Kun tabbatar da cewa an sarrafa sassan don ƙayyadaddun bayanai. Yanzu, tabbatar da cewa kun ɗauki matakai don kare waɗannan sassa a cikin yanayin da abokan cinikin ku suke tsammani. # asali.
Passivation ya kasance muhimmin mataki na haɓaka juriya na asali na ɓarna na sassa da na'ura na bakin karfe da majalisai. Yana iya yin bambanci tsakanin aiki mai gamsarwa da gazawar da bai kai ba.
Passivation hanya ce ta bayan fabrication wacce ke haɓaka juriyar juriya na baƙin ƙarfe na ƙarfe waɗanda ke samar da aikin aikin.
Babu wata yarjejeniya ta gaba ɗaya game da ainihin tsarin yadda aikin wucewa ke aiki.Amma yana da tabbacin cewa akwai fim ɗin kariya na oxide akan saman bakin karfen da ba a iya gani ba.Wannan fim ɗin da ba a iya gani ba ana tsammanin yana da sirara sosai, ƙasa da 0.0000001 inch kauri, kusan 1/100,000th kauri na gashin ɗan adam!
Wani sashi mai tsabta, sabon inji, goge ko tsince bakin karfe zai sami wannan fim ɗin ta atomatik ta atomatik saboda bayyanarsa zuwa iskar oxygen na yanayi.A ƙarƙashin yanayi mai kyau, wannan Layer oxide mai kariya gabaɗaya ya rufe dukkan sassan ɓangaren.
A aikace, duk da haka, ƙazantattun abubuwa irin su dattin kantin sayar da kaya ko ƙananan ƙarfe daga kayan aikin yankan na iya canjawa wuri zuwa saman sassa na bakin karfe a lokacin aikin machining.Idan ba a cire su ba, waɗannan kasashen waje na iya rage tasirin fim ɗin kariya na asali.
A lokacin machining, gano yawa na free baƙin ƙarfe iya sawa kashe kayan aiki da kuma canja wurin zuwa surface na bakin karfe workpiece.A wasu lokuta, a bakin ciki Layer na tsatsa iya bayyana a kan part.This shi ne ainihin lalata da karfe da kayan aiki, ba na tushe karfe.Lokaci, crevices na saka karfe barbashi daga yankan kayan aikin ko su lalata kayayyakin iya haifar da yashwar da kayan aiki.
Hakanan, ƙananan barbashi na dattin kantin sayar da ƙarfe na iya mannewa saman ɓangaren.Ko da yake ƙarfe na iya bayyana yana haskakawa a cikin yanayin injin, bayan bayyanar iska, ƙwayoyin ƙarfe marasa ganuwa na iya haifar da tsatsawar saman.
fallasa sulfides kuma na iya zama matsala.Sun zo daga ƙara sulfur zuwa bakin karfe don inganta machinability.Sulfides ƙara gami ta ikon samar da kwakwalwan kwamfuta a lokacin machining, wanda za a iya gaba daya sloughed kashe yankan tool.In sai dai sassan da aka yadda ya kamata passivated, sulfides iya zama farkon batu ga surface lalata a kerarre kayayyakin.
A cikin lokuta biyu, passivation ake bukata don kara da na halitta lalata juriya na bakin karfe.It cire surface gurɓatacce, kamar ferrous shagon datti barbashi da baƙin ƙarfe barbashi a yankan kayan aikin, da za su iya samar da tsatsa ko zama farkon batu ga lalata.Passivation kuma cire sulfides fallasa a saman free-yanke bakin karfe gami.
Hanya na mataki biyu yana ba da mafi kyawun juriya na lalata: 1. Tsaftacewa, hanya mai mahimmanci amma wani lokacin rashin kula;2. Acid wanka ko maganin wucewa.
Tsaftacewa ya kamata koyaushe ya zama fifiko. Dole ne a tsabtace filaye sosai da maiko, mai sanyaya ko wasu tarkace kanti don ingantaccen juriya na lalata.Machining tarkace ko sauran dattin shago za a iya goge su a hankali daga ɓangaren. Kasuwancin degreasers ko masu tsaftacewa za a iya amfani da su don cire mai sarrafa mai ko masu sanyaya. Bakin al'amura kamar su thermal oxides na iya zama da za a cire su ta hanyoyin niƙa.
