Koj tau txheeb xyuas tias cov khoom yog tsim los rau specification.Tam sim no xyuas kom tseeb tias koj ua cov kauj ruam los tiv thaiv cov khoom no hauv ib puag ncig koj cov neeg siv khoom xav tau.#base
Passivation tseem yog ib kauj ruam tseem ceeb hauv kev ua kom muaj kev tiv thaiv corrosion ntawm cov khoom thiab cov khoom sib dhos ua los ntawm cov hlau tsis muaj steel.Qhov no tuaj yeem ua rau qhov sib txawv ntawm qhov ua tau zoo txaus siab thiab ua tsis tiav ntxov.Passivation tsis raug tuaj yeem ua rau corrosion.
Passivation yog cov txheej txheem tom qab tsim khoom uas ua rau kom muaj qhov zoo tshaj plaws corrosion tsis kam ntawm cov hlau tsis muaj hlau los ntawm cov khoom ua haujlwm.Qhov no tsis yog descaling los yog painting.
Tsis muaj kev pom zoo rau qhov tseeb mechanism uas passivation ua haujlwm.Tab sis nws paub tseeb tias muaj cov yeeb yaj kiab tiv thaiv oxide nyob rau saum npoo ntawm passivated stainless hlau.Cov yeeb yaj kiab tsis pom no tau hais tias nyias nyias, tsawg dua 0.0000001 nti tuab, uas yog kwv yees li 1/100,000th tuab ntawm tib neeg cov plaub hau!
Ib qho huv, tshiab tshiab, polished, los yog pickled stainless hlau ib feem yuav tau txais cov oxide zaj duab xis vim raug rau atmospheric oxygen.Nyob rau hauv cov xwm txheej zoo tagnrho, txheej tiv thaiv oxide no npog tag nrho cov chaw ntawm qhov chaw.
Hauv kev xyaum, txawm li cas los xij, cov kab mob xws li lub Hoobkas av lossis cov khoom hlau los ntawm cov cuab yeej txiav tuaj yeem nkag mus rau ntawm qhov chaw ntawm cov hlau tsis huv thaum ua haujlwm.Yog tias tsis muab tshem tawm, lub cev txawv teb chaws no tuaj yeem txo qhov ua tau zoo ntawm cov yeeb yaj kiab tiv thaiv thawj.
Thaum lub sij hawm machining, cov kab ntawm cov hlau dawb tuaj yeem raug tshem tawm ntawm lub cuab yeej thiab xa mus rau qhov chaw ntawm cov hlau tsis muaj steel workpiece.Qee zaum, txheej nyias ntawm xeb tuaj yeem tshwm rau ntawm qhov chaw.Qhov tseeb, qhov no yog qhov corrosion ntawm cov cuab yeej steel, tsis yog lub hauv paus hlau.Qee zaum cov kab nrib pleb los ntawm cov khoom siv hlau los ntawm cov cuab yeej txiav lossis lawv cov khoom siv corrosion tuaj yeem ua rau nws tus kheej.
Ib yam li ntawd, cov khoom me me ntawm ferrous metallurgical av tuaj yeem ua rau ntawm qhov chaw.Txawm hais tias cov hlau yuav zoo li ci ntsa iab hauv nws lub xeev tiav, tom qab raug huab cua, qhov pom tsis pom ntawm cov hlau dawb tuaj yeem ua rau xeb xeb.
Exposed sulfides kuj tuaj yeem ua teeb meem.Lawv yog tsim los ntawm kev ntxiv sulfur rau stainless hlau los txhim kho machinability.Sulfides nce lub peev xwm ntawm cov hlau los tsim cov chips thaum lub sij hawm machining, uas tuaj yeem raug tshem tawm tag nrho ntawm cov cuab yeej txiav.Yog hais tias qhov chaw tsis zoo passivated, sulfides tuaj yeem dhau los ua qhov chaw pib rau kev xeb ntawm cov khoom lag luam.
Nyob rau hauv ob qho tib si, passivation yuav tsum tau ua kom lub ntuj corrosion kuj ntawm stainless hlau.Nws tshem tawm cov kab mob saum npoo av xws li cov khoom hlau thiab cov khoom hlau hauv cov cuab yeej txiav uas tuaj yeem tsim xeb lossis ua qhov pib ntawm corrosion.Passivation kuj tshem tawm cov sulphides pom nyob rau saum npoo ntawm qhib txiav stainless hlau alloys.
