Ị hụla na a na-edozi akụkụ ndị ahụ na nkọwapụta. Ugbu a, jide n'aka na ị meela ihe iji chebe akụkụ ndị a na ọnọdụ ndị ahịa gị na-atụ anya ya.#Basic
Passivation ka bụ nzọụkwụ dị oke egwu n'ịkwalite nguzogide corrosion bụ isi nke akụkụ igwe anaghị agba nchara na mgbakọ. Ọ nwere ike ime ka ọdịiche dị n'etiti arụmọrụ na-eju afọ na ọdịda akaghi aka. E gburu ya n'ụzọ na-ezighị ezi, ngafe nwere ike ime ka corrosion.
Passivation bụ usoro mmepụta ihe nke na-eme ka nguzogide corrosion dị n'ime ya nke igwe anaghị agba nchara na-emepụta ihe na-arụ ọrụ.
Enweghị nkwekọrịta n'ozuzu na usoro ziri ezi nke otú passivation si arụ ọrụ. Ma o doro anya na e nwere ihe nkiri oxide na-echebe n'elu igwe anaghị agba nchara. A na-eche na ihe nkiri a na-adịghị ahụ anya dị oke mkpa, ihe na-erughị 0.0000001 inch, ihe dị ka 1/100,000th nke ntutu ntutu mmadụ!
Igwe anaghị agba nchara dị ọcha, nke ọhụrụ, nke a na-egbuke egbuke ma ọ bụ pickled ga-enweta ihe nkiri oxide a na-akpaghị aka n'ihi ikpughe ya na ikuku oxygen. N'okpuru ọnọdụ dị mma, oyi akwa oxide a na-echebe kpamkpam na-ekpuchi akụkụ niile nke akụkụ ahụ.
Otú ọ dị, na omume, ihe ndị na-emerụ emerụ dị ka unyi ụlọ ahịa ma ọ bụ ngwongwo ígwè sitere na ngwá ọrụ ịkpụ nwere ike ịnyefe n'elu akụkụ igwe anaghị agba nchara n'oge nhazi. Ọ bụrụ na ewepụghị ya, ndị mba ọzọ ndị a nwere ike ibelata irè nke ihe nkiri nchebe mbụ.
N'oge machining, Chọpụta ichekwa nke free ígwè nwere ike na-eyi apụ ngwá ọrụ na nyefee n'elu nke igwe anaghị agba nchara workpiece.N'ọnọdụ ụfọdụ, a mkpa oyi akwa nke nchara nwere ike ịpụta na part.This bụ n'ezie corrosion nke ígwè site na ngwá ọrụ, ọ bụghị nke isi metal.Mgbe ụfọdụ, crevices nke agbakwunyere ígwè irighiri si ọnwụ ngwaọrụ ma ọ bụ ha corrosion ngwaahịa nwere ike ime ka ozize nke nchara n'onwe ya.
N'otu aka ahụ, obere akụkụ nke unyi ụlọ ahịa ferrous nwere ike ịrapagidesi ike n'elu akụkụ ahụ. Ọ bụ ezie na ígwè nwere ike ịpụta na-egbuke egbuke na steeti igwe, mgbe ikpughe ikuku, ihe ndị a na-adịghị ahụ anya nke ígwè n'efu nwere ike ime ka nchara nchara.
Sulfide ekpughere nwekwara ike ịbụ nsogbu. Ha na-abịa site na ịgbakwunye sọlfọ na igwe anaghị agba nchara iji meziwanye machinability.Sulfides na-abawanye ikike alloy na-emepụta ibe n'oge a na-eji ígwè ọrụ, nke a ga-ewepụ kpamkpam n'ibe ngwá ọrụ. Ọ bụrụ na akụkụ ahụ na-agafe nke ọma, sulfides nwere ike ịghọ mmalite nke corrosion elu na ngwaahịa emepụtara.
