U-Old Zhang wachitha wonke umsebenzi wakhe e-Aerospace Materials Institute. Ngaphambi kokuthatha umhlalaphansi, isikhathi sakhe sokuzilibazisa ayesithanda kakhulu kwakuwukuthatha abafundi bakhe baye esitolo sokugcina impahla ukuze bathole izinto zokwakha. Wakhulula ibhakede lepulasitiki elimhlophe elinomoya ophansi, wakha isipuni esigcwele sempuphu emhlophe ecolekileyo, ekhilimu ngesipuni sokuhlola, wabe esesiphonsa kancane ngaphansi kokukhanya. Uthuli lwahlala kancane kancane emsebeni wokukhanya, lukhanya kancane. “Ungayithathi kancane lempuphu emhlophe,” kusho u-Old Zhang, ebuka amehlo akhe. “Ukuthi izindiza namarokhethi esiwakhayo angakwazi yini ukumelana nezinto ezisesibhakabhakeni ngezinye izikhathi kuncike emandleni alo ‘mpuphu.’”
“Impuphu emhlophe” ayekhuluma ngayo yayiyiimpuphu ye-alumina. Kuzwakala kuyinto evamile—akuyona nje into ecwengisiswe nge-bauxite? Kodwa i-alumina powder esetshenziswa ezindizayo ihluke ngokuphelele kwi-alumina ejwayelekile yezinga lezimboni. Ubumsulwa bayo bucishe bube yi-nines ezine ngemva kwephuzu ledesimali; usayizi wezinhlayiya zayo ulinganiswa ngama-nanometer nama-micrometer; ukuma kwayo—kungakhathaliseki ukuthi yizimbulunga, ama-flakes, noma izinaliti—konke kucatshangelwa ngokucophelela. Ngamazwi kaLao Zhang, “Lokhu ukudla okuhle ‘okwengeza i-calcium’ yemishini esindayo yesizwe.”
Ngokuqondene nalokho lokhu okungakwenza emkhakheni wezindiza, kunezinhlelo zokusebenza eziningi. Ake siqale “ngezinto eziqinile kakhulu”—ukunikeza izindiza “izikhali.” Yiziphi izinto eziyesabeka kakhulu kunoma yini endiza esibhakabhakeni, kungakhathaliseki ukuthi iyindiza yabantu abavamile noma indiza yempi yezempi? Amazinga okushisa aphezulu kakhulu kanye nokuguguleka. Ama-turbine blades enjini ajikeleza ngesivinini esikhulu kumagesi okukhipha umoya kuzinkulungwane zama-degree Celsius; izinsimbi ezivamile bezizothamba futhi zincibilike kudala. Okufanele ukwenze? Onjiniyela beza nesisombululo esihle kakhulu: ukumboza ubuso be-blade ngengubo ekhethekile ye-ceramic. Izinto eziyinhloko zesakhiwo sale ngubo zivame ukuba yi-alumina powder.
Kungani kufanele uyikhethe? Okokuqala, ayishisi, inezinga lokuncibilika elingaphezu kwama-degree Celsius angu-2000, okwenza ibe “isudi yokuvikela ukushisa” enhle kakhulu. Okwesibili, iqinile futhi ayigugi, ivikela ama-blade ekugugulekeni kwezinhlayiya zothuli ekugelezeni komoya okusheshayo. Okungcono nakakhulu, ngokulungisa usayizi wezinhlayiya zempuphu ye-alumina nokwengeza ezinye izakhi, i-porosity, ukuqina, kanye nokunamathela ku-substrate yensimbi yengubo kungalawulwa. Njengoba isisebenzi esinolwazi esisemsebenzini sisho ngokuhlekisa, “Kufana nokufaka ungqimba lwe-ceramic sunscreen yezinga eliphezulu kuma-turbine blades—ivikela ilanga futhi imelana nokuklwebheka.” Ibaluleke kangakanani le “sunscreen”? Ivumela ama-turbine blades ukuthi asebenze emazingeni okushisa aphezulu, futhi kuwo wonke ama-degree ayishumi izinga lokushisa lenjini liyakhuphuka, ukusunduza kuyanda kakhulu, kuyilapho ukusetshenziswa kukaphethiloli kwehla. Ezindizeni ezindiza amashumi ezinkulungwane zamakhilomitha, ukonga kukaphethiloli kanye nokuthuthukiswa kokusebenza kuyamangalisa. Uma i-thermal barrier coating “iyindlela yangaphandle,” khona-ke indima ye-alumina powder ezintweni ezihlanganisiwe “isengezo sangaphakathi.”
