Uqinisekise ukuba iindawo zicutshungulwe ngokweenkcukacha.Ngoku, qiniseka ukuba uthathe amanyathelo okukhusela la malungu kwiimeko ezilindelwe ngabathengi bakho.#isiseko
I-passivation ihlala ilinyathelo elibalulekileyo ekwandiseni ukuxhathisa kwesiseko se-corrosion yamacandelo angenasici kunye neendibano.
I-Passivation yindlela yokwenziwa kwe-post-fabrication eyandisa ukuxhathisa kwe-corrosion yendalo ye-alloys yensimbi engenasici evelisa i-workpiece.Akukona unyango lokuhla, kwaye akuyiyo i-coating yepeyinti.
Akukho mvumelwano ngokubanzi kwindlela echanekileyo yendlela yokugqithisa isebenza ngayo.Kodwa kuqinisekileyo ukuba kukho ifilimu ye-oxide ekhuselayo kumphezulu we-passivated stainless steel.Le filimu engabonakaliyo icingelwa ukuba incinci kakhulu, ingaphantsi kwe-intshi ye-0.0000001, malunga ne-1 / 100,000 ubukhulu beenwele zomntu!
Inxalenye ecocekileyo, esandul 'umatshini, epholisiweyo okanye ekhethiweyo yensimbi engenasici iya kufumana ngokuzenzekelayo le filimu ye-oxide ngenxa yokuvezwa kwayo kwi-oksijeni ye-atmospheric.Ngaphantsi kweemeko ezifanelekileyo, olu luhlu lwe-oxide olukhuselekileyo lugubungela ngokupheleleyo yonke indawo yenxalenye.
Enyanisweni, nangona kunjalo, ukungcola okufana nokungcola kwevenkile okanye iinqununu zentsimbi ezivela kwizixhobo zokusika zinokutshintshela kwindawo yentsimbi engenasici ngexesha lokucoca.Ukuba ayisuswanga, le mizimba yangaphandle inokunciphisa ukusebenza kwefilimu yokuqala yokukhusela.
Ngexesha lokucoca, ukulandelela izixa zentsimbi ekhululekileyo kunokugqoka isixhobo kwaye kudluliselwe kumphezulu womsebenzi wensimbi engenasici.Kwezinye iimeko, umgca omncinci we-rust ungabonakala kwi-part.Oku ngokwenene kukugqwala kwentsimbi ngesixhobo, kungekhona kwisiseko sesinyithi.Ngamaxesha athile, iinqununu zentsimbi ezifakwe kwizixhobo zokusika okanye ukubola kweemveliso zazo kunokubangela ukuguguleka.
Ngokufanayo, iincinci ezincinci ze-ferrous shop dilt zingabambelela kumphezulu wengxenye.Nangona isinyithi sinokubonakala sikhazimulayo kwimeko yomatshini, emva kokuvezwa emoyeni, iinqununu ezingabonakaliyo zentsimbi yamahhala zingabangela ukugqwala komhlaba.
I-sulfides evezwayo nayo ingaba yingxaki.Bavela ekufakeni isulfure kwintsimbi engenasici ukuphucula i-machinability.Sulfides yandisa amandla e-alloy ukwenza ii-chips ngexesha lokucoca, ezinokutshatyalaliswa ngokupheleleyo kwisixhobo sokusika.Ngaphandle kokuba iinxalenye zigqitywe ngokufanelekileyo, i-sulfides ingaba yindawo yokuqala yokubola komhlaba kwiimveliso eziveliswayo.
Kuzo zombini ezi meko, i-passivation iyadingeka ukunyusa ukuxhathisa kwemvelo ye-corrosion ye-stainless steel stainless.Isusa izinto ezingcolileyo ezingaphezulu, ezifana ne-ferrous shop dirt particles kunye neentsimbi zentsimbi kwizixhobo zokusika, ezinokuthi zenze i-rust okanye zibe yindawo yokuqala ye-corrosion.
Inkqubo yamanyathelo amabini ibonelela ngeyona ndlela ingcono yokuxhathisa ukubola: 1. Ukucoca, inkqubo esisiseko kodwa ngamanye amaxesha ingahoywa;2. Ukuhlamba nge-asidi okanye unyango lwe-passivation.
