I-Molybdenum ne-tungsten embonini yokukhula kwekristalu yesafire

Isafire iyimpahla eqinile, engagqoki futhi eqinile enezinga eliphezulu lokushisa elincibilikayo, ayizinzi ngamakhemikhali kakhulu, futhi ibonisa izici ezithakazelisayo zokubona. Ngakho-ke, isafire isetshenziselwa izinhlelo zokusebenza eziningi zobuchwepheshe lapho izinkambu eziyinhloko zomkhakha ziyi-optics ne-electronics. Namuhla ingxenye enkulu yesafire yezimboni isetshenziswa njenge-substrate yokukhiqizwa kwe-LED kanye ne-semiconductor, okulandelwa ukusetshenziswa njengamawindi amawashi, izingxenye zomakhalekhukhwini noma izikena zekhodi yebha, ukusho izibonelo ezimbalwa [1]. Namuhla, izindlela ezihlukahlukene zokutshala i-sapphire crystals eyodwa ziyatholakala, ukubuka konke okuhle kungatholakala isb ku- [1, 2]. Kodwa-ke, izindlela ezintathu ezikhulayo zenqubo ye-Kyropoulos (KY), indlela yokushintshanisa ukushisa (HEM) kanye ne-edged-defined film-fed growth (EFG) zenza ngaphezu kuka-90 % wamandla okukhiqiza amasafire emhlabeni wonke.

Umzamo wokuqala wekristalu ekhiqizwe ngokwenziwa wenziwe ngo-1877 kumakristalu amancane angama-ruby [2]. Ngokushesha ngo-1926 inqubo ye-Kyropoulos yasungulwa. Isebenza ku-vacuum futhi ivumela ukukhiqiza ama-boules ama-cylindrical shape amakhulu ekhwalithi ephezulu kakhulu. Enye indlela ethokozisayo yokukhulisa isafire ukukhula okufunzwa ngamafilimu. Inqubo ye-EFG isuselwe kumzila we-capillary ogcwele i-liquid-melt futhi ivumela ukukhulisa amakristalu esafire amise okwezinduku, amashubhu noma amashidi (abizwa nangokuthi amaribhoni). Ngokuphambene nalezi zindlela indlela yokushintshanisa ukushisa, eyazalwa ngasekupheleni kwawo-1960, ivumela ukuba kukhule ama-boules amakhulu esafire ngaphakathi kwe-spun crucible ngesimo se-crucible ngokukhipha ukushisa okuchazwe phansi. Ngenxa yokuthi i-sapphire boule inamathela ku-crucible ekupheleni kwenqubo yokukhula, ama-boules angaqhekeka enqubo epholile futhi i-crucible ingasetshenziswa kanye kuphela.
Noma yibuphi lobu buchwepheshe bokukhula kwekristalu yesafire bufana nokuthi izingxenye eziyinhloko - ikakhulukazi izinsimbi - zidinga izinsimbi eziphikisayo ezishisa kakhulu. Ngokuya ngendlela ekhulayo ama-crucibles enziwe nge-molybdenum noma i-tungsten, kodwa izinsimbi zibuye zisetshenziselwe kabanzi izifudumezi eziphikisanayo, ama-die-pack kanye ne-hot-zone shieldings [1]. Kodwa-ke, kuleli phepha sigxile engxoxweni yethu ezihlokweni ezihlobene ne-KY ne-EFG njengoba kusetshenziswa iziphambano ezicindezelwe ezicindezelwe kulezi zinqubo.
Kulo mbiko sethula izifundo zokwenziwa kwabalingiswa bezinto ezibonakalayo kanye nophenyo mayelana nokumiswa kwendawo okungaphezulu kwezinto ezicindezelwe njenge-molybdenum (Mo), i-tungsten (W) nama-alloys ayo (MoW). Engxenyeni yokuqala ukugxila kwethu kudatha yemishini yezinga lokushisa eliphezulu kanye nezinga lokushisa le-ductile ukuya ku-brittle. Ukuhambisana nezakhiwo zemishini siye safunda izici ze-thermo-physical, okungukuthi i-coefficient yokwanda okushisayo kanye nokuhamba kwe-thermal. Engxenyeni yesibili sethula izifundo zesu lokumisa ubuso ngokukhethekile ukuze kuthuthukiswe ukumelana kweziphambano ezigcwele i-alumina melt. Engxenyeni yesithathu sibika ngezilinganiso zama-engeli wokumanzisa we-alumina ewuketshezi ezinsimbi eziphikisayo ku-2100 °C. Senze izivivinyo zokuncibilika kwe-Mo, W kanye ne-MoW25 alloy (75 wt.% molybdenum, 25 wt.% tungsten) futhi safunda ukuncika ezimweni ezihlukene zomkhathi. Njengomphumela wophenyo lwethu siphakamisa i-MoW njengento ethokozisayo kubuchwepheshe bokukhula kwesafire nanjengenye enye indlela engaba khona esikhundleni se-pure molybdenum ne-tungsten.
Izinga eliphezulu lokushisa mechanical kanye thermo-physical izakhiwo
Izindlela zokukhula kwekristalu yesafire i-KY ne-EFG zisebenza kalula ngaphezu kuka-85 % wenani lenani lesafire yomhlaba. Kuzo zombili izindlela, i-alumina ewuketshezi ifakwa ezitsheni ezicindezelwe-sintered, ngokuvamile ezenziwe nge-tungsten yenqubo ye-KY futhi zenziwe nge-molybdenum ngenqubo ye-EFG. Ama-crucibles ayingxenye yesistimu ebalulekile yalezi zinqubo ezikhulayo. Sihlose umqondo wokunciphisa izindleko ze-tungsten crucibles ohlelweni lwe-KY kanye nokwandisa impilo yonke ye-molybdenum crucibles ohlelweni lwe-EFG, sikhiqize futhi sahlola ngaphezu kwalokho ama-alloys e-MoW amabili, okungukuthi i-MoW30 equkethe u-70 wt.% Mo kanye no-30 wt. % W kanye ne-MoW50 equkethe u-50 wt.% Mo no-W ngayinye.
Kuzo zonke izifundo zokwenziwa kwabalingiswa okubalulekile sikhiqize ama-ingots acindezelwe we-Mo, MoW30, MoW50 kanye ne-W. Ithebula I libonisa ukuminyana kanye nosayizi wokusanhlamvu omaphakathi ohambisana nezimo zakuqala zezinto.

