Muva nje, ngidle isidlo sakusihlwa nomfundi engifunda naye esikoleni osebenza esikhungweni sokucwaninga ngezinto zezindiza. Sixoxe ngamaphrojekthi abo akamuva, futhi wangitshela ngokungaqondakali ukuthi, “Uyazi ukuthi yiziphi izinto ezintsha esizithanda kakhulu njengamanje? Ungase ungakholwa – yileyo mpuphu ebukeka njengesihlabathi esiluhlaza okotshani.” Ebona ubuso bami obudidekile, wamomotheka wabe esenezela, “I-micro-powder ye-silicon carbide eluhlaza, uke wezwa ngakho? Lokhu kungase kubangele ushintsho oluncane emkhakheni wezindiza.” Uma ngikhuluma iqiniso, ekuqaleni ngangingabaza: lezo zinto ezisetshenziswa kakhulu ekugayeni amasondo nasekusikeni amadiski zingahlobana kanjani nemboni yezindiza eyinkimbinkimbi? Kodwa njengoba echaza kabanzi, ngaqaphela ukuthi kukhona okungaphezu kwalokho engangikucabanga. Namuhla, ake sixoxe ngalesi sihloko.
I. Ukwazi Lokhu “Okuthembisayo”
I-silicon carbide eluhlaza empeleni uhlobo lwe-silicon carbide (SiC). Uma iqhathaniswa ne-silicon carbide emnyama evamile, ihlanzekile kakhulu futhi ingcola encane, yingakho inombala wayo oluhlaza okhanyayo ohlukile. Ngokuqondene nokuthi kungani “iyi-micro-powder,” ibhekisela kusayizi wayo omncane kakhulu wezinhlayiya, ngokuvamile phakathi kwama-micrometer ambalwa namashumi ama-micrometer – cishe ingxenye eyodwa kweziyishumi kuya kwengxenye yobubanzi bezinwele zomuntu. “Ungavumeli ukusetshenziswa kwayo kwamanje embonini yokuklwebha kukukhohlise,” kusho engifunda naye, “empeleni inezakhiwo ezinhle kakhulu: ubulukhuni obuphezulu, ukumelana nokushisa okuphezulu, ukuzinza kwamakhemikhali, kanye ne-coefficient ephansi yokwanda kokushisa. Lezi zici zenzelwe cishe insimu yezindiza.”
Kamuva, ngenza ucwaningo oluthile futhi ngathola ukuthi lokhu kuyiqiniso ngempela. Ubulukhuni be-silicon carbide eluhlaza bungowesibili kuphela kune-diamond ne-cubic boron nitride; emoyeni, ingamelana namazinga okushisa aphezulu angaba ngu-1600°C ngaphandle kokuxilisa; futhi i-coefficient yayo yokwanda kokushisa iyingxenye eyodwa kwezine kuya kwengxenye yesithathu kuphela yezinsimbi ezivamile. Lezi zinombolo zingase zibonakale zomile kancane, kodwa ensimini yezindiza, lapho izidingo zokusebenza kwezinto ziqinile kakhulu, yonke ipharamitha ingaletha inani elikhulu.
II. Ukunciphisa Isisindo: Ukuphishekela Imikhumbi-mkhathi Okuphakade
"Ezindiza, ukunciphisa isisindo kuyisihluthulelo njalo," kushoizindizaunjiniyela ungitshele. “Ikhilogremu ngayinye yesisindo esilondoloziwe ingonga inani elikhulu likaphethiloli noma yandise umthwalo.” Izinto zensimbi zendabuko sezifinyelele imingcele yazo maqondana nokunciphisa isisindo, ngakho-ke wonke umuntu usephendukele ezintweni zobumba ngokwemvelo. Izinhlanganisela ze-matrix ze-silicon carbide eziqinisiwe ze-ceramic zingenye yezinto ezithembisayo kakhulu. Lezi zinto ngokuvamile zinobukhulu obungamagremu angu-3.0-3.2 kuphela ngesentimitha le-cubic, okulula kakhulu kunensimbi (amagremu angu-7.8 ngesentimitha le-cubic) futhi futhi zinikeza inzuzo ecacile ngaphezu kwe-titanium alloys (amagremu angu-4.5 ngesentimitha le-cubic). Okubaluleke kakhulu, igcina amandla anele ngenkathi inciphisa isisindo.