Ukucoca kufuneka isoloko iphambili.Indawo kufuneka icocwe ngokucokisekileyo kwigrisi, into yokupholisa okanye enye inkunkuma yevenkile ukuze kuxhathiswe umhlwa.Ubutyobo beMachining okanye obunye ubumdaka bevenkile bunokusulwa ngocoselelo kwinxalenye.Iidegreas zentengiso okanye izicoci zingasetyenziselwa ukususa ii-oyile zenkqubo okanye ii-coolants.Imiba yangaphandle enjengeendlela zokuchola ezifana ne-thermal bending oxides zisuswe.
Ngamanye amaxesha umsebenzi womatshini unokutsiba ukucoca okusisiseko, ngempazamo ecinga ukuba ukucocwa kunye nokunyanzeliswa kuya kwenzeka ngaxeshanye ngokuthi nkxu indawo egcwele igrisi kwindawo yokuhlambela eneasidi.Ayinakwenzeka loo nto.Ngokuchaseneyo, igrisi engcolisekileyo idibana neasidi ukuze yenze amaqamza omoya.
Ukwenza izinto zibe mbi ngakumbi, ungcoliseko lwezisombululo ze-passivation, ezithi ngamanye amaxesha ziqulathe ukuxinana okuphezulu kweekloridi, zinokubangela "ukudanyaza." Ngokungafaniyo nokufumana ifilimu yeoksidi oyifunayo enomgangatho omenyezelayo, ococekileyo, ongagugiyo, ukufakwa kwe-flash kungakhokelela kumphezulu otyalwe kakhulu okanye omnyama-ukuwohloka komphezulu okulungiselelwe ukwenza ngcono.
Izahlulo ezenziwe martensitic steel stainless [magnetic, ngokwemodare ukumelana umhlwa, amandla isivuno ukuya kuthi ga malunga 280 ksi (1930 MPa)] ziqiniswe kumaqondo obushushu aphezulu kwaye emva koko ubushushu ukuqinisekisa ubulukhuni obufunwayo kunye noomatshini properties.Precipitation lukhuni ingxubevange, ezinamandla angcono kunye ne-corrosion ye-corrosion yokumelana ne-corrosion ephantsi, i-corrosion ye-corrosion iphathwa kakuhle, i-corrosion ye-corrosion ye-corrosion ephantsi, i-corrosion ye-corrosion ephathwayo. , kwaye emva koko wagqiba.
Kule meko, inxalenye kufuneka ihlanjululwe ngokucokisekileyo kunye ne-degreaser okanye i-cleaner ukususa nayiphi na impawu yokusika ulwelo ngaphambi konyango lobushushu.Kungenjalo, ulwelo lokusika oluseleyo kwinxalenye lunokubangela i-oxidation egqithisileyo.Le meko inokubangela ukuba iindawo ezingaphantsi komgangatho zihlanjululwe emva kokuba isikali sisusiwe nge-asidi okanye iindlela ezixubekileyo.Ukuba ukusika ulwelo kuvunyelwe ukuba kuhlale kwindawo eqaqambileyo ye-vacuum , njenge-atmospheric ye-furna, i-amospheric inokuthi yenzeke kwindawo yokukhusela i-vacuum okanye i-furna. ukumelana nomhlwa.
Emva kokucoca ngokucokisekileyo, iinxalenye zensimbi ezingenasici ziyakwazi ukucwiliswa kwindawo yokuhlamba i-asidi.Naziphi na iindlela ezintathu zingasetyenziswa - i-nitric acid passivation, i-nitric acid kunye ne-sodium dichromate passivation, kunye ne-citric acid passivation.Yeyiphi indlela yokusetyenziswa ixhomekeke kwibakala lensimbi engenasici kunye neendlela ezichaziweyo zokumkela.
Amabakala e-chrome-nickel anganyangekiyo ngakumbi kwi-corrosion-resistant kwi-20% (v / v) yokuhlamba i-nitric acid (Umfanekiso 1) .Njengoko kubonisiwe kwitheyibhile, isinyithi esingenasici esinganyangekiyo sinokugqithiswa ngokongeza i-sodium dichromate kwibhafu ye-nitric acid, okwenza isisombululo ngakumbi i-oxidizing kwaye ikwazi ukwenza i-sodium i-concentration ye-sodium kwi-sodium i-concentration ye-sodium kwi-passive film. i-asidi ye-tric ukuya kwi-50% ngevolumu.Zombini ukongezwa kwe-sodium dichromate kunye ne-concentration ephezulu ye-nitric acid kunciphisa ithuba lokukhanya okungafunekiyo.
