Sapphire abu ne mai wuya, sawa mai juriya da ƙarfi tare da babban zafin jiki mai narkewa, sinadarai ba shi da yawa, kuma yana nuna kaddarorin gani masu ban sha'awa. Don haka, ana amfani da sapphire don aikace-aikacen fasaha da yawa inda manyan filayen masana'antu sune na'urorin gani da lantarki. A yau mafi girman juzu'in sapphire na masana'antu ana amfani dashi azaman maƙalli don samar da LED da semiconductor, sannan kuma amfani dashi azaman windows don agogo, sassan wayar hannu ko na'urar sikanin lambar, don suna wasu misalai [1]. A yau, akwai hanyoyi daban-daban don girma sapphire lu'ulu'u ɗaya, ana iya samun bayyani mai kyau misali a cikin [1, 2]. Duk da haka, hanyoyin haɓaka uku na tsarin Kyropoulos (KY), hanyar musayar zafi (HEM) da haɓakar ci gaban fim mai ƙima (EFG) yana da fiye da 90% na ƙarfin samar da sapphire na duniya.

An yi ƙoƙari na farko don kristal da aka samar da shi a 1877 don ƙananan lu'ulu'u ɗaya na ruby ​​[2]. A cikin 1926 an ƙirƙira tsarin Kyropoulos. Yana aiki a cikin injina kuma yana ba da damar samar da manyan boules na silinda mai inganci. Wata hanyar girma sapphire mai ban sha'awa ita ce haɓakar haɓakar fim ɗin da aka ayyana gefen. Dabarar EFG ta dogara ne akan tashar capillary wanda ke cike da ruwa-narke kuma yana ba da damar girma lu'ulu'u na sapphire masu siffa irin su sanduna, tubes ko zanen gado (wanda ake kira ribbons). Ya bambanta da waɗannan hanyoyin hanyar musayar zafi, wanda aka haife shi a ƙarshen 1960, yana ba da damar girma manyan ɓangarorin sapphire a cikin ƙwanƙolin ƙwanƙwasa a cikin sifar crucible ta ma'anar hakar zafi daga ƙasa. Saboda sapphire boule yana manne da crucible a ƙarshen tsarin girma, boules na iya fashe a yanayin sanyi kuma ana iya amfani da crucible sau ɗaya kawai.
Duk wani ɗayan waɗannan fasahohin haɓaka kristal na sapphire suna da gama-gari cewa ainihin abubuwan haɗin gwiwa - musamman ma'auni - suna buƙatar ƙarfe mai zafi mai zafi. Dangane da tsarin girma ana yin crucibles da molybdenum ko tungsten, amma kuma ana amfani da karafa don juriya, fakiti da garkuwar yanki mai zafi [1]. Koyaya, a cikin wannan takarda mun mayar da hankali kan tattaunawarmu akan batutuwan da suka shafi KY da EFG tun lokacin da ake amfani da crucibles ɗin da aka danna a cikin waɗannan hanyoyin.
A cikin wannan rahoto mun gabatar da nazarin siffar kayan abu da bincike kan yanayin yanayin yanayin da aka matse-sintered irin su molybdenum (Mo), tungsten (W) da abubuwan haɗin sa (MoW). A kashi na farko mayar da hankalinmu ya ta'allaka ne kan bayanan injina masu zafi mai zafi da ductile zuwa gaɓoɓin zafin canjin yanayi. Madaidaicin kaddarorin inji mun yi nazarin kaddarorin ma'aunin zafi-jiki, watau ma'aunin haɓakar thermal faɗaɗa da haɓakar zafi. A kashi na biyu mun gabatar da nazari kan dabarar gyaran fuska musamman don inganta juriya na crucible cike da narke alumina. A kashi na uku mun bayar da rahoto game da ma'aunin jika na alumina na ruwa akan karafa masu jujjuyawa a 2100 ° C. Mun gudanar da gwaje-gwaje na narkewa akan Mo, W da MoW25 gami (75 wt.% molybdenum, 25 wt.% tungsten) kuma mun yi nazarin dogaro akan yanayin yanayi daban-daban. Sakamakon binciken mu mun ba da shawarar MoW a matsayin abu mai ban sha'awa a cikin fasahar haɓaka sapphire kuma a matsayin madaidaicin madadin molybdenum da tungsten.
High-zazzabi inji da thermo-jiki Properties
Hanyoyin haɓakar sapphire crystal KY da EFG suna aiki cikin sauri sama da 85% na rabon sapphire na duniya. A cikin hanyoyi guda biyu, ana sanya alumina mai ruwa a cikin ƙwanƙwasa-sintered, yawanci an yi shi da tungsten don tsarin KY kuma an yi shi da molybdenum don tsarin EFG. Crucibles sune mahimman sassan tsarin don waɗannan matakan girma. Nufin ra'ayin yiwu rage farashin tungsten crucibles a cikin KY tsari da kuma kara da rayuwar molybdenum crucibles a cikin EFG tsari, mun samar da kuma gwada bugu da žari biyu MoW alloys, watau MoW30 dauke da 70 wt.% Mo da 30 wt. % W da MoW50 dauke da 50 wt.% Mo da W kowanne.
Don duk nazarin halayen kayan aiki mun samar da ingots da aka danna-sintered na Mo, MoW30, MoW50 da W. Tebur na I yana nuna yawa da matsakaicin girman hatsi daidai da jihohin kayan farko.

