Ukushisela Ugongolo Lwelaser, ngesivinini sayo esiphezulu, ukunemba okuphezulu kanye nezici zayo zokungathinti, isetshenziswa kabanzi emikhakheni efana nezimoto, izindiza, kanye namadivayisi kagesi, ikakhulukazi okubonisa izinzuzo ezihlukile ekuxhumeni kwezinto ezingafani. Kodwa-ke, imifantu yokuqina (i-Solidification Cracking) ekhiqizwa ngesikhathi senqubo yokushisela ingenye yeziphambeko ezibalulekile ezivimbela ukusetshenziswa kwayo kwezimboni. Le mifantu ivame ukwenzeka ekupheleni kokuqina endaweni yokuhlangana (i-Fusion Zone), okubangelwa imiphumela ehlanganisiwe yokucindezeleka kokushisa, ukuncipha kokuqina kanye nefilimu yoketshezi emingceleni yokusanhlamvu, okunciphisa kakhulu izakhiwo zemishini kanye nokuphila kokukhathala kwejoyinti.
1. Indlela yokwakha
Indlela eyinhloko yokuqhekeka kokuqina itholakala kwifilimu ewuketshezi eseleyo emingceleni yokusanhlamvu ekupheleni kokuqina. Ngesikhathi senqubo yokuqina, ichibi elincibilikisiwe lihlukaniswe ngezindawo ezintathu: indawo yoketshezi yamahhala, indawo yoketshezi evinjelwe, kanye nendawo eqinile, njengoba kuboniswe kuMfanekiso 1. Endaweni yoketshezi evinjelwe, ukugeleza koketshezi kuyavinjelwa futhi akukwazi ukukhokhela ukucindezeleka okubangelwa ukuncipha kokuqina, okuholela ekuhlukanisweni komngcele wokusanhlamvu. Isilinganiso samandla omngcele wokusanhlamvu (γgb) kumandla esixhumi esiqinile-uketshezi (γsl) sinquma ukuzinza kwefilimu yoketshezi: uma i-γgb <2γsl, ifilimu yoketshezi ingazinzile futhi kwenzeka ukuhlangana kokusanhlamvu; ngokuphambene nalokho, ifilimu yoketshezi izinzile futhi ukuqala kokuqhekeka kungenzeka.
Ngaphezu kwalokho, ukwakheka kwemifantu yokuqina kuhlobene nezakhiwo zensimbi zezinto. Izinto ezahlukene zinezici ezihlukile zokuqina, njengobubanzi bokushisa bokuqina, izinga lokuncipha kokuqina, kanye nokusatshalaliswa kwezinto ze-alloy, njll. Lezi zici zithonya ukuzwela kwemifantu. Isibonelo, ezintweni eziqukethe inani elikhulu lezigaba ze-eutectic ezincibilikayo eziphansi, ukuzwela kwemifantu yokuqina kuphakeme ngoba lezi zigaba ze-eutectic zithambekele ekwakheni amafilimu oketshezi aqhubekayo ngesikhathi sokuqina, ngaleyo ndlela ziqinise ukwakheka kwemifantu.
Ngesikhathiinqubo yokushisela nge-laser, amapharamitha okushisela afana namandla e-laser, isivinini sokushisela, kanye nosayizi wamachashazi nawo anomthelela ekwakhekeni kwemifantu yokuqina. La mapharamitha athinta ukufakwa kokushisa kanye ne-gradient yokushisa ngesikhathi senqubo yokushisela, ngaleyo ndlela ashintshe isakhiwo sokuqina kanye nesimo sokusanhlamvu. Isibonelo, amandla aphezulu e-laser kanye nesivinini esiphansi sokushisela kuholela ekufakweni okukhulu kokushisa kanye nesilinganiso sokupholisa esihamba kancane, okukhuthaza ukukhula kwamakristalu ekholomu futhi kwandisa ukuzwela kokuqhekeka. Ngokuphambene nalokho, amandla aphansi e-laser kanye nesivinini esiphezulu sokushisela kuholela ekufakweni okuncane kokushisa kanye nesilinganiso sokupholisa esisheshayo, okwenza kube lula ukwakheka kwamakristalu alinganayo futhi kunciphise ukuzwela kokuqhekeka.