N'okwu abụọ ahụ, a na-achọ passivation iji bulie nguzogide corrosion eke nke igwe anaghị agba nchara. Ọ na-ewepụ ihe ndị na-emerụ emerụ n'elu, dị ka ferrous ụlọ ahịa unyi na ihe ndị dị na ígwè na-egbutu ngwá ọrụ, nke nwere ike ịmepụta nchara ma ọ bụ ghọọ mmalite maka corrosion.Passivation na-ewepụkwa sulfides kpughere n'elu nke free-ịcha igwe anaghị agba nchara.
Usoro ụzọ abụọ na-enye nkwụsị nke corrosion kacha mma: 1. Nhicha, usoro bụ isi ma mgbe ụfọdụ a na-eleghara anya;2. Acid bat ma ọ bụ ọgwụgwọ passivation.
Nchacha kwesịrị ịbụ ihe kacha mkpa mgbe niile. A ghaghị ihicha ihe ndị dị n'elu nke griiz, coolant ma ọ bụ ihe mkpofu ụlọ ahịa ndị ọzọ maka nkwụsị nke corrosion kacha mma. Enwere ike iji nlezianya kpochapụ ihe mkpofu ma ọ bụ ihe ndị ọzọ na-emepụta ihe na ụlọ ahịa.
Mgbe ụfọdụ a igwe ọrụ nwere ike ikwu isi ihicha, n'ụzọ hiere ụzọ na-eche na ihicha na passivation ga-eme n'out oge site nanị itinye a griiz-bujuru akụkụ na acid bath.That agaghị eme.Conversely, mmeru griiz reacts na acid na-etolite ikuku bubbles.These egosipụta na-anakọta na workpiece elu na-egbochi passivation.
Iji mee ka ihe ka njọ, mmetọ nke ngwọta passivation, nke nwere mgbe ụfọdụ nwere nnukwu chlorides, nwere ike ime ka "na-egbuke egbuke." N'adịghị ka ịnweta ihe nkiri oxide chọrọ na elu na-egbuke egbuke, dị ọcha, na-eguzogide corrosion, flash etching nwere ike ime ka elu dị elu ma ọ bụ gbachiri agbachi - mmebi elu nke e mere ngafe ka e mere iji kwalite.
Akụkụ ndị sitere na igwe anaghị agba nchara nke martensitic [magnetic, moderately eguzogide corrosion, na-enye ike ruo ihe dị ka 280 ksi (1930 MPa)] na-eme ka obi sie ike na okpomọkụ dị elu wee mee ka ọ dị ọkụ iji hụ na ike siri ike na ihe eji arụ ọrụ.
N'okwu a, a ghaghị ihicha akụkụ ahụ nke ọma na onye na-ekpo ọkụ ma ọ bụ onye na-ehicha ihe iji wepụ ihe ọ bụla nke ịcha mmiri tupu ọgwụgwọ okpomọkụ. Ma ọ bụghị ya, mmiri mmiri na-egbutu nke fọdụrụ na akụkụ ahụ nwere ike ime ka oxidation dị ukwuu. Nke a nwere ike ime ka akụkụ ndị na-adịghị ala ala na-agbaji mgbe e wepụsịrị ọnụ ọgụgụ ahụ site na acid ma ọ bụ abrasive ụzọ. .
Mgbe ihichachara nke ọma, akụkụ igwe anaghị agba nchara nwere ike imikpu n'ime mmiri ịsa mmiri na-agafe agafe. Enwere ike iji ụzọ atọ ọ bụla - nitric acid passivation, acid nitric acid na sodium dichromate passivation, na citric acid passivation. Kedu usoro a ga-eji na-adabere na ọkwa nke igwe anaghị agba nchara na njedebe nnabata a kapịrị ọnụ.
More corrosion-eguzogide chrome-nickel grades nwere ike passivated na a 20% (v / v) nitric acid bath (Nyocha 1) .Dịka e gosiri na tebụl, obere eguzogide ọgwụ igwe anaghị agba nchara nwere ike gafere site na-agbakwụnye sodium dichromate na a nitric acid bath, na-eme ka ngwọta ọzọ oxidizing na-enwe ike na-etolite a passive film na-agafe agafe na metal n'elu chromate 0 nitric acid na-abawanye na chromate acid. site na olu.Ma mgbakwunye nke sodium dichromate na ntinye dị elu nke nitric acid na-ebelata ohere nke ọkụ ọkụ na-achọghị.