Tebur I: Takaitacciyar kayan da aka danna-sintered da aka yi amfani da su don ma'auni akan kayan inji da thermo-jiki. Tebur yana nuna yawa da matsakaicin girman hatsi na jihohin farko na kayan

Saboda crucibles suna daɗe da fallasa ga yanayin zafi mai zafi, mun gudanar da gwaje-gwaje masu ƙarfi musamman a cikin yanayin zafi mai zafi tsakanin 1000 ° C da 2100 ° C. Hoto na 1 ya taƙaita waɗannan sakamakon don Mo, MoW30, da MoW50 inda aka nuna ƙarfin 0.2 % na yawan amfanin ƙasa (Rp0.2) da haɓakawa zuwa karaya (A). Don kwatantawa, ana nuna ma'aunin bayanai na matsi-sintered W a 2100 ° C.
Don ingantaccen tungsten mai narkewa a cikin molybdenum ana tsammanin Rp0.2 zai ƙaru idan aka kwatanta da kayan Mo mai tsabta. Don yanayin zafi har zuwa 1800 ° C duka MoW alloys suna nuna aƙalla sau 2 mafi girma Rp0.2 fiye da na Mo, duba Hoto 1(a). Don yanayin zafi mafi girma kawai MoW50 yana nuna ingantaccen Rp0.2. Matsa-sintered W yana nuna mafi girman Rp0.2 a 2100 °C. Gwaje-gwajen tensile sun kuma bayyana A kamar yadda aka nuna a hoto 1 (b). Duka MoW Alloys suna nuna kamanni na elongation zuwa karye dabi'u wanda yawanci rabin dabi'un Mo. Ya kamata a yi la'akari da girman A na tungsten a 2100 ° C saboda tsarinsa mai kyau idan aka kwatanta da Mo.
Don ƙayyade ductile zuwa gaggautsa zafin canjin yanayi (DBTT) na molybdenum tungsten gami da aka danna-sintered, kuma an gudanar da ma'auni akan kusurwar lanƙwasa a yanayin gwaji daban-daban. Ana nuna sakamakon a cikin Hoto 2. DBTT yana ƙaruwa tare da haɓaka abun ciki na tungsten. Yayin da DBTT na Mo ya yi ƙasa da ƙasa a kusan 250 °C, gami da MoW30 da MoW50 suna nuna DBTT na kusan 450 °C da 550 °C, bi da bi.

