Kun tabbatar da cewa an yi wa sassan injinan aiki yadda ya kamata. Yanzu, tabbatar kun ɗauki matakai don kare waɗannan sassan a cikin yanayin da abokan cinikin ku ke tsammani.#basic
Passivation ya kasance muhimmin mataki wajen haɓaka juriyar tsatsa na sassa da kayan aiki na bakin ƙarfe. Yana iya kawo bambanci tsakanin aiki mai gamsarwa da gazawar da wuri. Idan ba a aiwatar da shi yadda ya kamata ba, passivation na iya haifar da tsatsa.
Passivation wata hanya ce ta bayan ƙera kayan da ke ƙara juriya ga tsatsa na ƙarfen bakin ƙarfe da ke samar da kayan aikin. Ba maganin rage girman fenti ba ne, kuma ba rufin fenti ba ne.
Babu wata yarjejeniya ta gabaɗaya kan ainihin hanyar da passivation ke aiki. Amma tabbas akwai fim ɗin kariya daga oxide a saman bakin ƙarfe mai passivated. Ana tsammanin wannan fim ɗin da ba a gani yana da siriri sosai, ƙasa da inci 0.0000001 kauri, kusan kashi 1/100,000 na kauri na gashin ɗan adam!
Sashen bakin karfe mai tsabta, wanda aka yi masa injina, wanda aka goge ko aka yayyanka zai sami wannan fim ɗin oxide ta atomatik saboda fallasa shi ga iskar oxygen ta yanayi. A ƙarƙashin yanayi mai kyau, wannan Layer ɗin oxide mai kariya ya rufe dukkan saman ɓangaren gaba ɗaya.
Amma a aikace, gurɓatattun abubuwa kamar ƙurar shago ko barbashi na ƙarfe daga kayan aikin yankewa na iya canzawa zuwa saman sassan bakin ƙarfe yayin aikin injin. Idan ba a cire su ba, waɗannan ƙwayoyin waje na iya rage tasirin fim ɗin kariya na asali.
A lokacin ƙera, ƙaramin ƙarfe mai yawa na iya lalacewa daga kayan aikin kuma ya koma saman aikin ƙarfen bakin ƙarfe. A wasu lokuta, siririn tsatsa na iya bayyana a ɓangaren. Wannan a zahiri tsatsa ce ta ƙarfen da kayan aikin suka yi, ba ta ƙarfen tushe ba. Wani lokaci, ramuka na ƙwayoyin ƙarfe da aka saka daga kayan aikin yankewa ko samfuran tsatsa na iya haifar da lalacewar ɓangaren da kansa.
Haka kuma, ƙananan ƙwayoyin dattin dattin shagon na iya mannewa a saman ɓangaren. Duk da cewa ƙarfe na iya bayyana yana sheƙi a yanayin injin, bayan an fallasa shi ga iska, ƙwayoyin da ba a iya gani na ƙarfe mara ganuwa na iya haifar da tsatsa a saman.
Sulfide da aka fallasa suma na iya zama matsala. Suna fitowa ne daga ƙara sulfur a cikin bakin ƙarfe don inganta injin. Sulfide yana ƙara ƙarfin ƙarfe na samar da guntu yayin aikin ƙera, wanda za'a iya cire shi gaba ɗaya daga kayan aikin yankewa. Sai dai idan sassan ba su da kyau, sulfide na iya zama wurin farawa na tsatsa a saman samfuran da aka ƙera.
A duka yanayi biyu, ana buƙatar passivation don haɓaka juriyar tsatsa ta halitta ta bakin ƙarfe. Yana kawar da gurɓatattun abubuwa a saman, kamar ƙwayoyin datti na ferrous da ƙwayoyin ƙarfe a cikin kayan aikin yankewa, waɗanda zasu iya yin tsatsa ko zama wurin farawa na tsatsa. Passivation kuma yana cire sulfides da aka fallasa a saman ƙarfe mai yankewa.