Wani lokaci ma'aikacin na'ura na iya tsallake tsaftacewa na asali, kuskuren tunanin cewa tsaftacewa da wucewa za su faru a lokaci guda ta hanyar kawai tsoma wani ɓangaren maiko a cikin wanka na acid. Wannan ba zai faru ba.Conversely, gurɓataccen man shafawa yana amsawa tare da acid don samar da kumfa na iska.Waɗannan kumfa suna tattarawa akan farfajiyar aiki kuma suna tsoma baki tare da wucewa.
Don yin muni, gurɓatar hanyoyin wucewa, wanda wani lokaci yana ɗauke da babban adadin chlorides, na iya haifar da “flashing.” Ba kamar samun fim ɗin oxide da ake so tare da mai sheki, mai tsabta, mai juriya ba, walƙiya na walƙiya na iya haifar da ɓarnawar fuskar da aka ƙera wucewa don haɓakawa.
Sassan da aka yi daga martensitic bakin karfe [magnetic, moderately resistant to corrosion, yawan amfanin ƙasa har zuwa game da 280 ksi (1930 MPa)] an taurare a dagagge yanayin zafi sa'an nan kuma tempered don tabbatar da ake so taurin da inji Properties.Hazo hardenable gami, wanda da mafi alhẽri ƙarfi da lalata juriya fiye da martensitic alloys, wani partially za a iya bi da a zafin jiki na inji.
A wannan yanayin, dole ne a tsabtace sashi sosai tare da mai cirewa ko mai tsabta don cire duk wani alamun yankan ruwa kafin magani mai zafi. In ba haka ba, yankan ruwan da ya rage a kan sashi zai iya haifar da oxidation mai yawa.Wannan yanayin zai iya haifar da ƙananan sassa zuwa ƙananan bayan an cire sikelin ta hanyar acid ko abrasive. .
Bayan tsaftacewa sosai, sassan bakin karfe za a iya nutsar da su a cikin wanka na acid mai wucewa.Kowane daga cikin hanyoyi guda uku za a iya amfani da su - nitric acid passivation, nitric acid tare da sodium dichromate passivation, da citric acid passivation.Wace hanyar da za a yi amfani da ita ya dogara da darajar bakin karfe da ƙayyadaddun ka'idojin yarda.
More lalata-resistant chrome-nickel maki za a iya passivated a cikin wani 20% (v / v) nitric acid wanka (Figure 1) .Kamar yadda aka nuna a cikin tebur, kasa resistant bakin karfe za a iya passivated ta ƙara sodium dichromate zuwa wani nitric acid wanka, yin bayani mafi oxidizing kuma iya samar da wani m fim a kan karfe surface na nitric acid. da girma.Dukansu ƙari na sodium dichromate da mafi girma taro na nitric acid rage damar da ba a so walƙiya.
The hanya domin passivating free-machining bakin karfe (wanda aka nuna a Figure 1) ne da ɗan daban-daban daga cewa ga wadanda ba free-machining bakin karfe grades.Wannan shi ne saboda a lokacin passivation a cikin wani hali nitric acid wanka, wasu ko duk na sulfur-dauke da machinable sa sulfides an cire, samar da microscopic discontinuities a cikin surface na inji.
Ko da ruwan kurkure gabaɗaya mai tasiri na iya barin ragowar acid a cikin waɗannan abubuwan da za su daina bayan wucewar. Wannan acid ɗin zai kai hari a saman ɓangaren sai dai idan an cire shi ko an cire shi.
Don yadda ya kamata passivate sauƙi machinable bakin karfe, kafinta ya ɓullo da AAA (Alkali-Acid-Alkali) tsari, wanda neutralizes ragowar acid.Wannan passivation hanya za a iya kammala a kasa da 2 hours. Ga mataki-by-steki tsari:
Bayan ragewa, jiƙa sassan a cikin bayani na 5% sodium hydroxide a 160 ° F zuwa 180 ° F (71 ° C zuwa 82 ° C) na minti 30. Sa'an nan kuma kurkura sassan sosai a cikin ruwa. Na gaba, nutsar da sashi na minti 30 a cikin 20% (v / v) nitric acid bayani dauke da 22 chromate / l 22 chromate / l 1 od chromate / l sodium di chromate / l °F (49°C) zuwa 60°C.Bayan cire sashi daga wanka, wanke shi da ruwa sannan a nutsar da shi a cikin maganin sodium hydroxide na tsawon minti 30. A sake wanke sashi da ruwa da bushe, kammala hanyar AAA.
Citric acid passivation yana ƙara shahara tare da masana'antun da suke so su guje wa yin amfani da ma'adinai acid ko mafita dauke da sodium dichromate, kazalika da zubar da al'amurran da suka shafi da kuma mafi girma aminci damuwa hade da amfani da su.