Madaidaicin siffar inji mun kuma yi nazarin kaddarorin thermo-jiki. An auna ƙimar haɓakar haɓakar thermal (CTE) a cikin dilatometer na turawa [3] a cikin kewayon zazzabi har zuwa 1600 ° C ta amfani da samfuri mai tsayin Ø5 mm da 25 mm. Ana kwatanta ma'auni na CTE a cikin Hoto 3. Duk kayan suna nuna irin wannan dogaro na CTE tare da yawan zafin jiki. Ma'auni na CTE na alloys MoW30 da MoW50 suna tsakanin ƙimar Mo da W. Saboda ragowar porosity na kayan da aka danna-sintered ya ƙare kuma tare da ƙananan pores na mutum, CTE da aka samu yana kama da kayan haɓaka mai girma kamar zanen gado da zanen gado. sanduna [4].
An sami ƙarfin wutar lantarki na kayan da aka matse-sintered ta hanyar auna duka diffusivity na thermal da takamaiman zafi na samfur tare da Ø12.7 mm da kauri 3.5 mm ta amfani da hanyar filasha laser [5, 6]. Don kayan isotropic, irin su kayan da aka danna-sintered, ana iya auna takamaiman zafi tare da wannan hanya. An ɗauki ma'aunin a cikin kewayon zafin jiki tsakanin 25 ° C da 1000 ° C. Don ƙididdige ƙimar zafin zafi da muka yi amfani da ƙari abubuwan da yawa kamar yadda aka nuna a cikin Tebu I kuma muna ɗaukar yawan masu zaman kansu na zafin jiki. Hoto 4 yana nuna sakamakon zafin zafin jiki don matsa-sintered Mo, MoW30, MoW50 da W. Thermal conductivity

na MoW alloys ya kasance ƙasa da 100 W/mK don duk yanayin zafi da aka bincika kuma ya fi ƙanƙanta idan aka kwatanta da molybdenum da tungsten. Bugu da ƙari, abubuwan gudanarwa na Mo da W suna raguwa tare da ƙara yawan zafin jiki yayin da motsi na MoW alloy yana nuna karuwar dabi'u tare da yawan zafin jiki.
Ba a bincika dalilin wannan bambancin ba a cikin wannan aikin kuma zai kasance wani ɓangare na binciken nan gaba. An sani cewa ga karafa babban ɓangare na thermal conductivity a ƙananan zafin jiki shine gudunmawar phonon yayin da a yanayin zafi mai zafi gas na lantarki yana mamaye yanayin zafi [7]. phonons suna da lahani da lahani. Duk da haka, ana lura da haɓakar haɓakar thermal conductivity a cikin ƙananan zafin jiki ba kawai don kayan haɗin MoW ba har ma da sauran kayan aiki masu ƙarfi kamar tungsten-rhenium [8], inda gudunmawar lantarki ke taka muhimmiyar rawa.
Kwatanta kayan aikin injiniya da thermo-jiki yana nuna cewa MoW abu ne mai ban sha'awa don aikace-aikacen sapphire. Don yanayin zafi mai girma> 2000 ° C ƙarfin amfanin gona ya fi na molybdenum girma kuma ya kamata a yi yuwuwar tsawon rayuwar crucibles. Duk da haka, kayan ya zama mafi raguwa kuma ya kamata a gyara machining da handling. Matsakaicin raguwar ƙarancin wutar lantarki na MoW da aka danna-sintered kamar yadda aka nuna a hoto na 4 yana nuna cewa daidaita yanayin zafi da sanyi na tanderun girma na iya zama dole. Musamman a lokacin zafi, inda alumina ke buƙatar narke a cikin crucible, zafi ana ɗaukarsa kawai ta hanyar crucible zuwa kayan cikawa. Ya kamata a yi la'akari da rage yawan zafin jiki na MoW don kauce wa matsanancin zafi a cikin crucible. Matsakaicin ƙimar CTE na MoW alloys yana da ban sha'awa a cikin mahallin hanyar girma crystal na HEM. Kamar yadda aka tattauna a cikin tunani [9] CTE na Mo yana haifar da matse sapphire a cikin lokacin sanyi. Saboda haka, rage CTE na MoW alloy na iya zama mabuɗin don gane sake amfani da spun crucibles don tsarin HEM.
Yanayin yanayin da aka matse-sintered refractory karafa
Kamar yadda aka tattauna a cikin gabatarwar, ana amfani da matsi-sintered crucibles sau da yawa a cikin matakan girma na sapphire crystal don zafi da kiyaye alumina narke dan kadan sama da 2050 ° C. Ɗaya daga cikin mahimman buƙatu don ingancin kristal sapphire na ƙarshe shine kiyaye ƙazanta da kumfa na iskar gas a cikin narke gwargwadon yuwuwar. Sassan da aka danna-sintered suna da saura porosity kuma suna nuna kyakkyawan tsari. Wannan tsari mai kyau tare da rufaffiyar porosity yana da rauni ga haɓakar lalata ƙarfe musamman ta hanyar narkewar oxidic. Wata matsala ga lu'ulu'u na sapphire sune ƙananan kumfa gas a cikin narke. Samuwar kumfa na iskar gas yana haɓaka ta hanyar ƙãra ƙurawar ɓangarorin da ke da alaƙa da narke.

