Uqinisekisile ukuba ezi nxalenye zicwangciswe ngokweemfuno. Ngoku, qiniseka ukuba uthathe amanyathelo okukhusela ezi nxalenye kwiimeko ezilindelwe ngabathengi bakho. #esisiseko
Ukudlulisa umbane (passivation) kusaqhubeka njengenyathelo elibalulekileyo ekuphuculeni ukumelana nokugqwala kwezixhobo ezifakwe kwi-stainless machine kunye nee-assembly. Kunokwenza umahluko phakathi kokusebenza kakuhle kunye nokusilela kwangethuba. Ukuba kwenziwa ngendlela engafanelekanga, ukuhambisa umbane (passivation) kunokubangela ukugqwala.
I-passivation yindlela yokwenza emva kokwenziwa ephucula ukumelana nokugqwala kwezinto ezidityanisiweyo zentsimbi engagqwali ezivelisa umsebenzi. Ayisiyo indlela yokususa iikalika, kwaye ayisiyo ipeyinti.
Akukho mvumelwano ngokubanzi malunga nendlela esebenza ngayo i-passivation. Kodwa kuyacaca ukuba kukho ifilimu ye-oxide ekhuselayo kumphezulu wentsimbi engagqwaliyo engasebenziyo. Le filimu ingabonakaliyo icingelwa ukuba incinci kakhulu, ingaphantsi kwe-0.0000000 intshi enye ubukhulu, malunga ne-1/100,000th yobukhulu beenwele zomntu!
Inxalenye yentsimbi engagqwaliyo ecocekileyo, esandula ukucolwa, ukucolwa okanye ukucolwa iya kufumana le filimu ye-oxide ngokuzenzekelayo ngenxa yokuvezwa kwayo kwi-oxygen esemoyeni. Phantsi kweemeko ezifanelekileyo, le layer ye-oxide ekhuselayo igubungela ngokupheleleyo yonke indawo yenxalenye.
Nangona kunjalo, ngokwesiqhelo, izinto ezingcolisayo ezifana nothuli oluthengiweyo okanye amasuntswana esinyithi avela kwizixhobo zokusika zinokudluliselwa kumphezulu wezinto zentsimbi engagqwaliyo ngexesha lokwenziwa. Ukuba azisuswanga, ezi zinto zangaphandle zinokunciphisa ukusebenza kwefilimu yokukhusela yokuqala.
Ngexesha lokwenziwa kwesinyithi, ubungakanani obuncinci besinyithi esikhululekileyo bunokwaphuka kwisixhobo size sidluliselwe kumphezulu wesixhobo esingenasici. Kwezinye iimeko, kungavela umaleko omncinci womhlwa kwinxalenye. Oku kukwaphuka kwentsimbi ngesixhobo, kungekhona isinyithi esisisiseko. Ngamanye amaxesha, iimfanta zeengceba zentsimbi ezifakwe kwizixhobo zokusika okanye iimveliso zazo zomhlwa zinokubangela ukubola kwenxalenye ngokwayo.
Ngokufanayo, amasuntswana amancinci othuli oluyintsimbi anokuthi anamathele kumphezulu wenxalenye. Nangona isinyithi sinokubonakala sikhazimla kwimeko yomatshini, emva kokuvezwa emoyeni, amasuntswana angabonakaliyo esinyithi esikhululekileyo anokubangela ukugqwala komphezulu.
Iisulfide eziveziweyo nazo zinokuba yingxaki. Zivela ekongezeni isalfure kwintsimbi engatyiwayo ukuphucula ukusebenza kwayo. Iisulfide zonyusa amandla e-alloy okwenza iitships ngexesha lokwenziwa, ezinokususwa ngokupheleleyo kwisixhobo sokusika. Ngaphandle kokuba iindawo zingasetyenziswanga ngokufanelekileyo, iisulfide zinokuba yindawo yokuqala yokugqwala komphezulu kwiimveliso ezenziweyo.
