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Kusuntha kwa magetsi (passivation) kukadali gawo lofunika kwambiri pakukulitsa kukana kwa dzimbiri kwa zida ndi makonzedwe opangidwa ndi chitsulo chosapanga dzimbiri. Izi zingapangitse kusiyana pakati pa kugwira ntchito bwino ndi kulephera msanga. Kusuntha kolakwika kungayambitse dzimbiri.
Kusuntha ndi njira yopangira zinthu zomwe zimagwiritsidwa ntchito popanga zinthu zomwe zimapangitsa kuti zitsulo zosapanga dzimbiri zisawonongeke. Izi sizikutanthauza kuchotsa ma scaling kapena kupaka utoto.
Palibe mgwirizano pa njira yeniyeni yomwe passivation imagwirira ntchito. Koma zimadziwika bwino kuti pali filimu yoteteza oxide pamwamba pa chitsulo chosapanga dzimbiri chopanda kanthu. Filimu yosaoneka iyi imanenedwa kuti ndi yopyapyala kwambiri, yochepera mainchesi 0.0000001, yomwe ndi pafupifupi 1/100,000th ya makulidwe a tsitsi la munthu!
Chitsulo chosapanga dzimbiri choyera, chopangidwa mwatsopano, chopukutidwa, kapena choviikidwa mu chitsulo chosapanga dzimbiri chidzatenga filimu ya oxide iyi yokha chifukwa cha mpweya wa mlengalenga. Mu nyengo yabwino, gawo loteteza la oxide ili limaphimba malo onse a gawolo.
Komabe, m'zochita, zinthu zodetsa monga dothi la fakitale kapena tinthu tachitsulo kuchokera ku zida zodulira zimatha kufika pamwamba pa zitsulo zosapanga dzimbiri panthawi yokonza. Ngati sizichotsedwa, zinthu zakunjazi zitha kuchepetsa mphamvu ya filimu yoteteza yoyambirira.
Pa nthawi yopangira makina, zitsulo zotsalira zachitsulo zimatha kuchotsedwa pa chidacho ndikusamutsira pamwamba pa chogwirira ntchito chachitsulo chosapanga dzimbiri. Nthawi zina, dzimbiri lochepa lingawonekere pachogwiriracho. Ndipotu, uku ndi kuwononga kwa chitsulo cha chida, osati chitsulo choyambira. Nthawi zina ming'alu yochokera ku tinthu tachitsulo tomwe timayikidwa kuchokera ku zida zodulira kapena zinthu zawo zowononga zimatha kuwononga gawolo lokha.
Mofananamo, tinthu tating'onoting'ono ta dothi lachitsulo la ferrous tingamatirire pamwamba pa gawolo. Ngakhale kuti chitsulocho chingawoneke chowala bwino, pambuyo poti chalowa mumlengalenga, tinthu tosaoneka tachitsulo chomasuka tingayambitse dzimbiri pamwamba pake.
Ma sulfide owonekera angakhalenso vuto. Amapangidwa powonjezera sulfure ku chitsulo chosapanga dzimbiri kuti makinawo azigwira bwino ntchito. Ma sulfide amawonjezera mphamvu ya alloy kupanga tchipisi panthawi yopangira, zomwe zimatha kuchotsedwa kwathunthu pa chida chodulira. Ngati zigawo sizinagwiritsidwe ntchito bwino, ma sulfide amatha kukhala poyambira kuwonongeka kwa zinthu zamafakitale pamwamba.
Muzochitika zonsezi, kusinthasintha kwa mpweya kumafunika kuti chitsulo chosapanga dzimbiri chikhale cholimba kwambiri. Kumachotsa zinthu zodetsa pamwamba monga tinthu tachitsulo ndi tinthu tachitsulo mu zida zodulira zomwe zingapangitse dzimbiri kapena kukhala poyambira kusinthasintha kwa mpweya. Kusinthasintha kwa mpweya kumachotsanso ma sulfide omwe amapezeka pamwamba pa zitsulo zosapanga dzimbiri zodulidwa.
Njira ya magawo awiri imapereka kukana dzimbiri bwino: 1. Kuyeretsa, njira yaikulu, koma nthawi zina imanyalanyazidwa 2. Kusamba ndi asidi kapena kungokhala chete.
