Mwatsimikiza kuti ziwalozo zakonzedwa motsatira zomwe zanenedwa. Tsopano, onetsetsani kuti mwatenga njira zotetezera ziwalozi m'mikhalidwe yomwe makasitomala anu amayembekezera. #zoyambira
Kupatsirana kwa zinthu zosapanga dzimbiri (passivation) kudakali gawo lofunika kwambiri pakukulitsa kukana kwa dzimbiri kwa zinthu zosapanga dzimbiri zopangidwa ndi makina ndi zinthu zina. Kungapange kusiyana pakati pa kugwira ntchito bwino ndi kulephera msanga. Kupatsirana kwa zinthu mosagwira ntchito bwino kungayambitse dzimbiri.
Kutulutsa utoto ndi njira yopangira utoto yomwe imapangitsa kuti zitsulo zosapanga dzimbiri zisamavutike ndi dzimbiri. Si njira yochotsera utoto, komanso si njira yopaka utoto.
Palibe mgwirizano womveka bwino pa momwe kusuntha kwa tsitsi kumagwirira ntchito. Koma n'zosakayikitsa kuti pali filimu yoteteza ya oxide pamwamba pa chitsulo chosapanga dzimbiri chopanda madzi. Filimu yosaoneka iyi imaganiziridwa kuti ndi yopyapyala kwambiri, yochepera mainchesi 0.000000, pafupifupi 1/100,000th ya makulidwe a tsitsi la munthu!
Gawo loyera, lopangidwa mwatsopano, lopukutidwa kapena loviikidwa mu chitsulo chosapanga dzimbiri lidzatenga filimu ya oxide iyi yokha chifukwa cha mpweya woipa womwe umapezeka mumlengalenga. Munthawi yabwino, gawo loteteza la oxide ili limaphimba malo onse a gawolo.
Komabe, m'zochita, zinthu zodetsa monga dothi logulitsidwa kapena tinthu tachitsulo kuchokera ku zida zodulira zimatha kusamutsira pamwamba pa zitsulo zosapanga dzimbiri panthawi yopangira. Ngati sizichotsedwa, zinthu zakunjazi zitha kuchepetsa mphamvu ya filimu yoteteza yoyambirira.
Pa nthawi yokonza, chitsulo chocheperako chimatha kuwononga chidacho ndikuchiyika pamwamba pa chogwirira ntchito chachitsulo chosapanga dzimbiri. Nthawi zina, dzimbiri lochepa lingawonekere pachogwiriracho. Izi kwenikweni ndi dzimbiri la chitsulocho ndi chidacho, osati chitsulo choyambira. Nthawi zina, ming'alu ya tinthu tachitsulo tomwe timayikidwa kuchokera ku zida zodulira kapena zinthu zawo zowononga zingayambitse kuwonongeka kwa gawolo lokha.
Mofananamo, tinthu tating'onoting'ono ta dothi la ferrous shop tingamatirire pamwamba pa gawolo. Ngakhale kuti chitsulo chingawoneke chowala mu makinawo, tinthu tating'onoting'ono tosaoneka ta chitsulo chomasuka tingayambitse dzimbiri pamwamba pake.
Ma sulfide owonekera akhozanso kukhala vuto. Amachokera pakuwonjezera sulfure ku chitsulo chosapanga dzimbiri kuti makina azigwira bwino ntchito. Ma sulfide amawonjezera mphamvu ya alloy yopangira tchipisi panthawi yopangira, zomwe zimatha kuchotsedwa kwathunthu pa chida chodulira. Pokhapokha ngati zigawo zake sizikusinthidwa bwino, ma sulfide amatha kukhala poyambira kuwonongeka kwa pamwamba pa zinthu zopangidwa.
Muzochitika zonsezi, kusinthasintha kwa mpweya kumafunika kuti chitsulo chosapanga dzimbiri chikhale cholimba kwambiri. Kumachotsa zinthu zodetsa pamwamba, monga tinthu ta dothi la ferrous shop ndi tinthu tachitsulo mu zida zodulira, zomwe zingapangitse dzimbiri kapena kukhala poyambira kuzizira. Kusinthasintha kwa mpweya kumachotsanso ma sulfide omwe amapezeka pamwamba pa zitsulo zosapanga dzimbiri zodula zokha.
