Kev kho deg Defect Reaction Layers ntawm Titanium Phaj thiab Bars
Titanium daim hlau thiab cov tuav, txawm tias tsim los ntawm kub dov, forging, los yog casting, inevitably tsim deg cov txheej txheem thaum lub sij hawm siab - kub ua. Cov khaubncaws sab nraud povtseg no cuam tshuam qhov kev ncaj ncees ntawm qhov chaw, txo qis kev ua haujlwm qaug zog, thiab txo qis kev tiv thaiv corrosion tshwj tsis yog raug tshem tawm. Nkag siab txog qhov xwm txheej ntawm cov teeb meem no thiab siv cov txheej txheem kho kom zoo ua kom cov khoom titanium ua tiav lawv cov peev txheej engineering.
Xwm thiab tsim ntawm Nto Reaction Layers
Cov txheej txheej txheej txheej ntawm titanium yog los ntawm cov khoom siv tshuaj lom neeg heev ntawm qhov kub siab. Thaum kub siab tshaj li 600 degrees Celsius nyob rau hauv lub xub ntiag ntawm oxygen, nitrogen, los yog hydrogen, titanium sai absorbs cov interstitial ntsiab, tsim txawv metallurgical aav uas degrade txhua yam thiab tshuaj.
Covalpha cassawv cev rau feem ntau cov tshuaj tiv thaiv txheej, tsim thaum titanium ua tiav hauv oxidizing los yog cua cua. Oxygen thiab nitrogen diffuse mus rau saum npoo, stabilizing lub hexagonal kaw - ntim alpha theem thiab tsim kom muaj ib qho nyuaj, nkig txheej txheej saturated nrog interstitials. Cov txheej txheem no nthuav tawm cov txiaj ntsig microhardness ntau tshaj 400 HV, piv rau 150 txog 200 HV rau cov hlau tsis muaj kev cuam tshuam, thiab qhia txog qhov tsis zoo ductility. Cov ntaub ntawv alpha feem ntau tshwm sim li lub teeb -xim, etch- resistant txheej nyob rau hauv metallographic kuaj, nrog thickness xws li ob peb micrometers mus rau ntau tshaj 200 micrometers nyob ntawm qhov raug kub thiab ntev.
Hydrogen- cov txheej txheem ntxivdaim ntawv thaum titanium tiv tauj hydrogen- muaj cov huab cua thaum cua sov los yog pickling. Hydrogen diffuses interstitially, txo qhov kev hloov pauv kub thiab txhawb hydride nag lossis daus thaum txias. Titanium hydrides tshwm raws li koob-zoo li los yog platelet precipitates nyob rau hauv lub alpha matrix, embrittling cheeb tsam saum npoo thiab tsim tawg qhov chaw pib nyob rau hauv cyclic los yog cuam tshuam loading.
Oxide nplaitxhim kho raws li pom qhov chaw deposits thaum kub ua hauj lwm los yog kev kho cua sov. Cov nplai no feem ntau yog cov rutile (TiO₂) nrog cov suboxides tau (Ti₂O₃, TiO) ntawm cov hlau- nplai interface. Thaum feem ntau cov tshuaj pleev ib ce, tuab oxide nplai tuaj yeem npog cov ntaub ntawv alpha hauv qab thiab cuam tshuam nrog kev ua haujlwm tom ntej lossis tshuaj xyuas.
Cov khaubncaws sab nraud povtseglos ntawm cov roj nplua nyeem, cov khoom siv tuag, lossis cov khoom txawv teb chaws tuaj yeem ua cov khoom sib txuas los yog diffused rau hauv qhov chaw thaum lub sijhawm ua haujlwm kub, tsim cov teeb meem hauv cheeb tsam uas nthuav tawm mus rau hauv cov kab nrib pleb lossis corrosion pits.
Kev ntsuam xyuas thiab kev kuaj xyuas
Kev kho mob zoo pib nrog qhov tseeb tus yam ntxwv ntawm cov txheej txheem deg. Kev soj ntsuam pom pom pom tag nrho oxide scaling, discoloration, thiab mechanical puas, tab sis tsis tuaj yeem ntes cov ntaub ntawv nyias alpha lossis subsurface paug.
Microhardness profilesmuab ntau qhov kev ntsuas ntawm alpha case qhov tob. Lub hardness traverse ntawm nto mus rau hauv cov tub ntxhais qhia lub hardened txheej los ntawm elevated nyeem ntawv hloov mus rau hauv paus hlau hardness. Cov txheej txheem kev xyaum txhais tau hais tias qhov tob ntawm alpha li qhov deb ntawm qhov chaw mus rau qhov chaw hardness poob mus rau lub hauv paus hlau qib ntxiv rau 50 HV, los yog hloov mus rau qhov chaw pib hardness xws li 320 HV.