Don shawo kan waɗannan batutuwan kayan da aka danna-sintered muna amfani da jiyya ta saman injin. Mun gwada hanyar tare da kayan aiki mai latsawa inda na'urar yumbu ke aiki a saman ƙasa ƙarƙashin ƙayyadadden matsi na ɓangaren da aka danna [10]. Matsakaicin matsi mai tasiri a kan farfajiya yana da bambanci dangane da yanayin hulɗar kayan aikin yumbu yayin wannan yanayin yanayin. Tare da wannan jiyya za a iya amfani da matsananciyar matsananciyar damuwa a cikin gida zuwa saman kayan da aka daskare da kuma kayan da aka yi da filastik. Hoto na 5 yana nuna misali na samfurin molybdenum wanda aka danna-sintered wanda aka yi aiki da wannan fasaha.
Hoto na 6 yana nuna ƙwaƙƙwarar dogaro da matsananciyar matsa lamba akan matsa lamba na kayan aiki. An samo bayanan ne daga ma'auni na tambarin kayan aiki a cikin molybdenum da aka danna-sintered. Layin yana wakiltar dacewa da bayanai bisa ga ƙirar mu.

Hoto na 7 yana nuna sakamakon binciken da aka taƙaita don ƙayyadaddun yanayin da kuma ma'auni na ma'auni a matsayin aikin matsa lamba na kayan aiki don nau'o'in nau'i-nau'i-nau'i da aka shirya a matsayin diski. Kamar yadda aka nuna a cikin Hoto 7 (a) maganin yana haifar da taurin saman. Taurin duka kayan gwajin Mo da MoW30 yana ƙaruwa da kusan 150%. Don manyan matsalolin kayan aiki da taurin ba ya ƙara karuwa. Hoto na 7 (b) yana nuna cewa filaye masu santsi tare da Ra kamar ƙasa da 0.1 μm don Mo mai yiwuwa ne. Don haɓaka matsi na kayan aiki rashin ƙarfi na Mo yana ƙaruwa kuma. Saboda MoW30 (da W) sun fi na Mo, ƙimar Ra da aka samu na MoW30 da W gabaɗaya sau 2-3 sun fi na Mo. gwajin iyaka.
Binciken mu na sikanin lantarki (SEM) na abubuwan da suka dace sun tabbatar da bayanan rashin ƙarfi, duba Hoto 7(b). Kamar yadda aka nuna a cikin Hoto 8 (a), musamman matsi na kayan aiki na iya haifar da lalacewa ta fuskar hatsi da microcracks. Kwangila a matsanancin matsanancin damuwa na iya haifar da ko da cire hatsi daga saman, duba Hoto 8(b). Hakanan ana iya lura da irin wannan tasirin ga MoW da W a wasu sigogin injina.
Don nazarin tasirin dabarar yanayin yanayin sama game da tsarin hatsi na saman da yanayin zafinsa, mun shirya samfuran annealing daga fayafai na gwaji guda uku na Mo, MoW30 da W.

