Kulo msebenzi, i-CoCrFeNiSi-xTiB2 (x = 2. 5%, 5. 0%, 7. 5%, 10. 0%, ingxenyenamba enkulu) i-high entropy alloy (HEA) i-composite coating yayigqoke i-laser ebusweni be-40Cr. Isigaba, i-microstructure, ubulukhuni, ukungqubuzana nokuguga kanye nezakhiwo ze-electrochemical corrosion of the coating zahlaziywa, futhi umphumela wezinhlayiya ze-nano-TiB2 ze-ceramic ku-HEA zaxoxwa. Imiphumela ibonisa ukuthi uma x = 2. 5%, 5. 0%, 7. 5%, isigaba sokumboza sakhiwe i-FCC yezigaba ezimbili ne-BCC; lapho x = 10. 0%, i-boride CrB ikhiqizwa ngesisekelo sezigaba ezimbili, futhi ukwakheka kwe-microstructure kuyashintsha kusuka kumakristalu alinganayo kuya kuma-dendrite amakholomu ajwayelekile. I-microhardness ye-coating iyanda ngokukhula kwezinhlayiya ze-nano-TiB2, futhi uma x = 10. Uma okuqukethwe kwe-TiB2 kungu-0%, ubulukhuni obujwayelekile bokugqoka bufinyelela phezulu, okuyi-HV547.11, cishe izikhathi ezingu-2.72 kune-substrate. Izizathu eziyinhloko zokwanda kokuqina kwayo ukuqinisa isisombululo esiqinile nokuqinisa ukuhlakazeka. Ngokukhula kokuqukethwe kwe-TiB2, ukulahlekelwa kokugqokwa kwe-coating eyinhlanganisela kuncipha kakhulu. Uma x = 10.0%, isisindo sokulahlekelwa kokuguga singu-0.13 mg kuphela. Ngokuvamile, ukwanda kokuqukethwe kwe-TiB2 kushintsha indlela yokuguga eyinhloko yenhlanganisela eyinhlanganisela kusukela ekugugeni okunzima nokugqokwa kwe-oxidation kuya ekugugeni okuncane nokuguga kwe-oxidation, futhi ukumelana nokugqokwa kuba ngcono kakhulu. Kusixazululo se-NaCl esingu-3.5%, ukumelana nokugqwala kwenhlanganisela eyinhlanganisela kungcono kakhulu uma x = 7.5%. Amagama angukhiye: ingxubevange ephezulu ye-entropy (HEA), ukukhanya kwe-laser, i-nano-ceramics, ukumelana nokugqoka, ukumelana nokugqwala