Ithebula I: Isifinyezo sezinto ezicindezelwe-sintered ezisetshenziselwa izilinganiso zezakhiwo zemishini ne-thermo-physical. Ithebula libonisa ukuminyana kanye nosayizi wokusanhlamvu omaphakathi wezifunda zokuqala zezinto

MOW

Ngenxa yokuthi ama-crucibles anesikhathi eside echayeke kumazinga okushisa aphezulu, senze izivivinyo ezishubile ikakhulukazi emazingeni okushisa aphezulu aphakathi kuka-1000 °C no-2100 °C. Umfanekiso 1 ufingqa le miphumela ye-Mo, MoW30, kanye ne-MoW50 lapho amandla esivuno angu-0.2 % (Rp0.2) kanye nokwelulwa kokuphuka (A) kuboniswa. Ukuze uqhathanise, iphoyinti ledatha lika-W ocindezelwe-sintered liboniswa ku-2100 °C.
Ukuze uthole i-tungsten eqinile exazululiwe ku-molybdenum kulindeleke ukuthi i-Rp0.2 inyuke uma iqhathaniswa nempahla ye-Mo emsulwa. Ngamazinga okushisa afika ku-1800 °C womabili ama-alloys e-MoW abonisa okungenani izikhathi ezingu-2 ukuphakama ngo-Rp0.2 kune-Mo, bheka uMfanekiso 1(a). Kumazinga okushisa aphezulu kuphela i-MoW50 ebonisa i-Rp0.2 ethuthuke kakhulu. I-W ecindezelwe-sintered ibonisa i-Rp0.2 ephakeme kakhulu ku-2100 °C. Ukuhlola okuqinile kwembula futhi A njengoba kukhonjisiwe kuMfanekiso 1(b). Womabili ama-alloys e-MoW abonisa ubude obufana kakhulu namanani okuphuka ngokuvamile ayingxenye yamanani e-Mo. I-A ephakeme kakhulu ye-tungsten ku-2100 °C kufanele ibangwe ukwakheka kwayo okucoliseke kakhulu uma kuqhathaniswa ne-Mo.
Ukuze kunqunywe izinga lokushisa le-ductile to brittle transition (DBTT) lama-alloys e-molybdenum tungsten ecindezelwe, nezilinganiso ku-engeli yokugoba zenziwe kumazinga okushisa ahlukahlukene okuhlola. Imiphumela ikhonjiswe kuMfanekiso 2. I-DBTT iyanda ngokukhula kokuqukethwe kwe-tungsten. Nakuba i-DBTT ye-Mo iphansi ngokuqhathaniswa cishe ku-250 °C, ama-alloys i-MoW30 ne-MoW50 abonisa i-DBTT ecishe ibe ngu-450 °C no-550 °C, ngokulandelana.