Duk da yake citric acid passivation yana ba da fa'idodin muhalli masu ban sha'awa, shagunan da suka sami nasara tare da wucewar inorganic acid passivation kuma ba su da damuwa na tsaro na iya so su ci gaba da tafiya.Idan waɗannan masu amfani suna da shago mai tsabta, kayan aiki mai kyau da tsabta, mai sanyaya ba tare da lalata kantin sayar da ferrous ba, da tsari wanda ke haifar da sakamako mai kyau, ƙila babu ainihin buƙatar canje-canje.
Passivation a cikin wani citric acid wanka da aka samu da amfani ga babban kewayon bakin karfe, ciki har da dama mutum bakin karfe maki, kamar yadda aka nuna a cikin Hoto 2.Domin saukaka, da gargajiya nitric acid passivation hanya a cikin Figure 1 an hada da. Lura cewa tsofaffin nitric acid formulations aka bayyana a cikin girma kashi, yayin da sabon citric acid maida hankali ne bayyana a cikin nauyi kashi, lokacin da aiwatar da ba da muhimmanci ga zafin jiki lokaci da kuma lokacin da aiwatar da aiwatar da tsarin kula da zafin jiki. don guje wa “flashing” da aka kwatanta a baya.
Jiyya na wucewa sun bambanta bisa ga abun ciki na chromium da halayen injina na kowane aji. Lura da ginshiƙan da ke magana ko dai Tsarin 1 ko Tsari 2. Kamar yadda aka nuna a hoto na 3, Tsarin 1 ya ƙunshi matakai kaɗan fiye da Tsarin 2.
Gwaje-gwajen gwaje-gwaje sun nuna cewa tsarin wucewar citric acid ya fi dacewa da "flashing" fiye da tsarin nitric acid. Abubuwan da ke ba da gudummawa ga wannan harin sun hada da yawan zafin jiki na wanka, da tsawon lokacin jiƙa, da kuma gurɓataccen wanka.Citric acid kayayyakin da ke dauke da masu hana lalata da sauran abubuwan da suka hada da irin su wetting jamiái suna samuwa a kasuwa kuma an ruwaito su don rage rashin lahani ga "lalata".
Zaɓin zaɓi na ƙarshe na hanyar wucewa zai dogara ne akan sharuɗɗan yarda da abokin ciniki ya gindaya.Duba ASTM A967 don cikakkun bayanai. Ana iya samun dama ga www.astm.org.
Ana yin gwaje-gwaje sau da yawa don kimanta saman sassan da ke wucewa. Tambayar da za a amsa ita ce, "Shin passivation yana cire baƙin ƙarfe kyauta kuma yana inganta juriya na lalacewa na maki kyauta?"
Yana da mahimmanci cewa hanyar gwajin ta dace da darajar da ake tantancewa.Gwajin da ke da ƙarfi za su gaza cikar kayan aiki masu kyau, yayin da gwaje-gwajen da ba su da yawa za su wuce sassan da ba su da daɗi.
400 jerin hazo hardening da free-machining bakin karfe suna mafi kyau kimanta a cikin wani majalisa iya rike 100% zafi (rigar samfurori) for 24 hours a 95 ° F (35 ° C) .The giciye sashe ne sau da yawa mafi m surface, musamman ga free-yanke grades.One dalili na wannan shi ne cewa sulfide ne shugabanci a cikin wannan surface na sulfide.
Ya kamata a sanya wurare masu mahimmanci zuwa sama, amma a 15 zuwa 20 digiri daga tsaye don ba da izinin asarar danshi. Kayan da ya dace da kyau ba zai yi tsatsa ba, ko da yake yana iya nuna dan kadan.
Hakanan za'a iya ƙididdige maki Austenitic bakin karfe ta gwajin zafi. Lokacin da aka gwada haka, ɗigon ruwa ya kamata ya kasance a saman samfurin, yana nuna ƙarfe kyauta ta kasancewar kowane tsatsa.
Hanyoyin wucewa da aka saba amfani da su kyauta da kuma yanke bakin karfe a cikin citric ko nitric acid mafita suna buƙatar matakai daban-daban. Hoto 3 da ke ƙasa yana ba da cikakkun bayanai game da zaɓin tsari.
(a) Daidaita pH tare da sodium hydroxide. (b) Dubi Hoto na 3 (c) Na2Cr2O7 yana wakiltar 3 oz / gallon (22 g / l) sodium dichromate a cikin 20% nitric acid. madadin wannan cakuda shine 50% nitric acid ba tare da sodium dichromate ba.