2. Izindlela zokucindezela
Ukucindezela ngempumelelo imifantu yokuqina kuukushisela nge-laser, abacwaningi baphakamise amasu ahlukahlukene, agxile kakhulu ekulawuleni isakhiwo sokusanhlamvu, ukwenza ngcono amapharamitha okushisela, kanye nokuthuthukisa izakhiwo zezinto. Ngokulungisa isakhiwo sokusanhlamvu, inani lemingcele yokusanhlamvu lingandiswa, futhi ukuhlushwa kokuhlushwa kokucindezeleka kungancishiswa, ngaleyo ndlela kuncishiswe ukwakheka kwemifantu. Izifundo zibonise ukuthi ngokusebenzisa ubuchwepheshe bokushintshwa kwemifantu ye-laser, amakristalu e-columnar angaguqulwa abe amakristalu amahle alinganayo ngaphandle kokwengeza ezinye izinto. Ukushintshwa kwemifantu ye-laser kungasabalalisa amandla e-laser, okubangela ukuthi ichibi elincibilikisiwe likhiqize i-turbulence, ngaleyo ndlela kuphule isiqondiso sokukhula kwamakristalu e-columnar futhi kukhuthaze ukwakheka kwamakristalu alinganayo, njengoba kuboniswe kuMfanekiso 3. Ngaphezu kwalokho, ukushintshwa kwemifantu ye-laser kungandisa ububanzi bechibi elincibilikisiwe, kunciphise i-gradient yokushisa, futhi kwandise isikhathi sokuqina kwechibi elincibilikisiwe, okusiza ekusabalaleni kwezinyibilikisi kanye nokugcwaliswa kabusha kwamafilimu oketshezi, ngaleyo ndlela kunciphise kakhulu ukuzwela kwemifantu yokuqina.
Ukusatshalaliswa kwamafilimu oketshezi olusemngceleni wokusanhlamvu ngaphansi kwezimo ezahlukene zamachibi.
Umdwebo weskimu wechibi elicibilikisiwe lokushisela, a, b) ngaphandle kokunyakaza, c, d) ukunyakaza okuseceleni, e, f) ukunyakaza okude, g, h) ukunyakaza okujikelezayo.
Ngaphezu kwe-umsebe we-laserUbuchwepheshe bokunyakazisa, ukusebenzisa imithombo ye-laser ekabili nakho kungenye yezindlela ezisebenzayo zokucindezela imifantu yokuqina. Imithombo ye-laser ekabili ingafinyelela ukuguqulwa kusuka kumakristalu ekholomu kuya kumakristalu alinganayo ngokwenza ngcono umjikelezo wokushisa, ngaleyo ndlela kuncishiswe usayizi wokusanhlamvu kanye nokuhlushwa kokucindezeleka. Isibonelo, uma usebenzisa i-laser ye-CO₂ njengomthombo oyinhloko wokushisa kanye ne-laser eqhutshwa yi-Nd:YAG njengomthombo wokushisa osizayo, umjikelezo wokushisa olungiselelwe kahle ungakhiwa ngesikhathi sokushisela, okukhuthaza ukwakheka kwamakristalu alinganayo futhi kuncishiswe ukuzwela kwemifantu yokuqina, njengoba kuboniswe kuMfanekiso 4.