An yi amfani da samfurori na tsawon sa'o'i 2 a yanayin gwaji daban-daban a cikin kewayon 800 ° C zuwa 2000 ° C kuma an shirya microsections don nazarin microscope na haske.
Hoto na 9 yana nuna misalan microsection na molybdenum da aka danne. An gabatar da yanayin farko na saman da aka jiyya a cikin Hoto 9 (a). Filayen yana nuna wani nau'i na kusan m a cikin kewayon kusan 200 μm. A ƙasan wannan Layer ana iya ganin tsarin kayan abu na yau da kullun tare da pores na sintering, ragowar porosity kusan 5%. Matsakaicin da aka auna saura porosity a cikin saman saman ya yi ƙasa da 1 %. Hoto 9 (b) yana nuna tsarin hatsi bayan annealing na 2 h a 1700 ° C. Kaurin ɗigon ƙasa mai yawa ya ƙaru kuma hatsin sun fi girma da yawa fiye da hatsin da ke cikin ƙarar da ba a gyaggyarawa ta yanayin yanayin ƙasa. Wannan ƙwanƙƙarfan ƙaƙƙarfan ƙanƙara mai yawa zai yi tasiri don haɓaka juriya na kayan.
Mun yi nazarin dogara da zafin jiki na farfajiyar ƙasa game da kauri da girman hatsi don matsalolin kayan aiki daban-daban. Hoto na 10 yana nuna misalan wakilci don kauri daga saman Layer na Mo da MoW30. Kamar yadda aka kwatanta a hoto na 10(a) kauri na farko ya dogara da saitin kayan aikin injin. A yanayin zafi sama da 800 ° C kauri daga saman Layer na Mo ya fara karuwa. A 2000 ° C kauri Layer ya kai darajar 0.3 zuwa 0.7 mm. Don MoW30 ana iya lura da karuwar kauri na saman saman don yanayin zafi sama da 1500 ° C kamar yadda aka nuna Hoto 10 (b). Duk da haka a 2000 ° C kauri Layer na MoW30 yayi kama da Mo.

Kamar nazarin kauri na saman Layer, Hoto na 11 yana nuna matsakaicin girman adadin hatsi don Mo da MoW30 da aka auna a cikin saman saman a matsayin aikin yanayin zafi. Kamar yadda za'a iya fayyace daga alkaluman, girman hatsi shine - a cikin rashin tabbas na auna - mai zaman kansa daga saitin siga da aka yi. Girman girman hatsi yana nuna rashin haɓakar hatsin da ba a saba ba na shimfidar wuri wanda ya haifar da nakasar wurin. Kwayoyin Molybdenum suna girma a yanayin gwaji sama da 1100 ° C kuma girman hatsin ya kusan girma sau 3 a 2000 ° C idan aka kwatanta da girman hatsi na farko. Kwayoyin MoW30 na shimfidar yanayin shimfidar wuri sun fara girma sama da yanayin zafi na 1500 ° C. A zafin gwaji na 2000 ° C matsakaicin girman hatsi ya kai kusan sau 2 girman hatsin farko.
A taƙaice, binciken da muka yi a kan fasaha na gyaran fuska ya nuna cewa yana da kyau a yi amfani da shi don molybdenum tungsten alloys da aka danna-sintered. Yin amfani da wannan hanyar, ana iya samun saman tare da ƙãra taurin kai da kuma santsi mai santsi tare da Ra mai ƙasa da 0.5 μm. Dukiyar ta ƙarshe tana da fa'ida musamman don rage kumfa gas. Ragowar porosity a cikin saman Layer yana kusa da sifili. Annealing da microsection nazarin ya nuna cewa za a iya samun wani sosai m Layer Layer tare da hankula kauri na 500 μm. Ta haka ne ma'aunin injin zai iya sarrafa kauri. Lokacin fallasa kayan sharadi zuwa yanayin zafi kamar yadda aka saba amfani da su a cikin hanyoyin girma na sapphire, layin saman ya zama mara nauyi tare da girman hatsi sau 2-3 girma fiye da ba tare da injinan saman ba. Girman hatsi a cikin farfajiyar ƙasa ya kasance mai zaman kansa daga sigogin injin. An rage yawan iyakokin hatsi a saman ƙasa yadda ya kamata. Wannan yana haifar da babban juriya ga yaɗuwar abubuwa tare da iyakokin hatsi kuma harin narke yana ƙasa. Bugu da ƙari, babban juriya mai raɗaɗi na zafin jiki na molybdenum tungsten gami da aka danna-sintered yana inganta.