Tsarin matakai biyu yana samar da mafi kyawun juriya ga tsatsa: 1. Tsaftacewa, tsari ne mai sauƙi amma wani lokacin ana watsi da shi; 2. Maganin wanka mai guba ko maganin passivation.
Tsaftacewa ya kamata ya zama abin fifiko koyaushe. Dole ne a tsaftace saman da mai, ruwan sanyaya ko wasu tarkace na shago sosai don samun juriya ga tsatsa. Ana iya goge tarkacen injin ko wasu datti na shago a hankali daga ɓangaren. Ana iya amfani da na'urorin rage mai ko masu tsaftacewa na kasuwanci don cire mai ko na'urorin sanyaya. Ana iya cire abubuwa na ƙasashen waje kamar su thermal oxides ta hanyoyi kamar niƙa ko tsinken tsinkewa.
Wani lokaci mai aiki da injin zai iya tsallake tsaftacewa ta asali, yana tunanin kuskure cewa tsaftacewa da passivation za su faru a lokaci guda ta hanyar tsoma wani ɓangare mai mai a cikin baho mai acid. Wannan ba zai faru ba. Akasin haka, mai gurɓataccen mai yana amsawa da acid don samar da kumfa iska. Waɗannan kumfa suna taruwa a saman aikin kuma suna tsoma baki ga passivation.
Abin da ya ƙara ta'azzara lamarin shi ne, gurɓatar maganin passivation, wanda wani lokacin ke ɗauke da yawan sinadarin chloride, na iya haifar da "walƙiya." Ba kamar samun fim ɗin oxide da ake so ba tare da saman mai sheƙi, mai tsabta, mai jure tsatsa, walƙiyar walƙiya na iya haifar da lalacewar saman da aka yi wa fenti mai yawa ko duhu - wanda aka tsara passivation don ingantawa.
Ana taurare sassan da aka yi da bakin karfe mai kama da martensitic [magnetic, mai juriya ga tsatsa, ƙarfin samarwa har zuwa kusan 280 ksi (1930 MPa)] a yanayin zafi mai yawa sannan a daidaita su don tabbatar da taurin da ake so da kuma halayen injiniya. Ana iya magance matsalar tsatsa ta hanyar amfani da ruwan sama, waɗanda ke da ƙarfi da juriya ga tsatsa fiye da ƙarfe mai kama da martensitic, a yi musu maganin maganin, a yi musu aikin injin, a tsufa su a ƙananan yanayin zafi, sannan a gama su.
A wannan yanayin, dole ne a tsaftace ɓangaren sosai da man shafawa ko mai tsaftacewa don cire duk wani alamar ruwan yankewa kafin a yi amfani da shi a zafin jiki. In ba haka ba, ruwan yankewa da ya rage a ɓangaren na iya haifar da yawan iskar shaka. Wannan yanayin na iya sa ƙananan sassa su lalace bayan an cire sikelin ta hanyar amfani da hanyoyin acid ko abrasive. Idan aka bar ruwan yankewa ya kasance a kan sassa masu haske, kamar a cikin tanda mai tsabta ko yanayin kariya, carbonation na saman zai iya faruwa, wanda ke haifar da asarar juriya ga tsatsa.
Bayan tsaftacewa sosai, ana iya nutsar da sassan bakin karfe a cikin baho mai hana acid. Ana iya amfani da kowace hanya guda uku - hana acid nitric, hana sodium dichromate, da hana citric acid. Wace hanya za a yi amfani da ita ta dogara ne da matakin bakin karfe da kuma ƙa'idodin karɓuwa da aka ƙayyade.
Ana iya samun ƙarin ma'aunin chrome-nickel masu jure tsatsa a cikin baho na nitric acid na 20% (v/v) (Hoto na 1). Kamar yadda aka nuna a cikin tebur, ana iya rage ƙarfin bakin ƙarfe ta hanyar ƙara sodium dichromate a cikin baho na nitric acid, wanda ke sa maganin ya fi oxidizing kuma yana iya samar da fim mai aiki a saman ƙarfe. Wani zaɓi don maye gurbin nitric acid da sodium chromate shine ƙara yawan nitric acid zuwa 50% ta girma. Duk da ƙara sodium dichromate da yawan nitric acid yana rage damar walƙiya mara kyau.