Usoro maka passivating free-machining igwe anaghị agba nchara (nke egosiri na Figure 1) dịtụ iche na nke na-abụghị free-machining igwe anaghị agba nchara grades.Nke a bụ n'ihi na n'oge passivation na a ahụkarị nitric acid bath, ụfọdụ ma ọ bụ niile nke sọlfọ-nwere machinable ọkwa sulfides na-ewepụ, na-eke microscopic discontinuities na akụkụ nke elu.
Ọbụlagodi nchacha mmiri nke na-adịkarị mma nwere ike ịhapụ acid residual na nkwụsị ndị a mgbe passivation. Nke a acid ga-awakpo n'elu akụkụ ahụ ọ gwụla ma ewepụghị ya ma ọ bụ wepụ ya.
Iji rụọ ọrụ nke ọma passivate mfe machinable igwe anaghị agba nchara, Carpenter emepụtala usoro AAA (Alkali-Acid-Alkali), nke neutralizes residual acid.This passivation usoro nwere ike mechaa n'ime ihe na-erughị awa 2. Nke a bụ nzọụkwụ-site-nzọụkwụ usoro:
Mgbe ịchachara, gbanye akụkụ ahụ na 5% sodium hydroxide ngwọta na 160 ° F ruo 180 ° F (71 ° C ruo 82 ° C) maka nkeji 30. Mgbe ahụ, kpochaa akụkụ ahụ nke ọma na mmiri. Ọzọ, gbanye akụkụ ahụ maka nkeji 30 na 20% (v / v) nitric acid ngwọta nwere 22 chromate / l 22 chromate / l) sodium di chromate / l 2 chromate / l. Celsius F (49°C) ruo 60°C.Mgbe o wepụsịrị akụkụ ahụ na bat ahụ, kpochaa ya na mmiri wee tinye ya na ngwọta sodium hydroxide maka nkeji 30 ọzọ. Na-ehichapụ akụkụ ahụ ọzọ na mmiri na nkụ, na-emecha usoro AAA.
Citric acid passivation na-ewu ewu na ndị na-emepụta ihe na-achọ ka ha zere iji mineral acids ma ọ bụ ihe ngwọta nwere sodium dichromate, yana nsogbu mkpofu na nchebe dị ukwuu nke metụtara ojiji ha. A na-ewere Citric acid na gburugburu ebe obibi n'ụzọ ọ bụla.
Ọ bụ ezie na citric acid passivation na-enye uru gburugburu ebe obibi mara mma, ụlọ ahịa ndị nweworo ihe ịga nke ọma na passivation inorganic acid na enweghị nchebe nchebe nwere ike ịchọrọ ịnọgide na-eme ihe. Ọ bụrụ na ndị ọrụ a nwere ụlọ ahịa dị ọcha, nke a na-edozi nke ọma na nke dị ọcha, coolant free nke ụlọ ahịa ferrous ferrous, na usoro nke na-arụpụta ezigbo ihe, ọ gaghị adị mkpa maka mgbanwe.
Passivation na citric acid bath achọpụtara na ọ bara uru maka nnukwu ụdị igwe anaghị agba nchara, gụnyere ọtụtụ akara ule onye anaghị agba nchara, dị ka e gosiri na Figure 2. Maka mma, usoro nitric acid passivation nke omenala na Figure 1 gụnyere. Rịba ama na a na-egosipụta usoro mmepụta nitric acid ochie na pasent olu, ebe a na-egosipụta ntinye uche nke citric ọhụrụ ọhụrụ na pasent nke okpomọkụ, mgbe ọ dị mkpa iji nlezianya mee ihe na oge okpomọkụ. iji zere “ọkụ” a kọwara na mbụ.