Kuyeretsa kuyenera kukhala chinthu chofunika kwambiri nthawi zonse. Malo ayenera kutsukidwa bwino mafuta, choziziritsira kapena zinyalala zina kuti zitsimikizire kuti sizikukhudzidwa ndi dzimbiri. Zinyalala za makina kapena dothi lina la fakitale zitha kuchotsedwa pang'onopang'ono pamalopo. Zotsukira mafuta kapena zotsukira zamalonda zingagwiritsidwe ntchito kuchotsa mafuta opangidwa kapena zoziziritsira. Zinthu zakunja monga thermal oxides zingafunike kuchotsedwa pogwiritsa ntchito njira monga kugaya kapena kusakaniza.
Nthawi zina wogwiritsa ntchito makina angasiye kuyeretsa koyambira, poganiza molakwika kuti kuyeretsa ndi kusuntha zidzachitika nthawi imodzi, kungomiza gawo lopaka mafuta mu bafa la asidi. Sizichitika. Mosiyana ndi zimenezi, mafuta oipitsidwa amakumana ndi asidi kuti apange thovu la mpweya. Thovu zimenezi zimasonkhana pamwamba pa ntchito ndikusokoneza kusuntha.
Choyipa kwambiri n'chakuti, kuipitsidwa kwa njira zotulutsira mpweya, zomwe nthawi zina zimakhala ndi ma chloride ambiri, kungayambitse "kung'anima". Mosiyana ndi kupanga filimu ya oxide yomwe mukufuna yokhala ndi pamwamba pake yowala, yoyera, komanso yosagwira dzimbiri, kung'anima kwa kuwala kungayambitse kung'anima kwambiri kapena kuda kwambiri pamwamba pake—kuwonongeka kwa pamwamba komwe kung'anima kwapangidwa kuti kukhale koyenera.
Zitsulo zosapanga dzimbiri za Martensitic [zokhala ndi maginito, zosagwira dzimbiri pang'ono, zogwira ntchito mpaka 280 thousand psi (1930 MPa)] zimazimitsidwa kutentha kwambiri kenako zimatenthedwa kuti zipereke kuuma komwe mukufuna komanso mphamvu zamakina. Ma alloy olimba a mvula (omwe ali ndi mphamvu yabwino komanso osagwirizana ndi dzimbiri kuposa ma grade a martensitic) amatha kukonzedwa, kukonzedwa pang'ono, kusungidwa kutentha kochepa, kenako nkumalizidwa.
Pankhaniyi, gawolo liyenera kutsukidwa bwino ndi chotsukira mafuta kapena chotsukira musanatenthetse kuti muchotse zotsalira za madzi odulidwa. Kupanda kutero, choziziritsira chomwe chatsala pa gawolo chingayambitse okosijeni wambiri. Vutoli lingayambitse mawanga pazigawo zing'onozing'ono mutachotsa chiŵerengero pogwiritsa ntchito njira ya asidi kapena yokwapula. Ngati choziziritsiracho chasiyidwa pazigawo zowala zolimba, monga mu uvuni wa vacuum kapena mumlengalenga woteteza, kutentha kwa pamwamba kungachitike, zomwe zimapangitsa kuti dzimbiri lisathe.
Pambuyo poyeretsa bwino, zitsulo zosapanga dzimbiri zimatha kumizidwa mu bafa la asidi wosasunthika. Njira iliyonse mwa zitatuzi ingagwiritsidwe ntchito - kusuntha ndi nitric acid, kusuntha ndi nitric acid ndi sodium dichromate, ndi kusuntha ndi citric acid. Njira yogwiritsira ntchito imadalira mtundu wa chitsulo chosapanga dzimbiri ndi njira zomwe zatchulidwa.
Ma chromium ambiri a nickel osagwira dzimbiri amatha kusinthidwa kukhala opanda dzimbiri mu bafa ya nitric acid ya 20% (v/v) (Chithunzi 1). Monga momwe zasonyezedwera patebulo, zitsulo zosapanga dzimbiri zosagwira dzimbiri zitha kusinthidwa kukhala opanda dzimbiri powonjezera sodium dichromate mu bafa ya nitric acid kuti yankho likhale lokoma kwambiri komanso lotha kupanga filimu yosungunuka pamwamba pa chitsulo. Njira ina yosinthira nitric acid ndi sodium chromate ndikuwonjezera kuchuluka kwa nitric acid kufika pa 50% ndi voliyumu. Kuonjezera sodium dichromate ndi kuchuluka kwa nitric acid kumachepetsa mwayi wa kuwala kosafunikira.