Kuzo zombini iimeko, i-passivation iyadingeka ukuze kuphuculwe ukumelana nokugqwala kwendalo kwentsimbi engagqwali. Isusa izinto ezingcolisayo kumphezulu, ezifana neengceba ze-ferrous shop dirt kunye neengceba zesinyithi kwizixhobo zokusika, ezinokwenza umhlwa okanye zibe yindawo yokuqala yokugqwala. I-passivation ikwasusa ii-sulfide ezivezwe kumphezulu wee-alloys zentsimbi engagqwali ezisikiweyo.
Inkqubo enamanyathelo amabini inika ukhuselo olungcono kakhulu lokugqwala: 1. Ukucoca, inkqubo esisiseko kodwa ngamanye amaxesha ingahoywa; 2. Ukuhlamba nge-asidi okanye unyango lokukhupha umoya.
Ukucoca kufuneka kube yeyona nto iphambili ngalo lonke ixesha. Iindawo kufuneka zicocwe kakuhle ngegrisi, i-coolant okanye ezinye izinto ezimdaka zevenkile ukuze kuxhathiswe ukugqwala. Izinto ezimdaka zemashini okanye ezinye izinto ezimdaka zevenkile zinokusulwa ngononophelo kwindawo leyo. Izinto zokucoca okanye izicoci zorhwebo zinokusetyenziswa ukususa iioyile okanye izinto ezimdaka zenkqubo. Izinto zangaphandle ezifana ne-thermal oxides zisenokufuneka zisuswe ngeendlela ezifana nokugaya okanye ukuqhola.
Ngamanye amaxesha umqhubi womatshini unokungawucoci umsebenzi, ngempazamo ecinga ukuba ukucoca kunye nokungasebenzisi mafutha kuya kwenzeka ngaxeshanye ngokuntywilisela nje inxalenye egcwele amafutha kwindawo eneasidi. Oko akuyi kwenzeka. Ngokwahlukileyo koko, igrisi engcolisiweyo isabela kwiasidi ukuze yenze amaqamza omoya. La maqamza aqokelelana kumphezulu wezinto zokusebenza aze aphazamise ukungasebenzisi mafutha.
Okubi nangakumbi kukuba, ungcoliseko lwezisombululo zokungangenisi manzi, ngamanye amaxesha eziqulathe ubuninzi beekloridi, lunokubangela “ukukhazimla.” Ngokungafaniyo nokufumana ifilimu ye-oxide efunekayo enomphezulu okhazimlayo, ococekileyo, nongangenisi umhlwa, ukukhazimla kwe-flash kunokubangela umphezulu oqhekekileyo okanye omnyama—ukubola komphezulu okuyenzelwe ukuba ukungangenisi manzi kube ngcono.
Izinto ezenziwe ngentsimbi engagqwaliyo ye-martensitic [imagnethi, enganyamezeliyo ukugqwala, inika amandla afikelela kwi-280 ksi (1930 MPa)] ziyaqiniswa kubushushu obuphezulu kwaye emva koko ziqiniswa ukuqinisekisa ubulukhuni obufunekayo kunye neempawu zoomatshini. Ii-alloys eziqiniswayo zemvula, ezinamandla angcono kunye nokumelana nokugqwala kunee-alloys ze-martensitic, zinokunyangwa ngesisombululo, zenziwe ngomatshini kancinci, zivuthwe kubushushu obuphantsi, zize zigqitywe.
Kwimeko enjalo, inxalenye kufuneka icocwe kakuhle ngesixhobo sokususa igrisi okanye isicoci ukuze kususwe naziphi na iintsalela zolwelo lokusika ngaphambi kokuba kusetyenziswe ubushushu. Ngaphandle koko, ulwelo lokusika oluseleyo kwinxalenye lunokubangela i-oxidation egqithisileyo. Le meko inokubangela ukuba iindawo ezincinci zibe buthathaka emva kokuba isikali sisusiwe ngeendlela ze-asidi okanye ze-abrasive. Ukuba ulwelo lokusika luvunyelwe ukuba luhlale kwiindawo ezikhanyayo eziqinileyo, njengakwisithando somoya okanye kwindawo ekhuselayo, i-carburization yomphezulu inokwenzeka, nto leyo ekhokelela ekulahlekelweni kokumelana nokugqwala.