“Sicwaninga ngokusetshenziswa kwezingxenye ze-silicon carbide eziluhlaza okotshani ezimbozweni zenjini,” kwembula umklami wezinjini zezindiza. “Uma besisebenzisa izinto zendabuko, le ngxenye ibingaba nesisindo esingamakhilogremu angu-200, kodwa ngezinto ezintsha ezihlanganisiwe, ingancishiswa ibe cishe amakhilogremu angu-130. Kuyo yonke injini, lokhu kunciphisa okungamakhilogremu angu-70 kubalulekile.” Okungcono nakakhulu, umphumela wokunciphisa isisindo uyawohloka. Izingxenye zesakhiwo ezilula zivumela ukwehla kwesisindo okuhambisanayo ezakhiweni ezisekelayo, njengomphumela we-domino. Izifundo zibonise ukuthi emkhathini, ukwehla okungamakhilogremu angu-1 esisindweni sezingxenye zesakhiwo ekugcineni kungaholela ekunciphiseni okungamakhilogremu angu-5-10 esisindweni sezinga lesistimu.
III. Ukumelana Nokushisa Okuphezulu: “Isiqinisi” Ezinjinini
Amazinga okushisa okusebenza kwezinjini ze-aero ayanda njalo; izinjini ze-turbofan ezithuthukisiwe manje zinezinga lokushisa lokungena kwe-turbine elingaphezu kuka-1700°C. Kuleli zinga lokushisa, ngisho nama-alloy amaningi okushisa okuphezulu aqala ukwehluleka. “Izingxenye zengxenye eshisayo yenjini okwamanje zicindezela imikhawulo yokusebenza kwezinto ezibonakalayo,” kusho engifunda naye esikhungweni socwaningo. “Sidinga ngokushesha izinto ezingasebenza ngokuzinzile emazingeni okushisa aphezulu nakakhulu.” Ama-composites e-silicon carbide aluhlaza angadlala indima ebalulekile kule ndawo. I-silicon carbide emsulwa ingamelana namazinga okushisa angaphezu kuka-2500°C endaweni engasebenzi kahle, yize emoyeni, i-oxidation ikhawulela ukusetshenziswa kwayo cishe ku-1600°C. Kodwa-ke, lokhu kusesephezulu ngo-300-400°C kunezinye izinhlobo eziningi zokushisa okuphezulu.
Okubaluleke kakhulu, igcina amandla aphezulu emazingeni okushisa aphezulu. “Izinto zensimbi ‘zithambile’ emazingeni okushisa aphezulu, zibonise ukukhukhuleka okukhulu,” kuchaza unjiniyela ohlola izinto. “Kodwa izinhlanganisela ze-silicon carbide zingagcina amandla azo okushisa ekamelweni angaphezu kuka-70% ku-1200°C, okunzima kakhulu ukuthi izinto zensimbi zifezeke.” Njengamanje, ezinye izikhungo zocwaningo zizama ukusebenzisai-silicon carbide eluhlazaizinhlanganisela zokukhiqiza izingxenye ezingajikelezi njenge-nozzle guide vanes kanye nama-combustion chamber liner. Uma lezi zinhlelo zokusebenza zisetshenziswa ngempumelelo, ukugxila nokusebenza kahle kwezinjini kulindeleke ukuthi kuthuthuke kakhulu. IV. Ukuphathwa Kokushisa: Ukwenza Ukushisa “Kulalele”
Izimoto zezindiza zibhekene nezimo ezishisayo kakhulu esikhaleni: uhlangothi olubheke elangeni lungadlula u-100°C, kanti uhlangothi olunomthunzi lungase lwehle lube ngaphansi kuka-100°C. Lo mehluko omkhulu wokushisa ubeka inselele enkulu ezintweni nasemishinini. I-carbon carbide eluhlaza inesici esifiseleka kakhulu—ukushisa okuhle kakhulu. Ukushisa kwayo kuphindwe izikhathi ezingu-1.5-3 kunezinsimbi ezivamile kanye nokuphindwe izikhathi ezingaphezu kweziyishumi kunezinto ezivamile ze-ceramic. Lokhu kusho ukuthi ingadlulisa ngokushesha ukushisa kusuka ezindaweni ezishisayo kuya ezindaweni ezibandayo, inciphise ukushisa okwedlulele endaweni. “Sicabanga ukusebenzisa ama-composites e-silicon carbide aluhlaza ezinhlelweni zokulawula ukushisa zama-satellite,” kusho umklami wezindiza, “ngokwesibonelo, njengekhava lamapayipi okushisa noma njengezinto ezihambisa ukushisa, ukuze senze izinga lokushisa lohlelo lonke lifane kakhulu.”