Nazarin jika na alumina na ruwa akan karafa masu jujjuyawa
Jikin alumina na ruwa akan molybdenum ko tungsten yana da mahimmancin sha'awa ga masana'antar sapphire. Musamman don aiwatar da EFG halin alumina jika a cikin capillaries mutu-pack yana ƙayyade ƙimar girma na sandunan sapphire ko ribbons. Don fahimtar tasirin abin da aka zaɓa, rashin ƙarfi ko yanayin tsari mun gudanar da cikakken ma'auni na jika [11].
Don ma'aunin jika an samar da sinadarai masu girman 1 x 5 x 40 mm³ daga kayan Mo, MoW25 da W. Ta hanyar aika babban halin yanzu na lantarki ta cikin takaddar karfen za a iya samun zafin narkewar alumina na 2050 ° C cikin rabin minti. Don ma'aunin kusurwa an sanya ƙananan ƙwayoyin alumina a saman samfuran takarda kuma daga baya

narke cikin ɗigon ruwa. Tsarin hoto mai sarrafa kansa ya yi rikodin digo na narkewa kamar yadda aka kwatanta misali a cikin hoto na 12. Kowane gwaji na narkewa yana ba da damar auna kusurwar jika ta hanyar nazarin kwane-kwane na droplet, duba Hoto 12(a), kuma tushen tushe yawanci jim kaɗan bayan kashewa. dumama halin yanzu, duba Hoto 12(b).
Mun gudanar da ma'auni na jika don yanayin yanayi daban-daban guda biyu, injin a 10-5mbar da argon a matsa lamba 900 mbar. Bugu da kari, an gwada nau'ikan saman guda biyu, watau m saman tare da Ra ~ 1 μm da santsi tare da Ra ~ 0.1 μm.
Tebu na II yana taƙaita sakamakon duk ma'auni akan kusurwoyin jika don Mo, MoW25 da W don filaye masu santsi. Gabaɗaya, kusurwar jiƙa na Mo shine mafi ƙanƙanta idan aka kwatanta da sauran kayan. Wannan yana nuna cewa alumina narke yana jika Mo mafi kyau wanda ke da fa'ida a cikin fasahar girma na EFG. Kusurwoyin wetting da aka samu don argon suna da ƙasa da ƙasa fiye da kusurwoyi don vacuum. Domin m saman substrate muna samun a tsare-tsare da ɗan ƙananan kusurwoyi wetting. Waɗannan ƙimar yawanci kusan 2° ƙasa da kusurwoyin da aka bayar a Tebur II. Koyaya, saboda rashin tabbas na aunawa, ba za a iya ba da rahoton wani babban bambanci na kusurwa tsakanin santsi da tarkace.

Mun auna kusurwoyin jika kuma don wasu matsi na yanayi, watau ƙima tsakanin 10-5 mbar da 900 mbar. Binciken farko ya nuna cewa don matsa lamba tsakanin 10-5 mbar da 1 mbar mala'ikan jika ba ya canzawa. Kawai sama da 1 mbar kusurwar jika ya zama ƙasa da yadda aka gani a 900 mbar argon (Table II). Bayan yanayin yanayi, wani muhimmin mahimmanci ga yanayin jika na narke alumina shine matsa lamba na ɓangaren oxygen. Gwaje-gwajenmu sun ba da shawarar cewa hulɗar sinadarai tsakanin narke da abubuwan ƙarfe na faruwa a cikin cikakken tsawon lokacin awo (yawanci minti 1). Muna zargin narkar da tafiyar matakai na kwayoyin Al2O3 zuwa cikin wasu sassan oxygen wadanda ke yin mu'amala da kayan da ke kusa da digo na narkewa. Ana ci gaba da ƙarin karatu a halin yanzu don bincika dalla-dalla duka dogaro da matsa lamba na kusurwar jika da mu'amalar sinadarai na narkewa tare da karafa masu jujjuyawa.