Hanyar da ta fi sauri ita ce a yi amfani da mafita a cikin ASTM A380, "Standard Practice for Cleaning, Descaling, and Passivation of Stainless Steel Parts, Equipment, and Systems." Jarabawar ta ƙunshi shafan ɓangaren tare da bayani na jan karfe sulfate / sulfuric acid, ajiye shi rigar na minti 6 da kuma lura da tagulla plating. ting yana faruwa.Wannan gwajin bai kamata a yi amfani da shi a saman sassan sarrafa abinci ba. Hakanan, bai kamata a yi amfani da shi don 400 jerin martensitic ko ƙananan chromium ferritic steels kamar yadda sakamakon ƙarya na iya faruwa.
A tarihi, an yi amfani da gwajin feshin gishiri na 5% a 95°F (35°C) don kimanta samfuran da ba su wuce ba. Wannan gwajin yana da tsauri ga wasu maki kuma gabaɗaya ba a buƙata don tabbatar da cewa wucewa yana da tasiri.
Guji yin amfani da chloride mai yawa, wanda zai iya haifar da harin walƙiya mai cutarwa. Idan zai yiwu, yi amfani da ruwa mai inganci kawai tare da ƙasa da kashi 50 a kowace miliyan (ppm).
Yana da mahimmanci a maye gurbin wanka akai-akai don guje wa asarar yuwuwar wucewa wanda zai iya haifar da walƙiya da ɓarna.Ya kamata a kiyaye wanka a yanayin zafin da ya dace, saboda yanayin zafi na gudu na iya haifar da lalatawar gida.
Yana da mahimmanci don kula da ƙayyadaddun ƙayyadaddun ƙayyadaddun ƙayyadaddun sauye-sauyen bayani a yayin manyan ayyukan samarwa don rage yawan yiwuwar lalacewa.An yi amfani da samfurin sarrafawa don gwada tasirin wanka.Idan samfurin ya kai hari, lokaci ya yi don maye gurbin wanka.
Da fatan za a saka cewa wasu injuna suna yin bakin karfe kawai;yi amfani da mai sanyaya da aka fi so don yanke bakin karfe, ban da duk sauran karafa.
DO rack sassa ana bi da akayi daban-daban don kauce wa karfe-to-karfe lamba.Wannan yana da muhimmanci musamman ga free machining bakin karfe, kamar yadda free- gudana passivation da flushing mafita ake bukata don yada lalata kayayyakin a sulfide da kuma kauce wa samuwar acid Aljihuna.
Kar a wuce carburized ko nitrided bakin karfe sassa.Za a iya rage juriyar lalatawar sassan da ake bi da su har zuwa inda za a kai musu hari a cikin wankan wucewa.
Kada a yi amfani da kayan aikin ƙarfe a cikin wurin bita wanda ba shi da tsabta musamman. Ana iya guje wa ƙera ƙarfe ta amfani da kayan aikin carbide ko yumbu.
Kar ka manta cewa lalata na iya faruwa a cikin wanka mai wucewa idan ɓangaren ba a kula da zafi yadda ya kamata. High carbon, high chromium martensitic maki dole ne a taurare ga lalata juriya.
Passivation yawanci ana aiwatar da shi bayan zafin jiki na gaba ta amfani da yanayin zafi da ke kula da juriyar lalata.
Kada ku yi watsi da ƙwayar nitric acid a cikin wanka mai wucewa. Ya kamata a yi bincike na lokaci-lokaci ta amfani da hanya mai sauƙi na titration da Carpenter ke bayarwa.Kada ku wuce fiye da ɗaya bakin karfe a lokaci guda.Wannan yana hana rikicewa mai tsada kuma yana guje wa halayen galvanic.
Game da mawallafa: Terry A. DeBold ƙwararren bincike ne na bakin karfe da kuma ƙwararrun ci gaba kuma James W. Martin ƙwararren masanin ƙarfe ne a Carpenter Technology Corp. (Karanta, PA).
A cikin duniya na ƙara stringent surface gama bayani dalla-dalla, sauki "roughness" ma'auni ne har yanzu amfani. Bari mu dubi dalilin da ya sa surface auna yana da muhimmanci da kuma yadda za a iya duba a kan shagon bene tare da sophisticated šaukuwa ma'auni.
Shin kun tabbata kuna da mafi kyawun sakawa don wannan aikin juyawa? Bincika guntu, musamman idan ba a kula da su ba. Halayen guntu na iya gaya muku da yawa.