(1) Makhalidwe a brazing, mavuto omwe amapezeka mu graphite ndi diamond polycrystalline brazing ndi ofanana kwambiri ndi omwe amapezeka mu ceramic brazing. Poyerekeza ndi chitsulo, solder ndi yovuta kunyowetsa graphite ndi diamond polycrystalline zipangizo, ndipo coefficient yake ya expansion ya kutentha ndi yosiyana kwambiri ndi ya zipangizo zonse zomangamanga. Zonsezi zimatenthedwa mwachindunji mumlengalenga, ndipo oxidation kapena carbonization zidzachitika kutentha kukapitirira 400 ℃. Chifukwa chake, vacuum brazing iyenera kugwiritsidwa ntchito, ndipo vacuum degree siyenera kukhala yochepera 10-1pa. Chifukwa mphamvu ya zonsezi si yayikulu, ngati pali kupsinjika kwa kutentha panthawi ya brazing, ming'alu ingachitike. Yesani kusankha brazing filler metal yokhala ndi coefficient yochepa ya expansion ya kutentha ndikuwongolera mwamphamvu liwiro lozizira. Popeza pamwamba pa zinthu zotere sipangakhale ponyowetsa ndi zitsulo wamba zodzaza brazing, wosanjikiza wa 2.5 ~ 12.5um wandiweyani W, Mo ndi zinthu zina zitha kuyikidwa pamwamba pa zinthu za graphite ndi diamond polycrystalline mwa kusintha pamwamba (vacuum covering, ion sputtering, plasma spray ndi njira zina) musanazimitse ndi kupanga ma carbide ofanana nawo, kapena zitsulo zodzaza brazing zomwe zimagwira ntchito kwambiri zingagwiritsidwe ntchito.
Graphite ndi diamondi zili ndi magiredi ambiri, omwe amasiyana kukula kwa tinthu tating'onoting'ono, kuchulukana, kuyera ndi zina, ndipo ali ndi makhalidwe osiyanasiyana a brazing. Kuphatikiza apo, ngati kutentha kwa zinthu za diamondi za polycrystalline kupitirira 1000 ℃, chiŵerengero cha kuvala kwa polycrystalline chimayamba kuchepa, ndipo chiŵerengero cha kuvala chimachepa ndi kupitirira 50% pamene kutentha kukupitirira 1200 ℃. Chifukwa chake, pamene diamondi ya vacuum brazing, kutentha kwa brazing kuyenera kulamulidwa pansi pa 1200 ℃, ndipo digiri ya vacuum sayenera kuchepera 5 × 10-2Pa.
(2) Kusankha chitsulo chodzaza brazing kumadalira kwambiri kagwiritsidwe ntchito ndi kakonzedwe ka pamwamba. Chikagwiritsidwa ntchito ngati chinthu cholimba kutentha, chitsulo chodzaza brazing chokhala ndi kutentha kwakukulu kwa brazing komanso kukana kutentha bwino chiyenera kusankhidwa; Pazinthu zomwe sizimakhudzidwa ndi dzimbiri, zitsulo zodzaza brazing zokhala ndi kutentha kochepa kwa brazing komanso kukana dzimbiri bwino zimasankhidwa. Pa graphite pambuyo pa chithandizo cha chitsulo cha pamwamba, chosungunula cha mkuwa choyera chokhala ndi ductility yayikulu komanso kukana dzimbiri bwino chingagwiritsidwe ntchito. Chosungunula chogwira ntchito chochokera ku siliva ndi mkuwa chimakhala ndi kunyowa bwino komanso kusinthasintha kwa graphite ndi diamondi, koma kutentha kwa ntchito ya cholumikizira cholimba kumakhala kovuta kupitirira 400 ℃. Pazida za graphite ndi zida za diamondi zomwe zimagwiritsidwa ntchito pakati pa 400 ℃ ndi 800 ℃, maziko agolide, maziko a palladium, maziko a manganese kapena zitsulo zodzaza titanium nthawi zambiri zimagwiritsidwa ntchito. Pazida zomwe zimagwiritsidwa ntchito pakati pa 800 ℃ ndi 1000 ℃, zitsulo zodzaza zochokera ku nickel kapena kubowola ziyenera kugwiritsidwa ntchito. Pamene zinthu za graphite zikugwiritsidwa ntchito pamwamba pa 1000 ℃, zitsulo zodzaza zitsulo (Ni, PD, Ti) kapena zitsulo zodzaza zitsulo zokhala ndi molybdenum, Mo, Ta ndi zinthu zina zomwe zingapange ma carbide okhala ndi kaboni zingagwiritsidwe ntchito.
