(1) Cov yam ntxwv brazing cov teeb meem cuam tshuam nrog graphite thiab pob zeb diamond polycrystalline brazing zoo ib yam li cov uas tau ntsib hauv ceramic brazing.Piv nrog rau cov hlau, solder yog ib qho nyuaj rau ntub graphite thiab pob zeb diamond polycrystalline cov ntaub ntawv, thiab nws coefficient ntawm thermal expansion yog txawv heev los ntawm cov khoom siv qauv.Ob leeg yog cua sov ncaj qha rau hauv huab cua, thiab oxidation los yog carbonization yuav tshwm sim thaum kub tshaj 400 ℃.Yog li, lub tshuab nqus tsev brazing yuav tsum tau txais, thiab lub tshuab nqus tsev kawm ntawv yuav tsum tsis pub tsawg tshaj 10-1pa.Vim tias lub zog ntawm ob qho tib si tsis siab, yog tias muaj thermal stress thaum lub sij hawm brazing, tej zaum yuav tshwm sim.Sim xaiv brazing muab tub lim hlau nrog qis coefficient ntawm thermal expansion thiab nruj me ntsis tswj tus nqi cua txias.Txij li qhov saum npoo ntawm cov ntaub ntawv no tsis yooj yim rau wetted los ntawm cov hlau zoo tib yam brazing muab tub lim, txheej ntawm 2.5 ~ 12.5um tuab W, Mo thiab lwm yam tuaj yeem muab tso rau saum npoo ntawm graphite thiab pob zeb diamond polycrystalline cov ntaub ntawv los ntawm kev hloov kho deg (lub tshuab nqus tsev txheej. , ion sputtering, plasma spraying thiab lwm txoj hauv kev) ua ntej brazing thiab daim ntawv sib txuam carbides nrog lawv, los yog kev ua haujlwm siab brazing muab tub lim siv tau.
Graphite thiab pob zeb diamond muaj ntau qib, uas txawv ntawm qhov loj me, qhov ntom ntom, purity thiab lwm yam, thiab muaj cov yam ntxwv sib txawv.Tsis tas li ntawd, yog tias qhov kub ntawm cov ntaub ntawv polycrystalline pob zeb diamond siab tshaj 1000 ℃, qhov sib piv ntawm cov khoom siv polycrystalline pib txo, thiab qhov hnav piv yuav txo qis dua 50% thaum qhov kub siab tshaj 1200 ℃.Yog li, thaum lub tshuab nqus tsev brazing pob zeb diamond, lub brazing kub yuav tsum tau tswj hauv qab 1200 ℃, thiab lub tshuab nqus tsev kawm ntawv yuav tsum tsis pub tsawg tshaj 5 × 10-2Pa.
(2) Kev xaiv ntawm brazing muab tub lim hlau yog tsim los ntawm kev siv thiab kev ua haujlwm saum npoo.Thaum siv los ua cov khoom siv hluav taws xob, cov khoom siv hlau brazing uas muaj qhov kub thiab txias yuav tsum raug xaiv;Rau cov khoom siv tshuaj corrosion-resistant, brazing muab tub lim hlau nrog qis brazing kub thiab zoo corrosion kuj raug xaiv.Rau cov graphite tom qab kev kho deg metallization, ntshiab tooj liab solder nrog siab ductility thiab zoo corrosion kuj yuav siv tau.Cov nyiaj raws li tooj liab thiab tooj liab raws li cov khoom siv tau zoo wettability thiab fluidity rau graphite thiab pob zeb diamond, tab sis qhov kev pabcuam kub ntawm brazed sib koom yog qhov nyuaj tshaj 400 ℃.Rau graphite Cheebtsam thiab pob zeb diamond cov cuab yeej siv ntawm 400 ℃ thiab 800 ℃, kub puag, palladium puag, manganese puag lossis titanium puag muab tub lim hlau feem ntau yog siv.Rau cov pob qij txha siv nyob nruab nrab ntawm 800 ℃ thiab 1000 ℃, nickel raws li los yog laum raws li muab tub lim hlau yuav tsum tau siv.Thaum siv cov khoom siv graphite saum toj no 1000 ℃, cov hlau ntshiab hlau muab tub lim (Ni, PD, Ti) lossis cov hlau muab tub lim uas muaj molybdenum, Mo, Ta thiab lwm yam khoom uas tuaj yeem tsim cov carbide nrog cov pa roj carbon monoxide.
Rau graphite lossis pob zeb diamond yam tsis muaj kev kho mob saum npoo, cov hlau ua kom muaj zog hauv cov lus 16 tuaj yeem siv rau brazing ncaj qha.Feem ntau ntawm cov hlau muab tub lim no yog titanium raws li binary lossis ternary alloys.Ntshiab titanium reacts nrog graphite, uas muaj peev xwm tsim ib tug heev tuab carbide txheej, thiab nws linear expansion coefficient yog heev txawv ntawm cov graphite, uas yog ib qho yooj yim los tsim cov kab nrib pleb, yog li nws tsis tuaj yeem siv los ua solder.Qhov sib ntxiv ntawm Cr thiab Ni rau Ti tuaj yeem txo qhov melting point thiab txhim kho cov wettability nrog ceramics.Ti yog ternary alloy, feem ntau yog tsim los ntawm Ti Zr, nrog rau qhov sib ntxiv ntawm TA, Nb thiab lwm yam khoom.Nws muaj qhov qis coefficient ntawm linear expansion, uas tuaj yeem txo qhov kev nyuaj siab brazing.Lub ternary alloy feem ntau yog tsim los ntawm Ti Cu yog tsim rau brazing ntawm graphite thiab hlau, thiab qhov sib koom ua ke muaj siab corrosion kuj.
