Kev kho nitriding
Nitrided iav
Nitriding kev kho yog hais txog cov txheej txheem kev kho cua sov uas cov nitrogen atoms nkag mus rau saum npoo ntawm lub workpiece hauv ib qho nruab nrab ntawm qhov kub thiab txias. Cov khoom siv nitrided muaj kev hnav zoo heev, qaug zog tiv thaiv, corrosion tsis kam, thiab kub-resistant.
Ntawm no peb saib ntawm Netrex's video, Netrex piav qhia zoo heev tias nitriding yog dab tsi.
Taw qhia txog Kev Kho Nitriding
Cov txhuas, chromium, vanadium, thiab molybdenum cov ntsiab lus hauv cov khoom siv hlau hlau yog qhov zoo heev rau nitriding. Thaum cov ntsiab lus no nkag mus rau hauv kev sib cuag nrog cov nascent nitrogen atoms ntawm nitriding kub, ruaj khov nitrides raug tsim.
Hauv particular, cov khoom molybdenum tsis tsuas yog ua raws li cov khoom siv rau kev tsim cov nitrides, tab sis kuj ua raws li kev txo qis hauv brittleness uas tshwm sim ntawm qhov kub ntawm nitriding. Cov ntsiab lus hauv lwm cov hlau alloy, xws li npib tsib xee, tooj liab, silicon, manganese, thiab lwm yam, tsis muaj txiaj ntsig ntau rau cov yam ntxwv nitriding.
Feem ntau hais lus, yog tias cov hlau muaj ib lossis ntau dua nitride-forming ntsiab, cov nyhuv tom qab nitriding kuj zoo. Ntawm lawv, txhuas yog qhov muaj zog tshaj nitride, thiab nitriding nrog 0.85 mus rau 1.5 feem pua txhuas muaj qhov zoo tshaj plaws.
Raws li hais txog chromium-muaj chromium steel, yog tias muaj cov ntsiab lus txaus, cov txiaj ntsig zoo kuj tuaj yeem tau txais. Tab sis tsis muaj cov pa roj carbon steel uas muaj alloy vim tias cov txheej nitrided yog nkig heev thiab yooj yim rau tev tawm, yog li nws tsis haum rau nitriding hlau.
Muaj 6 feem ntau siv nitriding steels raws li hauv qab no:
(1) Tsawg alloy steel uas muaj txhuas (tus qauv nitrided steel)
(2) SAE 4100, 4300, 5100, 6100, 8600, 8700, 9800 series ntawm nruab nrab carbon tsawg alloy hlau uas muaj chromium.
(3) Kub ua hauj lwm tuag steel (muaj li ntawm 5 feem pua chromium) SAE H11 (SKD-61) H12, H13
(4) Ferritic thiab martensitic stainless hlau SAE 400 series
(5) Austenitic stainless hlau SAE 300 series
(6) Precipitation hardening stainless hlau 17-4PH, 17-7PH, A-286, thiab lwm yam.
Cov txheej txheem nitrided steel uas muaj txhuas tuaj yeem tau txais lub siab tawv thiab siab hnav tsis kam nto txheej tom qab nitriding, tab sis cov txheej tawv tawv kuj yog nkig heev. Ntawm qhov tsis sib xws, chromium-muaj cov hlau tsis tshua muaj hlau tsis tshua muaj zog, tab sis cov txheej txheem tawv tawv yog tawv dua, thiab nws qhov chaw kuj tseem muaj qhov hnav tsis kam thiab beam kuj. Yog li ntawd, thaum xaiv cov ntaub ntawv, koj yuav tsum xyuam xim rau cov yam ntxwv ntawm cov ntaub ntawv thiab ua kom tag nrho cov kev siv ntawm lawv zoo kom tau raws li lub functionality ntawm qhov chaw. Raws li cov cuab yeej steel xws li H11 (SKD61) D2 (SKD{5}}), lawv muaj qhov tawv tawv tawv thiab cov tub ntxhais siab zog.
nyhuv
Ua kom cov hnav tsis kam, qhov tawv tawv, kev qaug zog txwv, thiab corrosion kuj ntawm steel qhov chaw.
Txheej txheem txheej txheem
Nto tu ntawm qhov chaw ua ntej nitriding
Feem ntau cov khoom tuaj yeem nitrided tam sim ntawd tom qab degreasing los ntawm roj degreasing. Qee qhov chaw kuj yuav tsum tau ntxuav nrog roj av, tab sis yog tias txoj kev ua tiav kawg ua ntej nitriding siv polishing, sib tsoo, polishing, thiab lwm yam, nws yuav tsim ib txheej txheej uas cuam tshuam nitriding, ua rau tsis sib npaug lossis tsis sib xws tom qab nitriding.