I-40Cr alloy structural steel ingenye yezinsimbi ezisetshenziswa kakhulu ekukhetheni umshini wokumba amalahle. Inezici ezinhle ezibanzi zemishini, ukuqina komthelela ophansi wokushisa, ukuzwela kwenotshi ephansi, kanye nenani elifanele le-alloy element, ngakho isetshenziswa kabanzi embonini yokukhiqiza imishini. Kodwa-ke, ngenxa yesimo esinzima sokusebenza, i-40Cr ivamise ukumpintsheka futhi igundwe lapho kusikwa imithungo yamalahle, ejwayele ukuguga, ukugqwala, ukonakala kwamazinyo nokunye ukukhubazeka, okuthinta kakhulu impilo yesevisi. Ubuchwepheshe be-Laser cladding bungenye yezindlela ezisetshenziswa kakhulu emkhakheni wokulungiswa kwendawo eminyakeni yamuva. Lobu buchwepheshe busebenzisa i-laser enamandla amakhulu ukuze incibilike futhi iqinise impushana enamathelayo kanye nendawo engaphansi ukuze yakhe ibhondi ye-metallurgical enhle. Ngasikhathi sinye, i-laser cladding nayo inezinzuzo zokupholisa okusheshayo, ukuqina okusheshayo, indawo encane ethinteke ukushisa, kanye nesakhiwo sokumboza esiminyene. Ingakwazi ukuthuthukisa ubulukhuni, ukumelana nokugqoka kanye nokumelana nokugqwala kwendawo yokugqoka. Izinzuzo zayo eziyingqayizivele kanye namathemba amakhulu wohlelo lokusebenza kuyenza ikhathazeke kabanzi. Ngokungafani nama-alloys endabuko, ama-alloys aphezulu-entropy (ama-HEA) angama-alloys akhiwe izakhi ezinhlanu noma ngaphezulu ngokulingana okulinganayo noma okucishe kulingane kwe-molar. Emcabangweni we-alloy wendabuko, lapho izakhi eziningi eziyinhloko zixutshwe, izinhlanganisela ze-intermetallic zikhiqizwa kalula, okuholela ekwehleni okuphawulekayo ekusebenzeni okuphelele kwezinto. Ama-HEA ahlukile. Zinezingqayizivele "imiphumela emine" engavimbela ukwakheka kwezinhlanganisela ze-intermetallic, okwenza zibe namandla aphezulu, ukuqina okuphezulu, ukusebenza kahle kakhulu kokushisa okuphezulu nokugqoka nokumelana nokugqwala. Isakhiwo sabo sangaphakathi sivame ukuhlukaniswa ngezigaba zesisombululo esiqinile se-FCC, BCC, ne-HCP. Ama-HEA athuthukisa izakhiwo zemishini yama-alloys ngokuqiniswa kwesisombululo esiqinile kanye nokuqiniswa kwesigaba sesibili. Ucwaningo luye lwabonisa ukuthi ubuchwepheshe be-laser cladding bunomphumela wokucwenga okusanhlamvu. Ngakho-ke, ukulungisa ama-HEA nge-laser cladding kuyisinqumo esingcono kakhulu.

Ukuze kuthuthukiswe ukuthuthukiswa kokuqina nokugqoka ukumelana kwezingubo ze-HEA, abacwaningi banaka kakhulu imiphumela yezinhlayiya ezihlukahlukene ze-ceramic (ezifana ne-TiC, NbC, B4C ne-TiB2) ekusebenzeni kwe-HEAs. Shang et al. ulungise i-nano-TiC eqiniswe yizinhlayiyana (i-Cr-Fe4Co4Ni4)Cr3HEA ebusweni bensimbi engagqwali engu-904L. Ngokungezwa kwe-TiC, ubulukhuni, ukumelana nokugqoka kanye nokumelana nokugqwala kwe-coating eyinhlanganisela kwathuthuka kancane kancane. Lapho i-15% (ingxenye yevolumu) yengezwa, i-microhardness ye-composite coating cishe iphindwe kabili kune-substrate. Dong et al. ulungise inhlanganisela ye-Al-CrCoFeNi2.1-xTiB2HEAs eyinhlanganisela yensimbi engagqwali engu-304 ngokuvala nge-laser ye-ultra-high-speed. Imiphumela yabonisa ukuthi ukungezwa kwe-TiB2 kuthuthukisa ubulukhuni nokumelana nokugqoka kwe-coating, futhi izinga lokugqoka lehla ngokunyuka kwezinhlayiya ze-TiB2. UZhao et al. izinhlayiya ze-ceramic ezilungisiwe ze-B4C ne-SiC eziqiniswe i-CoCrFeNiTi HEA nge-laser cladding technology. Imiphumela yabonisa ukuthi i-B4C yayisebenza kahle kakhulu ekusebenzeni kwe-alloy. Ukuqina kokumboza kukhuphuke kusuka ku-HV0.5666.2 kuya ku-HV0.5886.9. Ngesikhathi esifanayo, ukumelana nezinga lokushisa kwegumbi kwathuthukiswa, futhi isilinganiso sokungqubuzana nesilinganiso sokugqoka sehle kakhulu. Phakathi kwezinhlayiya ze-ceramic, izinhlayiya ze-TiB2 zingenye yezigaba ezinzima ezivame ukusetshenziswa. Zinobunzima obuphezulu, i-coefficient ephansi yokwandisa okushisayo, ukuzinza okuhle kokushisa, nokugqoka okuhle kakhulu nokumelana nokugqwala. Lezi zici zingathuthukisa kangcono izakhiwo zemishini yezingubo ze-HEA.