Ukuthuthukisa amapharamitha okushisela nakho kuyindlela ebalulekile yokucindezela imifantu yokuqina. Ngokulungisa amapharamitha afana namandla e-laser, isivinini sokushisela, kanye nosayizi wamachashazi, ukufakwa kokushisa kanye ne-gradient yokushisa ngesikhathi senqubo yokushisela kungalawulwa, ngaleyo ndlela kuthonye isakhiwo sokuqina kanye nesimo sezinhlamvu. Izifundo zibonise ukuthi ukwelashwa kokushisa kwangaphambilini kunganciphisa izinga lokupholisa, kukhuthaze ukwakheka kwamakristalu alinganayo, futhi ngaleyo ndlela kunciphise ukuzwela kwemifantu yokuqina, njengoba kuboniswe kuMfanekiso 5. Ngaphezu kwalokho, izindlela ezinjengokusebenzisa ukushisela kwe-laser okushukunyiswayo kanye nokwandisa ijubane lokushisela nazo zingafeza ukuguqulwa kusuka kumakristalu ekholomu kuya kumakristalu alinganayo ngokushintsha izinga lokufaka ukushisa kanye nokupholisa, ngaleyo ndlela kuncishiswe ukuzwela kwemifantu.
Umfanekiso 5. a) Okungashisi, b) Okusanhlamvu okulinganayo okushisiwe okungu-300°C.
Lapho kushintshwa izinto ezingafani ngama-laser, ngenxa yomehluko omkhulu ezimpahleni zomzimba nezamakhemikhali phakathi kwezinto, ama-compounds aqhekekile aphakathi kwe-metallic avame ukwakheka, okuyimbangela eyinhloko yokuqhekeka kokuqina. Ngakho-ke, ukulungisa amapharamitha nezilungiselelo ze-laser ukuze kuncishiswe ukwakheka noma inani lama-compounds aphakathi kwe-metallic nakho kuyisu elibalulekile lokucindezela imifantu yokuqina. Isibonelo, ekushisweni kwe-laser kwezinto ezingafani zethusi ne-aluminium, ngokulawula ukushintshwa kogongolo lwe-laser kanye nesivinini sokushiswa, isilinganiso sokuxuba sethusi ne-aluminium echibini elincibilikisiwe singancishiswa, ngaleyo ndlela kuncishiswe ukwakheka kwama-compounds aqhekekile aphakathi kwe-metallic futhi kuncishiswe ukuzwela kwemifantu. Ngaphezu kwalokho, ukusebenzisa izinto zokugcwalisa kungathuthukisa nokusebenza kwejoyinti elihlanganisiwe futhi kuncishiswe ukwakheka kwemifantu. Izinto zokugcwalisa zinganciphisa ukwakheka kwama-compounds aphakathi kwe-metallic ngokushintsha ukwakheka kanye nesakhiwo esincane sejoyinti elihlanganisiwe futhi kuthuthukiswe ukuqina kwejoyinti elihlanganisiwe.
Imifantu yokuqinisa ingenye yeziphambeko ezivamile ezinqubweni zokushisela nge-laser. Indlela yokwakheka kwayo iyinkimbinkimbi futhi ihilela ukusebenzisana kwezinto eziningi njengokushisa, imishini, kanye ne-metallurgy. Ngokutadisha ngokujulile indlela yokwakheka kwemifantu yokuqinisa, isisekelo semfundiso singanikezwa sokucindezela imifantu. Eminyakeni yamuva nje, abacwaningi baphakamise amasu ahlukahlukene okucindezela imifantu yokuqinisa, agxile kakhulu ekulawuleni isakhiwo sokusanhlamvu, ukwenza ngcono amapharamitha okushisela, kanye nokuthuthukisa izakhiwo zezinto. Umkhuba ubonise ukuthi lawa masu anganciphisa ngempumelelo ukuzwela kwemifantu yokuqinisa ngezinga elithile futhi athuthukise ikhwalithi nokuthembeka kokushisela nge-laser. Kodwa-ke, ngenxa yobunzima nokuhlukahluka kwenqubo yokushisela nge-laser, kusekhona ukuntuleka okuthile ocwaningweni lwamanje. Isibonelo, ngezindlela zokuvimbela imifantu yokuqinisa ngaphansi kwezinto ezahlukene kanye nezimo zokushisela, kusadingeka ucwaningo olujulile olwengeziwe.
Isikhathi sokuthunyelwe: Mashi-20-2025