Tsarin da ake bi wajen sarrafa ƙarfe marasa matsewa (wanda kuma aka nuna a Hoto na 1) ya ɗan bambanta da na ƙarfe marasa matsewa. Wannan saboda a lokacin da ake amfani da shi a cikin wanka na nitric acid na yau da kullun, ana cire wasu ko duk sulfides masu ɗauke da sulfur, wanda ke haifar da rashin daidaituwa a saman ɓangaren da aka yi amfani da shi.
Ko da kurkurawar ruwa mai inganci na iya barin ragowar acid a cikin waɗannan katsewar bayan an cire shi. Wannan acid ɗin zai kai hari kan saman ɓangaren sai dai idan an cire shi ko an cire shi.
Domin inganta aikin ƙarfe mai sauƙin sarrafawa, Carpenter ya ƙirƙiro tsarin AAA (Alkali-Acid-Alkali), wanda ke kawar da ragowar acid. Wannan hanyar passivation za a iya kammala ta cikin ƙasa da awanni 2. Ga tsarin mataki-mataki:
Bayan an cire mai, a jiƙa sassan a cikin maganin sodium hydroxide na 5% a 160°F zuwa 180°F (71°C zuwa 82°C) na tsawon mintuna 30. Sannan a wanke sassan sosai a cikin ruwa. Na gaba, a nutsar da sashin na tsawon mintuna 30 a cikin maganin nitric acid na 20% (v/v) wanda ke ɗauke da sodium dichromate na 3 oz/gal (22 g/l) a 120°F zuwa 140°F (49°C) zuwa 60°C). Bayan cire sashin daga wanka, a wanke shi da ruwa sannan a nutsar da shi a cikin maganin sodium hydroxide na tsawon mintuna 30. A sake kurkure sashin da ruwa sannan a bushe, a kammala hanyar AAA.
Rashin sinadarin citric acid yana ƙara zama ruwan dare a tsakanin masana'antun da ke son guje wa amfani da ma'adanai ko mafita waɗanda ke ɗauke da sodium dichromate, da kuma matsalolin zubar da shi da kuma matsalolin tsaro da ke tattare da amfani da shi. Ana ɗaukar Citric acid a matsayin mai kyau ga muhalli ta kowace hanya.
Duk da cewa sinadarin citric acid yana ba da fa'idodi masu kyau ga muhalli, shagunan da suka yi nasara tare da sinadarin inorganic acid passivation kuma ba su da wata damuwa game da tsaro na iya son ci gaba da aiki. Idan waɗannan masu amfani suna da shago mai tsabta, kayan aiki masu kyau da tsafta, na'urar sanyaya ruwa ba tare da gurɓataccen bututun ferrous ba, da kuma tsarin da ke samar da sakamako mai kyau, ƙila babu buƙatar canje-canje.
An gano cewa rashin amfani da sinadarin citric acid a cikin baho yana da amfani ga nau'ikan ƙarfe masu yawa, gami da nau'ikan ƙarfe daban-daban, kamar yadda aka nuna a Hoto na 2. Don saukaka amfani, an haɗa da hanyar passivation ta gargajiya ta nitric acid a Hoto na 1. Lura cewa an bayyana tsoffin tsarin nitric acid a cikin kashi na girma, yayin da sabbin yawan citric acid ana bayyana su a cikin kashi na nauyi. Yana da mahimmanci a lura cewa lokacin aiwatar da waɗannan hanyoyin, daidaita lokacin jiƙa, zafin wanka da yawan amfani yana da mahimmanci don guje wa "walƙiya" da aka bayyana a baya.
Maganin rashin daidaituwa ya bambanta dangane da abun ciki na chromium da halayen injin kowane aji. Lura da ginshiƙan da ke nuni ga Tsarin 1 ko Tsarin 2. Kamar yadda aka nuna a Hoto na 3, Tsarin 1 ya ƙunshi matakai kaɗan fiye da Tsarin 2.