Njira ya magawo awiri imapereka chitetezo chabwino kwambiri ku dzimbiri: 1. Kuyeretsa, njira yosavuta koma nthawi zina imaiwalika; 2. Kusamba ndi asidi kapena kuchiza kuzizira.
Kuyeretsa kuyenera kukhala chinthu chofunika kwambiri nthawi zonse. Malo ayenera kutsukidwa bwino mafuta, choziziritsira kapena zinyalala zina za m'sitolo kuti asamavutike ndi dzimbiri. Zinyalala za makina kapena zinyalala zina za m'sitolo zitha kuchotsedwa mosamala kuchokera ku chinthucho. Zotsukira kapena zotsukira zamalonda zingagwiritsidwe ntchito kuchotsa mafuta opangira kapena zoziziritsira. Zinthu zakunja monga ma thermal oxides zingafunike kuchotsedwa pogwiritsa ntchito njira monga kugaya kapena kusakaniza.
Nthawi zina wogwiritsa ntchito makina angalephere kuyeretsa koyambira, poganiza molakwika kuti kuyeretsa ndi kusuntha zinthu zidzachitika nthawi imodzi pongoviika gawo lodzaza ndi mafuta mu bafa la asidi. Izi sizingachitike. Mosiyana ndi zimenezi, mafuta oipitsidwa amakumana ndi asidi kuti apange thovu la mpweya. Thovu zimenezi zimasonkhana pamwamba pa ntchito ndikusokoneza kusuntha zinthu.
Choyipa kwambiri n'chakuti, kuipitsidwa kwa njira zotulutsira mpweya, zomwe nthawi zina zimakhala ndi ma chloride ambiri, kungayambitse "kuwala." Mosiyana ndi kupeza filimu ya oxide yomwe mukufuna yokhala ndi malo owala, oyera, komanso osapsa ndi dzimbiri, kuwotcha kwa kuwala kungayambitse kuwonongeka kwakukulu kapena kwamdima - pamwamba pake komwe kuzizirako kumapangidwira kuti kukhale koyenera.
Zigawo zopangidwa ndi chitsulo chosapanga dzimbiri cha martensitic [cholimba, cholimba pang'ono ku dzimbiri, chimapereka mphamvu mpaka pafupifupi 280 ksi (1930 MPa)] zimalimbikitsidwa kutentha kwambiri kenako zimafewetsedwa kuti zitsimikizire kuuma komwe mukufuna komanso mphamvu zamakina. Ma alloy olimba a mvula, omwe ali ndi mphamvu zabwino komanso kukana dzimbiri kuposa ma alloy a martensitic, amatha kukonzedwa, kukonzedwa pang'ono, kusungidwa kutentha kochepa, kenako nkumalizidwa.
Pankhaniyi, gawolo liyenera kutsukidwa bwino ndi chotsukira mafuta kapena chotsukira kuti muchotse zotsalira za madzi odulidwa musanagwiritse ntchito kutentha. Apo ayi, madzi odulidwa omwe atsala pa gawolo angayambitse okosijeni wambiri. Vutoli likhoza kupangitsa kuti magawo osakula apindike pambuyo poti sikelo yachotsedwa pogwiritsa ntchito njira ya asidi kapena yokwapula. Ngati madzi odulidwa aloledwa kukhalabe pa magawo owala olimba, monga mu uvuni wa vacuum kapena mlengalenga woteteza, kusungunuka kwa pamwamba kungachitike, zomwe zimapangitsa kuti kukana dzimbiri kutayike.
Pambuyo poyeretsa bwino, zigawo zachitsulo chosapanga dzimbiri zimatha kumizidwa mu bafa la asidi wosasunthika. Njira iliyonse mwa zitatuzi ingagwiritsidwe ntchito - nitric acid passivation, nitric acid yokhala ndi sodium dichromate passivation, ndi citric acid passivation. Njira yogwiritsira ntchito imadalira mtundu wa chitsulo chosapanga dzimbiri ndi njira zovomerezeka zomwe zatchulidwa.
