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Passivation imakhalabe gawo lofunika kwambiri pakukulitsa kukana kwa dzimbiri kwa magawo osapanga dzimbiri ndi misonkhano. Ikhoza kupanga kusiyana pakati pa magwiridwe antchito okhutiritsa ndi kulephera msanga.
Passivation ndi njira ya post-fabrication yomwe imakulitsa kukana kwa dzimbiri kwa zitsulo zosapanga dzimbiri zomwe zimapanga chogwirira ntchito.
Palibe mgwirizano wamba pa njira yeniyeni ya momwe passivation imagwirira ntchito.Koma ndizowona kuti pali filimu yoteteza oxide pamwamba pa zitsulo zosapanga dzimbiri zosapanga dzimbiri. Filimu yosaonekayi imaganiziridwa kuti ndi yopyapyala kwambiri, yosakwana 0.0000001 inchi wandiweyani, pafupifupi 1/100,000th makulidwe a tsitsi la munthu!
Gawo loyera, lopangidwa kumene, lopukutidwa kapena lopangidwa ndi chitsulo chosapanga dzimbiri lidzangotenga filimu ya oxide iyi chifukwa cha kukhudzana kwake ndi mpweya wa mumlengalenga.
Mwachizoloŵezi, komabe, zonyansa monga dothi la masitolo kapena zitsulo zachitsulo kuchokera ku zida zodulira zimatha kusamutsira pamwamba pazitsulo zosapanga dzimbiri panthawi ya machining.Ngati sizikuchotsedwa, matupi akunjawa amatha kuchepetsa mphamvu ya filimu yotetezera yoyambirira.
Pamakina, kufufuza kuchuluka kwa chitsulo chaulere kumatha kutha chida ndikusamutsira pamwamba pa chitsulo chosapanga dzimbiri.Nthawi zina, dzimbiri laling'ono limatha kuwoneka pagawo.Izi kwenikweni ndi dzimbiri lachitsulo ndi chida, osati zitsulo zoyambira.Nthawi zina, mikwingwirima ya tinthu tating'onoting'ono tomwe timatulutsa kuchokera ku zida zodulira kapena kuwonongeka kwa zinthuzo kungayambitse kukokoloka kwa gawolo.
Momwemonso, tinthu tating'onoting'ono tating'onoting'ono timene timayendetsa bwino zimatha kuwonekera pamtunda wa gawo la gawo la gawo lachitatu.
Ma sulfide owonekera angakhalenso vuto. Iwo amachokera ku kuwonjezera sulfure ku zitsulo zosapanga dzimbiri kuti apititse patsogolo machinability.Sulfides amawonjezera mphamvu ya alloy kupanga tchipisi panthawi ya makina, omwe amatha kuchotsedwa pa chida chodula.
Pazochitika zonsezi, kupititsa patsogolo kumafunika kukulitsa kukana kwachilengedwe kwa chitsulo chosapanga dzimbiri. Kumachotsa zonyansa zapamtunda, monga tinthu tating'onoting'ono tating'onoting'ono ta sitolo ndi tinthu tachitsulo tating'onoting'ono tating'onoting'ono tating'onoting'ono tomwe timapanga dzimbiri kapena kukhala poyambira.
Njira ziwiri zimapereka njira yabwino kwambiri yothanirana ndi dzimbiri: 1. Kuyeretsa, njira yoyambira koma nthawi zina imanyalanyazidwa; 2. Kusamba kwa asidi kapena chithandizo cha passivation.
Kuyeretsa kuyenera kukhala kofunikira nthawi zonse. Pamwamba payenera kutsukidwa bwino ndi mafuta, zoziziritsa kukhosi kapena zinyalala za m'sitolo kuti zisawonongeke bwino. Zinyalala za Machining kapena dothi lina la m'sitolo likhoza kufufutidwa mosamala kuchoka pagawolo.
Nthawi zina wogwiritsa ntchito makina akhoza kulumpha kuyeretsa, molakwika kuganiza kuti kuyeretsa ndi kusuntha kudzachitika nthawi imodzi mwa kungoviika gawo lodzaza mafuta mu bafa la asidi.
Choipitsitsacho, kuipitsidwa kwa mankhwala otsekemera, omwe nthawi zina amakhala ndi ma chloride ochulukirapo, angayambitse "kuthwanima." Mosiyana ndi kupeza filimu yomwe mukufuna yomwe mukufuna yokhala ndi filimu yonyezimira, yoyera, yosachita dzimbiri, kung'anima kumatha kupangitsa kuti pakhale mdima wandiweyani kapena wakuda kwambiri - pamwamba pake pamakhala kuwonongeka komwe kumapangidwira kuti kukhale bwino.