MoW30

 

MoW50

Ukuhambisana nesici somshini siphinde safunda izici ze-thermo-physical. I-coefficient of thermal expansion (CTE) ikalwe nge-push-rod dilatometer [3] ebangeni lokushisa elifika ku-1600 °C kusetshenziswa isifanekiso esinobude obungu-Ø5 mm no-25 mm. Izilinganiso ze-CTE ziboniswa kuMfanekiso 3. Zonke izinto ezisetshenziswayo zibonisa ukuncika okufanayo kakhulu kwe-CTE ngezinga lokushisa elikhulayo. Amanani e-CTE ama-alloys MoW30 kanye ne-MoW50 aphakathi kwamanani e-Mo kanye ne-W. Ngenxa yokuthi i-porosity eyinsalela yezinto ezicindezelweyo ayibonakali futhi inezimbotshana ezincane ezingazodwana, i-CTE etholiwe iyafana nezinto eziminyanisa kakhulu njengamashidi kanye izinduku [4].
I-thermal conductivity yezinto ezicindezelwe-sintered itholwe ngokulinganisa kokubili ukuhluka okushisayo kanye nokushisa okuqondile kwesifanekiso nge-Ø12.7 mm kanye no-3.5 mm ubukhulu kusetshenziswa indlela ye-laser flash [5, 6]. Okwezinto ze-isotropic, njengezinto ezicindezelwe-sintered, ukushisa okuthile kungalinganiswa ngendlela efanayo. Izilinganiso zithathwe ebangeni lokushisa eliphakathi kuka-25 °C no-1000 °C. Ukuze sibale i-thermal conductivity sisebenzise ngaphezu kwalokho ukuminyana kwezinto njengoba kuboniswe kuThebula I futhi sithathe ukuminyana okuzimele kwezinga lokushisa. Umfanekiso 4 ubonisa umphumela wokushisa oshisayo we-Mo, MoW30, MoW50 kanye ne-W. I-thermal conductivity ecindezelweyo.

 