Cov txheej txheem ob-kauj ruam muab qhov zoo tshaj plaws corrosion kuj: 1. Kev tu, cov txheej txheem tseem ceeb, tab sis qee zaum tsis quav ntsej 2. Acid da dej lossis passivation.
Kev ntxuav yuav tsum yog qhov tseem ceeb.Nto yuav tsum tau ntxuav kom huv si ntawm roj, coolant los yog lwm yam khib nyiab kom zoo corrosion kuj.Machining khib nyiab lossis lwm lub Hoobkas av tuaj yeem maj mam so tawm ntawm qhov.Kev lag luam degreasers lossis cov tshuaj ntxuav tuaj yeem siv los tshem tawm cov txheej txheem roj lossis cov khoom ua kom txias.Cov khoom txawv teb chaws xws li thermal oxides yuav tsum tau muab tshem tawm los ntawm txoj kev xws li kev sib tsoo los yog pickling.
Qee lub sij hawm tus neeg teb xov tooj tuaj yeem hla kev tu yooj yim, ua yuam kev ntseeg tias kev tu thiab kev ua kom lub cev yuav tshwm sim tib lub sijhawm, tsuas yog immersing cov roj hauv cov kua qaub da dej.Nws yuav tsis tshwm sim.Piv txwv li, cov roj uas tsis muaj paug reacts nrog cov kua qaub los tsim cov pa npuas.Cov npuas no sau rau ntawm qhov chaw ua haujlwm thiab cuam tshuam nrog passivation.
Tsis tas li ntawd, kev sib kis ntawm cov kev daws teeb meem passivation, uas qee zaum muaj cov tshuaj chlorides siab, tuaj yeem ua rau "flash".Nyob rau hauv sib piv rau qhov xav tau oxide zaj duab xis nrog ib tug ci iab, huv si, corrosion-resistant nto, flash etching yuav ua rau mob heev etching los yog blackening ntawm nto - ib tug deterioration nyob rau hauv qhov chaw uas passivation yog tsim los optimize.
Martensitic stainless hlau qhov chaw [magnetic, me ntsis corrosion resistant, yield zog txog li 280 txhiab psi (1930 MPa)] yog quenched ntawm qhov kub thiab txias thiab ces tempered los muab qhov xav tau hardness thiab txhua yam khoom.Cov nag lossis daus hardened alloys (uas muaj lub zog zoo dua thiab kev tiv thaiv corrosion ntau dua li qib martensitic) tuaj yeem kho tau, qee qhov tshuab, hnub nyoog qis dua, thiab tom qab ntawd tiav.
Nyob rau hauv cov ntaub ntawv no, ib feem yuav tsum tau muab ntxuav kom huv si nrog ib tug degreaser los yog ib tug huv si ua ntej kev kho cua sov kom tshem tawm tej kab ntawm tej kua.Txwv tsis pub, coolant seem ntawm qhov yuav ua rau oxidation ntau dhau.Cov kab mob no tuaj yeem ua rau cov dents los ntawm qhov me me tom qab descaling nrog cov kua qaub los yog abrasive txoj kev.Yog tias cov dej txias tso rau ntawm qhov ci ntsa iab, xws li hauv lub tshuab nqus tsev lossis hauv qhov chaw tiv thaiv, qhov chaw carburization tuaj yeem tshwm sim, ua rau poob ntawm corrosion kuj.
Tom qab ua kom huv si, cov hlau tsis muaj steel tuaj yeem muab tso rau hauv lub pas dej ua kua qaub.Ib qho ntawm peb txoj kev siv tau - passivation nrog nitric acid, passivation nrog nitric acid nrog sodium dichromate, thiab passivation nrog citric acid.Txoj kev siv twg yog nyob ntawm qib ntawm stainless hlau thiab cov txheej txheem kev lees paub.
Ntau cov corrosion resistant nickel chromium qib yuav passivated hauv 20% (v/v) nitric acid da dej (Daim duab 1).Raws li pom nyob rau hauv lub rooj, tsis tshua muaj resistant stainless steels yuav passivated los ntawm kev ntxiv sodium dichromate rau ib da dej ntawm nitric acid kom cov tshuaj ntau oxidizing thiab muaj peev xwm tsim ib tug passivating zaj duab xis ntawm cov hlau nto.Lwm qhov kev xaiv rau kev hloov nitric acid nrog sodium chromate yog kom cov concentration ntawm nitric acid mus rau 50% los ntawm ntim.Ob qho ntxiv ntawm sodium dichromate thiab siab dua ntawm nitric acid txo qhov tshwm sim ntawm qhov tsis xav tau flash.