Kunezifundo ezimbalwa ngomphumela wezinhlayiya zensimbi ze-nano-TiB2 ze-ceramic ekusebenzeni kwe-CoCrFeNiSi HEA. Ngakho-ke, lo msebenzi ulungiselele i-CoCrFeNiSi-xTiB2 (x = 2.5%, 5.0%, 7.5%, 10.0%, ingxenye enkulu, efanayo ngezansi) I-HEA eyinhlanganisela ye-HEA ebusweni bensimbi engu-40Cr nge-laser cladding, futhi yahlaziya umphumela we-nano-TiB2 ku-microhardness kanye nokuguquguquka kwezakhiwo kanye nokugoqa kwe-HEA isakhiwo enamathela kanye nesigaba.

1. Linga

I-substrate iyinsimbi engu-40Cr enobukhulu obungu-150 mm×60 mm×8 mm. Izinto zokuvala ziyi-40-70 μm high-purity Co, Cr, Fe, Ni, Si single powders kanye nama-650-800 nm TiB2 powders. U-2.5%, 5.0%, 7.5%, kanye no-10.0% we-TiB2 metal powders ye-ceramic yengezwa kuzimpushana ze-CoCrFeNiSiHEA ngokulandelana, futhi izimpushana zixutshwa kumshini wokugaya weplanethi we-KQM-ZB amahora angu-3. I-YLS-2000 fiber laser isetshenziselwa ukwenza i-laser cladding ngendlela yezimpushana zokusetha ngaphambilini. Ngaphambi kokumboza, izimpushana ezixutshwe zinyakaziswa ngokulinganayo nge-binder polyvinyl alcohol (2%) bese zisethwa kuqala ku-substrate enogqinsi luka-1.45 mm. Ngokocwaningo lokuhlola lokuqala lweqembu locwaningo, imingcele yenqubo efanele yokuvala amandla e-laser angu-900 W, izinga lokuskena elingu-4 mm·s-1, nobubanzi bendawo obungu-2. 0 mm, izinga lokugqagqana elingu-30%. Ukuqinisekisa ikhwalithi yesendlalelo se-cladding, i-argon yasetshenziswa njengegesi evikelayo ngesikhathi senqubo yokuhlanganisa.

Ngemuva kwenqubo yokuhlanganisa, isampula yacutshungulwa ngokusikwa ngocingo nge-electrospark, futhi ubukhulu bayo buyi-8 mm × 8 mm×8 mm, futhi usayizi wesampula wokugqagqana wawungu-25 mm×8 mm×8 mm, wabe usupholishwa nge-sandpaper. Isakhiwo sesigaba sokumbozwa kwengxubevange sitholwe nge-D8-Advance X-ray diffractometer, into eqondiwe bekuyithagethi yethusi, futhi ububanzi bokuskena babungu-20-100°. I-Aqua regia (isilinganiso sevolumu ye-hydrochloric acid egxilile kuya ku-nitric acid egxilile engu-3:1) ikhethwe njengesixazululo sokugqwala, futhi ukwakheka okuncane kwesampula kwabonwa ngesibonakhulu se-4XB esihlanekezelwe se-metallographic kanye ne-SUPRA55VP ye-electron emission microscope. I-Energy dispersive spectrometer (EDS) yasetshenziswa ukuze kuhlaziywe ukusatshalaliswa kwezakhi, futhi ukuqina kwento enamathelayo kukalwa ngomhloli wokuqina okuncane. Umthwalo osetshenzisiwe wawungu-1 000 N, futhi isikhathi sokulayisha sasiyimizuzwana eyi-15. Esigabeni sesiphambano sesampula, ukuhlolwa kwenziwa kusukela phezulu kwe-coating kuya phezulu kwe-substrate. Isampula ngayinye ikalwe izikhathi ezintathu futhi inani elimaphakathi lathathwa. Ukuhlolwa kokugqokwa kwenziwa kusetshenziswa i-M-5000 friction and wear machine. Ukungqubuzana okuphindaphindayo kokuslayida okomile kukhethiwe. Ipheya yokugaya i-Si3N4 isetshenzisiwe. Umthwalo ojwayelekile wawungu-20 N, imvamisa yayingu-2 Hz, isikhathi sokugqoka sasingu-30 min, futhi ibanga elibuyiselayo lalingu-20 mm. Isivinini sokushelela kanye nebanga eliphelele lokushelela kubalwe ukuthi libe ngu-4 cm/s no-72 m, ngokulandelana.