Mitundu yambiri ya chrome-nickel yosagonjetsedwa ndi dzimbiri ikhoza kusinthidwa kukhala yopanda dzimbiri mu bafa ya nitric acid ya 20% (v/v) (Chithunzi 1). Monga momwe tawonetsera patebulo, chitsulo chosapanga dzimbiri chosalimba kwambiri chikhoza kusinthidwa kukhala yopanda dzimbiri powonjezera sodium dichromate ku bafa ya nitric acid, zomwe zimapangitsa kuti yankho likhale losungunuka kwambiri komanso lotha kupanga filimu yopanda madzi 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 flash yosafunikira.
Njira yogwiritsira ntchito zitsulo zosapanga dzimbiri zopanga zokha (zomwe zawonetsedwanso pa Chithunzi 1) ndi yosiyana pang'ono ndi ya zitsulo zosapanga dzimbiri zopanga zokha zopanda mphamvu. Izi zili choncho chifukwa panthawi yogwiritsira ntchito zitsulo zosapanga dzimbiri mu bafa ya nitric acid, ma sulfide ena kapena onse okhala ndi sulfure amachotsedwa, zomwe zimapangitsa kuti pakhale kusiyana kwa microscopic pamwamba pa gawo lopangidwa.
Ngakhale kutsuka m'madzi kogwira mtima kungasiye asidi wotsala m'malo osagwirizana awa atatha kupumula. Asidi uyu adzaukira pamwamba pa gawolo pokhapokha ngati silikuchotsedwa kapena kuchotsedwa.
Kuti chitsulo chosapanga dzimbiri chizigwira ntchito mosavuta, Carpenter wapanga njira ya AAA (Alkali-Acid-Alkali), yomwe imaletsa asidi wotsala. Njira iyi yochepetsera kupanikizika imatha kumalizidwa pasanathe maola awiri. Nayi njira yotsatizana:
Mukachotsa mafuta, zilowerereni mu yankho la 5% sodium hydroxide 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 yankho la 20% (v/v) nitric acid 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 yankho la sodium hydroxide kwa mphindi zina 30. Tsukani gawolo kachiwiri ndi madzi ndipo liume, ndikumaliza njira ya AAA.
Kuletsa kugwiritsa ntchito asidi wa citric kukuchulukirachulukira kwa opanga omwe akufuna kupewa kugwiritsa ntchito ma asidi a mchere kapena mankhwala okhala ndi sodium dichromate, komanso mavuto otaya zinthu komanso nkhawa zazikulu zokhudzana ndi chitetezo chogwiritsidwa ntchito. Asidi wa citric amaonedwa kuti ndi woteteza chilengedwe m'njira iliyonse.
Ngakhale kuti kuletsa kugwiritsa ntchito citric acid kumapereka ubwino wosangalatsa pa chilengedwe, masitolo omwe apambana ndi kuletsa kugwiritsa ntchito inorganic acid ndipo alibe nkhawa zachitetezo angafune kupitirizabe kugwiritsa ntchito. Ngati ogwiritsa ntchito awa ali ndi malo ogulitsira oyeretsa, zida zosamalidwa bwino komanso zoyera, choziziritsira chopanda chitsulo m'sitolo, komanso njira yomwe imabweretsa zotsatira zabwino, sipangakhale chifukwa chenicheni chosinthira.
Kutulutsa mpweya mu bafa ya citric acid kwapezeka kuti n'kothandiza pazitsulo zambiri zosapanga dzimbiri, kuphatikizapo mitundu ingapo ya zitsulo zosapanga dzimbiri, monga momwe zasonyezedwera pa Chithunzi 2. Kuti zikhale zosavuta, njira yachikhalidwe yotulutsira mpweya mu Chithunzi 1 ikuphatikizidwa. Dziwani kuti mapangidwe akale a nitric acid amafotokozedwa mu kuchuluka kwa voliyumu, pomwe kuchuluka kwatsopano kwa citric acid kumafotokozedwa mu kulemera kwa peresenti. Ndikofunikira kudziwa kuti pochita njira izi, kulinganiza mosamala nthawi yonyowa, kutentha kwa bafa ndi kuchuluka kwa madzi ndikofunikira kuti tipewe "kung'anima" komwe kwafotokozedwa kale.