Cov txheej txheem passivation rau machinable stainless hlau (tseem qhia hauv daim duab 1) yog qhov txawv me ntsis ntawm cov txheej txheem rau cov qib tsis-machinable stainless hlau.Qhov no yog vim hais tias thaum lub sij hawm passivation nyob rau hauv ib tug nitric acid da dej ib co los yog tag nrho cov machinable sulfur-muaj sulfides raug tshem tawm, tsim microscopic inhomogeneities nyob rau saum npoo ntawm workpiece.
Txawm tias ib txwm siv dej ntxhua zoo tuaj yeem tso cov kua qaub seem hauv cov kev tsis sib xws tom qab passivation.Cov kua qaub no yuav tawm tsam qhov chaw ntawm qhov chaw yog tias tsis nruab nrab lossis tshem tawm.
Rau kev ua haujlwm tau zoo ntawm cov tshuab stainless hlau yooj yim, Carpenter tau tsim cov txheej txheem AAA (Alkaline-Acid-Alkaline), uas neutralizes residual acid.Txoj kev passivation no tuaj yeem ua tiav hauv tsawg dua 2 teev.Ntawm no yog cov txheej txheem step-by-step:
Tom qab degreasing, soak qhov chaw hauv 5% sodium hydroxide tov ntawm 160 ° F txog 180 ° F (71 ° C txog 82 ° C) rau 30 feeb.Tom qab ntawd yaug qhov chaw kom huv si hauv dej.Tom qab ntawd muab tso rau hauv qhov chaw rau 30 feeb hauv 20% (v / v) nitric acid tov uas muaj 3 oz / gal (22 g / l) sodium dichromate ntawm 120 ° F txog 140 ° F (49 ° C) txog 60 ° C.) Tom qab tshem tawm ib feem ntawm lub da dej, yaug nws nrog dej, ces muab tso rau hauv cov tshuaj sodium hydroxide rau 30 feeb.Yaug ib feem ntxiv nrog dej thiab qhuav, ua tiav AAA txoj kev.
Citric acid passivation tau dhau los ua neeg nyiam nrog cov tuam txhab uas xav kom zam kev siv cov ntxhia acids lossis cov kev daws teeb meem uas muaj sodium dichromate, nrog rau cov teeb meem pov tseg thiab kev txhawj xeeb txog kev nyab xeeb ntxiv nrog rau lawv siv.Citric acid yog suav tias yog ib puag ncig tus phooj ywg nyob rau hauv tag nrho cov respects.
Thaum citric acid passivation muaj cov txiaj ntsig zoo ib puag ncig, cov khw muag khoom uas tau ua tiav nrog inorganic acid passivation thiab tsis muaj kev txhawj xeeb txog kev nyab xeeb yuav xav nyob hauv chav kawm.Yog tias cov neeg siv khoom no muaj lub khw muag khoom huv si, cov cuab yeej siv tau zoo thiab huv si, lub coolant tsis muaj lub Hoobkas ferrous deposits, thiab cov txheej txheem ua tau zoo, tej zaum yuav tsis muaj kev hloov pauv tiag tiag.
Citric acid da dej passivation tau pom tias muaj txiaj ntsig zoo rau ntau yam ntawm cov hlau tsis muaj steel, nrog rau ob peb qib ntawm stainless hlau, raws li qhia hauv daim duab 2. Rau kev yooj yim, Daim duab 2. 1 suav nrog cov txheej txheem ntawm passivation nrog nitric acid.Nco ntsoov tias cov laus nitric acid formulations qhia raws li feem pua ​​ntawm ntim, thaum tshiab citric acid concentrations yog qhia raws li feem pua ​​ntawm pawg.Nws yog ib qho tseem ceeb uas yuav tsum nco ntsoov tias thaum ua cov txheej txheem no, ua tib zoo sib npaug ntawm lub sij hawm ntub dej, qhov kub thiab txias yog qhov tseem ceeb kom tsis txhob "flashing" tau piav qhia saum toj no.
Passivation txawv nyob ntawm cov ntsiab lus chromium thiab cov yam ntxwv ntawm txhua yam.Daim ntawv ceeb toom cov kab rau txheej txheem 1 lossis txheej txheem 2. Raws li pom hauv daim duab 3, Txheej Txheem 1 muaj tsawg dua cov txheej txheem 2.