Kev ntsuam xyuas metallographicntawm mounted ntoo khaub lig- ntu, npaj nrog cov etchants tsim nyog xws li Kroll's reagent (2 feem pua HF, 4 feem pua HNO₃, sib npaug dej), qhia txog cov ntaub ntawv alpha raws li cov txheej txheem etched los yog maj mam sib txawv ntawm cov txheej txheem hlau etched. Optical microscopy daws cov khaubncaws sab nraud povtseg ntawm kwv yees li 5 micrometers, thaum scanning electron microscopy nrog lub zog-dispersive spectroscopy muab lub ntsiab lus qhia txog cov pa oxygen thiab nitrogen enrichment.
Eddy kev sim tam sim nomuaj tsis yog -kev ntsuam xyuas kev puas tsuaj ntawm qhov chaw, kuaj xyuas qhov sib txawv ntawm qhov sib txawv ntawm qhov cuam tshuam nrog kev txhawb nqa interstitial. Cov txheej txheem no haum rau kev tswj hwm kev tsim khoom, tab sis yuav tsum tau calibration tiv thaiv cov qauv metallographic.
Ultrasonic nto yoj kuajtuaj yeem ntes tau nyob ze - qhov tsis sib xws thiab cov khoom gradients, txawm hais tias daim ntawv thov rau nyias alpha cov ntaub ntawv yuav tsum tau siab - zaus transducers thiab sophisticated teeb liab txhais.
Mechanical Removal Methods
Cov txheej txheem tshem tawm cov txheej txheem lub cev abrade los yog tawg ntawm cov tshuaj tiv thaiv txheej txheej, nthuav tawm suab hauv qab hlau hauv qab.
Machining thiab tigtshem tawm cov khaubncaws sab nraud povtseg los ntawm cov txheej txheem txiav. Rau titanium tuav, precision tig ua tiav cov khoom tswj kev tshem tawm nrog qhov chaw roughness haum rau kev ua tiav tom ntej. Kev txiav cov kev ntsuas yuav tsum sib npaug ntawm cov khoom tsim tawm tiv thaiv cov khoom siv hluav taws xob ntau dhau uas tuaj yeem hloov kho alpha rooj plaub thaum lub tshuab ua haujlwm. Sharp carbide los yog polycrystalline pob zeb diamond cov cuab yeej nrog siab - cua txias xa khoom txo qis thermal puas.
Sib tsoonrog aluminium oxide los yog silicon carbide log muab cov txheej txheem tshem tawm cov phaj thiab cov tuav uas xav tau qhov tseeb. Creep- pub kev sib tsoo ua tiav cov khoom sib sib zog nqus tshem tawm hauv ib qho dhau los, thaum kev sib tsoo nto ua rau cov npoo sib npaug. Kev sib tsoo ntawm titanium xav tau ceev ceev xaiv lub log thiab daim ntawv thov txias kom tiv thaiv kev thauj khoom, kub hnyiab, thiab seem tensile stresses uas tuaj yeem ua rau qaug zog ua haujlwm.
Txoj siv tawv sib tsoo thiab abrasive blastinghaum rau qhov chaw loj dua thiab tsis xwm yeem geometry. Txoj siv tawv sib tsoo nrog zirconia lossis ceramic abrasive siv txuas ntxiv tshem tawm cov txheej txheem tshuaj tiv thaiv, nrog rau kev sib tsoo feem ntau nce los ntawm 80-grit ntxhib tshem tawm los ntawm 320-grit tiav. Abrasive blasting nrog alumina los yog garnet media ntawm kev tswj lub siab thiab lub kaum sab xis muab cov txheej txheem zoo ib yam, txawm hais tias embedment ntawm abrasive hais yuav tsum zam dhau los ntawm cov kua qaub tom ntej.
Barrel thiab vibratory xovtxheej txheem loj ntawm cov tuav me me los yog txiav daim, siv cov khoom siv hluav taws xob lossis cov khoom siv hluav taws xob nrog cov kev daws teeb meem kom tshem tawm cov txheej txheej saum npoo los ntawm kev ua tiav loj. Txoj kev no haum rau cov khoom lag luam tus qauv uas kev tuav tus kheej ua pov thawj tsis txaus ntseeg.
Kev tshem tawm tshuab yuav tsum ua kom tiav cov ntaub ntawv alpha tshem tawm yam tsis muaj cov khoom lag luam ntau dhau. Cov kev tshem tawm ib txwm muaj li ntawm 0.5 mus rau 2.0 millimeters ib qhov chaw rau kub- cov khoom ua haujlwm, nrog qhov tseeb qhov tob txiav txim siab los ntawm microhardness pov thawj ntawm cov qauv seem.