Emva kokucoca ngokucokisekileyo, iindawo zentsimbi engatyiwayo zingafakwa kwisitya sokuhlambela esine-asidi engasebenziyo. Nayiphi na kwezi ndlela zintathu ingasetyenziswa - i-nitric acid passivation, i-nitric acid ene-sodium dichromate passivation, kunye ne-citric acid passivation. Yeyiphi indlela omawuyisebenzise ixhomekeke kudidi lwentsimbi engatyiwayo kunye nemigangatho yokwamkelwa echaziweyo.
Iigreyidi ze-chrome-nickel ezinganyangekiyo nokugqwala zinokungangeniswa kwibhafu ye-nitric acid engama-20% (v/v) (Umfanekiso 1). Njengoko kubonisiwe kwitheyibhile, intsimbi engagqwaliyo enganyangekiyo ingangeniswa ngokongeza i-sodium dichromate kwibhafu ye-nitric acid, okwenza isisombululo sibe ne-oxidizing ngakumbi kwaye sikwazi ukwenza ifilimu engasebenziyo kumphezulu wesinyithi. Olunye ukhetho lokutshintsha i-nitric acid nge-sodium chromate kukunyusa uxinzelelo lwe-nitric acid ukuya kwi-50% ngomthamo. Kokubini ukongezwa kwe-sodium dichromate kunye noxinzelelo oluphezulu lwe-nitric acid kunciphisa ithuba lokukhanya okungafunekiyo.
Inkqubo yokudlulisa iintsimbi ezingenasici ezisebenza ngomatshini okhululekileyo (ikwaboniswe kuMfanekiso 1) yahlukile kancinci kuleyo yeentlobo zentsimbi engenasici ezisebenza ngomatshini ongekho simahla. Oku kungenxa yokuba ngexesha lokudlulisa kwisitya esiqhelekileyo se-nitric acid, ezinye okanye zonke ii-sulfide ze-machinable grade eziqulethe i-sulfur ziyasuswa, nto leyo eyenza ukungahambelani okuncinci kumphezulu wenxalenye eyenziwe ngomatshini.
Nokuba ukuhlamba ngamanzi okusebenzayo ngokubanzi kunokushiya i-asidi eseleyo kwezi ndawo zingaqhubekiyo emva kokungasebenzi. Le asidi iya kuhlasela umphezulu wenxalenye ngaphandle kokuba ayisuswanga okanye ayisuswanga.
Ukuze intsimbi engagqwaliyo ekwaziyo ukunyibilika ngokulula, uCarpenter uphuhlise inkqubo ye-AAA (Alkali-Acid-Alkali), ethintela i-asidi eseleyo. Le ndlela yokudlulisa ingasetyenziswa ngaphantsi kweeyure ezi-2. Nantsi inkqubo yenyathelo ngenyathelo:
Emva kokususa amafutha, faka ezi ndawo kwisisombululo se-5% sodium hydroxide kwi-160°F ukuya kwi-180°F (71°C ukuya kwi-82°C) imizuzu engama-30. Emva koko hlambulula ezi ndawo kakuhle emanzini. Emva koko, faka loo ndawo imizuzu engama-30 kwisisombululo se-20% (v/v) se-nitric acid esine-3 oz/gal (22 g/l) sodium dichromate kwi-120°F ukuya kwi-140°F (49°C) ukuya kwi-60°C). Emva kokususa loo ndawo ebhafini, yihlambe ngamanzi uze uyihlambe kwisisombululo se-sodium hydroxide eminye imizuzu engama-30. Hlamba loo ndawo kwakhona ngamanzi uze uyomise, ugqibezele indlela ye-AAA.