Cov kev kuaj sim tau pom tias cov txheej txheem citric acid passivation yog feem ntau "boiling" dua li cov txheej txheem nitric acid.Cov yam tseem ceeb uas ua rau muaj kev tawm tsam no suav nrog kev da dej kub dhau, lub sij hawm ntub dej ntev dhau, thiab da dej paug.Citric acid-raws li cov khoom uas muaj corrosion inhibitors thiab lwm yam additives xws li wetting agents muaj nyob rau hauv kev lag luam thiab tau tshaj tawm tias yuav txo tau "flash corrosion" susceptibility.
Qhov kev xaiv kawg ntawm txoj kev passivation yuav nyob ntawm seb qhov kev lees paub tau teev tseg los ntawm tus neeg siv khoom.Saib ASTM A967 kom paub meej.Nws tuaj yeem nkag mus rau ntawm www.astm.org.
Kev ntsuam xyuas feem ntau yog ua los ntsuas qhov chaw ntawm passivated qhov chaw.Cov lus nug yuav tsum tau teb yog "Puas passivation tshem tawm cov hlau dawb thiab optimize corrosion kuj ntawm alloys rau tsis siv neeg txiav?"
Nws yog ib qho tseem ceeb uas txoj kev xeem yuav tsum sib phim rau cov chav kawm uas raug ntsuas.Cov kev sim uas nruj dhau yuav tsis dhau cov ntaub ntawv zoo, thaum cov kev sim uas tsis muaj zog dhau yuav dhau qhov tsis txaus siab.
PH thiab yooj yim-machining 400 series stainless hlau yog qhov zoo tshaj plaws ntsuas nyob rau hauv lub chamber muaj peev xwm tswj 100% av noo (piv txwv ntub) rau 24 teev ntawm 95 ° F (35 ° C).Txoj kev 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 tau rub hauv lub tshuab kev taw qhia thoob plaws qhov chaw no.
Qhov chaw tseem ceeb yuav tsum tau muab tso rau sab saud, tab sis ntawm lub kaum sab xis ntawm 15 txog 20 degrees los ntawm ntsug, kom tso cai rau cov dej noo.Cov khoom siv passivated kom zoo yuav tsis xeb, txawm tias me me yuav tshwm sim ntawm nws.
Austenitic stainless hlau qib kuj tuaj yeem ntsuas los ntawm kev ntsuas dej noo.Hauv qhov kev sim no, cov tee dej yuav tsum muaj nyob rau saum npoo ntawm cov qauv, qhia tias cov hlau tsis muaj hlau los ntawm qhov muaj cov xeb.
Cov txheej txheem Passivation rau feem ntau siv tsis siv neeg thiab phau ntawv stainless hlau stainless hauv citric los yog nitric acid daws yuav tsum muaj txheej txheem sib txawv.Ntawm daim duab.3 hauv qab no qhia meej txog cov txheej txheem xaiv.
(a) Kho cov pH nrog sodium hydroxide.(b) See fig.3 (c) Na2Cr2O7 yog 3 oz / gal (22 g / L) sodium dichromate hauv 20% nitric acid.Ib qho ntxiv rau qhov sib tov no yog 50% nitric acid tsis muaj sodium dichromate.
Txoj hauv kev nrawm dua yog siv ASTM A380, Txuj Ci Kev Ua Haujlwm rau Kev Tu, Descaling, thiab Passivation ntawm Stainless Hlau Qhov Chaw, Khoom Siv, thiab Tshuab.Qhov kev sim no suav nrog so qhov chaw nrog tooj liab sulfate / sulfuric acid tov, ua kom nws ntub rau 6 feeb, thiab saib xyuas cov tooj liab plating.Xwb, ib feem tuaj yeem muab tso rau hauv cov tshuaj rau 6 feeb.Yog tias hlau yaj, tooj liab plating tshwm sim.Qhov kev sim no tsis siv rau qhov chaw ntawm cov khoom noj khoom haus.Tsis tas li ntawd, nws yuav tsum tsis txhob siv rau ntawm 400 series martensitic steels los yog tsawg chromium ferritic steels raws li cov txiaj ntsig tsis zoo yuav tshwm sim.
Keeb kwm, 5% ntsev tshuaj tsuag ntawm 95 ° F (35 ° C) kuj tau siv los ntsuas 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 tuaj yeem ua rau muaj kev phom sij txaus ntshai.Siv cov dej zoo uas muaj tsawg dua 50 feem ntawm ib lab (ppm) chloride thaum twg los tau.Cov dej kais dej feem ntau yog txaus, thiab qee zaum nws tuaj yeem tiv taus txog li ob peb puas feem ntawm cov chlorides.