Usoro ọgwụgwọ ngafe na-adịgasị iche dabere na ọdịnaya chromium na njirimara nhazi nke ọkwa ọ bụla. Rụba ama na kọlụm ndị na-ezo aka ma ọ bụ Usoro 1 ma ọ bụ Usoro 2. Dị ka egosiri na foto 3, Usoro 1 gụnyere usoro ole na ole karịa Usoro 2.
Nnwale nyocha ụlọ nyocha egosila na usoro passivation citric acid na-adịkarị mfe "na-egbuke egbuke" karịa usoro nitric acid. Ihe ndị na-enye aka na mwakpo a gụnyere oke okpomọkụ bat, oke ogologo oge, na mmetọ bat. Ngwaahịa Citric acid nwere ihe mgbochi corrosion na ihe mgbakwunye ndị ọzọ dị ka ndị na-emepụta wetting na-ere ahịa ma na-akọ na ọ ga-ebelata ihe ize ndụ maka ire ere.
Nhọrọ ikpeazụ nke usoro ngafe ga-adabere na njirisi nnabata nke ndị ahịa manyere. Lee ASTM A967 maka nkọwa. Enwere ike ịnweta ya na www.astm.org.
A na-emekarị ule iji nyochaa elu akụkụ ndị na-agafe agafe. Ajụjụ ịza bụ, "passivation ọ na-ewepụ ígwè n'efu ma na-ebuli nguzogide corrosion nke akara ule n'efu?"
Ọ dị mkpa na usoro nyocha ahụ dabara na ọkwa a na-enyocha. Nnwale ndị siri ike ga-adaba ihe dị mma nke ọma, ebe ule ndị na-adịghị mma ga-agafe akụkụ ndị na-adịghị mma.
400 usoro mmiri ozuzo hardening na free-machining igwe anaghị agba nchara na-kacha mma enyocha na a kabinet ike ịnọgide na-enwe 100% iru mmiri (mmiri samples) maka 24 awa na 95 ° F (35 Celsius C) .The cross ngalaba bụ mgbe kasị oké egwu elu, karịsịa maka free-ịcha grades.One ihe kpatara nke a bụ na sulfide bụ elongated igwe n'elu a.
Ekwesịrị idobe ebe dị egwu n'elu, ma na 15 ruo 20 degrees site na vetikal iji mee ka mmiri ghara ikpofu. Ihe na-agafe agafe nke ọma agaghị adị ka nchara, ọ bụ ezie na ọ nwere ike igosi ntakịrị ntụpọ.
Enwere ike nyochaa ọkwa Austenitic igwe anaghị agba nchara site na nyocha iru mmiri. Mgbe a nwalere ya, ụmụ irighiri mmiri kwesịrị ịdị n'elu ihe nlele ahụ, na-egosi ígwè n'efu site na nchara ọ bụla.
Usoro maka ịgafefe nke a na-ejikarị eme ihe n'efu na nke na-adịghị egbutu igwe anaghị agba nchara na citric ma ọ bụ nitric acid ngwọta chọrọ usoro dị iche iche. Foto 3 dị n'okpuru na-enye nkọwa gbasara nhọrọ usoro.
(a) Dozie pH na sodium hydroxide.
Usoro ngwa ngwa bụ iji ngwọta dị na ASTM A380, "Standard Practice for Cleaning, Descaling, and Passivation of Stainless Steel Parts, Equipment, and Systems. "Nnwale ahụ gụnyere ihichapụ akụkụ ahụ na ngwọta ọla kọpa sulfate / sulfuric acid, na-edebe ya mmiri maka nkeji 6 ma na-ekiri maka ịkwanye ọla kọpa. ting emee. E kwesịghị iji ule a mee ihe n'elu akụkụ nke nhazi nri. Ọzọkwa, e kwesịghị iji ya mee ihe maka usoro 400 martensitic ma ọ bụ obere chromium ferritic steels dị ka nsonaazụ ụgha nwere ike ime.