Inkqubo ye-passivating free-machining steels stainless (kwakhona kuboniswe kwi-Figure 1) ihluke ngandlel' ithile kuleyo ye-non-free-machining imigangatho yensimbi engenasici. Oku kungenxa yokuba ngexesha lokugqithisa kwi-asidi ye-nitric bath, ezinye okanye zonke i-sulfide ze-machinable grade machinable sulfide ziyasuswa, zenze i-microscopic surface discontinuities in the machine discontinuities.
Nokuba ukuhlanjululwa kwamanzi okusebenzayo ngokubanzi kunokushiya i-asidi eshiyekileyo kwezi discontinuities emva kokudlula.
Ukugqithisa ngokufanelekileyo isinyithi esingenasici esingenakulinganiswa, uMchweli uye waphuhlisa inkqubo ye-AAA (i-Alkali-Acid-Alkali), eyenza i-asidi eseleyo.Le ndlela yokugqithisa ingagqitywa ngaphantsi kweeyure ze-2.
Emva kokunciphisa, gcoba iinxalenye kwi-5% yesisombululo se-sodium hydroxide kwi-160 ° F ukuya kwi-180 ° F (71 ° C ukuya ku-82 ° C) imizuzu engama-30. Emva koko uhlambulule iinxalenye ngokucokisekileyo emanzini. Okulandelayo, cwilisa inxalenye yemizuzu ye-30 kwi-20% (v / v) isisombululo se-nitric / l ye-nitric / l equkethe i-12 g ye-sodium ye-120 ye-sodium equkethe i-3 oz 40°F (49°C) ukuya kuma-60°C).Emva kokususa inxalenye ekuhlambeni, yihlambulule ngamanzi uze uyifake kwisisombululo se-sodium hydroxide enye imizuzu engama-30. Hlanza inxalenye kwakhona ngamanzi kwaye uyomile, uzalise indlela ye-AAA.
I-Citric acid passivation iyanda ngokuthandwa ngabavelisi abanqwenela ukuphepha ukusetyenziswa kwee-acids zamaminerali okanye izisombululo eziqukethe i-sodium dichromate, kunye nemiba yokulahla kunye nokukhathazeka okukhulu kokhuseleko oluhambelana nokusebenzisa kwabo.I-asidi ye-Citric ithathwa njengendalo engqongileyo kuzo zonke iindlela.
Ngelixa i-citric acid passivation inika iingenelo ezithandekayo zokusingqongileyo, iivenkile eziye zanempumelelo kunye ne-inorganic acid passivation kwaye zingenazo iinkxalabo zokhuseleko zinokufuna ukuhlala kwikhosi.Ukuba aba basebenzisi banevenkile ecocekileyo, izixhobo ezigcinwe kakuhle nezicocekileyo, i-coolant yasimahla yokungcolisa i-ferrous shop, kunye nenkqubo evelisa iziphumo ezilungileyo, kusenokungabikho mfuneko yokwenyani yotshintsho.
Ukugqithiswa kwindawo yokuhlambela i-citric acid kufunyenwe luncedo kuluhlu olukhulu lweentsimbi ezingenasici, kubandakanywa amabakala amaninzi ensimbi engenasici, njengoko kuboniswe kwi-Figure 2. Ukuze kube lula, indlela yendabuko ye-nitric acid passivation kuMzobo 1 ifakiwe.Qaphela ukuba ukuqulunqwa kwe-asidi ye-nitric endala kubonakaliswe kwipesenti yevolumu, ngelixa i-citric acid concentrations entsha ibonakaliswe ngokucokisekileyo kwiinkqubo ze-bancing ye-bancing ibonakaliswe ngokucokisekileyo kwiipesenti ze-bancing yeqondo lokushisa. kwaye ugxininiso lubalulekile ukuphepha "ukudanyaza" okuchazwe ngaphambili.