Mankhwala oletsa kusuntha amasiyana malinga ndi kuchuluka kwa chromium ndi mawonekedwe a makina a kalasi iliyonse. Onani mizati yomwe ikuwonetsa Njira 1 kapena Njira 2. Monga momwe zasonyezedwera pa Chithunzi 3, Njira 1 ikuphatikizapo masitepe ochepa kuposa Njira 2.
Mayeso a labotale asonyeza kuti njira yotulutsira asidi ya citric imakhala yosavuta "kung'anima" kuposa njira ya nitric acid. Zinthu zomwe zimayambitsa izi ndi monga kutentha kwambiri m'bafa, nthawi yayitali yonyowa, komanso kuipitsidwa ndi bafa. Zinthu za citric acid zomwe zili ndi zoletsa dzimbiri ndi zina zowonjezera monga zonyowetsa zimapezeka m'masitolo ndipo zanenedwa kuti zimachepetsa chiopsezo cha "kung'anima".
Kusankha komaliza kwa njira yosinthira deta kudzadalira njira zovomerezeka zomwe kasitomala wapereka. Onani ASTM A967 kuti mudziwe zambiri. Itha kupezeka pa www.astm.org.
Mayeso nthawi zambiri amachitidwa kuti awone pamwamba pa ziwalo zomwe sizinagwiritsidwe ntchito. Funso loti liyankhe ndi lakuti, "Kodi kusinthasintha kumachotsa chitsulo chopanda ntchito ndikuwonjezera kukana dzimbiri kwa zinthu zomwe sizingadulidwe?"
Ndikofunikira kuti njira yoyesera igwirizane ndi giredi yomwe ikuyesedwa. Mayeso okhwima kwambiri adzalephera bwino kwambiri, pomwe mayeso otayirira kwambiri adzapambana magawo osakwanira.
Kuuma kwa precipitation ya 400 series ndi zitsulo zosapanga dzimbiri zopangidwa ndi free-machine zimayesedwa bwino mu kabati yomwe imatha kusunga chinyezi cha 100% (chitsanzo chonyowa) kwa maola 24 pa 95°F (35°C). Gawo lopingasa nthawi zambiri ndilo malo ofunikira kwambiri, makamaka pa ma free-cutting grades. Chifukwa chimodzi cha izi ndichakuti sulfide imatambasulidwa mbali ya makina, ndikudutsa pamwamba pake.
Malo ofunikira ayenera kuyikidwa mmwamba, koma pa madigiri 15 mpaka 20 kuchokera pamwamba kuti chinyezi chisatayike. Zinthu zosagwiritsidwa ntchito bwino sizingapange dzimbiri, ngakhale zingasonyeze utoto pang'ono.
Magiredi a chitsulo chosapanga dzimbiri cha Austenitic amathanso kuyesedwa pogwiritsa ntchito mayeso a chinyezi. Akayesedwa, madontho amadzi ayenera kukhala pamwamba pa chitsanzo, kusonyeza chitsulo chopanda kanthu chifukwa cha dzimbiri lililonse.
Njira zodulira zitsulo zosapanga dzimbiri zomwe zimagwiritsidwa ntchito nthawi zambiri monga kudula momasuka komanso zopanda kudula momasuka mu njira za citric kapena nitric acid zimafuna njira zosiyanasiyana. Chithunzi 3 pansipa chikuwonetsa tsatanetsatane wa njira yosankha.
(a) Sinthani pH ndi sodium hydroxide.(b) Onani Chithunzi 3 (c) Na2Cr2O7 ikuyimira 3 oz/galoni (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 yankho mu 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'anira kuti lipake mkuwa. M'malo mwake, gawolo likhoza kumizidwa mu yankholo kwa mphindi 6. Ngati chitsulo chasungunuka, mkuwa umachitika. Kuyesaku sikukugwira ntchito pamwamba pa zigawo zopangira chakudya. Komanso, sikuyenera kugwiritsidwa ntchito pa zitsulo 400 za martensitic kapena low chromium ferritic chifukwa zotsatira zabodza zitha kuchitika.