2 Imiphumela nengxoxo

2.1 Ukuhlaziya isigaba

Umfanekiso 1 ubonisa i-XRD spectrum ye-CoCrFeNiSi-xTiB2HEA eyinhlanganisela ye-coating. I-spectra ye-XRD ibonisa ukuthi i-CoCrFeNiSi-xTiB2 (x = 2.5%, 5.0%, 7.5%) i-HEA eyinhlanganisela ye-HEA yakhiwe isigaba se-BCC nesigaba se-FCC. Uma x = 10.0%, inhlanganisela eyinhlanganisela ikhiqiza i-intermetallic compound CrB ngesisekelo sezigaba ezimbili zokuqala. Lokhu kungase kubangelwe ukuhlanganisa okunegethivu kwe-enthalpy ye-elementi B engeyona eyensimbi kanye ne-Cr element. Ngokukhula kwe-nano-TiB2, okuqukethwe kwesigaba se-FCC kuncipha kancane kancane futhi okuqukethwe kwesigaba se-BCC kuyanda kancane kancane. Isizathu siwukuthi ingxenye yezakhi ze-Ti ne-B eziboliswe i-nano-TiB2 ekuhlanganisweni kwe-laser ikhuthaza ukwakheka kwesigaba se-BCC, esihambisana nemiphumela yezinye izifundo zangaphambilini [23-26], okubonisa ukuthi izakhi ze-Ti ne-B ezengezwe ku-HEA zingadlala indima ye-BCC stabilizer kanye nesithuthukisi sesixazululo esiqinile. Ngaphezu kwalokho, alikho inani eliphakeme le-TiB2 diffraction elibonwe ku-spectra yazo zonke izimbotshana eziyinhlanganisela, okubonisa ukuthi izinhlayiya ze-nano-TiB2 zazibole ngokuphelele noma inombolo yazo yayingaphansi kwebanga lokutholwa kwe-XRD. Ukubuka isithombe sendawo esikhulisiwe ekhoneni eliphezulu kwesokudla soMfanekiso 1, kungabonakala ngokucacile ukuthi ukuphakama kwe-diffraction (110) kwesigaba se-BCC kuya ku-engeli enkulu, okubonisa ukuthi i-lattice constant ye-BCC iyehla. Lokhu kungase kube ngenxa yokubola kwezinhlayiya ze-TiB2 ngesikhathi sokuvala nge-laser, okubangela ama-athomu B anerediyasi ye-elementi encane ukuthi ancibilike futhi amiselele ezinye izakhi kusakhiwo sesigaba se-BCC. Ngokomthetho we-Bragg, ukuphakama okuyinhloko kwe-BCC diffraction ye-alloy coating ishintshela kwesokudla. Umsuka wasetshenziselwa ukulingana ngokushesha i-spectrum ye-XRD, futhi usayizi wokusanhlamvu (D) we-CoCrFeNiSi-xTiB2 HEA oyinhlanganisela ye-HEA ubalwe ngefomula (1), njengoba kuboniswe kuThebula 1. Isilinganiso sosayizi wokusanhlamvu (D*) we-CoCrFeNiSi-xTiB2 (x = 2.5%, 5.0%0%, i-coating ye-7.5%) yi-compiles engu-7.5%. 15.89, 15.30, 14.97, 14.12 nm, ngokulandelana, okubonisa ukuthi ukungezwa kwezinhlayiya ze-nano-TiB2 ku-CoCrFeNiSi HEA yokugqoka kunganciphisa ngokuphumelelayo usayizi wokusanhlamvu ojwayelekile wezingubo futhi kucwengisise isakhiwo sokusanhlamvu sezingubo eziyinhlanganisela. Lokhu kungenxa yokuthi izinhlayiya ze-TiB2 ziyi-ejenti evamile ye-nucleating engavamile engakhuphula izinga le-nucleation futhi ngaleyo ndlela icwenge okusanhlamvu okunamathelayo.
Bona ifomula (1) emfanekisweni, lapho: u-k engaguquki (0.89), u-λ uyi-X-ray wavelength (0.15405 nm), u-β ububanzi obuyingxenye yobude be-diffraction peak (FWHM), futhi u-θ i-engeli ye-diffraction.