Magawo opangidwa kuchokera ku chitsulo chosapanga dzimbiri cha martensitic [maginito, osagwirizana ndi dzimbiri, opatsa mphamvu mpaka 280 ksi (1930 MPa)] amaumitsidwa pa kutentha kokwera kenako amatenthedwa kuti atsimikizire kuuma komwe kumafunidwa ndi makina amakina. wokalamba pa kutentha otsika, ndiyeno anamaliza.
Pankhaniyi, gawolo liyenera kutsukidwa bwino ndi degreaser kapena zotsukira kuchotsa zizindikiro zilizonse zamadzimadzi asanayambe kutentha kutentha.Kupanda kutero, kudula madzi otsalira pa gawolo kungayambitse oxidation yochuluka. kuchititsa kutaya kukana dzimbiri.
Pambuyo poyeretsa bwino, zigawo zazitsulo zosapanga dzimbiri zimatha kumizidwa mu bath passivating acid. Njira iliyonse mwa njira zitatu ingagwiritsidwe ntchito - nitric acid passivation, nitric acid ndi sodium dichromate passivation, ndi citric acid passivation.Njira yogwiritsira ntchito imadalira kalasi ya chitsulo chosapanga dzimbiri ndi ndondomeko yovomerezeka yovomerezeka.
Kuchuluka kwa dzimbiri zosagwira chrome-nickel magiredi akhoza passivated mu 20% (v/v) nitric acid kusamba (Chithunzi 1) . Monga momwe taonera pa tebulo, zosagwira zosapanga dzimbiri zitsulo akhoza passivated powonjezera sodium dichromate ndi nitric asidi kusamba, kupanga yankho oxidizing kwambiri ndi wokhoza kupanga m'malo mwa nitric asidi filimu njira ndi sodium chitsulo chosapanga dzimbiri ndi chitsulo chosapanga dzimbiri. kuonjezera kuchuluka kwa nitric acid ku 50% ndi voliyumu.Kuwonjezera kwa sodium dichromate ndi kuchuluka kwa nitric acid kumachepetsa mwayi wa kung'anima kosafunika.
Kachitidwe ka passivating free-machining zitsulo zosapanga dzimbiri (zomwe zikuwonetsedwanso mu Chithunzi 1) ndizosiyana pang'ono ndi zomwe sizimapangidwa ndi zitsulo zosapanga dzimbiri. Izi ndichifukwa choti pakudutsa mumsamba wamba wa nitric acid, zina kapena zonse za sulfure zomwe zili ndi sulfidi zimachotsedwa, ndikupanga magawo ang'onoang'ono osapitilira pamakina.
Ngakhale kuchapa kwamadzi komwe kumakhala kothandiza kwambiri kumatha kusiya asidi otsalira m'ma discontinuities awa pambuyo pa passivation.This asidi ndiye amaukira pamwamba pa gawolo pokhapokha atachotsedwa kapena kuchotsedwa.
Kuti athetse mosavuta zitsulo zosapanga dzimbiri zosapanga dzimbiri, Carpenter wapanga njira ya AAA (Alkali-Acid-Alkali), yomwe imalepheretsa asidi otsalira.
Pambuyo pothira mafuta, zilowerereni zigawozo mu 5% sodium hydroxide solution pa 160 ° F mpaka 180 ° F (71 ° C mpaka 82 ° C) kwa mphindi 30. Kenaka yambani zigawozo bwinobwino m'madzi. Kenako, imbani gawolo kwa mphindi 30 mu 20% (v / v) nitric acid / gal solution yokhala ndi 2 dich2 sodium (2 oz 3 g) 120°F mpaka 140°F (49°C) mpaka 60°C). Pambuyo pochotsa gawolo mu kusamba, tsukani ndi madzi ndikuviika mu sodium hydroxide solution kwa mphindi zina 30. Sambani gawolo kachiwiri ndi madzi ndi kuuma, kukwaniritsa njira ya AAA.
Citric acid passivation ikuchulukirachulukira ndi opanga omwe akufuna kupewa kugwiritsa ntchito mineral acids kapena mayankho omwe ali ndi sodium dichromate, komanso nkhani zotaya komanso nkhawa zambiri zokhudzana ndi chitetezo chokhudzana ndi kugwiritsa ntchito kwawo.Citric acid imatengedwa kuti ndi yogwirizana ndi chilengedwe mwanjira iliyonse.