N'akụkọ ihe mere eme, a na-ejikwa ule ịgba nnu 5% dị na 95°F (35°C) iji nyochaa ihe nlele agafeghị oke.
Zere iji chloride na-agafe agafe, nke nwere ike ịkpata mwakpo ọkụ na-emerụ ahụ. Ọ bụrụ na ọ ga-ekwe omume, jiri naanị mmiri dị elu nke na-erughị akụkụ 50 kwa nde (ppm) chloride. Mmiri mgbata na-abụkarị nke zuru oke ma nwee ike ịnagide ihe ruru narị ppm chloride n'ọnọdụ ụfọdụ.
Ọ dị mkpa iji dochie bat ahụ mgbe niile iji zere nkwụsị nke ikike ngafe nke nwere ike iduga na-egbuke egbuke na akụkụ mebiri emebi.
Ọ dị mkpa iji nọgide na-enwe usoro mgbanwe mgbanwe ngwọta dị iche iche n'oge mmepụta dị elu iji belata ohere nke mmetọ. A na-eji akara nchịkwa iji nwalee ịdị irè nke bat ahụ. Ọ bụrụ na a na-awakpo ihe nlele ahụ, ọ bụ oge iji dochie bat ahụ.
Biko kọwaa na ụfọdụ igwe na-eme igwe anaghị agba nchara naanị;jiri otu coolant ọkachamma ma bechapụ igwe anaghị agba nchara, ewezuga ọla ndị ọzọ niile.
A na-emeso akụkụ DO rack n'otu n'otu iji zere kọntaktị metal-to-metal. Nke a dị mkpa karịsịa maka free machining igwe anaghị agba nchara, dị ka free-asọ asọ na flushing ngwọta na-achọrọ na-agbasasị corrosion ngwaahịa na sulfides ma zere guzobe nke acid akpa.
Adịla passivate carburized ma ọ bụ nitrided igwe anaghị agba nchara akụkụ.The corrosion eguzogide nke akụkụ otú mesoo nwere ike ibelata ruo n'ókè ebe ha ga-wakpo na passivation bat.
Ejila ngwaọrụ ferrous na gburugburu ogbako na-adịghị ọcha nke ọma. Enwere ike ịzere grit ígwè site na iji carbide ma ọ bụ seramiiki ngwaọrụ.
Echefula na corrosion nwere ike ime na bat passivation ma ọ bụrụ na akụkụ ahụ adịghị ekpo ọkụ na-emeso ya nke ọma. High carbon, chromium martensitic grades ga-esi ike maka nkwụsị corrosion.
A na-emekarị ngafe mgbe iwe ọkụ na-esote na-eji okpomọkụ na-ejigide nguzogide corrosion.
Elegharala ntinye uche nitric acid na bath passivation. A ga-eme nyocha oge oge site na iji usoro titration dị mfe nke Carpenter nyere. Akwụsịla ihe karịrị otu igwe anaghị agba nchara n'otu oge. Nke a na-egbochi mgbagwoju anya dị oke ọnụ ma na-ezere mmeghachi omume galvanic.
Banyere ndị na-ede akwụkwọ: Terry A. DeBold bụ onye nyocha na ọkachamara mmepe nke igwe anaghị agba nchara na James W. Martin bụ onye na-ahụ maka ụlọ ọrụ na-arụ ọrụ na Carpenter Technology Corp. (Ịgụ, PA).
Na a ụwa nke esiwanye stringent elu imecha nkọwa, mfe "roughness" nha ka bara uru. Ka anyị lee anya na ihe mere n'elu nha dị mkpa na otú ọ nwere ike na-elele na ụlọ ahịa n'ala na ọkaibe obere gauges.
Ị ji n'aka na ị nwere ihe ntinye kacha mma maka ọrụ ntụgharị a? Lelee mgbawa ahụ, karịsịa ma ọ bụrụ na ahapụghị ya. Àgwàetiti mgbawa nwere ike ịgwa gị ọtụtụ ihe.