Izindiza zanamuhla, amasathelayithi, namarokhethi zisebenzisa kakhulu izinto ezihlanganisiwe ukuze zinciphise isisindo. Kodwa-ke, lezi zinhlanganisela ezisekelwe ku-resin zinobuthakathaka—azikwazi ukumelana nokuguguleka, zisengozini yokushisa okuphezulu, futhi azinabo ubulukhuni obanele. Ososayensi bezinto ezihlakaniphile bafake i-alumina powder, ikakhulukazi ngobukhulu obuncane.impuphu ye-alumina, ngokulinganayo ku-resin, njengenhlama yokuxova. Lokhu kuhlanganiswa kunemiphumela emangalisayo: ubulukhuni bento, ukumelana nokuguguleka, ukumelana nokushisa, kanye nokuzinza kobukhulu konke kuthuthuka kakhulu.
Isibonelo, phansi kwekhabhini lezindiza, izingxenye ezithile zangaphakathi, ngisho nezinye izingxenye zesakhiwo ezingathwali umthwalo zisebenzisa le nto ehlanganisiwe eqiniswe yi-alumina. Lokhu akugcini nje ngokuzenza zibe lula futhi ziqine kodwa futhi kuyabambezela ngempumelelo, okuthuthukisa ukuphepha kakhulu. Ithuluzi elinembile elisekela kumasathelayithi, adinga ushintsho oluncane kakhulu ngaphansi kwemijikelezo yokushisa okukhulu, futhi lidinga okuningi kule nto. Kufana "nokufaka" uhlaka lwesikhumba epulasitikini eguquguqukayo, okwenza lube namandla futhi luguquguquke.
Impuphu ye-alumina nayo "inekhono elifihliwe," elibalulekile emkhakheni wezindiza—iyinto enhle kakhulu yokuvikela ukushisa kanye nezinto ezingavumeli ukubola.
Lapho indizamkhathi iphinda ingena emkhathini isuka emkhathini, kufana nokuwela esithandweni se-plasma samadigri ayizinkulungwane. Igobolondo langaphandle le-capsule yokungena kabusha kumele libe nengqimba engamelani nokushisa "eyazidela ngenxa yenzuzo enkulu." Impuphu ye-alumina idlala indima ebalulekile ekwakhiweni kwezinto eziningi ezingamelani nokushisa. Uma ihlanganiswa nezinye izinto, yakha ungqimba lwe-ceramic oluqinile, olunezimbobo, noluvikela kakhulu ebusweni. Lolu ngqimba luyasha kancane kancane emazingeni okushisa aphezulu, luthwala ukushisa futhi lugcine izinga lokushisa lekhabhinethi ngaphakathi kwebanga lokusinda kwabashayeli bezindiza ngokusebenzisa ukusetshenziswa kwalo. "Njalo lapho ngibona i-capsule ebuyayo ifika ngempumelelo, futhi ungqimba lwangaphandle lwezinto ezingamelani nokushisa lumnyama oshisiwe, ngicabanga ngalawo mafomula asekelwe ku-alumina esiwahlanze ngokuphindaphindiwe," kusho unjiniyela omkhulu ophethe izinto ezingamelani nokushisa. "Yasha, kodwa umsebenzi wayo wafezwa kahle kakhulu."