Kev puas tsuaj xws li khoov tau tshwm sim. Lub sijhawm no, ib qho ntawm ob txoj hauv qab no yuav tsum tau siv los tshem tawm cov txheej txheem saum npoo. Thawj txoj kev ua ntej siv cov roj kom tshem tawm cov roj ua ntej nitriding. Tom qab ntawd siv alumina hmoov rau sandblast lub nto (abrasive tu). Qhov thib ob txoj kev yog siv phosphate txheej rau saum npoo.
Tso pa tawm ntawm nitriding rauv
Muab cov khoom ua tiav rau hauv lub cub tawg nitriding thiab kaw lub qhov cub kom sov, tab sis ua ntej cua sov mus rau 150 degree, lub cub tawg yuav tsum tau tso tseg. Lub luag haujlwm tseem ceeb ntawm lub cub tawg yog tiv thaiv cov roj tawg los ntawm kev sib cuag nrog huab cua thaum ammonia decomposed, thiab tiv thaiv oxidation ntawm qhov chaw ntawm cov khoom tiav thiab kev txhawb nqa.
Cov roj siv yog ammonia thiab nitrogen. Qhov tseem ceeb rau kev tshem tawm cov huab cua hauv qhov cub yog raws li nram no:
①Tom qab cov khoom yuav tsum tau ua tiav, lub qhov cub npog yog kaw, thiab cov pa roj ammonia pib pib, thiab tus nqi ntws siab npaum li qhov ua tau.
② Teem lub ntsuas kub tsis siv neeg lub tshuab cua sov rau 150 degree thiab pib cua sov (nco ntsoov tias qhov cub kub tsis tuaj yeem siab tshaj 150 degree).
③Thaum huab cua nyob rau hauv lub cub tawg raug tshem tawm tsawg dua 10 feem pua, los yog cov pa pa muaj ntau tshaj 90 feem pua NH3, ces lub cub tawg kub yog nce mus rau nitriding kub.
Ammonia decomposition tus nqi
Nitriding yog nqa tawm los ntawm kev sib cuag nrog lwm yam alloying ntsiab lus nrog nascent nitrogen, tab sis zus tau tej cov nascent nitrogen yog cov hlau nws tus kheej ua ib tug catalyst thaum ammonia roj los rau hauv kev sib cuag nrog cov rhuab hlau los txhawb lub decomposition ntawm ammonia.
Txawm hais tias nitriding tuaj yeem ua tau raws li ammonia nrog ntau tus nqi decomposition, tus nqi decomposition feem ntau yog 15-30 feem pua , thiab cov thickness yuav tsum tau rau nitriding yog khaws cia tsawg kawg yog 4-10 teev, thiab kev kho kub yog khaws cia ntawm txog 520 degree.
Txias cia
Feem ntau cov khoom siv hluav taws xob nitriding muaj cov hluav taws xob sib hloov kom ceev cov cua sov cua sov thiab cov khoom ua tiav tom qab ua tiav cov haujlwm nitriding. Ntawd yog, tom qab nitriding tiav lawm, lub tshuab cua sov yog muab tua kom txo tau qhov kub ntawm lub cub tawg li ntawm 50 degree, thiab tom qab ntawd tus nqi ammonia ntws yog ob npaug thiab lub tshav kub exchanger pib.
Lub sijhawm no, ua tib zoo saib xyuas seb puas muaj cov npuas dej ntws hauv lub khob iav txuas nrog cov yeeb nkab kom paub meej tias qhov zoo ntawm qhov cub. Tom qab cov roj ammonia nkag mus rau hauv lub cub tawg tau ruaj khov, qhov ntws ntawm ammonia tuaj yeem raug txo kom txog thaum lub siab zoo hauv lub cub tawg.
Thaum lub cub tawg kub qis dua 150 degree, lub qhov cub npog tuaj yeem qhib tau tom qab qhia huab cua lossis nitrogen siv txoj kev tshem cov roj hauv lub cub tawg raws li tau piav qhia saum toj no.
Roj nitriding
Gas nitriding tau luam tawm los ntawm German AF ry hauv xyoo 1923. Lub workpiece tau muab tso rau hauv lub cub tawg, thiab NH3 roj tau ncaj qha mus rau hauv lub qhov cub nitriding ntawm 500-550 degree thiab khaws cia rau 20-100 teev kom decompose cov nH3 roj. mus rau hauv lub xeev atomic.