Gwaje-gwajen dakin gwaje-gwaje sun nuna cewa tsarin passivation na citric acid ya fi saurin "walƙiya" fiye da tsarin nitric acid. Abubuwan da ke haifar da wannan harin sun haɗa da yawan zafin wanka, tsawon lokacin jiƙawa, da gurɓatar wanka. Kayayyakin citric acid waɗanda ke ɗauke da hana tsatsa da sauran ƙari kamar abubuwan jika suna samuwa a kasuwa kuma an ruwaito suna rage saurin kamuwa da "lalata walƙiya".
Zaɓin ƙarshe na hanyar wucewa zai dogara ne akan ƙa'idodin karɓa da abokin ciniki ya sanya. Duba ASTM A967 don ƙarin bayani. Ana iya samunsa a www.astm.org.
Sau da yawa ana yin gwaje-gwaje don tantance saman sassan da ba a sarrafa su ba. Tambayar da za a amsa ita ce, "Shin passivation yana cire ƙarfe kyauta kuma yana inganta juriyar tsatsa na matakan yankewa kyauta?"
Yana da mahimmanci cewa hanyar gwajin ta yi daidai da makin da ake tantancewa. Jarabawar da ta yi tsauri sosai za ta gaza kayan aiki masu kyau, yayin da gwaje-gwajen da suka yi sako-sako za su wuce sassa marasa gamsarwa.
Ana iya kimanta taurarewar ruwan sama mai jerin 400 da kuma ƙarfe mai sarrafa kansa ba tare da injin ba a cikin kabad mai iya kiyaye danshi 100% (samfurin ya jike) na tsawon awanni 24 a zafin jiki na 95°F (35°C). Sashen giciye galibi shine saman da ya fi mahimmanci, musamman don matakan yankewa ba tare da yankewa ba. Ɗaya daga cikin dalilan wannan shine cewa sulfide yana da tsayi a cikin alkiblar injin, yana haɗuwa da wannan saman.
Ya kamata a sanya saman da ke da mahimmanci a sama, amma a digiri 15 zuwa 20 daga tsaye don ba da damar asarar danshi. Kayan da ba su da kyau ba zai yi tsatsa ba, kodayake yana iya nuna ɗan tabo.
Ana iya kimanta ma'aunin bakin ƙarfe na Austenitic ta hanyar gwajin danshi. Idan aka gwada hakan, ya kamata a sami ɗigon ruwa a saman samfurin, wanda ke nuna ƙarfe mara lahani ta hanyar kasancewar kowane tsatsa.
Hanyoyin da ake bi wajen cire ƙarfe marasa yankewa da kuma waɗanda ba a cirewa ba a cikin ruwan citric ko nitric acid suna buƙatar matakai daban-daban. Hoto na 3 da ke ƙasa yana ba da cikakkun bayanai kan zaɓin tsari.
(a) Daidaita pH da sodium hydroxide.(b) Duba 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
Hanya mafi sauri ita ce amfani da maganin a cikin ASTM A380, "Aikin Tsaftacewa, Ragewa, da Ragewa na Sassan Karfe, Kayan Aiki, da Tsarin." Gwajin ya ƙunshi goge ɓangaren da maganin jan ƙarfe sulfate/sulfuric acid, ajiye shi a jika na tsawon mintuna 6 da kuma lura da jan ƙarfe plating. A madadin haka, ana iya nutsar da ɓangaren a cikin maganin na tsawon mintuna 6. Idan ƙarfen ya narke, plating na jan ƙarfe yana faruwa. Wannan gwajin bai shafi saman sassan sarrafa abinci ba. Hakanan, bai kamata a yi amfani da shi ga ƙarfe 400 na martensitic ko ƙananan ƙarfe ferritic ferritic ba saboda sakamakon ƙarya na iya faruwa.
