Hanyar PVT, wacce cikakken sunanta shine Physical Vapor Transportation, hanya ce da aka saba amfani da ita wajen noman silicon carbide (SiC) lu'ulu'u a ƙarƙashin zafin jiki mai yawa da matsin lamba mai yawa. Babban ƙa'idarsa ita ce a dumama foda silicon carbide zuwa sublimation a zafin da ya wuce 2300℃ kuma a cikin yanayin ƙarancin matsin lamba kusa da injin, wanda ke samar da iskar gas mai amsawa wanda ke ɗauke da abubuwan gas kamar Si, Si2C, da SiC2. Saboda matsin lamba daban-daban na ɓangaren gas-phase na sassan Si da C waɗanda aka samar ta hanyar amsawar sublimation mai ƙarfi, rabon stoichiometric na Si/C ya bambanta da rarraba filin zafi. Saboda haka, ya zama dole a sarrafa rarrabawa da jigilar sassan gas-phase don tabbatar da cewa sun isa takamaiman matsayin crystallization a cikin ɗakin girma.
Domin hana samuwar polycrystalline silicon carbide mai matsala, ana sanya lu'ulu'u na irin silicon carbide a saman ɗakin girma. A ƙarƙashin ƙarfin supersaturation na gas, abubuwan da ke cikin tsarin iskar gas za su yi ta zuba a saman lu'ulu'u na iri don samar da lu'ulu'u na silicon carbide guda ɗaya. Duk tsarin amsawar yana faruwa ne a cikin ɗakin girma a rufe, inda dukkan sigogi na tsarin amsawar ke haɗuwa da juna. Duk wani canji a yanayin girma zai shafi kwanciyar hankalin girmar lu'ulu'u ɗaya.
Bugu da ƙari, tsarin lu'ulu'u masu kama da silicon carbide iri-iri dangane da yanayin lu'ulu'unsu yana haifar da hanyoyi daban-daban na haɗin atomic da haɗin kai, don haka yana samar da nau'ikan lu'ulu'u sama da 200 na isomers na silicon carbide. Katangar canza makamashi tsakanin nau'ikan lu'ulu'u daban-daban yana da ƙarancin yawa, don haka canjin siffar lu'ulu'u yana da yuwuwar faruwa a cikin tsarin girma na lu'ulu'u ɗaya na PVT, wanda ke haifar da rashin daidaituwar siffofin lu'ulu'u da kuma lahani daban-daban na lu'ulu'u. Saboda haka, ya zama dole a yi amfani da kayan aikin dubawa na musamman don gano siffar lu'ulu'u da lahani daban-daban na lu'ulu'u.
Tsarin shirya silicon carbide yana da buƙatu masu yawa, galibi yana bayyana a cikin waɗannan fannoni:
- Akwai datti da yawa a cikin tsarin haɗa foda na silicon carbide, wanda hakan ke sa ya zama da wahala a sami foda mai tsafta. Rashin cikar amsawar da ke tsakanin foda na silicon da foda na carbon a matsayin tushen amsawar yana iya haifar da rashin daidaito a cikin rabon Si/C. Siffar lu'ulu'u da girman barbashi na foda na silicon carbide bayan haɗawa suna da wahalar sarrafawa.
- A ƙarƙashin yanayin zafi mai yawa sama da 2300℃ da kuma kusa da injin tsabtace iska, silicon carbide yana fuskantar canjin "solid-gas-solid" da kuma sake yin amfani da shi a cikin ɗakin graphite mai rufewa. Wannan tsari yana da tsawon zagayowar girma, yana da wahalar sarrafawa, kuma yana iya fuskantar lahani kamar ƙananan tubules da abubuwan da ke ciki.
- Silicon carbide ya ƙunshi nau'ikan lu'ulu'u sama da 200 daban-daban, amma samarwa yawanci yana buƙatar siffar lu'ulu'u ɗaya kawai. A lokacin girma, canjin siffar lu'ulu'u yana da saurin faruwa, wanda ke haifar da lahani ga nau'ikan nau'ikan da yawa. A lokacin shiri, yana da wuya a sarrafa takamaiman nau'in lu'ulu'u ɗaya, kuma shingen canza makamashi tsakanin nau'ikan lu'ulu'u daban-daban yana da ƙasa sosai, wanda ke ƙara wahalar sarrafawa. Kula da sigogi da bincike mai alaƙa a wannan lokacin yana buƙatar babban farashi na bincike da haɓakawa, wanda kuma shine ɗayan dalilan da ke haifar da tsadar silicon carbide mai jituwa.
Lokacin Saƙo: Yuli-03-2025