Mo1

ama-alloys e-MoW angaphansi kuka-100 W/mK kuwo wonke amazinga okushisa aphenyiwe futhi mancane kakhulu uma kuqhathaniswa ne-molybdenum ne-tungsten emsulwa. Ukwengeza, ama-conductivity e-Mo no-W ayancipha ngezinga lokushisa elikhulayo kuyilapho ukuqhutshwa kwe-alloy ye-MoW kubonisa amanani akhuphukayo nezinga lokushisa elikhulayo.
Isizathu salo mehluko asiphenywanga kulo msebenzi futhi sizoba yingxenye yophenyo oluzayo. Kuyaziwa ukuthi ngezinsimbi ingxenye ebusayo ye-conductivity eshisayo emazingeni okushisa aphansi ingumnikelo we-phonon ngenkathi emazingeni okushisa aphezulu igesi ye-electron ibusa ukuqhutshwa kokushisa [7]. Amaphononi athintwa ukungapheleli nokushiyeka kwezinto ezibonakalayo. Nokho, ukwanda kokusebenza okushisayo ebangeni lokushisa eliphansi akubonwa nje kuphela kuma-alloys e-MoW kodwa nakwezinye izinto ezinesixazululo esiqinile njengesibonelo i-tungsten-rhenium [8], lapho umnikelo we-electron udlala indima ebalulekile.
Ukuqhathaniswa kwezakhiwo zemishini kanye ne-thermo-physical kukhombisa ukuthi i-MoW iyinto ethokozisayo yokusetshenziswa kwesafire. Emazingeni okushisa aphezulu > 2000 °C amandla okukhiqiza aphezulu kunawe-molybdenum futhi ukuphila okude kwama-crucibles kufanele kwenzeke. Nokho, impahla iba brittle kakhudlwana futhi machining kanye nokusingatha kufanele kulungiswe. Ukushisa okuncishisiwe kakhulu kwe-MoW ecindezelwe-sintered njengoba kukhonjisiwe kuMdwebo 4 kubonisa ukuthi amapharamitha okushisa ashintshiwe kanye nokupholisa phansi kwesithando somlilo angase adingeke. Ikakhulukazi esigabeni sokushisa, lapho i-alumina idinga ukuncibilika ku-crucible, ukushisa kuhanjiswa kuphela nge-crucible kuya kumpahla yayo yokugcwalisa eluhlaza. Ukuncishiswa kwe-thermal conductivity ye-MoW kufanele kucatshangelwe ukuze kugwenywe ukucindezeleka okuphezulu kokushisa ku-crucible. Ububanzi bamanani e-CTE ama-alloys e-MoW buyathakazelisa kumongo wendlela yokukhula kwekristalu ye-HEM. Njengoba kuxoxiwe kunkomba [9] i-CTE ye-Mo ibangela ukucindezelwa kwesafire esigabeni esipholile. Ngakho-ke, i-CTE encishisiwe ye-alloy ye-MoW ingase ibe ukhiye wokubona iziphambano eziphothiwe ezingasetshenziswa kabusha zenqubo ye-HEM.
Ukulungiswa kwendawo okucindezelwe-sintered refractory
Njengoba kuxoxiwe esingenisweni, iziphamba ezicindezelwe ezicindezelwe zivame ukusetshenziswa ezinqubweni zokukhula kwekristalu yesafire ukuze kushiswe futhi kugcinwe i-alumina incibilika kancane ngaphezu kuka-2050 °C. Imfuneko eyodwa ebalulekile yekhwalithi yokugcina yekristalu yesafire ukugcina ukungcola namabhamuza egesi ekuncibilikeni kuphansi ngangokunokwenzeka. Izingxenye ezicindezelwe zine-porosity eyinsalela futhi zibonisa ukwakheka okusanhlamvu. Lesi sakhiwo esinohlamvu olucolekile esine-porosity evaliwe sintekenteke ekugqwaleni okuthuthukisiwe kwensimbi ikakhulukazi ngenxa yokuncibilika kwe-oxidic. Enye inkinga yamakristalu esafire amabhamuza amancane egesi ngaphakathi kokuncibilika. Ukwakheka kwamabhamuza egesi kuthuthukiswa ukwanda kokuqina kwengxenye ye-refractory ehlangene nokuncibilika.

Ukuze sinqobe lezi zinkinga zezinto ezicindezelwe-sintered sisebenzisa ukwelashwa kwendawo eyimishini. Sihlole indlela ngethuluzi lokucindezela lapho idivayisi ye-ceramic isebenza ngaphezulu ngaphansi kwengcindezi echaziwe yengxenye ecindezelwe-sintered [10]. Ukucindezela okuphumelelayo kokucindezela okungaphezulu kuphambene kuye ngokuthi indawo yokuxhumana yethuluzi le-ceramic phakathi nalokhu kulungiswa kwendawo. Ngalokhu kwelashwa ukucindezela okuphezulu kungasetshenziswa endaweni endaweni yezinto ezicindezelwe-sintered futhi indawo ebonakalayo ikhubazekile ngokwepulasitiki. Umfanekiso wesi-5 ubonisa isibonelo sesifanekiso se-molybdenum esicindezelwe esisetshenziswe ngale ndlela.
Umfanekiso wesi-6 ukhombisa ngokwekhwalithi ukuncika kokucindezela okusebenzayo kungcindezi yethuluzi. Idatha ithathwe ezilinganisweni zezimpawu ezimile zethuluzi ku-molybdenum ecindezelwe-sintered. Ulayini umele ukulingana kwedatha ngokuya ngemodeli yethu.

ishidi le-moly

isampulaisampula

 