Nitriding kev kho nrog (N) roj thiab (H) roj yog lub hom phiaj tseem ceeb ntawm kev tsim cov hnav-resistant thiab corrosion-resistant compound txheej ntawm cov hlau. Nws thickness yog hais txog 002-0.02m/m, thiab nws qhov xwm yog heev nyuaj Hv 1000 ~ 1200, thiab nkig heev. Tus nqi decomposition ntawm NH3 txawv nyob ntawm tus nqi ntws thiab kub.
Qhov loj dua tus nqi ntws, qhov qis dua tus nqi decomposition, qhov tsawg dua tus nqi ntws, qhov siab dua tus nqi decomposition, thiab qhov kub siab dua, qhov decomposition ntau dua. Qhov kub thiab txias, qhov qis decomposition tus nqi. NH3 gas undergoes thermal decomposition ntawm 570 degree raws li hauv qab no:
NH3 →〔N〕Fe plus 3/2 H2
Lub decomposed N ces diffuses rau saum npoo ntawm cov hlau los tsim. Phase Fe2-3N gas nitriding, qhov tsis zoo ntawm cov txheej txheem yog nyias nyias thiab lub sij hawm nitriding ntev.
Cov roj nitriding muaj qhov ua haujlwm tsawg vim yog qhov decomposition ntawm NH3 rau nitriding, yog li nws feem ntau kho kom xaiv cov hlau uas tsim nyog rau nitriding, xws li muaj Al, Cr, Mo thiab lwm yam nitriding, txwv tsis pub nitriding yuav tsis ua tau.
Feem ntau, JIS thiab SACM1 yog siv. JIS tshiab, SACM645 thiab SKD61 tseem hu ua quenching thiab tempering nrog ntxiv dag zog thiab toughening kev kho mob. Vim hais tias Al, Cr, Mo, thiab lwm yam yog tag nrho cov ntsiab lus uas ua rau kom qhov hloov pauv kub, qhov kub thiab txias yog siab dua, thiab qhov kub thiab txias kuj tseem siab dua li cov qauv hlau zoo tib yam. Tempering brittleness tshwm sim thaum lub sij hawm ntev cua sov ntawm nitriding kub, yog li cov quenching thiab tempering kho yog thov ua ntej.
NH3 roj nitriding, vim hais tias qhov saum npoo yog ntxhib, tawv thiab nkig vim lub sij hawm ntev, nws tsis yooj yim rau grind, thiab lub sij hawm ntev yuav tsis yig. Nws yog siv rau nitriding ntawm lub raj pub mis thiab ntsia hlau pas nrig ntawm cov yas txhaj tshuaj molding tshuab.
Ua kua nitriding
Lub ntsiab sib txawv ntawm cov kua nitrocarburizing yog tias muaj Fe3Nε theem nyob rau hauv cov txheej nitrided, Fe4Nr theem tshwm sim tab sis tsis yog Fe2Nξ theem nitride. Lub ξ theem compound yog ib qho nyuaj thiab nkig nyob rau hauv cov txheej txheem nitriding, uas tsis zoo nyob rau hauv toughness, thiab kua nitrocarburizing Txoj kev yog tshem tawm xeb, degrease, preheat lub workpiece thiab muab tso rau hauv ib tug nitriding crucible.
Lub crucible yog ua los ntawm TF-1 raws li lub ntsiab ntsev, thiab nws yog rhuab mus rau 560-600 degree rau ob peb feeb mus rau ob peb teev. , Qhov tob ntawm txheej nitriding yog txiav txim siab raws li qhov loj ntawm cov khoom siv sab nraud ntawm lub workpiece. Thaum lub sij hawm ua, lub raj cua yuav tsum tau muab tso rau hauv qab ntawm lub crucible kom decompose ib tug npaum li cas ntawm cov pa nitriding tus neeg saib xyuas rau hauv CN los yog CNO, uas yuav nkag mus rau thiab diffuse mus rau lub chaw ua hauj lwm nto, thiaj li hais tias lub sab nraud compound ntawm lub workpiece nto. yog 8-9 feem pua wt ntawm N thiab ib qho me me ntawm C thiab diffusion txheej.
Nitrogen atoms diffuse mus rau hauv lub hauv paus -Fe kom cov hlau ntau zog tiv taus. Thaum lub sij hawm nitriding, vim yog decomposition thiab noj CNO, yog li ntawd, nws yog ib qho tsim nyog yuav tsum tsis tu ncua kuaj cov ntsev muaj pes tsawg leeg hauv 6-8 teev ntawm kev kho mob txhawm rau kho cov huab cua ntim lossis ntxiv ntsev tshiab.
Cov khoom siv rau kev kho cov kua muag nitriding yog hlau hlau. Qhov saum npoo tawv tom qab nitriding yog siab dua yog tias qhov tawv tawv muaj Al, Cr, Mo, Ti, thiab cov ntsiab lus kub ntau dua, qhov tob tob ntawm nitriding, xws li carbon steel Hv 350 -650, stainless hlau Hv {{1} }, nitrided hlau Hv 800-1100.