Ngakhale kuti citric acid passivation imapereka ubwino wowoneka bwino wa chilengedwe, masitolo omwe akhala ndi chipambano ndi organic acid passivation ndipo alibe nkhawa za chitetezo angafune kukhalabe njira.Ngati ogwiritsa ntchitowa ali ndi sitolo yoyera, zipangizo zosamalidwa bwino komanso zoyera, zoziziritsa kuzizira zopanda ferrous shop fouling, ndi ndondomeko yomwe imapanga zotsatira zabwino, sipangakhale kufunikira kwenikweni kwa kusintha.
Kudutsa mumadzi osambira a citric acid kwapezeka kuti n'kothandiza pazitsulo zambiri zosapanga dzimbiri, kuphatikizapo magulu angapo a zitsulo zosapanga dzimbiri, monga momwe tawonetsera pa Chithunzi 2. Kuti zikhale zosavuta, njira yachikhalidwe ya nitric acid passivation mu Chithunzi 1 ikuphatikizidwa.Dziwani kuti mapangidwe akale a nitric acid amasonyezedwa mu chiwerengero cha voliyumu, pamene zowonjezera zowonjezera za citric acid zimasonyezedwa mosamala pa ndondomeko ya kulemera kwake. nthawi, kutentha kusamba ndi ndende n'kofunika kupewa "kuthwanima" tafotokozazi.
Thandizo la Passivation limasiyanasiyana malinga ndi zomwe zili mu chromium ndi mawonekedwe a makina a giredi iliyonse. Dziwani kuti zigawo zomwe zikulozera Njira 1 kapena Njira 2. Monga momwe zasonyezedwera pa Chithunzi 3, Njira 1 imakhudza masitepe ocheperapo kuposa Njira 2.
Mayesero a ma laboratory asonyeza kuti citric acid passivation process imakonda kwambiri "kuwotcha" kusiyana ndi ndondomeko ya nitric acid. Zomwe zimayambitsa kuukira kumeneku zikuphatikizapo kutentha kwambiri kwa kusamba, nthawi yayitali kwambiri, ndi kusamba.
Chisankho chomaliza cha njira yotsatsira chidzadalira njira zovomerezeka zoperekedwa ndi kasitomala.Onani ASTM A967 kuti mudziwe zambiri.Itha kupezeka pa www.astm.org.
Mayesero nthawi zambiri amachitidwa kuti awone momwe zinthu zilili. Funso loti liyankhe ndilakuti, "Kodi passivation imachotsa chitsulo chaulere ndikukulitsa kukana kwa dzimbiri kwa magiredi odula?"
Ndikofunika kuti njira yoyesera ifanane ndi kalasi yomwe ikuyesedwa.Mayeso omwe ali okhwima kwambiri adzalephera zipangizo zabwino kwambiri, pamene mayesero omwe ali otayirira adzadutsa mbali zosasangalatsa.
400 mndandanda wa mpweya kuumitsa ndi free-machining zitsulo zosapanga dzimbiri zimayesedwa bwino mu kabati yomwe imatha kusunga chinyezi cha 100% (chitsanzo chonyowa) kwa maola 24 pa 95 ° F (35 ° C) .
Malo ovuta ayenera kuikidwa mmwamba, koma pa madigiri 15 mpaka 20 kuchokera kumtunda kuti alole kutayika kwa chinyezi.
Austenitic zitsulo zosapanga dzimbiri zitsulo zingathenso kuyesedwa ndi kuyesedwa kwa chinyezi.Akayesedwa, madontho amadzi ayenera kukhala pamwamba pa chitsanzo, kusonyeza chitsulo chaulere ndi kukhalapo kwa dzimbiri lililonse.
Njira zodutsamo zitsulo zosapanga dzimbiri zomwe zimagwiritsidwa ntchito momasuka komanso zosadulidwa mu citric kapena nitric acid solution zimafuna njira zosiyanasiyana.
(a) Sinthani pH ndi sodium hydroxide.(b) Onani Chithunzi 3 (c) Na2Cr2O7 ikuyimira 3 oz/gallon (22 g/l) sodium dichromate mu 20% nitric acid. Njira ina yosakanikirana ndi 50% nitric acid popanda sodium dichromate
Njira yachangu ndikugwiritsa ntchito yankho mu ASTM A380, "Standard Practice for Cleaning, Descaling, and Passivation of Stainless Steel Parts, Equipment, and Systems." Mayesowa amakhala ndi kupukuta gawolo ndi yankho la copper sulfate/sulfuric acid, ndikulisunga lonyowa kwa mphindi 6 ndikuyang'ana njira ina yomizidwa ndi mkuwa. Mphindi.Ngati chitsulo chikusungunuka, plating yamkuwa imapezeka.Kuyesaku sikugwiritsidwa ntchito pazitsulo zazitsulo zopangira chakudya.Komanso, sayenera kugwiritsidwa ntchito pazitsulo za 400 za martensitic kapena low chromium ferritic monga zotsatira zabodza zikhoza kuchitika.