Pa graphite kapena diamondi popanda kukonza pamwamba, zitsulo zodzaza zomwe zili patebulo 16 zingagwiritsidwe ntchito popangira brazing mwachindunji. Zambiri mwa zitsulo zodzaza izi ndi titanium based binary kapena ternary alloys. Titanium yoyera imagwira ntchito mwamphamvu ndi graphite, yomwe imatha kupanga carbide layer yokhuthala kwambiri, ndipo linear expansion coefficient yake ndi yosiyana kwambiri ndi ya graphite, yomwe ndi yosavuta kupanga ming'alu, kotero singagwiritsidwe ntchito ngati solder. Kuwonjezera Cr ndi Ni ku Ti kungachepetse kusungunuka ndikuwonjezera kunyowa ndi ceramics. Ti ndi ternary alloy, yomwe imapangidwa makamaka ndi Ti Zr, yokhala ndi TA, Nb ndi zinthu zina. Ili ndi coefficient yochepa ya linear expansion, yomwe ingachepetse brazing stress. ternary alloy yomwe imapangidwa makamaka ndi Ti Cu ndi yoyenera brazing ya graphite ndi chitsulo, ndipo cholumikiziracho chili ndi kukana kwambiri dzimbiri.
Tebulo 16 zitsulo zodzaza brazing zogwiritsira ntchito graphite ndi diamondi mwachindunji
(3) Njira yopangira chitsulo, njira zopangira chitsulo za graphite zitha kugawidwa m'magulu awiri, limodzi ndi chitsulo chopangira chitsulo pambuyo pa chitsulo chopangira chitsulo, ndipo lina ndi chitsulo chopangira chitsulo popanda kukonzedwa pamwamba. Kaya njira iti ikugwiritsidwa ntchito, weldment iyenera kukonzedwa kale isanaphatikizidwe, ndipo zodetsa pamwamba pa zinthu za graphite ziyenera kutsukidwa ndi mowa kapena acetone. Ngati chitsulo chopangira chitsulo pamwamba, wosanjikiza wa Ni, Cu kapena wosanjikiza wa Ti, Zr kapena molybdenum disilicide uyenera kuphimbidwa pamwamba pa graphite ndi kupopera kwa plasma, kenako chitsulo chopangira chitsulo chopangira chitsulo kapena siliva chopangira chitsulo chiyenera kugwiritsidwa ntchito popangira chitsulo chopangira chitsulo. Direct brazing yokhala ndi solder yogwira ntchito ndiyo njira yomwe imagwiritsidwa ntchito kwambiri pakadali pano. Kutentha kwa chitsulo chopangira chitsulo kungasankhidwe malinga ndi solder yomwe yaperekedwa patebulo 16. Solder ikhoza kulumikizidwa pakati pa cholumikizira chopangira chitsulo kapena pafupi ndi mapeto amodzi. Mukapangira chitsulo chokhala ndi coefficient yayikulu ya expansion ya kutentha, Mo kapena Ti yokhala ndi makulidwe enaake ingagwiritsidwe ntchito ngati wosanjikiza wapakati wa buffer. Chosinthirachi chingapangitse kuti pulasitiki isinthe nthawi yotenthetsera, kuyamwa kutentha komanso kupewa kusweka kwa graphite. Mwachitsanzo, Mo imagwiritsidwa ntchito ngati cholumikizira chosinthira cha vacuum brazing cha graphite ndi hastelloyn. B-pd60ni35cr5 solder yokhala ndi kukana bwino ku dzimbiri la mchere wosungunuka ndi kuwala kwa dzuwa imagwiritsidwa ntchito. Kutentha kwa brazing ndi 1260 ℃ ndipo kutentha kumasungidwa kwa mphindi 10.