Ngaphezu kwalokho, i-coefficient yayo yokwanda kokushisa incane kakhulu, cishe i-4×10⁻⁶/℃, okuyingxenye eyodwa kwezinhlanu zaleyo ye-aluminium alloy. Ubukhulu bayo abushintshi kangako ngokushintsha kwezinga lokushisa, isici esibaluleke kakhulu ezinhlelweni ze-aerospace optical kanye nezinhlelo ze-antenna ezidinga ukulungiswa okunembile. “Cabanga,” umklami unikeze isibonelo, “i-antenna enkulu esebenza ku-orbit, enomehluko wokushisa wamakhulu ama-degree Celsius phakathi kwezinhlangothi ezibheke elangeni nezinomthunzi. Uma kusetshenziswa izinto zendabuko, ukwanda kokushisa kanye nokufinyela kungabangela ukuguquka kwesakhiwo, kuthinte ukunemba kokukhomba. Uma kusetshenziswa izinto ezihlanganisiwe ze-silicon carbide eluhlaza okukhula kancane, le nkinga ingancishiswa kakhulu.”
V. Ukuzifihla Nokuvikela: Okungaphezu Kokuthi “Ukumelana” Nje
Izimoto zezindiza zanamuhla zinezidingo eziphakeme kakhulu ekusebenzeni okucashile. Ukucashile kwe-radar kufezwa kakhulu ngokuklama isimo kanye nezinto ezimunca i-radar, kanti i-silicon carbide eluhlaza nayo inamandla okulawula kule ndawo. “I-silicon carbide emsulwa iyi-semiconductor, futhi izakhiwo zayo zikagesi zingalungiswa ngokusebenzisa i-doping,” kwethula uchwepheshe wezinto ezisebenzayo. “Singaklama izinto ezihlanganisiwe ze-silicon carbide ezinokumelana okuthile ukuze zimunce amaza e-radar ngaphakathi kwebanga elithile lemvamisa.” Nakuba lesi sici sisesesigabeni sokucwaninga, amanye amalabhorethri asevele ekhiqize amasampula ezinto ezihlanganisiwe ezisekelwe ku-silicon carbide anokusebenza okuhle kokumunca i-radar ku-X-band (8-12 GHz).
Ngokuphathelene nokuvikelwa kwesikhala, inzuzo yobulukhuni be-i-silicon carbide eluhlazakuyabonakala futhi. Kunenani elikhulu lama-micrometeoroid kanye nemfucumfucu yasemkhathini esikhaleni. Nakuba isisindo saso ngasinye sincane kakhulu, ijubane laso liphezulu kakhulu (kufika kumashumi amakhilomitha ngomzuzwana), okuholela emandleni omthelela aphezulu kakhulu. “Ukuhlolwa kwethu kubonisa ukuthi izinto ezihlanganisiwe ze-silicon carbide eluhlaza zinokuphikiswa okuphindwe kathathu kuya kahlanu komthelela wezinhlayiya zesivinini esikhulu uma kuqhathaniswa nama-alloy e-aluminium anobukhulu obufanayo,” kusho umcwaningi wokuvikela isikhala. “Uma kusetshenziswa ezingqimbeni zokuvikela zeziteshi zasemkhathini noma kuma-probe esikhala ajulile esikhathini esizayo, kungathuthukisa kakhulu ukuphepha.”
Umlando wokuthuthukiswa kwezindiza, ngandlela thile, ungumlando wentuthuko yezinto ezibonakalayo. Kusukela okhunini nasendwangu kuya kuma-alloy e-aluminium, bese kuba ama-alloy e-titanium nezinto ezihlanganisiwe, ukusungulwa ngakunye kwezinto ezibonakalayo kuye kwaholela ekukhuleni kwezindiza. Mhlawumbe i-powder ye-silicon carbide eluhlaza kanye nezinto zayo ezihlanganisiwe kuzoba ngenye yezinto ezibalulekile eziqhuba intuthuko elandelayo. Labo ososayensi bezinto ezibonakalayo abacwaninga ngenkuthalo emalabhorethri futhi belwela ukwenza kahle ezimbonini bangase bashintshe buthule ikusasa lesibhakabhaka. Futhi i-silicon carbide eluhlaza, le nto ebonakala ijwayelekile, ingaba “yi-powder yomlingo” ezandleni zabo, isiza isintu ukuba sindize siye phezulu, kude, futhi siphephe.