Njira yogwiritsira ntchito passivation ya zitsulo zosapanga dzimbiri zogwiritsidwa ntchito pamakina (yomwe yawonetsedwanso pa Chithunzi 1) ndi yosiyana pang'ono ndi njira yogwiritsira ntchito magiredi a zitsulo zosapanga dzimbiri zosapanga dzimbiri. Izi zili choncho chifukwa panthawi yogwiritsira ntchito passivation mu bafa ya nitric acid, ma sulfide ena kapena onse ogwiritsidwa ntchito pamakina okhala ndi sulfure amachotsedwa, zomwe zimapangitsa kuti pakhale kusafanana kwa microscopic pamwamba pa workpiece.
Ngakhale kutsuka m'madzi kogwira ntchito bwino nthawi zambiri kumatha kusiya asidi wotsala m'malo osagwirizana awa atatha kupumula. Asidi uyu amaukira pamwamba pa gawolo ngati sakuchotsedwa kapena kuchotsedwa.
Kuti chitsulo chosapanga dzimbiri chosavuta kugwiritsa ntchito chizimitse mpweya bwino, Carpenter wapanga njira ya AAA (Alkaline-Acid-Alkaline), yomwe imaletsa asidi wotsala. Njira iyi yochepetsera mpweya imatha kumalizidwa pasanathe maola awiri. Nayi njira ya sitepe ndi sitepe:
Mukachotsa mafuta, zilowerereni mu 5% sodium hydroxide solution pa 160°F mpaka 180°F (71°C mpaka 82°C) kwa mphindi 30. Kenako tsukani bwino zigawozo m'madzi. Kenako ikani gawolo kwa mphindi 30 mu 20% (v/v) nitric acid solution yokhala ndi 3 oz/gal (22 g/l) sodium dichromate pa 120°F mpaka 140°F (49°C) mpaka 60°C. ) Mukachotsa gawolo m'bafa, litsukeni ndi madzi, kenako livikeni mu sodium hydroxide solution kwa mphindi 30. Tsukaninso gawolo ndi madzi ndikulipukuta, ndikumaliza njira ya AAA.
Kuletsa kugwiritsa ntchito asidi wa citric kukukhala kofala kwambiri kwa opanga omwe akufuna kupewa kugwiritsa ntchito ma asidi a mchere kapena mankhwala okhala ndi sodium dichromate, komanso mavuto otaya zinthu komanso nkhawa zowonjezeka zokhudzana ndi chitetezo zomwe zimagwiritsidwa ntchito. Asidi wa citric amaonedwa kuti ndi woteteza chilengedwe m'mbali zonse.
Ngakhale kuti kuletsa asidi a citric kumapereka ubwino wosangalatsa pa chilengedwe, masitolo omwe apambana ndi kuletsa asidi osapangidwa m'chilengedwe ndipo alibe nkhawa zachitetezo angafune kupitirizabe. Ngati ogwiritsa ntchito awa ali ndi sitolo yoyera, zida zili bwino komanso zoyera, choziziritsira chilibe zitsulo za fakitale, ndipo njirayi ikupereka zotsatira zabwino, sipangakhale chifukwa chenicheni chosinthira.
Kusamutsa madzi m'bafa la citric acid kwapezeka kuti n'kothandiza pa zitsulo zosiyanasiyana zosapanga dzimbiri, kuphatikizapo mitundu ingapo ya zitsulo zosapanga dzimbiri, monga momwe zasonyezedwera pa Chithunzi 2. Kuti zikhale zosavuta, Chithunzi 2. 1 chikuphatikizapo njira yachikhalidwe yotsamutsa madzi pogwiritsa ntchito nitric acid. Dziwani kuti mapangidwe akale a nitric acid amafotokozedwa ngati maperesenti ndi voliyumu, pomwe kuchuluka kwa citric acid kwatsopano kumafotokozedwa ngati maperesenti ndi kulemera. Ndikofunikira kudziwa kuti pochita njirazi, nthawi yonyowa bwino, kutentha kwa bafa, ndi kuchuluka ndikofunikira kwambiri kuti tipewe "kung'anima" komwe kwafotokozedwa pamwambapa.