M'mbuyomu, kuyesa kwa mchere wa 5% pa 95 ° F (35 ° C) kwagwiritsidwanso ntchito poyesa zitsanzo zomwe sizinachitike.
Pewani kugwiritsa ntchito ma chloride owonjezera, omwe angayambitse kung'anima kovulaza.Ngati nkotheka, gwiritsani ntchito madzi apamwamba okha okhala ndi magawo 50 pa miliyoni (ppm) chloride.Madzi apampopi nthawi zambiri amakhala okwanira ndipo amatha kupirira mpaka mazana angapo a ppm chloride nthawi zina.
Ndikofunikira m'malo kusamba nthawi zonse kuti asataye passivation angathe, zomwe zingachititse kugunda kwa mphezi ndi kuonongeka mbali.Kusamba ayenera anakhalabe pa kutentha koyenera, monga kutentha othawa kungachititse dzimbiri m'dera.
Ndikofunika kukhalabe ndi ndondomeko yeniyeni yosinthira njira yothetsera nthawi yochita kupanga kwambiri kuti kuchepetsa kuthekera kwa contamination.Chitsanzo chowongolera chinagwiritsidwa ntchito kuyesa mphamvu ya bath.Ngati chitsanzo chikuwukiridwa, ndi nthawi yoti mulowe m'malo osamba.
Chonde tchulani kuti makina ena amapanga zitsulo zosapanga dzimbiri zokha; gwiritsani ntchito choziziritsira chozizira chomwechi podula zitsulo zosapanga dzimbiri, kupatula zitsulo zina zonse.
DO ziwiya rack amachitidwa padera kuti apewe zitsulo-to-zitsulo contact.Izi ndi zofunika kwambiri machining zitsulo zosapanga dzimbiri, monga free-othamanga passivation ndi flushing solutions amayenera kufalitsa mankhwala dzimbiri sulfide ndi kupewa mapangidwe matumba asidi.
Musati passivate carburized kapena nitrided zosapanga dzimbiri parts.The dzimbiri kukana mbali kotero ankachitira mwina kuchepetsedwa mpaka pamene iwo anaukira mu bafa passivation.
Osagwiritsa ntchito zida zachitsulo pamalo ochitira msonkhano omwe sali oyera kwambiri.Nyengo zachitsulo zitha kupewedwa pogwiritsa ntchito zida za carbide kapena ceramic.
Musaiwale kuti dzimbiri zitha kuchitika posambiramo ngati gawolo silinatenthedwe bwino. Mpweya wa carbon, high chromium martensitic scores uyenera kuumitsa kuti usawonongeke.
Passivation nthawi zambiri ikuchitika pambuyo kutentha wotsatira ntchito kutentha kuti kusunga kukana dzimbiri.
Musanyalanyaze kuchuluka kwa nitric acid mu bath passivation.Kuwunika kwanthawi ndi nthawi kuyenera kupangidwa pogwiritsa ntchito njira yosavuta ya titration yoperekedwa ndi Carpenter.Musapitirire zitsulo zosapanga dzimbiri pa nthawi imodzi.Izi zimalepheretsa chisokonezo chokwera mtengo komanso zimapewa kuchitapo kanthu kwa galvanic.
Za olemba: Terry A. DeBold ndi katswiri wofufuza ndi chitukuko cha zitsulo zosapanga dzimbiri komanso James W. Martin ndi bar metallurgist ku Carpenter Technology Corp. (Reading, PA).
M'dziko lovuta kwambiri, miyeso yosavuta ya "kukalipa" ikadali yothandiza. Tiyeni tiwone chifukwa chake kuyeza kwa pamwamba kuli kofunika komanso momwe kungawunikidwe pansi pa sitolo ndi geji zapamwamba zonyamulika.
Kodi mukutsimikiza kuti muli ndi choyikapo chabwino kwambiri chokhotakhota? Onani chip, makamaka ngati sichinasamalidwe. Makhalidwe a Chip angakuuzeni zambiri.