Ukususwa kwe-asidi ye-citric kuthandwa kakhulu ngabavelisi abanqwenela ukuphepha ukusetyenziswa kwee-asidi zeminerali okanye izisombululo ezine-sodium dichromate, kunye nemiba yokulahla kunye neenkxalabo zokhuseleko ezihambelana nokusetyenziswa kwazo. I-asidi ye-citric ithathwa njengenobuhlobo nokusingqongileyo ngandlela zonke.
Nangona ukukhutshwa kwe-citric acid kunika iingenelo ezintle kwindalo esingqongileyo, iivenkile eziye zaphumelela ekukhutshweni kwe-inorganic acid kwaye ezingenazo iingxaki zokhuseleko zisenokufuna ukuqhubeka. Ukuba aba basebenzisi banevenkile ecocekileyo, izixhobo ezigcinwe kakuhle nezicocekileyo, isibandisi esingenazo i-ferrous shop disinfect, kunye nenkqubo evelisa iziphumo ezilungileyo, kusenokubakho mfuneko yokwenyani yotshintsho.
Ukudlulisa amanzi kwi-citric acid bath kufunyenwe kuluncedo kuluhlu olukhulu lweentsimbi ezingenasici, kuquka neendidi ezahlukeneyo zentsimbi engenasici, njengoko kubonisiwe kuMfanekiso 2. Ukuze kube lula, indlela yendabuko yokudlulisa amanzi kwi-nitric acid kuMfanekiso 1 ifakiwe. Qaphela ukuba iifomyula ze-nitric acid ezindala zibonakaliswa ngepesenti yomthamo, ngelixa amanqanaba amatsha e-citric acid ebonakaliswa ngepesenti yobunzima. Kubalulekile ukuqaphela ukuba xa kusetyenziswa ezi nkqubo, ukulinganisela ngononophelo ixesha lokuntywila, ubushushu bokuhlamba kunye noxinzelelo kubalulekile ukuze kuthintelwe "ukukhanya" okuchazwe ngaphambili.
Unyango lwe-passivation luyahluka ngokwesiqulatho se-chromium kunye neempawu ze-machining zebanga ngalinye. Qaphela iikholamu ezibhekisa kwiNkqubo yoku-1 okanye kwiNkqubo yesi-2. Njengoko kubonisiwe kuMfanekiso wesi-3, Inkqubo yoku-1 ibandakanya amanyathelo ambalwa kuneNkqubo yesi-2.
Uvavanyo lwelabhoratri lubonise ukuba inkqubo yokudlulisa i-citric acid ithambekele kakhulu "ekukhanyeni" kunenkqubo ye-nitric acid. Izinto ezinegalelo kolu hlaselo ziquka ubushushu obuphezulu kakhulu bokuhlamba, ixesha elide lokuntywila, kunye nongcoliseko lokuhlamba. Iimveliso ze-citric acid eziqulethe izithinteli zokubola kunye nezinye izongezo ezifana nee-wetting agents ziyafumaneka kurhwebo kwaye zibikwa ukuba zinciphisa ukubola "okukhanyayo".
Ukhetho lokugqibela lwendlela yokudlulisa umyalezo luxhomekeke kwiikhrayitheriya zokwamkelwa ezibekwe ngumthengi. Jonga i-ASTM A967 ukuze ufumane iinkcukacha. Ingafumaneka ku-www.astm.org.
Uvavanyo ludla ngokwenziwa ukuze kuvavanywe umphezulu weendawo ezingasebenziyo. Umbuzo ekufuneka uphendulwe ngulo, "Ngaba ukungasebenziyo kususa isinyithi esikhululekileyo kwaye kwenze ngcono ukumelana nokugqwala kwamanqanaba okusika akhululekileyo?"
Kubalulekile ukuba indlela yovavanyo ihambelane nomgangatho ovavanywayo. Uvavanyo olungqongqo kakhulu luya kusilela kwizixhobo ezilungileyo ngokupheleleyo, ngelixa uvavanyo olukhululekileyo kakhulu luya kudlula kwiindawo ezinganelisiyo.