Kusinthasintha kwa madzi kumasiyana malinga ndi kuchuluka kwa chromium ndi mawonekedwe a ntchito ya mtundu uliwonse. Onani mizati ya Njira 1 kapena Njira 2. Monga momwe zasonyezedwera pa Chithunzi 3, Njira 1 ili ndi masitepe ochepa kuposa Njira 2.
Mayeso a labotale asonyeza kuti njira yotulutsira asidi ya citric imatentha kwambiri kuposa njira ya nitric acid. Zinthu zomwe zimayambitsa izi ndi monga kutentha kwambiri m'bafa, nthawi yayitali yonyowa, komanso kuipitsidwa ndi bafa. Zinthu zopangidwa ndi citric acid zomwe zili ndi zoletsa dzimbiri ndi zina zowonjezera monga zonyowetsa zimapezeka m'masitolo ndipo akuti zimachepetsa chiopsezo cha "kuphulika kwa kuwala".
Kusankha komaliza kwa njira yosinthira deta kudzadalira njira zovomerezeka zomwe kasitomala wakhazikitsa. Onani ASTM A967 kuti mudziwe zambiri. Itha kupezeka pa www.astm.org.
Mayeso nthawi zambiri amachitika kuti awone pamwamba pa zinthu zopanda ntchito. Funso loti liyankhe ndi lakuti, "Kodi kuletsa kugwiritsa ntchito zinthu zopanda ntchito kumachotsa chitsulo chopanda ntchito ndikuwonjezera kukana kwa dzimbiri kwa zinthu zopangira zinthu kuti zidulidwe zokha?"
Ndikofunikira kuti njira yoyesera igwirizane ndi kalasi yomwe ikuyesedwa. Mayeso okhwima kwambiri sadzapambana zipangizo zabwino kwambiri, pomwe mayeso ofooka kwambiri adzapambana zigawo zosakwanira.
PH ndi zitsulo zosapanga dzimbiri za 400 series zosavuta kupanga zimayesedwa bwino m'chipinda chomwe chingathe kusunga chinyezi cha 100% (chitsanzo chonyowa) kwa maola 24 pa 95°F (35°C). Gawo lopingasa nthawi zambiri ndilo malo ofunikira kwambiri, makamaka pamitengo yodula momasuka. Chifukwa chimodzi cha izi ndichakuti sulfide imakokedwa mbali ya makina kudutsa pamwamba apa.
Malo ofunikira ayenera kuyikidwa mmwamba, koma pa ngodya ya madigiri 15 mpaka 20 kuchokera pa malo oimirira, kuti chinyezi chisatayike. Zinthu zosagwira ntchito bwino sizingapange dzimbiri, ngakhale kuti madontho ang'onoang'ono angawonekere pamenepo.
Magiredi a chitsulo chosapanga dzimbiri cha Austenitic angayesedwenso poyesa chinyezi. Mu mayesowa, madontho a madzi ayenera kukhala pamwamba pa chitsanzocho, kusonyeza kuti chitsulocho chilibe dzimbiri.
Njira zoyendetsera zitsulo zosapanga dzimbiri zokhazikika komanso zopangidwa ndi manja zomwe zimagwiritsidwa ntchito nthawi zambiri mu njira za citric kapena nitric acid zimafuna njira zosiyanasiyana. Pa chithunzi 3 pansipa pali tsatanetsatane wa njira yosankha.
(a) Sinthani pH ndi sodium hydroxide. (b) Onani chithunzi 3(c) Na2Cr2O7 ndi 3 oz/gal (22 g/L) sodium dichromate mu 20% nitric acid. Njira ina yosinthira izi ndi 50% nitric acid yopanda sodium dichromate.
Njira yachangu ndiyo kugwiritsa ntchito ASTM A380, Standard Practice for Cleaning, Descaling, and Passivation of Stainless Steel Parts, Equipment, and Systems. Kuyesaku kumaphatikizapo kupukuta gawolo ndi yankho la copper sulfate/sulfuric acid, kulisunga lonyowa kwa mphindi 6, ndikuyang'ana plating ya copper. Kapenanso, gawolo likhoza kumizidwa mu yankholo kwa mphindi 6. Ngati chitsulo chasungunuka, plating ya copper imachitika. Kuyesaku sikukugwira ntchito pamwamba pa zigawo zopangira chakudya. Komanso, sikuyenera kugwiritsidwa ntchito pa zitsulo 400 za martensitic kapena zitsulo zochepa za chromium ferritic chifukwa zotsatira zabodza zitha kuchitika.