Nws yog ib qho tseem ceeb uas yuav tsum tau hloov lub da dej tsis tu ncua kom tsis txhob poob lub peev xwm passivation, uas tuaj yeem ua rau xob laim thiab puas rau qhov chaw.Lub da dej yuav tsum tau khaws cia ntawm qhov kub thiab txias, vim tias qhov ntsuas kub tsis tau tswj tau tuaj yeem ua rau muaj kev cuam tshuam hauv cheeb tsam.
Nws yog ib qho tseem ceeb uas yuav tsum tau ua raws li lub sijhawm hloov kho tshwj xeeb thaum lub sijhawm ua haujlwm loj kom txo tau qhov muaj paug.Cov qauv tswj tau siv los ntsuas qhov ua tau zoo ntawm cov da dej.Yog tias tus qauv tau raug tawm tsam, nws yog lub sijhawm los hloov lub da dej.
Thov nco ntsoov tias qee lub tshuab tsuas yog tsim cov hlau tsis muaj steel;siv tib lub tshuab ua kom txias txias rau kev txiav stainless hlau kom tshem tawm tag nrho lwm cov hlau.
DO khib qhov chaw yog machined cais kom tsis txhob muaj hlau mus rau hlau.Qhov no yog qhov tseem ceeb tshwj xeeb tshaj yog rau kev ua haujlwm dawb ntawm cov hlau tsis muaj steel, vim tias yooj yim-flowing passivation thiab flushing kev daws teeb meem yuav tsum tau diffuse sulfide corrosion khoom thiab tiv thaiv kev tsim cov kua qaub hauv hnab ris.
Tsis txhob passivate carburized los yog nitrided stainless hlau qhov chaw.Qhov kev tiv thaiv corrosion ntawm qhov chaw kho nyob rau hauv txoj kev no tuaj yeem raug txo kom zoo li qhov uas lawv tuaj yeem raug puas tsuaj nyob rau hauv passivation da dej.
Tsis txhob siv cov cuab yeej hlau ferrous hauv kev cob qhia uas tsis huv tshwj xeeb.Cov chips hlau tuaj yeem zam tau los ntawm kev siv cov khoom siv carbide lossis ceramic.
Nco ntsoov tias corrosion tuaj yeem tshwm sim hauv lub da dej passivation yog tias qhov tsis tau kho cua sov kom zoo.Martensitic qib nrog siab carbon thiab chromium cov ntsiab lus yuav tsum tau hardened rau corrosion kuj.
Passivation feem ntau yog ua tom qab tempering tom qab ntawm qhov kub thiab txias uas tswj kev tiv thaiv corrosion.
Tsis txhob hnov ​​​​qab txog qhov concentration ntawm nitric acid nyob rau hauv passivation da dej.Kev kuaj xyuas ib ntus yuav tsum tau ua los ntawm kev siv cov txheej txheem titration yooj yim qhia los ntawm Carpenter.Tsis txhob passivate ntau tshaj ib qho stainless hlau ib zaug.Qhov no tiv thaiv tus nqi tsis meej pem thiab tiv thaiv cov tshuaj tiv thaiv galvanic.
Hais txog Cov Kws Sau Ntawv: Terry A. DeBold yog Stainless Hlau Alloys R & D Tus Kws Tshaj Lij thiab James W. Martin yog Bar Metallurgy Specialist ntawm Carpenter Technology Corp.(Nyeem, Pennsylvania).
Nws npaum li cas?Kuv xav tau qhov chaw ntau npaum li cas?Kuv yuav ntsib teeb meem dab tsi?Txoj kev kawm nkhaus npaum li cas?Dab tsi yog anodizing?Hauv qab no yog cov lus teb rau cov lus nug thawj zaug ntawm tus tswv txog anodizing sab hauv.
Tau txais kev sib raug zoo, cov txiaj ntsig zoo los ntawm cov txheej txheem kev sib tsoo tsis sib haum yuav tsum muaj kev nkag siab yooj yim.Feem ntau ntawm cov teeb meem ntawm daim ntawv thov cuam tshuam nrog kev sib tsoo tsis muaj qhov nruab nrab tshwm sim los ntawm kev tsis nkag siab txog cov hauv paus ntsiab lus.Kab lus no piav qhia vim li cas cov txheej txheem tsis nco qab ua haujlwm thiab siv nws li cas kom zoo tshaj hauv koj lub rooj cob qhia.