1. Ntawv Taw Qhia
Hauv kev tsim khoom ntxiv (AM), ultrashort pulse (USP) lasers tuaj yeem siv los ua cov ntaub ntawv ntau yam thiab muaj peev xwm txo qhov loj thiab cov duab ntawm cov khoom tsim los ntawm kev siv tshuab no. Qhov kev ua haujlwm no qhia tau hais tias USP lasers yog lwm txoj hauv kev rau laser hmoov txaj fusion (LPBF), tshwj xeeb tshaj yog thaum yuav tsum tau muaj qhov tseeb dua hauv kev tsim khoom ntawm qee qhov tseem ceeb. Txoj kev tshawb no ua tiav cov txiaj ntsig xav tau siv kev cai- ua thiab tus kheej- ua stainless hlau hmoov hmoov, thiab tsim cov txheej xwm txheej xwm txheej los ntawm cov txheej txheem kev ua kom zoo dua qub.
Txoj kev tshawb no lees paub tias cov txheej txheem tsis ua lub luag haujlwm tseem ceeb thaum siv hom laser no, txawm tias qhov sib txawv me me hauv ib qho kev ntsuas tuaj yeem ua rau tsis tiav. Melting tau ua tiav ntawm qis mem tes repetition tus nqi (500 kHz) thiab qis nruab nrab lub zog laser qhov tseem ceeb (0.5-1 W) los ntawm kev txo cov scan nrawm los tsim kom muaj cua sov. Qhov no qhib qhov muaj peev xwm ntxiv rau txo qhov tsawg kawg nkaus ntawm qhov chaw thiab tseem ceeb thaum siv USP lasers hauv AM.
2. Cov ntawv sau tag nrho
Nrog rau txoj kev loj hlob ntawm additive manufacturing technology, femtosecond lasers muaj broad daim ntawv thov prospects nyob rau hauv lub laser ua ntawm 316L stainless hlau. Daim ntawv no qhia txog cov ntaub ntawv tshawb fawb txog kev kawm txog cov txheej txheem tsis nyob hauv femtosecond laser ua ntawm 316L stainless hlau. Lub hom phiaj tseem ceeb ntawm qhov kev tshawb fawb no yog los tshawb xyuas qhov cuam tshuam ntawm cov txheej txheem tsis xws li laser fais fab, hmoov particle loj, scanning ceev, thiab duab ntxoov ntxoo kab nrug ntawm qhov zoo thiab kev ua tau zoo ntawm cov khoom ua tiav, txhawm rau txhim kho cov txheej txheem ua haujlwm.
Nyob rau hauv txoj kev tshawb no, pab neeg tshawb fawb thawj zaug qhia txog cov yam ntxwv thiab kev siv ntawm 316L stainless hlau thiab elaborated ntawm lub hauv paus ntsiab lus thiab cov txheej txheem ntawm femtosecond laser ua. Tom qab ntawd, lawv tau tsom mus rau kev cuam tshuam ntawm cov txheej txheem tseem ceeb xws li lub zog laser, hmoov particle loj, scanning ceev, thiab duab ntxoov ntxoo kab nrug ntawm kev ua tau zoo.
Los ntawm kev sim kev tshawb fawb, pab pawg tshawb fawb tau txiav txim siab lub zog laser tsim kom tsis txhob muaj kev puas tsuaj ntau dhau thiab cov khoom puas tsuaj. Lawv kuj tau kawm txog cov txiaj ntsig ntawm cov hmoov sib txawv ntawm qhov ntau thiab tsawg ntawm kev ua tau zoo, pom tias cov hmoov nplej zoo dua tuaj yeem ua tau zoo dua molten pas dej ua ke tswj thiab ntau dua kev ua kom raug. Tsis tas li ntawd, pab pawg tshawb fawb tau tshawb xyuas qhov cuam tshuam ntawm kev ntsuas nrawm thiab duab ntxoov ntxoo kab nyob deb ntawm qhov chaw zoo thiab kev ua haujlwm ntawm cov khoom. Los ntawm kev kho cov scanning ceev thiab duab ntxoov ntxoo kab nyob deb, lawv ua tau zoo txo qhov tsis xws luag thiab void tsim, thiab txhim kho kev ua tau zoo thiab efficiency.