Ukuqina kwemvula kunye neentsimbi ezingenasici ezisebenza ngomatshini ezingama-400 kuvavanywa ngcono kwikhabhinethi ekwaziyo ukugcina ukufuma kwe-100% (iisampulu ezimanzi) iiyure ezingama-24 kwi-95°F (35°C). Icandelo elinqamlezileyo lidla ngokuba ngumphezulu obaluleke kakhulu, ngakumbi kwiindidi zokusika ezikhululekileyo. Esinye isizathu soku kukuba i-sulfide inde kwicala lomatshini, idibana nalo mphezulu.
Iindawo ezibalulekileyo mazibekwe phezulu, kodwa kwiidigri ezili-15 ukuya kwezingama-20 ukusuka phezulu ukuze kuvumeleke ukulahleka komswakama. Izinto ezingasetyenziswanga kakuhle aziyi kugqwala, nangona zinokubonisa ukudaya okuncinci.
Iiklasi zentsimbi engagqwaliyo yase-Austenitic nazo zinokuvavanywa ngovavanyo lokufuma. Xa kuvavanywa njalo, amathontsi amanzi kufuneka abe khona kumphezulu wesampuli, nto leyo ebonisa ukuba akukho ntsimbi ikhululekileyo ngokubakho komhlwa.
Iinkqubo zokudlulisa iintsimbi ezingenasici ezisetyenziswa rhoqo ezisikiweyo ngokukhululekileyo nezingesiso esikiweyo ngokukhululekileyo kwizisombululo ze-citric okanye ze-nitric acid zifuna iinkqubo ezahlukeneyo. Umfanekiso 3 ngezantsi unika iinkcukacha malunga nokukhetha inkqubo.
(a) Lungisa i-pH nge-sodium hydroxide.(b) Jonga uMfanekiso 3 (c) I-Na2Cr2O7 imele i-3 oz/gallon (22 g/l) ye-sodium dichromate kwi-20% ye-nitric acid. Enye indlela kule mxube yi-50% ye-nitric acid ngaphandle kwe-sodium dichromate.
Indlela ekhawulezayo kukusebenzisa isisombululo esikwi-ASTM A380, “Indlela Eqhelekileyo Yokucoca, Ukususa Iikali, kunye Nokudluliswa Kweenxalenye Zentsimbi Engagqwaliyo, Izixhobo, kunye Neenkqubo.” Olu vavanyo luquka ukusula inxalenye ngesisombululo se-copper sulfate/sulfuric acid, ukuyigcina imanzi imizuzu emi-6 kunye nokujonga ukuba iplatiwe nge-copper. Njengenye indlela, inxalenye ingantywiliselwa kwisisombululo imizuzu emi-6. Ukuba isinyithi siyanyibilika, iplatiwe nge-copper. Olu vavanyo akufuneki lusetyenziswe kwiindawo zokulungisa ukutya. Kwakhona, akufuneki lusetyenziswe kwiintsimbi ze-martensitic ezingama-400 okanye ze-chromium ferritic eziphantsi njengoko iziphumo ezingalunganga zinokwenzeka.
Ngokwembali, uvavanyo lwe-5% yetyuwa olutshizwayo kwi-95°F (35°C) lukwasetyenziswa ukuvavanya iisampulu ezingasebenziyo. Olu vavanyo lungqongqo kakhulu kwezinye iiklasi kwaye ngokubanzi akufuneki ukuqinisekisa ukuba ukusetyenziswa kwetyuwa kuyasebenza.
Kuphephe ukusebenzisa ii-chloride ezigqithisileyo, ezinokubangela ukuhlaselwa ngequbuliso okuyingozi. Ukuba kunokwenzeka, sebenzisa amanzi asemgangathweni ophezulu kuphela aneenxalenye ezingaphantsi kwama-50 kwisigidi (ppm) se-chloride. Amanzi epompo adla ngokwanela kwaye anokunyamezela ukuya kuthi ga kumakhulu aliqela e-ppm chloride kwezinye iimeko.
