txoj kev xaiv rau kev hloov nitric acid nrog sodium chromate yog kom nce qhov concentration ntawm nitric acid mus rau 50% los ntawm ntim. Ob qho tib si ntxiv sodium dichromate thiab qhov concentration siab dua ntawm nitric acid txo qhov yuav tshwm sim ntawm qhov tsis xav tau flash.
Cov txheej txheem passivation rau cov hlau tsis xeb uas siv tau (kuj qhia hauv daim duab 1) txawv me ntsis ntawm cov txheej txheem rau cov hlau tsis xeb uas siv tsis tau. Qhov no yog vim tias thaum lub sijhawm passivation hauv lub dab dej nitric acid qee lossis tag nrho cov sulfides uas muaj sulfur uas siv tau raug tshem tawm, tsim cov teeb meem me me ntawm qhov chaw ntawm cov khoom ua haujlwm.
Txawm tias ntxuav nrog dej zoo li qub los kuj tseem yuav muaj cov kua qaub seem nyob rau hauv cov kev sib txuas no tom qab passivation. Cov kua qaub no yuav tawm tsam qhov chaw ntawm qhov khoom yog tias tsis neutralize lossis tshem tawm.
Rau kev ua kom cov hlau stainless hlau yooj yim siv, Carpenter tau tsim cov txheej txheem AAA (Alkaline-Acid-Alkaline), uas ua rau cov kua qaub seem tsis muaj zog. Txoj kev ua kom cov kua qaub no ua tiav hauv tsawg dua 2 teev. Nov yog cov txheej txheem ib kauj ruam zuj zus:
Tom qab tshem cov roj tawm, muab cov khoom tso rau hauv 5% sodium hydroxide kua ntawm 160°F txog 180°F (71°C txog 82°C) li 30 feeb. Tom qab ntawd yaug cov khoom kom huv si hauv dej. Tom qab ntawd muab cov khoom tso rau hauv 20% (v/v) nitric acid kua uas muaj 3 oz/gal (22 g/l) sodium dichromate li 30 feeb ntawm 120°F txog 140°F (49°C) txog 60°C.) Tom qab tshem cov khoom tawm ntawm lub dab da dej, yaug nrog dej, tom qab ntawd muab tso rau hauv sodium hydroxide kua rau 30 feeb. Yaug cov khoom dua nrog dej thiab ziab, ua tiav txoj kev AAA.
Kev siv citric acid passivation tab tom nrov zuj zus nrog cov chaw tsim khoom uas xav kom tsis txhob siv cov mineral acids lossis cov tshuaj uas muaj sodium dichromate, nrog rau cov teeb meem pov tseg thiab kev txhawj xeeb txog kev nyab xeeb ntxiv uas cuam tshuam nrog lawv siv. Citric acid suav tias yog tus phooj ywg ib puag ncig hauv txhua yam.
Txawm hais tias kev siv citric acid passivation muaj txiaj ntsig zoo rau ib puag ncig, cov khw muag khoom uas tau ua tiav nrog kev siv inorganic acid passivation thiab tsis muaj kev txhawj xeeb txog kev nyab xeeb yuav xav nyob twj ywm. Yog tias cov neeg siv no muaj lub khw huv si, cov khoom siv zoo thiab huv si, cov dej txias tsis muaj cov hlau hauv Hoobkas, thiab cov txheej txheem ua tau zoo, tej zaum yuav tsis tas yuav hloov pauv tiag tiag.
Kev siv citric acid da dej passivation tau pom tias muaj txiaj ntsig zoo rau ntau hom stainless hlau, suav nrog ntau qib ntawm stainless hlau, raws li pom hauv Daim Duab 2. Rau kev yooj yim, Daim Duab 2. 1 suav nrog txoj kev ib txwm muaj ntawm passivation nrog nitric acid. Nco ntsoov tias cov qauv nitric acid qub tau qhia ua feem pua ​​​​​​los ntawm ntim, thaum cov citric acid tshiab tau qhia ua feem pua ​​​​​​los ntawm pawg. Nws yog ib qho tseem ceeb uas yuav tsum nco ntsoov tias thaum ua cov txheej txheem no, kev sib npaug zoo ntawm lub sijhawm ntub dej, qhov kub thiab txias da dej, thiab kev sib xyaw yog qhov tseem ceeb kom tsis txhob muaj "flashing" piav qhia saum toj no.
Kev ua kom tsis muaj zog (passivation) sib txawv nyob ntawm cov ntsiab lus chromium thiab cov yam ntxwv ntawm kev ua txhua yam. Saib cov kab rau Txheej Txheem 1 lossis Txheej Txheem 2. Raws li pom hauv Daim Duab 3, Txheej Txheem 1 muaj tsawg dua cov kauj ruam dua Txheej Txheem 2.