A tarihi, an yi amfani da gwajin fesa gishiri na kashi 5% a zafin jiki na 95°F (35°C) don tantance samfuran da aka yi amfani da su. Wannan gwajin ya yi tsauri sosai ga wasu maki kuma gabaɗaya ba a buƙatar tabbatar da cewa passivation yana da tasiri.
A guji amfani da sinadarin chloride mai yawa, wanda zai iya haifar da hare-haren walƙiya masu cutarwa. Idan zai yiwu, a yi amfani da ruwa mai inganci kawai tare da ƙasa da sassa 50 a kowace miliyan (ppm) chloride. Ruwan famfo yawanci ya isa kuma yana iya jure wa har zuwa ɗaruruwan ppm chloride a wasu lokuta.
Yana da mahimmanci a riƙa maye gurbin wanka akai-akai domin kada a rasa ƙarfin passivation, wanda zai iya haifar da walƙiya da lalacewar sassa. Ya kamata a kula da wanka a yanayin zafi mai kyau, domin yanayin zafi mai yawa na iya haifar da tsatsa a yankin.
Yana da mahimmanci a kiyaye takamaiman jadawalin canza mafita yayin yawan samar da kayayyaki don rage yuwuwar gurɓatawa. An yi amfani da samfurin sarrafawa don gwada ingancin wanka. Idan aka kai hari ga samfurin, lokaci ya yi da za a maye gurbin wanka.
Da fatan za a fayyace cewa wasu injuna suna yin bakin ƙarfe ne kawai; yi amfani da irin wannan abin sanyaya da aka fi so don yanke bakin ƙarfe, ban da duk sauran ƙarfe.
Ana kula da sassan rack ɗin DO daban-daban don guje wa hulɗar ƙarfe da ƙarfe. Wannan yana da mahimmanci musamman ga injinan ƙarfe kyauta, saboda ana buƙatar mafita masu gudana kyauta don yaɗa samfuran lalata sulfide da kuma guje wa samuwar aljihunan acid.
Kada a yi amfani da sassan ƙarfe masu ƙarfe masu kauri ko nitride. Juriyar tsatsa na sassan da aka yi wa magani za ta iya raguwa har ta kai ga kai musu hari a cikin baho mai kauri.
Kada a yi amfani da kayan aikin ferrous a cikin wurin aiki wanda ba shi da tsafta sosai. Ana iya guje wa gurɓataccen ƙarfe ta amfani da kayan aikin carbide ko yumbu.
Kar a manta cewa tsatsa na iya faruwa a cikin baho mai lalacewa idan ba a yi wa ɓangaren magani da zafi yadda ya kamata ba. Dole ne a taurare yawan sinadarin carbon da chromium mai yawa don juriya ga tsatsa.
Ana yin amfani da passivation bayan an yi amfani da shi ta hanyar amfani da yanayin zafi wanda ke kiyaye juriya ga tsatsa.
Kada ka yi watsi da yawan sinadarin nitric acid a cikin baho mai narkewa. Ya kamata a yi gwajin lokaci-lokaci ta amfani da tsarin titration mai sauƙi da Carpenter ya bayar. Kada a yi amfani da fiye da ƙarfe ɗaya a lokaci guda. Wannan yana hana rikicewa mai tsada kuma yana guje wa halayen galvanic.
Game da marubutan: Terry A. DeBold ƙwararre ne a fannin bincike da haɓaka ƙarfe mai ƙarfe, kuma James W. Martin ƙwararre ne a fannin ƙarfe a Carpenter Technology Corp. (Reading, PA).
A cikin duniyar da ke cike da ƙa'idodin ƙarewar saman da ke ƙara tsauri, ma'aunin "ƙarfi" masu sauƙi har yanzu suna da amfani. Bari mu dubi dalilin da yasa auna saman yake da mahimmanci da kuma yadda za a iya duba shi a ƙasan shagon ta amfani da na'urori masu sauƙin ɗauka.
Shin kana da tabbacin kana da mafi kyawun abin sakawa don wannan aikin juyawa? Duba guntu, musamman idan ba a kula da shi ba. Halayen guntu na iya gaya maka abubuwa da yawa.