Ukunyangwa kwe-passivation kuyahluka ngokomxholo we-chromium kunye neempawu ze-machining zebakala ngalinye.Qaphela iikholamu ezibhekiselele nokuba yiNkqubo 1 okanye Inkqubo 2.Njengoko kuboniswe kuMfanekiso 3, Inkqubo 1 ibandakanya amanyathelo ambalwa kuneNkqubo yesi-2.
Iimvavanyo zebhubhoratri zibonise ukuba inkqubo ye-citric acid passivation iyakwazi "ukukhanya" kunenkqubo ye-nitric acid.Izinto ezibangela ukuhlaselwa kolu hlaselo ziquka ubushushu obuphezulu bokuhlamba, ixesha elide lokucwina, kunye nokungcoliswa kwebhafu.Imveliso ye-asidi ye-citric equkethe i-corrosion inhibitors kunye nezinye izongezo ezifana ne-agent yokumanzisa zifumaneka ngokurhweba kwaye zichazwe ukunciphisa i-susceptibility susceptibility.
Ukhetho lokugqibela lwendlela yokuphumelela luya kuxhomekeka kwindlela yokwamkelwa ebekwe ngumthengi.Bona i-ASTM A967 ngeenkcukacha.Inokufumaneka kwi-www.astm.org.
Uvavanyo luhlala lwenziwa ukuvandlakanya umphezulu weendawo ezigqithisiweyo. Umbuzo omawuphendule ngulo, "Ingaba i-passivation iyayisusa i-iron esimahla kwaye ikhulisa ukuxhathisa umhlwa kumabanga asimahla?"
Kubalulekile ukuba indlela yovavanyo ihambelane nebakala elivavanywayo.Uvavanyo olungqongqo kakhulu luya kusilela kwiimathiriyeli ezilungileyo ngokugqibeleleyo, ngelixa iimvavanyo eziyeke kakhulu ziya kuphumelela iindawo ezinganelisiyo.
I-400 series precipitation lukhuni kunye ne-free-machining steels stainless zihlolwe kakuhle kwikhabhinethi ekwazi ukugcina i-100% yomswakama (iisampulu ezimanzi) kwiiyure ze-24 kwi-95 ° F (35 ° C) .Icandelo lomnqamlezo lihlala liwona mhlaba obaluleke kakhulu, ngakumbi kumabanga akhululekileyo.
Imiphezulu ebalulekileyo kufuneka ibekwe phezulu, kodwa kwi-15 ukuya kwi-20 degrees ukusuka kwinqanaba ukuze uvumele ukulahleka komswakama.
I-Austenitic stainless steel grade zingaphinda zihlolwe ngovavanyo lokufuma.Xa kuvavanywa njalo, amaconsi amanzi kufuneka abe khona phezu kwesampulu, ebonisa isinyithi samahhala ngobukho bayo nayiphi na irusi.
Iinkqubo ze-passivating ezisetyenziswa ngokuqhelekileyo zisetyenziselwa ukusika kunye neentsimbi ezingenasici ezingenasici kwi-citric okanye i-nitric acid solutions zifuna iinkqubo ezahlukeneyo.Umfanekiso 3 apha ngezantsi unika iinkcukacha malunga nokukhethwa kwenkqubo.
(a) Lungisa i-pH nge-sodium hydroxide.(b) Jonga uMfanekiso 3 (c) i-Na2Cr2O7 imele i-3 oz/gallon (22 g/l) i-sodium dichromate kwi-20% ye-nitric acid.Enye indlela kulo mxube yi-50% ye-nitric acid ngaphandle kwe-sodium dichromate.
Indlela ekhawulezayo kukusebenzisa isisombululo kwi-ASTM A380, "Ukuziqhelanisa okuMgangatho wokuCoca, ukuKhawulwa, kunye nokuPassyithwa kwaMacandelo eNtsimbi eNgatyiwayo, izixhobo, kunye neeNkqubo." Uvavanyo lubandakanya ukosula inxalenye ngesisombululo sobhedu sesulfate / sulfuric acid, ukuyigcina imanzi imizuzu emi-6 kwaye ijonge enye indawo yobhedu kwi-iron. isombulula, i-copper plating iyenzeka.Olu vavanyo alufanele lusetyenziswe kwiindawo zokulungisa ukutya.Kwakhona, akufanele kusetyenziswe i-400 series martensitic okanye i-chromium ephantsi yeentsimbi ze-ferritic njengoko iziphumo zobuxoki zingenzeka.