Cov kev kuaj hauv chav kuaj tau qhia tias cov txheej txheem citric acid passivation yooj yim dua rau "ua kom npau" dua li cov txheej txheem nitric acid. Cov yam tseem ceeb uas ua rau muaj qhov kev tawm tsam no suav nrog qhov kub thiab txias hauv da dej siab dhau, lub sijhawm ntub dej ntev dhau, thiab kev ua qias tuaj hauv da dej. Cov khoom lag luam uas muaj citric acid uas muaj cov tshuaj tiv thaiv xeb thiab lwm yam khoom ntxiv xws li cov tshuaj ntub dej muaj nyob hauv khw thiab tau tshaj tawm tias txo qhov kev pheej hmoo ntawm "corrosion ceev ceev".
Qhov kev xaiv kawg ntawm txoj kev passivation yuav nyob ntawm cov qauv kev lees txais uas tus neeg siv khoom teeb tsa. Saib ASTM A967 kom paub meej ntxiv. Nws tuaj yeem nkag mus rau ntawm www.astm.org.
Feem ntau cov kev ntsuam xyuas raug ua los ntsuam xyuas qhov chaw ntawm cov khoom uas tau passivated. Lo lus nug uas yuav tsum tau teb yog "Puas yog passivation tshem tawm cov hlau dawb thiab ua kom zoo dua qhov kev tiv thaiv corrosion ntawm cov alloys rau kev txiav tsis siv neeg?"
Nws yog ib qho tseem ceeb uas txoj kev xeem phim cov chav kawm uas raug soj ntsuam. Cov kev xeem uas nruj dhau yuav tsis dhau cov ntaub ntawv zoo kiag li, thaum cov kev xeem uas tsis muaj zog dhau yuav dhau cov ntu tsis txaus siab.
Cov hlau tsis xeb 400 series PH thiab yooj yim-machining raug soj ntsuam zoo tshaj plaws hauv lub chamber uas muaj peev xwm tswj tau 100% av noo (qauv ntub) rau 24 teev ntawm 95 ° F (35 ° C). Qhov seem hla feem ntau yog qhov tseem ceeb tshaj plaws, tshwj xeeb tshaj yog rau cov qib txiav dawb. Ib qho laj thawj rau qhov no yog tias cov sulphide raug rub mus rau hauv qhov kev taw qhia ntawm lub tshuab hla qhov chaw no.
Cov chaw tseem ceeb yuav tsum tau muab tso rau saum toj, tab sis ntawm lub kaum ntawm 15 txog 20 degrees ntawm ntsug, kom tso cai rau cov dej noo poob. Cov khoom siv passivated kom zoo yuav tsis xeb, txawm hais tias tej zaum yuav muaj cov pob me me tshwm rau ntawm nws.
Cov qib Austenitic stainless hlau kuj tseem tuaj yeem soj ntsuam los ntawm kev kuaj dej noo. Hauv qhov kev xeem no, cov tee dej yuav tsum muaj nyob rau ntawm qhov chaw ntawm cov qauv, qhia tias muaj hlau dawb los ntawm qhov muaj xeb.
Cov txheej txheem passivation rau cov hlau tsis siv neeg thiab tes uas feem ntau siv hauv cov kua citric lossis nitric acid xav tau cov txheej txheem sib txawv. Hauv daim duab 3 hauv qab no qhia cov ntsiab lus ntawm kev xaiv cov txheej txheem.
(a) Kho qhov pH nrog sodium hydroxide. (b) Saib daim duab 3(c) Na2Cr2O7 yog 3 oz/gal (22 g/L) sodium dichromate hauv 20% nitric acid. Lwm txoj hauv kev rau qhov sib tov no yog 50% nitric acid tsis muaj sodium dichromate.
Ib txoj hauv kev sai dua yog siv ASTM A380, Standard Practice for Cleaning, Descaling, and Passivation of Stainless Steel Parts, Equipment, and Systems. Qhov kev sim no suav nrog kev so qhov chaw nrog cov kua tooj liab sulfate/sulfuric acid, ua kom nws ntub rau 6 feeb, thiab saib cov plating tooj liab. Xwb, qhov chaw tuaj yeem raug muab tso rau hauv cov kua rau 6 feeb. Yog tias hlau yaj, cov plating tooj liab tshwm sim. Qhov kev sim no tsis siv rau ntawm cov nto ntawm cov khoom ua zaub mov. Tsis tas li ntawd, nws yuav tsum tsis txhob siv rau ntawm 400 series martensitic steels lossis cov hlau chromium ferritic qis vim tias cov txiaj ntsig tsis tseeb yuav tshwm sim.
Keeb kwm los, qhov kev sim tshuaj tsuag ntsev 5% ntawm 95 ° F (35 ° C) kuj tau siv los ntsuam xyuas cov qauv passivated. Qhov kev sim no nruj dhau rau qee cov cultivars thiab feem ntau tsis tas yuav tsum tau lees paub qhov ua tau zoo ntawm passivation.