Umfanekiso wesi-7 ubonisa imiphumela yokuhlaziya efingqiwe yobulukhuni bobuso kanye nezilinganiso zobulukhuni bobuso njengomsebenzi wokucindezela kwethuluzi lezinto ezihlukahlukene ezicindezelwe ezilungiswe njengamadiski. Njengoba kukhonjisiwe kuMfanekiso 7(a) umphumela wokwelapha ukuqina kobuso. Ubulukhuni bazo zombili izinto ezihloliwe i-Mo ne-MoW30 bukhuphuka cishe ngo-150 %. Ngezingcindezi zamathuluzi aphezulu, ubulukhuni abusanda. Umfanekiso 7(b) ubonisa ukuthi izindawo ezibushelelezi kakhulu ezino-Ra ophansi njengo-0.1 μm we-Mo zingenzeka. Ukwandisa izingcindezi zamathuluzi ubulukhuni be-Mo bukhuphuka futhi. Ngenxa yokuthi i-MoW30 (kanye no-W) kuyizinto ezisetshenziswayo eziqinile kune-Mo, amanani afinyelelwe e-Ra we-MoW30 kanye no-W ngokuvamile aphakeme ngokuphindwe izikhathi ezingu-2-3 kune-Mo. Ngokuphikisana ne-Mo, ubulukhuni obungaphezulu buka-W buyancipha ngokusebenzisa izingcindezi zamathuluzi eziphakeme ngaphakathi ububanzi obuhloliwe bepharamitha.
Ucwaningo lwethu lwe-electron microscopy (SEM) lokuskena kwendawo enesimo luqinisekisa idatha yobunzima obungaphezulu, bheka uMdwebo 7(b). Njengoba kuboniswe kuMfanekiso 8(a), ikakhulukazi ukucindezela kwamathuluzi aphezulu kungaholela ekulimaleni kwendawo yokusanhlamvu nama-microcracks. Ukubeka isimo ekucindezelekeni okuphezulu kakhulu kungabangela ngisho nokukhishwa okusanhlamvu ebusweni, bheka uMdwebo 8(b). Imiphumela efanayo ingabonwa ku-MoW kanye ne-W kumapharamitha athile womshini.
Ukutadisha umthelela wendlela yokumisa ubuso ngokuphathelene nesakhiwo sokusanhlamvu okungaphezulu kanye nokuziphatha kwaso kwezinga lokushisa, silungiselele amasampuli a-annealing asuka kumadiski amathathu okuhlola e-Mo, MoW30 kanye ne-W.

I-SEM

Amasampuli aphathwe amahora angu-2 emazingeni okushisa ahlukene okuhlola ebangeni elingu-800 °C kuya ku-2000 °C futhi ama-microsection alungiselelwa ukuhlaziywa kwe-microscopy ekhanyayo.
Umfanekiso 9 ubonisa izibonelo ze-microsection ye-cindezelwe-sintered molybdenum. Isimo sokuqala sendawo ephathwayo sivezwe kuMfanekiso 9(a). Ingaphezulu libonisa ungqimba olucishe luminyene phakathi kwebanga elingama-200 μm. Ngezansi kwalesi sendlalelo isakhiwo esivamile sezinto ezibonakalayo esinama-pores sintering siyabonakala, i-porosity esele imayelana no-5%. I-porosity eyinsalela elinganiselwe ngaphakathi kongqimba olungaphezulu ingaphansi kuka-1%. Umfanekiso 9(b) ubonisa ukwakheka kokusanhlamvu ngemva kokushiswa kwama-2 h ku-1700 °C. Ugqinsi longqimba lwangaphezulu oluminyene lunyukile futhi izinhlamvu zinkulu kakhulu kunezinhlamvu zevolumu ezingalungiswanga ngokumiswa kwendawo. Lesi sendlalelo esiminyene kakhulu esinezinhlamvu ezimahhadla sizosebenza ukuthuthukisa ukumelana nokukhasa kwezinto.
Sifunde ukuncika kwezinga lokushisa kongqimba olungaphezulu mayelana nogqinsi nosayizi wokusanhlamvu wezingcindezi zamathuluzi ahlukahlukene. Umfanekiso 10 ubonisa izibonelo ezimele ukujiya kongqimba olungaphezulu lwe-Mo ne-MoW30. Njengoba kubonisiwe kuMfanekiso 10(a) ukujiya kwesendlalelo sendawo yokuqala kuncike ekusethweni kwethuluzi lomshini. Emazingeni okushisa okushisa angaphezu kuka-800 °C ubukhulu bengqimba ye-Mo buqala ukwanda. Ku-2000 °C ukujiya kongqimba kufinyelela kumanani ka-0.3 kuya ku-0.7 mm. Ku-MoW30 ukwanda kogqinsi kongqimba lwangaphezulu kungabonwa kuphela emazingeni okushisa angaphezu kuka-1500 °C njengoba kukhonjisiwe Umfanekiso 10(b). Noma kunjalo ku-2000 °C ubukhulu bengqimba ye-MoW30 bufana kakhulu ne-Mo.