Tshuaj thiab Electrochemical Removal Methods
Cov txheej txheem tshuaj yaj cov txheej txheem tshuaj tiv thaiv los ntawm kev tswj xyuas corrosion, muab qhov zoo rau cov geometries nyuaj nkag tsis tau rau cov cuab yeej siv tshuab.
Acid picklingnrog hydrofluoric-nitric acid sib tov sawv cev rau cov txheej txheem tshuaj kho rau titanium. Cov qauv tsim muaj 2 mus rau 5 feem pua hydrofluoric acid thiab 20 mus rau 40 feem pua nitric acid, nrog cov dej sib npaug. Cov hydrofluoric acid dissolves titanium thiab nws cov oxides, thaum nitric acid tswj passivation ntawm lub hauv paus hlau, tiv thaiv kev tawm tsam ntau dhau thiab nqus hydrogen. Pickling tus nqi yog nyob ntawm acid concentration, kub, thiab agitation, nrog raug tshem tawm tus nqi ntawm 10 mus rau 50 micrometers ib feeb ntawm ambient kub.
Rau cov ntaub ntawv hnyav alpha lossis oxide nplai, ua ntej pickling hauv cov tshuaj hydrofluoric acid muaj zog (10 mus rau 20 feem pua) lossis molten ntsev da dej (sodium hydroxide nrog oxidizing additives) yuav ua ntej cov txheej txheem pickling. Molten ntsev descaling ntawm 400 mus rau 500 degrees Celsius sai tshem tawm cov tuab oxide teev los ntawm kev txo cov tshuaj lom neeg thiab lub cev spalling.
Electrochemical polishingnyob rau hauv perchloric acid -acetic acid electrolytes los yog alkaline glycerol cov kev daws teeb meem ua tiav tswj anodic dissolution nrog superior nto tiav piv rau tshuaj pickling. Cov txheej txheem nyiam ua kom cov av asperities thiab cov txheej txheem tshuaj tiv thaiv, ua daim iav -zoo li cov chaw nrog tsawg tsawg hydrogen pickup. Electrochemical polishing suits precision Cheebtsam thiab kev kho mob implants xav tau kev pom kev ncaj ncees.
Alkaline ntxuavnrog sodium hydroxide los yog poov tshuaj hydroxide daws tshem tawm cov kab mob organic thiab qee cov oxide zaj duab xis, ua cov kauj ruam npaj es tsis yog thawj txheej txheej txheej tawm. Txawm li cas los xij, lub sijhawm ntev alkaline raug rau ntawm qhov kub siab tuaj yeem tawm tsam titanium, yuav tsum tau ua tib zoo tswj cov txheej txheem.
Kev kho tshuaj xav tau kev tswj xyuas nruj kom tiv thaiv hydrogen embrittlement. Acid pickling solutions muaj fluorides uas tsis muaj oxidizing neeg ua hauj lwm txaus txhawb hydrogen absorption, tshwj xeeb tshaj yog nyob rau hauv high acid concentrations thiab tsis kub. Kev soj ntsuam cov ntsiab lus hydrogen hauv cov khoom siv pickled, feem ntau yog los ntawm inert gas fusion tsom xam nrog cov pib qis dua 125 mus rau 150 feem ntawm ib lab nyob ntawm daim ntawv thov, txheeb xyuas cov txheej txheem txaus.
Thermal Treatment Methods
Thermal le caag tshem tawm cov txheej txheem tshuaj tiv thaiv los ntawm kev sib txawv thermal expansion lossis theem transformations.
Nqus annealingntawm 700 txog 850 degrees Celsius hauv lub tshuab nqus tsev siab (qis dua 10⁻³ pascals) tuaj yeem txo cov pa oxygen thiab nitrogen concentrations los ntawm kev sib kis mus rau hauv lub tshuab nqus tsev, tab sis cov txheej txheem no ua pov thawj qeeb qeeb rau qhov tseem ceeb alpha tshem tawm thiab muaj kev pheej hmoo loj hlob hauv cov hlau hauv paus.
Hydrogenation -dehydrogenationKev ua haujlwm txhob txwm ua kom titanium nrog hydrogen kom embrittle cov tshuaj tiv thaiv txheej txheej saum npoo, ua kom yooj yim tshem tawm cov neeg kho tshuab los ntawm decrepitation, ua raws li lub tshuab nqus tsev dehydrogenation los kho cov ductility. Cov txheej txheem tshwj xeeb no pom muaj tsawg daim ntawv thov vim cov txheej txheem nyuaj thiab kev tswj hwm hydrogen.