Cov kua nitrocarburizing yog tsim rau hnav-resistant thiab qaug zog-resistant tsheb qhov chaw, tshuab xaws, koob yees duab, thiab lwm yam, xws li lub tog raj kheej liner ua, valve ua, piston chim ua, thiab tsis-deformable pwm. Lub teb chaws uas siv cov kua nitrocarburizing muaj xws li Western European lub teb chaws, Tebchaws Meskas, Soviet Union, thiab Nyiv.
Ion nitriding
Txoj kev no yog muab cov khoom ua haujlwm rau hauv lub cub tawg nitriding, nqus lub qhov cub rau 10-2-10-3 Torr (㎜Hg) ua ntej, tom qab ntawd qhia cov roj N2 lossis N2 ntxiv rau H2 cov roj sib xyaw, thiab kho lub qhov cub kom ncav cuag {{4} } Torr, txuas lub tshuab ua kom sov lub cev rau lub anode, lub workpiece rau cathode, thiab siv ntau pua volts ntawm DC voltage ntawm ob tug ncej.
Lub sijhawm no, cov roj N2 hauv lub cub tawg yuav ci ntsa iab tawm mus rau hauv cov ions zoo thiab txav mus rau qhov chaw ua haujlwm. Qhov hluav taws xob poob qis, ua rau qhov zoo ions maj nrawm rau saum npoo ntawm cathode ntawm kev kub ceev, hloov lub zog kinetic rau hauv lub zog roj, kom qhov kub thiab txias ntawm lub workpiece tuaj yeem nce, vim muaj kev cuam tshuam ntawm nitrogen ions, qhov chaw. ntawm lub workpiece yog splashed nrog Fe.CO thiab lwm yam khoom ua ke nrog nitrogen ions. FeN, yog li ntawd, hlau nitride yog maj mam adsorbed ntawm lub workpiece los tsim nitriding.
Ion nitriding yeej siv nitrogen, tab sis yog tias hydrocarbon gas ntxiv, nws tuaj yeem siv rau ion soft nitriding, tab sis nws feem ntau hu ua ion nitrogen tshuaj kho, nitrogen concentration ntawm qhov chaw ntawm lub workpiece tuaj yeem hloov kho los ntawm kev hloov ib feem ntawm qhov siab. ntawm cov roj sib xyaw (N2 ntxiv rau H2) tau ntim rau hauv qhov cub.
Thaum ntshiab ion nitriding, ib-theem r′ (Fe4N) qauv ntawm qhov chaw ua hauj lwm muaj N cov ntsiab lus Ntawm 5.7 mus rau 6.1 feem pua wt, lub thickness ntawm txheej yog nyob rau hauv 10μm. Cov txheej txheej yog muaj zog thiab tsis ntxeem tau, thiab nws tsis yooj yim rau poob. Vim hais tias cov hlau nitride yog tas li absorbed los ntawm lub workpiece thiab diffuses mus rau hauv lub sab hauv, cov qauv ntawm lub nto mus rau sab hauv yog FeN → Fe2N → Fe3N → Fe4N hloov nyob rau hauv ib ntus, ib theem ε (Fe3N) muaj 5. {{13} }}.0 feem pua wt ntawm N, thiab ib theem ξ (Fe2N) muaj 11.0-11.35 feem pua wt.
Cov ion nitriding ua ntej tsim cov r theem thiab tom qab ntawd ntxiv Nyob rau hauv rooj plaub ntawm hydrogen carbide, txheej txheej thiab diffusion txheej uas hloov mus rau theem epsilon, qhov nce hauv cov txheej diffusion ua rau muaj zog ntau ntxiv rau kev qaug zog.Cov erodibility yog qhov zoo tshaj plaws hauv ε theem.
Cov degree ntawm ion nitriding kev kho mob tuaj yeem pib ntawm 350 degree. Lub sijhawm kho mob tuaj yeem yog ob peb feeb lossis txawm tias lub sijhawm ntev xav txog cov khoom siv thiab nws cov khoom siv kho tshuab muaj feem xyuam. Txoj kev no yog tib yam li yav dhau los kev kho nitriding siv thermal decomposition txoj kev. Txoj kev sib txawv. Vim tias txoj kev no siv lub zog ion siab, cov khoom siv xws li stainless hlau, titanium, cobalt, thiab lwm yam, uas tau pom tias nyuaj rau kev kho yav dhau los, kuj tuaj yeem kho tau yooj yim nrog cov tawv tawv zoo heev.
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