M'mbuyomu, mayeso a 5% a mchere pa 95°F (35°C) adagwiritsidwanso ntchito poyesa zitsanzo zopanda mpweya. Mayesowa ndi ovuta kwambiri pa magiredi ena ndipo nthawi zambiri safunika kutsimikizira kuti kuletsa mpweya kumagwira ntchito.
Pewani kugwiritsa ntchito ma chloride ochulukirapo, omwe angayambitse kuukira kwadzidzidzi koopsa. Ngati n'kotheka, gwiritsani ntchito madzi abwino okha okhala ndi chloride yosakwana magawo 50 pa miliyoni (ppm). Madzi apampopi nthawi zambiri amakhala okwanira ndipo nthawi zina amatha kupirira chloride yokwana mazana angapo a ppm.
Ndikofunikira kusintha bafa nthawi zonse kuti musataye mphamvu ya kugwedezeka kwa madzi, zomwe zingayambitse kugunda kwa mphezi ndi kuwonongeka kwa ziwalo. Bafa liyenera kusungidwa kutentha koyenera, chifukwa kutentha komwe kumatuluka kungayambitse dzimbiri pamalopo.
Ndikofunikira kusunga 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 bafalo lisinthidwe.
Chonde tchulani kuti makina ena amapanga chitsulo chosapanga dzimbiri chokha; gwiritsani ntchito choziziritsira chomwe mumakonda kudula chitsulo chosapanga dzimbiri, kupatula zitsulo zina zonse.
Zigawo za DO rack zimakonzedwa padera kuti zisakhudze chitsulo ndi chitsulo. Izi ndizofunikira kwambiri pakupanga chitsulo chosapanga dzimbiri chopanda chitsulo, chifukwa njira zotulutsira madzi ndi kutsuka zimayenera kufalitsa zinthu zowononga za sulfide ndikupewa kupanga matumba a asidi.
Musamasule zitsulo zosapanga dzimbiri zopangidwa ndi carburised kapena nitride. Kukana dzimbiri kwa zinthu zomwe zakonzedwa kungachepe mpaka kufika poti zingaukiridwe mu bafa yosambiramo.
Musagwiritse ntchito zida zachitsulo pamalo ogwirira ntchito omwe si oyera kwenikweni. Udzu wachitsulo ukhoza kupewedwa pogwiritsa ntchito zida za carbide kapena ceramic.
Musaiwale kuti dzimbiri limatha kuchitika m'bafa losambira ngati gawolo silinakonzedwe bwino kutentha. Mpweya wambiri, chromium martensitic grades iyenera kulimba kuti dzimbiri lisawonongeke.
Kuchepetsa kutentha nthawi zambiri kumachitika pambuyo potenthetsa kutentha pogwiritsa ntchito kutentha komwe kumasunga kukana dzimbiri.
Musanyalanyaze kuchuluka kwa nitric acid mu bafa yosambira. Kuwunika kuyenera kuchitika nthawi ndi nthawi pogwiritsa ntchito njira yosavuta yopezera titration yoperekedwa ndi Carpenter. Musamasule zitsulo zosapanga dzimbiri zoposa chimodzi nthawi imodzi. Izi zimaletsa chisokonezo chokwera mtengo komanso kupewa galvanic reactions.
Za olemba: Terry A. DeBold ndi katswiri wofufuza ndi kupanga zitsulo zosapanga dzimbiri ndipo James W. Martin ndi katswiri wa zitsulo zotsukira mipiringidzo ku Carpenter Technology Corp. (Reading, PA).
Mu dziko lomwe lili ndi mfundo zolimba kwambiri zomaliza pamwamba, miyeso yosavuta ya "kukhwima" ikadali yothandiza. Tiyeni tiwone chifukwa chake kuyeza pamwamba ndikofunikira komanso momwe kungawonedwere m'sitolo pogwiritsa ntchito zida zamakono zonyamulika.
Kodi mukutsimikiza kuti muli ndi choyikapo chabwino kwambiri chogwiritsira ntchito potembenuza uku? Yang'anani chip, makamaka ngati sichikusamalidwa. Makhalidwe a chip angakuuzeni zambiri.