Ua ke thiab Advanced Treatment Approaches
Kev xyaum tam sim no feem ntau sib txuas ntau yam txuj ci kom tau txais txiaj ntsig zoo. Ib ntus rau kub- dov titanium phaj tej zaum yuav muaj xws li: abrasive blasting rau scale tshem tawm, alkaline tu rau degreasing, kua qaub pickling rau alpha case dissolution, mechanical sib tsoo rau seem rov qab, thiab zaum kawg electrochemical polishing rau nto optimization.
Laser nto remeltingsai melts thiab resolidifies nto txheej nyob rau hauv inert cua, dissolving alpha rooj rau hauv tej thiab ua ib tug refined, homogeneous nto microstructure. Cov nqi cua txias ceev heev uas muaj los ntawm kev ua laser tiv thaiv kev cuam tshuam tseem ceeb thaum tshem tawm ua ntej - cov txheej txheem tshuaj tiv thaiv uas twb muaj lawm.
Plasma electrolytic oxidationhloov cov oxide saum npoo mus rau hauv tuab, ceramic-zoo li txheej nrog tswj porosity thiab hardness, zoo faus cov tshuaj tiv thaiv txheej hauv qab txheej txheej ua haujlwm zoo dua li tshem tawm lawv. Txoj kev no haum rau cov ntawv thov uas hnav tsis kam lossis dielectric zog yog qhov tseem ceeb tshaj qhov siab tshaj plaws substrate ductility.
Daim Ntawv Pov Thawj Zoo thiab Kev Txais Txais
Tom qab-Kev kuaj xyuas kev kho mob kom ua tiav cov txheej txheem tshem tawm cov tshuaj tiv thaiv thiab pom zoo rau saum npoo. Microhardness traverses ntawm cov pov thawj cov qauv los yog cov khoom seem paub meej tias alpha case tshem tawm los ntawm hardness profiles raws li cov txheej txheem. Kev ntsuam xyuas metallographic validates microstructural soundness, tsis muaj hydride precipitates, thiab txais tau grain loj.
Surface roughness ntsuas ntsuas qhov ua tiav zoo, nrog rau qhov yuav tsum tau sib txawv ntawm Ra 0.4 micrometers rau qhov tseeb cov kabmob rau Ra 3.2 micrometers rau kev siv cov qauv siv. Eddy kev tshuaj xyuas tam sim no muab ntau lawm- kab ntawv pov thawj ntawm qhov sib xws ntawm qhov chaw.
Hydrogen tsom xam, feem ntau yog los ntawm inert gas fusion, paub meej tias cov tshuaj kho mob tsis tau qhia txog cov teeb meem hydrogen. Kev lees txais qhov pib sib txawv los ntawm daim ntawv thov, nrog rau kev cog lus kho mob thiab cov khoom siv hauv aerospace xav tau qis dua 80 txog 125 feem ntawm ib lab, thaum cov ntawv thov kev lag luam tuaj yeem zam txog li 150 txog 200 feem ntawm ib lab.
Daim ntawv thov -Kev txiav txim siab tshwj xeeb
Rauaerospace structural Cheebtsam, ua kom tiav cov ntaub ntawv tshem tawm alpha yog qhov yuav tsum tau ua, nrog rau kev ua haujlwm zoo li ntawm 1.0 txog 2.0 millimeters ib qhov chaw ntawm kub - cov khoom ua haujlwm. Cov kev kho mob tom qab nrog rau kev txhaj tshuaj peening lossis qis-plasticity burnishing tuaj yeem ua kom muaj kev ntxhov siab ntxiv los txhim kho kev qaug zog.
Raukho mob implants, cov khaubncaws sab nraud povtseg yuav tsum tau muab tshem tawm kom ntseeg tau tias biocompatibility, nrog rau cov kev xav tau ntxiv rau kev huv huv, passivation, thiab tsis muaj cov kab mob hlau. Electrochemical polishing ua raws li nitric acid passivation ua kom pom cov oxide txheej rau cov ntaub so ntswg kev koom ua ke.
Rauchemical txheej txheem khoom siv, cov txheej txheem tshem tawm cov tshuaj tiv thaiv tsom rau kev ua kom muaj kev tiv thaiv corrosion, nrog rau kev kho mob pickling thiab passivation tsim kom muaj kev tiv thaiv oxide zaj duab xis xav tau rau kev pabcuam hauv kev tawm tsam hnyav.
Raukev siv architectural, aesthetic sib xws thiab formability tswj kev xaiv kev kho mob, nrog rau txhua yam xov thiab lub teeb pickling ua tus yam xav tau nto yam tsis muaj ntau yam khoom tshem tawm.