M'mbuyomu, mayeso a 5% a mchere pa 95°F (35°C) adagwiritsidwanso ntchito poyesa zitsanzo zosagwiritsidwa ntchito. Mayesowa ndi ovuta kwambiri kwa mitundu ina ya zomera ndipo nthawi zambiri safunika kutsimikizira kuti kusagwiritsidwa ntchito bwino kwa zomera sikuli koyenera.
Pewani kugwiritsa ntchito ma chloride ochulukirapo, omwe angayambitse kuphulika koopsa. Gwiritsani ntchito madzi abwino okha okhala ndi chloride yosakwana magawo 50 pa miliyoni imodzi (ppm) nthawi iliyonse yomwe ingatheke. Madzi apampopi nthawi zambiri amakhala okwanira, ndipo nthawi zina amatha kupirira mpaka magawo mazana angapo pa miliyoni imodzi ya ma chloride.
Ndikofunikira kusintha bafa nthawi zonse kuti musataye mphamvu ya kusuntha kwa madzi, zomwe zingayambitse kugunda kwa mphezi ndi kuwonongeka kwa ziwalo zina. Bafa liyenera kusungidwa kutentha koyenera, chifukwa kutentha kosalamulirika kungayambitse dzimbiri pamalopo.
Ndikofunikira kutsatira ndondomeko yeniyeni yosinthira yankho panthawi yopanga zinthu zambiri kuti muchepetse kuipitsidwa. Chitsanzo chowongolera chinagwiritsidwa ntchito kuyesa momwe bafa limagwirira ntchito. Ngati chitsanzocho chawukiridwa, ndi nthawi yoti musinthe bafa.
Dziwani kuti makina ena amapanga chitsulo chosapanga dzimbiri chokha; gwiritsani ntchito choziziritsira chomwe mumakonda podula chitsulo chosapanga dzimbiri kupatula zitsulo zina zonse.
Zigawo za DO rack zimapangidwa padera kuti chitsulo chisakhudze chitsulo. Izi ndizofunikira kwambiri pakupanga chitsulo chosapanga dzimbiri momasuka, chifukwa njira zosavuta zotulutsira madzi ndi kutsuka zimayenera kufalitsa zinthu zowononga za sulfide ndikuletsa mapangidwe a matumba a asidi.
Musamasule zitsulo zosapanga dzimbiri zopangidwa ndi carburized kapena nitride. Kukana dzimbiri kwa ziwalo zomwe zakonzedwa motere kungachepe kwambiri moti zingawonongeke mu bafa losambira.
Musagwiritse ntchito zida zachitsulo zachitsulo m'malo ogwirira ntchito omwe si oyera kwenikweni. Zidutswa zachitsulo zitha kupewedwa pogwiritsa ntchito zida za carbide kapena ceramic.
Dziwani kuti dzimbiri likhoza kuchitika m'bafa losagwiritsa ntchito mpweya ngati gawolo silinakonzedwe bwino kutentha. Magulu a Martensitic okhala ndi mpweya wambiri ndi chromium ayenera kulimba kuti asawonongeke ndi dzimbiri.
Kusinthasintha kwa kutentha nthawi zambiri kumachitika pambuyo potenthetsa kutentha komwe kumasunga kukana dzimbiri.
Musanyalanyaze kuchuluka kwa nitric acid mu bafa yosambira. Kuyang'ana nthawi ndi nthawi kuyenera kuchitika pogwiritsa ntchito njira yosavuta yoyezera titration yomwe Carpenter adapereka. Musagwiritse ntchito zitsulo zosapanga dzimbiri zoposa chimodzi panthawi imodzi. Izi zimaletsa chisokonezo chokwera mtengo komanso kupewa galvanic reactions.
Zokhudza Olemba: Terry A. DeBold ndi Katswiri wa Kafukufuku ndi Kupititsa Patsogolo kwa Zitsulo Zosapanga Chitsulo ndipo James W. Martin ndi Katswiri wa Zachitsulo ku Carpenter Technology Corp.(Reading, Pennsylvania).
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