Ngaphandle kwalezi zinhlelo zokusebenza ezinzima "ezisesitejini esingaphambili",impuphu ye-aluminakuyinto ebaluleke kakhulu “ngemuva kwezigcawu.” Isibonelo, ekukhiqizeni izingxenye ezinembile zezindiza namarokhethi, ama-alloy amaningi anamandla aphezulu adinga ukushiswa. Ngesikhathi sokushiswa, izingxenye ze-powder metallurgy zidinga ukusekelwa esithandweni sokushisa okuphezulu kusetshenziswa “ama-shim” athile noma “amapuleti okudubula.” Lawa mapuleti kumele angashisi, angaguquki, futhi anganamatheli kumkhiqizo. Amapuleti okudubula enziwe nge-ceramic ye-alumina emsulwa kakhulu aba ukukhetha okuhle kakhulu. Ngaphezu kwalokho, ezinqubweni zokugaya nokupholisha zezinye izingxenye ezinembe kakhulu, i-micropowder ye-alumina emsulwa kakhulu iyindlela yokupholisha ephephile nephumelelayo.
Yiqiniso, izinto ezibaluleke kangaka azikwazi ukusetshenziswa ngokunganaki. Ingabe ubumsulwa buyanele? Ingabe ukusatshalaliswa kosayizi wezinhlayiya kuyafana? Ingabe kukhona ukuhlangana? Ingabe ukuhlakazeka kuhle? Yonke inkomba ithinta ukusebenza komkhiqizo wokugcina. Emkhakheni wezindiza, ngisho nephutha elincane kakhulu lingaholela emiphumeleni emibi kakhulu. Ngakho-ke, kusukela ekukhethweni kwezinto zokusetshenziswa kanye nokuguqulwa kokucubungula kuya kumasu okusebenzisa, isinyathelo ngasinye singaphansi kwezindinganiso zokulawula ezinzima, ezicishe zifuneke.
Uma umi esitshalweni sesimanje sokuhlanganisa izindiza, ubuka i-fuselage ethambile ekhanya ngaphansi kwezibani, uyaqaphela ukuthi lolu hlelo oluyinkimbinkimbi olukhuphuka esibhakabhakeni luwumphumela wezinto eziningi ezibonakala zivamile njenge-alumina powder, ngayinye idlala indima yayo ngokugcwele. Ayenzi uhlaka oluyinhloko, kodwa iqinisa isakhiwo; ayinikezi amandla amakhulu, kodwa ivikela umongo wohlelo lokunyakaza; ayinqumi ngqo indlela, kodwa iqinisekisa ukuphepha kwendiza.
Kusukela ekumbozweni okumelana nokushisa okuphezulu kuya ezintweni ezihlanganisiwe eziqinisiwe, ngisho nezendlalelo ezizidelayo ezimelana nokushisa, ukusetshenziswa kweimpuphu ye-aluminaemkhakheni wezindiza uyaqhubeka nokujula uye endaweni elula, eqinile, futhi emelene nezimo ezimbi kakhulu. Esikhathini esizayo, ngokuthuthukiswa kwezinto ze-alumina ezihlanzekile kakhulu kanye nezakhiwo ezihlukile (njengezintambo ezincane kanye nama-nanosheet), zingadlala indima engalindelekile ekuphathweni kokushisa, ekushabalaleni kokushisa kwedivayisi kagesi, ngisho nasekukhiqizweni kwendawo esikhaleni.
Lo mpuphu omhlophe, othule futhi ozinzile, uqukethe amandla amakhulu asekela ukuhlola kwesintu amazulu. Usikhumbuza ukuthi ohambweni oluya ezinkanyezini, asidingi nje kuphela imibono emikhulu namandla akhuphukayo, kodwa futhi nalawa “maphiko angabonakali” athule futhi aqinile akhulisa ukusebenza kwezinto eziyisisekelo. Ngesikhathi esizayo lapho ubheka phezulu endizeni endiza phezulu noma ubuka umbukwane omuhle kakhulu wokukhishwa kwerokhethi, ungase ukhumbule ukuthi ngaphakathi kwalowo mzimba wensimbi nezinto ezihlanganisiwe, kukhona “umoya omhlophe” onjalo, ovikela buthule ukuphepha kanye nobuhle bendiza ngayinye.