Ngokwembali, i-5% yovavanyo lwesitshizi setyuwa kwi-95 ° F (35 ° C) nayo iye yasetyenziselwa ukuvavanya iisampulu eziphumeleleyo.
Kuphephe ukusebenzisa iikloridi ezigqithisileyo, ezinokubangela uhlaselo oluyingozi lweflash.Ukuba kunokwenzeka, sebenzisa amanzi akumgangatho ophezulu kuphela anamalungu angaphantsi kwama-50 ngesigidi (ppm) sekloride. Amanzi ompompo adla ngokwaneleyo kwaye anokunyamezela ukuya kutsho kumakhulu aliqela ekloridi yeppm kwezinye iimeko.
Kubalulekile ukutshintsha indawo yokuhlambela rhoqo ukuze ugweme ilahleko ye-passivation enokuthi ibangele i-flashover kunye neendawo ezonakeleyo.
Kubalulekile ukugcina ishedyuli echanekileyo yokutshintsha isisombululo ngexesha lokuveliswa kwemveliso ephezulu ukunciphisa amandla okungcola.Isampuli yokulawula isetyenziselwa ukuvavanya ukusebenza kakuhle kwebhafu.Ukuba isampuli ihlaselwe, lixesha lokutshintsha indawo yokuhlamba.
Nceda ucacise ukuba oomatshini abathile benza insimbi engenasici kuphela;sebenzisa isixhobo sokupholisa esithandwayo ukusika intsimbi engatyiwa, ngaphandle kwazo zonke ezinye iintsimbi.
I-DO i-rack parts iphathwa ngabanye ukuze igweme i-metal-to-metal contact.Oku kubaluleke kakhulu kwi-machining machining steel stainless steel, njengoko i-passivation ehambayo kunye nezisombululo ezigungxulwayo zifunekayo ukusabalalisa iimveliso ze-corrosion kwi-sulfides kwaye ugweme ukubunjwa kweepokotho ze-asidi.
Musa ukudlula i-carburized okanye i-nitrided stainless steel parts.I-corrosion resistance ye-corrosion yeendawo eziphathwayo zinokuncitshiswa ukuya kwindawo apho ziya kuhlaselwa kwindawo yokuhlambela.
Musa ukusebenzisa izixhobo ze-ferrous kwindawo yokusebenzela engacocekanga ngokukodwa.I-grit yensimbi inokuphetshwa ngokusebenzisa i-carbide okanye izixhobo ze-ceramic.
Ungalibali ukuba i-corrosion ingenzeka kwi-bath passivation ukuba inxalenye ayiphathwanga ngokufanelekileyo ubushushu.Ikhabhoni ephezulu, i-chromium martensitic grade ephezulu kufuneka iqiniswe ukuxhathisa ukubola.
I-passivation idla ngokuqhutywa emva kobushushu obulandelayo kusetyenziswa amaqondo obushushu agcina ukuxhathisa ukudleka.
Ungayihoyi i-nitric acid concentration kwi-passivation bath.Iitshekhi zePeriodic kufuneka zenziwe ngokusebenzisa inkqubo ye-titration elula ebonelelwa nguCarpenter.Musa ukudlula ngaphezu kwentsimbi enye engenasici ngexesha.Oku kuthintela ukudideka okuxabisa kakhulu kwaye kuphephe ukuphendula kwe-galvanic.
Malunga nababhali: UTerry A. DeBold uyingcali yophando lwensimbi engenasici kunye nophuhliso kunye noJames W. Martin uyi-metallurgist yebar kwiCarpenter Technology Corp. (Ukufunda, PA).
Kwihlabathi lemilinganiselo yokugqiba engqongqo, imilinganiselo “yoburhabaxa” iseluncedo. Makhe sijonge ukuba kutheni umlinganiselo womphezulu ubalulekile kwaye ungajongwa njani kumgangatho wevenkile ngeegeyiji eziphathwayo ezintsonkothileyo.
Uqinisekile ukuba unelona fakelo lungcono kulo msebenzi wokujika?Jonga itshiphu, ngakumbi ukuba ishiywe ingajongwanga.Iimpawu zeChip zinokukuxelela okuninzi.