phezulu

ukwehlisa

Njengokuhlaziywa kogqinsi kwesendlalelo esingaphezulu, Umfanekiso 11 ubonisa idatha yosayizi wokusanhlamvu emaphakathi ye-Mo ne-MoW30 elinganiswa kusendlalelo esingaphezulu njengomsebenzi wamazinga okushisa okubamba. Njengoba kungacatshangwa ngezibalo, usayizi wokusanhlamvu ungaphakathi - ngaphakathi kokungaqiniseki kokulinganisa - uzimele ekusethweni kwepharamitha esetshenzisiwe. Ukukhula kosayizi wokusanhlamvu kubonisa ukukhula okungavamile kokusanhlamvu kongqimba olungaphezulu okubangelwa ukuwohloka kwendawo engaphezulu. Izinhlamvu ze-molybdenum zikhula emazingeni okushisa okuhlola angaphezu kuka-1100 °C futhi usayizi wokusanhlamvu ucishe ube mkhulu ngokuphindwe ka-3 ku-2000 °C uma kuqhathaniswa nosayizi wokuqala wokusanhlamvu. Izinhlamvu ze-MoW30 zongqimba olunesimo esingaphezulu ziqala ukukhula ngaphezu kwamazinga okushisa angu-1500 °C. Ezingeni lokushisa lokuhlola lika-2000 °C isilinganiso sikasayizi wokusanhlamvu cishe siphindwe izikhathi ezi-2 kunosayizi wokuqala wokusanhlamvu.
Kafushane, uphenyo lwethu mayelana nendlela yokumisa indawo engaphezulu ibonisa ukuthi isebenza kahle kuma-alloys e-molybdenum tungsten ecindezelwe. Ngokusebenzisa le ndlela, izindawo ezinokuqina okwandayo kanye nezindawo ezibushelelezi ezine-Ra ngaphansi kuka-0.5 μm zingatholakala. Indawo yokugcina inenzuzo ikakhulukazi ekunciphiseni amabhamuza egesi. I-porosity eyinsalela kungqimba olungaphezulu iseduze noziro. Ucwaningo lwe-Annealing kanye ne-microsection lubonisa ukuthi ungqimba lwangaphezulu oluminyene kakhulu olunogqinsi olujwayelekile lwama-500 μm lungatholakala. Ngale ndlela ipharamitha yomshini ingalawula ukushuba kongqimba. Lapho kuvezwa okokusebenza okufakwe isimo emazingeni okushisa aphezulu njengoba ngokuvamile asetshenziswa ezindleleni zokukhulisa isafire, ungqimba olungaphezulu luba lukhuni ngokusanhlamvu olunosayizi wokusanhlamvu ngokuphindwe izikhathi ezingu-2-3 kunangaphandle komshini womshini. Usayizi wokusanhlamvu kungqimba olungaphezulu uzimele kumapharamitha womshini. Inombolo yemingcele yokusanhlamvu ebusweni iyancipha ngokuphumelelayo. Lokhu kuholela ekumelaneni okuphezulu ngokumelene nokusabalalisa kwezakhi eduze kwemingcele yokusanhlamvu futhi ukuhlasela kwe-ncibilika kuphansi. Ukwengeza, ukumelana nezinga lokushisa eliphezulu lokunyakazisa ama-alloys e-molybdenum tungsten ecindezelwe kuyathuthukiswa.