Thaum kawg, pab neeg tshawb fawb tau sib tham txog daim ntawv thov kev cia siab ntawm femtosecond lasers hauv laser ua ntawm 316L stainless hlau, thiab taw qhia txog cov teeb meem hauv kev tshawb fawb tam sim no thiab cov lus qhia kev txhim kho yav tom ntej.
3. Graphical Analysis Ultrashort pulse (USP) lasers tuaj yeem tsim cov mem tes luv luv, feem ntau nyob rau hauv lub sij hawm ntawm femtoseconds (10⁻¹⁵ vib nas this) rau picoseconds (10⁻¹² vib nas this). Lub hauv paus ntsiab lus ntawm USP lasers yog ua raws li cov teebmeem optical nonlinear thiab ultrafast optics technology.
Cov khoom tseem ceeb ntawm USP laser yog ib lub laser resonant kab noj hniav, uas muaj xws li ib tug laser nruab nrab (xws li ib tug Nd: YAG siv lead ua los yog Ti: sapphire siv lead ua) thiab ib tug laser nce nruab nrab (xws li laser diode los yog flash teeb) uas ua kom lub teeb.
Lub laser amplification txheej txheem yog tiav los ntawm stimulated emission. Nyob rau hauv qhov kev txiav txim ntawm excitation qhov chaw (xws li lub laser diode los yog flash teeb), atoms los yog ions nyob rau hauv lub laser nruab nrab yog zoo siab rau ib tug siab zog theem. Thaum lawv rov qab los rau hauv av, lawv tso tawm photons los ntawm kev tawm dag zog. Cov photons no tau rov qab los rau hauv cov kab noj hniav resonant, nthuav dav los ntawm qhov nce nruab nrab, thiab thaum kawg tsim lub zog laser tso zis.
Lub USP laser muaj peev xwm tsim tau ultrashort pulses los ntawm kev siv cov teebmeem nonlinear ntawm lub teeb thiab ultrafast optics. Hauv qhov nruab nrab ntawm lub laser, kev nthuav tawm ntawm lub teeb ua rau muaj kev cuam tshuam tsis zoo xws li tus kheej - theem kev hloov kho thiab kho qhov muag tsis pom kev. Cov teebmeem no ua rau muaj kev hloov pauv ntawm cov mem tes spectrum, ua rau nws dav dua. Los ntawm kev qhia cov khoom siv kho qhov muag uas tsis yog-linear (xws li zaus- ob npaug ntawm cov muaju lossis cov khoom siv kho qhov muag) rau hauv cov kab noj hniav resonant, cov mem tes spectrum tuaj yeem hloov kho ntxiv, nqaim nws thiab tsim cov pulses ultrashort.
Tsis tas li ntawd, USP laser siv ultrafast optics kom ua tiav cov mem tes compression. Los ntawm kev siv cov khoom xws li gratings, optical fibers, thiab nonlinear crystals, cov mem tes tuaj yeem compressed hauv lub sijhawm, ua tiav cov mem tes dav hauv femtosecond thiab picosecond ntau yam.
Daim duab 1 qhia qhov ntsuas kub hloov pauv raws li qhov sib txawv ntawm lub zog laser. Thaum tus nqi hluav taws xob siab dhau (liab nkhaus), qhov kub siab tshaj qhov pib rau melting thiab ablation; thaum thaum tus nqi hluav taws xob tsawg dhau (ntsuab nkhaus), qhov kub tsis ncav cuag qhov pib melting. Ntawm qhov zoo tshaj plaws lub zog muaj nuj nqis (xiav nkhaus), qhov kub thiab txias txaus los yaj cov khoom tsis ua rau ablation.
Ceit muaj peev xwm muab kev cai hlau hmoov rau AM. Leveraging qhov kom zoo dua no, Ceit tau pib siv nws tus kheej tsim cov pa roj- atomized hlau hmoov hais. Txhawm rau tshawb xyuas cov txiaj ntsig ntawm cov hmoov me me ntawm cov txiaj ntsig, ob qhov sib txawv ntawm cov hmoov sib txawv tau raug xaiv thiab muaj npe, nyob rau hauv kev txiav txim, hmoov coarse (20-45µm particle loj faib) thiab hmoov zoo (<20µm particle size distribution) to distinguish them, as shown in Figure 2.