Daimondi yachilengedwe ikhoza kukulungidwa mwachindunji ndi b-ag68.8cu16.7ti4.5, b-ag66cu26ti8 ndi zosungunula zina zogwira ntchito. Kukulungidwa kuyenera kuchitika pansi pa vacuum kapena chitetezo chochepa cha argon. Kutentha kwa kukulungidwa sikuyenera kupitirira 850 ℃, ndipo kutentha kofulumira kuyenera kusankhidwa. Nthawi yogwira kutentha kwa kukulungidwa siyenera kukhala yayitali kwambiri (nthawi zambiri pafupifupi 10s) kuti tipewe kupangika kwa wosanjikiza wopitilira pa malo olumikizirana. Mukakulungidwa diamondi ndi chitsulo cha alloy, pulasitiki yolumikizira kapena wosanjikiza wotsika wa alloy iyenera kuwonjezedwa kuti isinthe kuti tipewe kuwonongeka kwa tinthu ta diamondi komwe kumachitika chifukwa cha kutentha kwambiri. Chida chosinthira kapena chida choboola cha makina olondola kwambiri chimapangidwa ndi njira yokulungidwa, yomwe imakulungidwa diamondi yaying'ono ya 20 ~ 100mg pa thupi lachitsulo, ndipo mphamvu yolumikizira ya cholumikizira cha kukulungidwa imafika 200 ~ 250mpa
Daimondi ya polycrystalline ikhoza kupangidwa ndi lawi, ma frequency ambiri kapena vacuum. Kupangidwa ndi ma frequency ambiri kapena lawi kuyenera kugwiritsidwa ntchito pa chitsulo chozungulira cha diamondi kapena mwala. Chitsulo chodzaza cha Ag Cu Ti chokhala ndi malo otsika osungunuka chiyenera kusankhidwa. Kutentha kwa brazing kuyenera kulamulidwa pansi pa 850 ℃, nthawi yotenthetsera siyenera kukhala yayitali kwambiri, ndipo kuzizira pang'onopang'ono kuyenera kutengedwa. Ma diamondi a polycrystalline omwe amagwiritsidwa ntchito pobowola mafuta ndi geological ali ndi mikhalidwe yoyipa yogwirira ntchito ndipo amanyamula katundu wambiri. Chitsulo chodzaza cha nickel chochokera ku nickel chingasankhidwe ndipo zojambulazo zamkuwa zoyera zingagwiritsidwe ntchito ngati cholumikizira cha vacuum brazing. Mwachitsanzo, makapisozi 350 ~ 400 Ф 4.5 ~ 4.5mm columnar polycrystalline diamond imapangidwa ndi ma clamp mu 35CrMo kapena 40CrNiMo chitsulo kuti apange mano odulira. Kuphimba kwa vacuum kumatengedwa, ndipo digiri ya vacuum si yochepera 5 × 10-2Pa, kutentha kwa kuvala ndi 1020 ± 5 ℃, nthawi yogwirira ndi 20 ± 2min, ndipo mphamvu yocheka ya cholumikizira cha kuvala ndi yayikulu kuposa 200mpa.
Pa nthawi yopangira zitsulo, kulemera kwa weldment kuyenera kugwiritsidwa ntchito popangira zinthu ndi kuziyika momwe zingathere kuti chitsulocho chikanikizire graphite kapena polycrystalline zinthu zomwe zili pamwamba. Pogwiritsa ntchito chopangira zitsulo poyika zinthu, zinthuzo ziyenera kukhala zinthu zomwe zili ndi mphamvu yowonjezereka ya kutentha yofanana ndi ya weldment.
Nthawi yotumizira: Juni-13-2022