Qhov zoo tshaj plaws microstructure ntawm sintered hlau nplaum yog cov nplua thiab zoo ib yam theem tseem ceeb nplej nyob ib puag ncig los ntawm cov khoom sib luag, nyias ntxiv, nrog rau cov lus qhia yooj yim magnetization ntawm cov theem tseem ceeb ntawm cov nplej tau npaj raws li qhov ua tau raws li qhov kev taw qhia. Cov kab noj hniav, cov nplej loj, thiab qhov loj me me ntawm cov hlau nplaum sib nqus yuav ua rau txo qis lub zog ntawm cov hlau nplaum, thaum cov nplej uas nws qhov kev taw qhia magnetization deviates los ntawm kev taw qhia yuav ib txhij txo qhov squareness ntawm cov hlau nplaum seem thiab demagnetization curves. Rau lub hom phiaj no, alloy ingots los yog ceev txias flakes yuav tsum tau ua nyob rau hauv ib tug crystal particles nrog ib tug nruab nrab particle loj ntawm 3 ~ 5 μm, ib tug siab tshaj particle loj ntawm tsawg tshaj li 20 μm, thiab ib tug nyob ze rau lub kheej kheej. Nyob rau tib lub sijhawm, qhov kev faib ua feem ntawm cov nplej zoo heev yuav tsum tau tswj kom tsis txhob muaj kev nyiam oxidation loj ntawm cov hmoov. , yog tias tsim nyog, siv cov hmoov av kho los txhim kho lub peev xwm los tiv thaiv oxidation ntawm cov hmoov thiab txhim kho filling thiab compressibility.
1. Cov txheej txheem kev siv tshuab crushing
Tsis tshua muaj ntiaj teb hloov pauv pawg intermetallic tebchaw muaj siab hardness thiab brittleness. Alloy ingots tuaj yeem tawg yooj yim rau hauv cov me me uas siv lub puab tsaig crusher lossis cov tshuab zoo sib xws, thiab tom qab ntawd mechanically crushed kauj ruam los ntawm kauj ruam mus rau qhov nruab nrab particle loj ntawm 3 ~ 5 μm. Txawm li cas los xij, cov khoom siv coj los ua impurities kuj tseem cuam tshuam rau qhov zoo ntawm cov hmoov. Vim yog qhov hnyav oxidation nyiam ntawm cov hlau tsis tshua muaj hauv ntiaj teb thiab lawv cov sib txuas sib txuas, ntxhib crushing (~ 10mm qib) thiab nruab nrab crushing (~ 100μm qib) feem ntau yog ua los ntawm kev tiv thaiv huab cua xws li nitrogen lossis argon, thaum sib tsoo zoo (nruab nrab particle. loj 3 ~ 5μm) Xaiv cov kua tiv thaiv pob zeb los yog nitrogen lossis inert gas flow zeb.
Ob txoj kev alloy los yog ntau txoj kev alloy ntawm sintered NdFeB kuj tau siv dav. Feem ntau, ib qho alloy ze rau Nd2Fe14B zoo tivthaiv thiab Nd-nplua nuj ceev-txias alloy yog tov thiab hauv av, thiab me me-ntim Nd-nplua nuj hmoov yog tusyees faib Nws yog ze li ntawm muab faib mus rau hauv lub ntsiab ntawm alloy hmoov.
2. Hydrogen Decrepitation (HD)
Kev tshawb fawb txog kev coj tus cwj pwm hydrogen absorption ntawm cov hlau tsis tshua muaj hauv ntiaj teb, alloys, thiab intermetallic compounds thiab lub cev thiab tshuaj lom neeg ntawm hydrides yeej ib txwm yog ib qho teeb meem loj hauv kev siv cov av tsawg. Qhov piv txwv ncaj tshaj yog cov roj teeb hydrogen. Alloy ingots ntawm lub ntiaj teb tsis tshua muaj cov khoom siv hlau nplaum ruaj khov kuj muaj lub siab nyiam nqus hydrogen. Hydrogen atoms nkag mus rau hauv qhov chaw interstitial nyob rau hauv lub ntsiab theem ntawm intermetallic compound thiab lub ntiaj teb tsis tshua muaj nplua nuj grain ciam teb rau tsim interstitial atomic tebchaw, uas ua rau kom lub atomic spacing thiab nthuav lub lattice ntim. , qhov tshwm sim hauv kev ntxhov siab ua rau grain ciam teb tawg (intergranular fracture), grain tawg (transgranular fracture), los yog ductile tawg ntawm cov hlau nyob rau hauv heev nkig alloys. Vim tias qhov tawg no tuaj yeem nrog lub suab tawg, nws hu ua "hydrogen crushing" lossis "hydrogen bursting."
3. Ammonia dav hlau milling txoj kev
Hauv cov chaw soj nstuam lossis cov txheej txheem tsim khoom loj, fluidized txaj dav hlau mills siv high-pressure (0.6MPa), thiab high-purity (99.995%) nitrogen raws li lub zog siv feem ntau. Qhov nruab nrab particle loj D50 ntsuas los ntawm laser particle loj analyzer yog nyob ib ncig ntawm 5 μm. Xav tias cov roj siab yog proportional rau qhov nruab nrab kinetic zog ntawm cov roj molecules, nyob rau hauv tib lub siab, roj nrog ib tug me me molecular hnyav muaj ib tug ntau dua ya davhlau ceev, thiab ib tug nce nyob rau hauv cov roj txaus tus nqi yog conducive mus nce lub zaus ntawm ntuj sib tsoo ntawm hmoov. cov khoom. Hydrogen molecules thiab helium molecules yog cov neeg sib tw zoo tshaj plaws, tab sis vim yog qhov tawg ntawm hydrogen, helium yog qhov kev xaiv zoo tshaj plaws. Tus nqi ntws ntawm helium yog 2.9 npaug ntawm nitrogen, thiab Nd-Fe-B coarse hmoov tuaj yeem ua hmoov hauv lub sijhawm luv. Crush rau D50=2μm lossis tsawg dua.