Txhawm rau daws qhov kev sib tw ntawm kev ua tiav qhov xav tau zoo hmoov deposition, lub substrate nto yog thawj laser - kho kom nws roughness thiab txhim khu adhesion ntawm substrate thiab cov hmoov. Ua raws li cov txheej txheem laser ablation, thaj chaw kho mob tau ua tiav siv 3D optical profileometer (Sensofar S Neox), yielding tus nqi Sa ntawm 3.3 µm thiab qhov tob ntawm 51.499 µm. Ib txheej thawj zaug tau thov rau thaj chaw no siv cov hniav tsis muaj grooves, cia cov hmoov sau thiab ua raws li cov substrate. Tom qab ntawd, cov khaubncaws sab nraud povtseg tau siv los ntawm kev sib xyaw ntawm cov hniav nrog cov grooves ntxiv, tsim cov qauv txog li 250 µm tuab. Txoj kev no ua tiav cov txheej txheej tuab: 100 thiab 200 µm rau cov hmoov coarse thiab 50 µm rau cov hmoov zoo. Cov txheej txheem hmoov txheej tau ua tiav siv cov hniav, raws li qhia hauv daim duab 3.
Thaum thov USP lasers rau AM, ib qho kev sib tw loj yog xa lub zog siab ntawm femtosecond laser pulses rau hlau hmoov kom yaj lawv thaum tsis txhob ablation. Ablation tshwm sim yog tias lub zog siab dhau los yog tus nqi xa khoom tsis raug. Ablation tuaj yeem tshwm sim hauv cov hmoov av lossis cov substrate. Cov tom kawg ua rau cov khoom raug tshem tawm ntawm qhov chaw ua haujlwm mus rau thaj chaw ib puag ncig ablated, raws li qhia hauv daim duab 4a) mus rau c).
Los ntawm kev txo lub hwj chim hauv qab qhov siab tshaj plaws uas tau txais txiaj ntsig ntawm qhov ablation ntau, qhov kev hloov pauv sai heev los ntawm lub substrate kiag li tsis muaj kev cuam tshuam rau lub substrate lossis cov hmoov tuaj yeem pom. Qhov no zoo ib yam nrog cov txiaj ntsig pom los ntawm Groeningdick thiab Mayer hauv lawv qhov kev sim. Qhov kev hloov pauv no kuj tshwm sim thaum siv cov pulses ntev dua, tab sis lub qhov rais txheej txheem yog qhov nqaim dua nyob rau hauv cov ntaub ntawv ntawm femtosecond pulses. Hauv kev sim siv cov hmoov zoo, qhov kev txwv qis dua kuj pom hauv qab uas cov hmoov tsis cuam tshuam. Hauv qhov no, cov txiaj ntsig zoo ib yam li cov tau pom hauv daim duab 4-d) tau pom thaum lub zog qis dua 0.5 W. Thaum lub zog nce siab tshaj tus nqi no, cov hmoov pib yaj, thiab cov khoom sib xyaw ua ke los tsim cov spheres loj dua.
Ua ntej, lub zog laser tau hloov mus rau qis qis ntawm lub qhov rais txheej txheem, siv lub zog muaj nuj nqis ntawm 0.68W thiab 0.765W. Tom qab ntawd, lub scan ceev tau txo los ntawm 5mm / s mus rau tus nqi qis tshaj plaws. Rau thawj qhov kev sim, peb siv 0.68W. Raws li tus naj npawb ntawm cov pulses ib cheeb tsam tau nce, cov cua kub tsub zuj zuj zuj zus, cov hmoov hlau pib yaj, cov khoom sib txuas rau ib leeg, thiab tsim cov khoom loj dua los ntawm agglomeration.
Nyob rau hauv daim duab 6, thaum lub scan ceev tau txo mus rau ib nrab ntawm nws tus nqi qub, peb tuaj yeem soj ntsuam qhov nce ntawm qhov loj me me, uas ua rau muaj cov hmoov loj dua agglomerate hauv cov txheej txheem. Qhov kev loj hlob no ua rau Sa nce ntawm 5.43µm mus rau 6.75µm. Conversely, nyob rau hauv qhov kev sim ua ntawm 0.765W, txo qhov scan ceev ua rau ib tug me ntsis txo nyob rau hauv Sa los ntawm 6.89µm. Ntawm ob theem zog, txo qhov nrawm nrawm tau txais txiaj ntsig zoo dua, txo tus nqi Sa rau 3.9–4.1µm. Qhov no yog vim hais tias raws li qhov ceev txo, cov agglomerates zoo li coalesce rau hauv ib txheej, ua rau ib tug ntau yam qauv.