Table 16 brazing muab tub lim hlau rau ncaj qha brazing ntawm graphite thiab pob zeb diamond
(3) Brazing txheej txheem cov txheej txheem brazing ntawm graphite tuaj yeem muab faib ua ob pawg, ib qho yog brazing tom qab metallization nto, thiab lwm yam yog brazing yam tsis muaj kev kho deg.Txawm hais tias siv txoj kev twg los xij, lub vuam yuav tsum tau pretreated ua ntej sib dhos, thiab cov khoom paug ntawm cov khoom siv graphite yuav tsum tau muab ntxuav nrog cawv lossis acetone.Nyob rau hauv cov ntaub ntawv ntawm nto metallization brazing, ib txheej ntawm Ni, Cu los yog ib txheej ntawm Ti, Zr los yog molybdenum disilicide yuav tsum tau plated nyob rau hauv graphite nto los ntawm plasma spraying, thiab ces tooj liab raws li muab tub lim hlau los yog nyiaj raws li muab tub lim hlau yuav tsum tau siv rau brazing. .Direct brazing nrog active solder yog feem ntau siv txoj kev tam sim no.Lub brazing kub tuaj yeem xaiv tau raws li cov khoom siv hauv lub rooj 16. Lub solder tuaj yeem clamped nyob rau hauv nruab nrab ntawm lub brazed sib koom los yog nyob ze ntawm ib kawg.Thaum brazing nrog ib tug hlau nrog ib tug loj coefficient ntawm thermal expansion, Mo los yog Ti nrog ib tug tej thickness yuav siv tau raws li ib tug intermediate tsis txheej.Cov txheej txheem hloov pauv tuaj yeem tsim cov yas deformation thaum lub sij hawm brazing cua sov, nqus cov thermal stress thiab tsis txhob graphite cracking.Piv txwv li, Mo yog siv los ua kev hloov pauv sib koom ua ke rau lub tshuab nqus tsev ntawm graphite thiab hastelloyn Cheebtsam.B-pd60ni35cr5 solder nrog zoo tiv thaiv molten ntsev corrosion thiab hluav taws xob yog siv.Lub brazing kub yog 1260 ℃ thiab kub yog khaws cia rau 10min.
Ntuj pob zeb diamond tuaj yeem ncaj qha brazed nrog b-ag68.8cu16.7ti4.5, b-ag66cu26ti8 thiab lwm yam active solders.Lub brazing yuav tsum tau ua nyob rau hauv lub tshuab nqus tsev los yog tsawg argon tiv thaiv.Lub brazing kub yuav tsum tsis txhob ntau tshaj 850 ℃, thiab yuav tsum tau xaiv ib tug ceev cua sov tus nqi.Lub sijhawm tuav ntawm qhov kub ntawm lub brazing yuav tsum tsis txhob ntev dhau (feem ntau txog 10s) kom tsis txhob tsim cov txheej txheem txuas ntxiv ntawm qhov sib txuas.Thaum brazing pob zeb diamond thiab hlau alloy, yas interlayer lossis qis expansion alloy txheej yuav tsum tau ntxiv rau kev hloov mus rau kev tiv thaiv kev puas tsuaj ntawm pob zeb diamond nplej los ntawm kev kub ntxhov ntau dhau.Cov cuab yeej tig los yog tho txawv rau ultra precision machining yog tsim los ntawm cov txheej txheem brazing, uas brazes 20 ~ 100mg me me particle pob zeb diamond mus rau lub cev steel, thiab lub zog sib koom ua ke ntawm kev sib koom tes brazing ncav cuag 200 ~ 250mpa
Polycrystalline pob zeb diamond tuaj yeem ua los ntawm cov nplaim hluav taws, lub tshuab nqus tsev siab lossis lub tshuab nqus tsev.High zaus brazing los yog nplaim brazing yuav tsum tau saws rau pob zeb diamond ncig saw hniav txiav hlau lossis pob zeb.Ag Cu Ti active brazing muab tub lim hlau nrog qis melting point yuav tsum raug xaiv.Lub brazing kub yuav tsum tau tswj hauv qab 850 ℃, lub cua sov lub sij hawm yuav tsum tsis txhob ntev heev, thiab ib tug qeeb txias tus nqi yuav tsum tau saws.Polycrystalline pob zeb diamond cov khoom siv hauv roj av thiab geological drilling muaj kev ua haujlwm tsis zoo thiab ua rau muaj kev cuam tshuam loj heev.Nickel raws li brazing muab tub lim hlau tuaj yeem xaiv tau thiab cov ntawv ci tooj liab ntshiab tuaj yeem siv los ua interlayer rau lub tshuab nqus tsev.Piv txwv li, 350 ~ 400 capsules Ф 4.5 ~ 4.5mm columnar polycrystalline pob zeb diamond yog brazed rau hauv cov perforations ntawm 35CrMo los yog 40CrNiMo steel rau cov hniav txiav.Nqus brazing yog saws, thiab lub tshuab nqus tsev kawm ntawv tsis tsawg tshaj 5 × 10-2Pa, lub brazing kub yog 1020 ± 5 ℃, lub sij hawm tuav yog 20 ± 2min, thiab lub zog shear ntawm lub brazing sib koom yog ntau tshaj 200mpa
Thaum lub sij hawm brazing, nws tus kheej qhov hnyav ntawm qhov vuam yuav tsum tau siv rau kev sib dhos thiab muab tso rau ntau li ntau tau kom cov hlau ntu nias cov khoom siv graphite lossis polycrystalline ntawm sab saud.Thaum siv lub fixture rau qhov chaw, cov khoom fixture yuav tsum yog cov khoom uas muaj thermal expansion coefficient zoo ib yam li cov welment.
Post lub sij hawm: Jun-13-2022