Kubalulekile ukutshintsha igumbi lokuhlambela rhoqo ukuze kuthintelwe ukulahleka kwamandla okubangela ukuphaphatheka nokuqhekeka kweendawo ezithile. Igumbi lokuhlambela kufuneka ligcinwe kubushushu obufanelekileyo, njengoko amaqondo obushushu aphumayo anokubangela ukugqwala kwendawo ethile.
Kubalulekile ukugcina ishedyuli ethile yokutshintsha isisombululo ngexesha lemveliso ephezulu ukunciphisa amathuba okungcola. Isampulu yokulawula isetyenzisiwe ukuvavanya ukusebenza kakuhle kwebhafu. Ukuba isampulu ihlaselwe, lixesha lokutshintsha ibhafu.
Nceda ucacise ukuba oomatshini abathile benza intsimbi engagqwaliyo kuphela; sebenzisa i-coolant efanayo ukusika intsimbi engagqwaliyo, ngaphandle kwezinye iintsimbi.
Iindawo ze-DO rack ziphathwa ngokwahlukeneyo ukuze kuthintelwe ukudibana kwentsimbi nesinyithi. Oku kubaluleke kakhulu kwi-machining yentsimbi engagqwaliyo, njengoko izisombululo zokuthambisa ezikhululekileyo kunye nokuhlanjwa ziyafuneka ukuze kusasazwe iimveliso zokugqwala kwi-sulfides kwaye kuthintelwe ukwakheka kweepokotho ze-asidi.
Musa ukukhupha izinto zentsimbi engagqwaliyo ezifakwe ikhabhoni okanye ezifakwe i-nitride. Ukumelana nokugqwala kwezinto eziphathwe ngolo hlobo kunokuncipha ukuya kwinqanaba apho zinokuhlaselwa khona kwindawo yokuhlambela.
Musa ukusebenzisa izixhobo zentsimbi kwindawo yokusebenzela engacocekanga kangako. Ulwelo lwentsimbi lungathintelwa ngokusebenzisa izixhobo zekhabhayithi okanye zeseramikhi.
Ungalibali ukuba ukugqwala kungenzeka kwindawo yokuhlambela ukuba inxalenye ayiphathwanga kakuhle ngobushushu. Iikhabhoni ephezulu, ii-chromium martensitic grades eziphezulu kufuneka ziqiniswe ukuze zikwazi ukumelana nokugqwala.
Ukudlulisa amandla kudla ngokwenziwa emva kokufudumala okulandelayo kusetyenziswa amaqondo obushushu agcina ukumelana nokugqwala.
Musa ukuyityeshela i-nitric acid concentration kwi-passivation bath. Kufuneka kuhlolwe amaxesha ngamaxesha kusetyenziswa inkqubo elula ye-titration ebonelelwe nguCarpenter. Musa ukuyitshiza i-stainless steel ngaphezulu kwesinye ngexesha. Oku kuthintela ukudideka okubiza kakhulu kwaye kuthintela ukusabela kwe-galvanic.
Malunga nababhali: UTerry A. DeBold yingcali yophando nophuhliso lwe-alloy yentsimbi engagqwaliyo kwaye uJames W. Martin yingcali yesinyithi kwiCarpenter Technology Corp. (Reading, PA).
Kwihlabathi elineenkcukacha ezingqongqo zokugqitywa komphezulu, imilinganiselo elula "yoburhabaxa" isaluncedo. Makhe sijonge ukuba kutheni ukulinganisa umphezulu kubalulekile kwaye kungajongwa njani kumgangatho wevenkile ngeegeyiji eziphathwayo ezintsonkothileyo.
Uqinisekile ukuba unayo eyona ingcono yokufakelwa kolu sebenzi lokujika? Jonga itshiphu, ingakumbi ukuba ayishiywanga ijongiwe. Iimpawu zetshiphu zinokukuxelela lukhulu.