Tsis txhob siv cov tshuaj chloride ntau dhau, uas yuav ua rau muaj kev phom sij. Siv tsuas yog cov dej zoo uas muaj tsawg dua 50 feem ib lab (ppm) chloride thaum twg ua tau. Cov dej kais feem ntau txaus, thiab qee zaum nws tuaj yeem tiv taus txog li ntau pua feem ib lab ntawm cov tshuaj chloride.
Nws yog ib qho tseem ceeb uas yuav tsum tau hloov lub dab da dej tsis tu ncua kom tsis txhob poob qhov muaj peev xwm passivation, uas tuaj yeem ua rau xob laim thiab ua rau cov khoom puas tsuaj. Lub dab da dej yuav tsum tau tswj kom sov li qub, vim tias qhov kub tsis tswj tau tuaj yeem ua rau xeb hauv zos.
Nws yog ib qho tseem ceeb uas yuav tsum ua raws li lub sijhawm hloov pauv cov tshuaj tshwj xeeb thaum lub sijhawm tsim khoom loj kom txo qhov ua tau ntawm kev ua qias tuaj. Ib qho qauv tswj tau siv los sim qhov ua tau zoo ntawm lub dab da dej. Yog tias cov qauv tau raug tawm tsam, nws yog lub sijhawm los hloov lub dab da dej.
Thov nco ntsoov tias qee lub tshuab tsuas yog tsim cov hlau tsis xeb xwb; siv tib yam dej txias uas nyiam rau kev txiav hlau tsis xeb kom tsis txhob siv lwm yam hlau.
Cov khoom seem ntawm DO khib nyiab raug tshuab sib cais kom tsis txhob muaj hlau sib chwv. Qhov no tseem ceeb heev rau kev siv cov hlau tsis xeb dawb, vim tias yuav tsum muaj cov tshuaj passivation thiab cov tshuaj ntxuav kom yooj yim los ntxuav cov khoom sulfide corrosion thiab tiv thaiv kom tsis txhob muaj cov kua qaub.
Tsis txhob siv cov khoom siv hlau tsis xeb uas tau carburized lossis nitrided passivate. Qhov kev tiv thaiv corrosion ntawm cov khoom uas tau kho li no tuaj yeem txo qis kom txog thaum lawv tuaj yeem puas tsuaj hauv lub dab dej passivation.
Tsis txhob siv cov cuab yeej hlau hauv cov chaw ua haujlwm uas tsis huv heev. Siv cov cuab yeej carbide lossis ceramic los tiv thaiv cov hlau tawg.
Nco ntsoov tias xeb tuaj yeem tshwm sim hauv lub dab dej passivation yog tias qhov khoom tsis tau kho cua sov kom zoo. Cov qib Martensitic nrog cov pa roj carbon thiab chromium ntau yuav tsum tau ua kom tawv kom tiv taus xeb.
Feem ntau passivation yog ua tom qab tempering ntawm qhov kub uas tswj tau corrosion.
Tsis txhob tso tseg qhov concentration ntawm nitric acid hauv lub dab dej passivation. Yuav tsum tau kuaj xyuas tsis tu ncua siv cov txheej txheem titration yooj yim uas Carpenter tau hais. Tsis txhob passivate ntau tshaj ib lub stainless hlau ib zaug. Qhov no tiv thaiv kev tsis meej pem kim thiab tiv thaiv kev cuam tshuam galvanic.
Txog Cov Kws Sau Ntawv: Terry A. DeBold yog Tus Kws Tshwj Xeeb R&D ntawm Cov Hlau Stainless Alloys thiab James W. Martin yog Tus Kws Tshwj Xeeb Bar Metallurgy ntawm Carpenter Technology Corp.(Reading, Pennsylvania).
Nws yog npaum li cas? Kuv xav tau qhov chaw ntau npaum li cas? Kuv yuav ntsib teeb meem ib puag ncig li cas? Qhov kev kawm nyuaj npaum li cas? Anodizing yog dab tsi? Hauv qab no yog cov lus teb rau cov lus nug thawj zaug ntawm cov kws tshaj lij txog anodizing sab hauv.
Tau txais cov txiaj ntsig zoo thiab ruaj khov los ntawm cov txheej txheem sib tsoo tsis muaj qhov chaw nruab nrab yuav tsum muaj kev nkag siab yooj yim. Feem ntau ntawm cov teeb meem ntawm kev siv uas cuam tshuam nrog kev sib tsoo tsis muaj qhov chaw nruab nrab yog los ntawm kev tsis nkag siab txog cov hauv paus ntsiab lus. Tsab xov xwm no piav qhia vim li cas cov txheej txheem tsis muaj lub siab ua haujlwm thiab yuav siv nws li cas kom zoo tshaj plaws hauv koj lub chaw ua haujlwm.