Izifundo zokumanzisa i-alumina ewuketshezi ezinsimbini eziphikisayo
Ukumanziswa kwe-alumina ewuketshezi ku-molybdenum noma i-tungsten kuyintshisekelo enkulu embonini yesafire. Ikakhulukazi ngenqubo ye-EFG ukuziphatha kokumanzisa kwe-alumina kuma-die-pack capillaries kunquma izinga lokukhula kwezinduku zesafire noma amaribhoni. Ukuze siqonde umthelela wezinto ezikhethiwe, ubuhwaqane obungaphezulu noma umkhathi wenqubo senze izilinganiso ze-engeli zokumanzisa ezinemininingwane [11].
Ukuhlola izilinganiso zokumanzisa izingxenye ezingaphansi ezinosayizi ongu-1 x 5 x 40 mm³ zakhiqizwa kusuka ku-Mo, MoW25 kanye nezinto zeshidi le-W. Ngokuthumela amandla kagesi aphezulu nge-substrate yeshidi lensimbi izinga lokushisa elincibilikayo le-alumina lika-2050 °C lingafinyelelwa phakathi nengxenye yomzuzu. Ukuze uthole izilinganiso zama-engeli izinhlayiya ezincane ze-alumina zabekwa phezu kwamasampula eshidi futhi kamuva

ancibilike abe amaconsi. Isistimu yokuthwebula ezenzakalelayo irekhoda iconsi elincibilikayo njengoba kubonisiwe njengesibonelo kuMfanekiso 12. Isilingo ngasinye se-melt-drop sivumela ukukala i-engeli yokumanzisa ngokuhlaziya i-contour yamaconsi, bheka uMfanekiso 12(a), kanye nesisekelo se-substrate ngokuvamile ngemva nje kokucisha ukushisa kwamandla, bheka uMfanekiso 12(b).
Senze izilinganiso ze-engeli yokumanzisa izimo ezimbili ezihlukene zomkhathi, ivacuum ku-10-5mbar kanye ne-argon ku-900 mbar pressure. Ngaphezu kwalokho, kwahlolwa izinhlobo ezimbili ezingaphezulu, okungukuthi izindawo ezimaholoholo ezine-Ra ~ 1 μm kanye nezindawo ezibushelelezi ezine-Ra ~ 0.1 μm.
Ithebula II lifingqa imiphumela yazo zonke izilinganiso kuma-engeli wokumanzisa we-Mo, MoW25 kanye noW ukuze uthole izindawo ezibushelelezi. Ngokuvamile, i-engeli yokumanzisa ye-Mo incane kakhulu uma iqhathaniswa nezinye izinto. Lokhu kusho ukuthi i-alumina iyancibilika imanzisa i-Mo engcono kakhulu enenzuzo endleleni yokukhula ye-EFG. Ama-engeli okumanzisa atholwe i-argon aphansi kakhulu kunama-engeli e-vacuum. Ezindaweni ezimaholoholo ze-substrate sithola ama-engeli okumanzisa aphansi ngokuhlelekile. Lawa manani acishe abe ngaphansi ngo-2° kunama-engeli anikezwe kuThebula II. Nokho, ngenxa yokungaqiniseki kokulinganisa, awukho umehluko obalulekile we-engeli phakathi kwezindawo ezibushelelezi nezimangelengele ongabikwa.

umfanekiso 1

ithebula 2

Silinganise ama-engeli wokumanzisa nokunye ukucindezela komkhathi, okungukuthi amanani aphakathi kuka-10-5 mbar no-900 mbar. Ukuhlaziywa kokuqala kubonisa ukuthi ngengcindezi ephakathi kuka-10-5 mbar no-1 mbar ingelosi yokumanzisa ayishintshi. Ngaphezulu kuka-1 mbar kuphela i-engeli yokumanzisa iba ngaphansi kunaleyo ebonwa ku-900 mbar argon (Ithebula II). Ngaphandle kwesimo somkhathi, esinye isici esibalulekile sokuziphatha kokumanzisa kwe-alumina ncibilika ukucindezela kwengxenye ye-oxygen. Ukuhlola kwethu kusikisela ukuthi ukusebenzisana kwamakhemikhali phakathi kokuncibilika nama-substrates ensimbi kwenzeka phakathi nesikhathi sokulinganisa esiphelele (ngokujwayelekile iminithi elingu-1). Sisola izinqubo zokuncibilika kwama-molecule e-Al2O3 abe kwezinye izingxenye ze-oxygen ezisebenzisana ne-substrate material eduze kwe-melt droplet. Ucwaningo olwengeziwe okwamanje lusaqhubeka ukuze luphenye kabanzi kokubili ukuncika kwengcindezi ye-engeli yokumanzisa kanye nokusebenzisana kwamakhemikhali okuncibilika ngezinsimbi eziphikisayo.


Isikhathi sokuthumela: Jun-04-2020