2. 2 Isakhiwo esincane

I-microstructure ye-CoCrFeNiSi-xTiB2 HEA eyinhlanganisela ye-HEA ikhonjisiwe kuMfanekiso 2. Okuqukethwe kwekhemikhali okuhambisanayo kwezindawo ezimakiwe kuMfanekiso 2 kufakwe kuhlu kuThebula 2. Kusukela ezithombeni ze-SEM, kungabonakala ukuthi ukwakheka kwe-CoCrFeNiSi-xTiB2 HEA okuyinhlanganisela ye-HEA kuveza izifunda ezimbili ezihlukene ezikhanyayo: (ID) izifunda. Izifunda ze-DR kanye ne-ID ziyizakhiwo ezijwayelekile zesisombululo esiqinile embotsheni ye-HEA elungiswe nge-laser cladding. Kusukela ekuhlaziyweni kwe-EDS kwamaphoyinti okuhlola okuhlanganisa, kungabonakala ukuthi isifunda se-DR sihlanganisa ikakhulukazi izici ze-Fe ne-Ni, kuyilapho isifunda se-ID sihlanganisa ikakhulukazi izici ze-Fe, Cr ne-Ti. Ngakho-ke, isifunda se-DR sihambisana nesakhiwo sesixazululo esiqinile se-FCC esicebile ku-Fe ne-Ni, futhi isifunda se-ID sihambisana nesakhiwo sesixazululo esiqinile se-BCC esicebile ku-Fe ne-Cr, esihambisana nemiphumela yokuhlaziywa kwe-XRD yangaphambilini. Ngokuqhubekayo kuhlanganiswe ne-Figure 2 kanye neThebula 2, kungabonakala ukuthi uma x = 2.5%, i-microstructure ye-coating iyi-uniform equiaxed crystal structure. Uma i-x = 5.0%, i-microstructure enamathelayo iyashintsha isuka ku-equiaxed crystal iye ku-columnar dendrite structure. Uma x = 7.5%, 10.0%, i-microstructure yokumboza ishintshe ngokuphelele ibe yi-columnar dendrite. Umfanekiso wesi-3 ubonisa ukuskena kwendawo ye-EDS kanye nokusatshalaliswa kwesici koqweqwe oluhlanganisiwe lapho x = 5.0%, 10.0%. Kuhlanganiswe nedatha kuThebula lesi-2, kungabonakala ukuthi uma inani elincane lezinhlayiya ze-nano-TiB2 zengezwa (x = 2.5%), ukumbozwa okuyinhlanganisela kubonisa ukuhlukaniswa okusobala kwesici se-Si, futhi ngokwanda kokuqukethwe kwe-TiB2, ukuhlukaniswa kwe-Si element kuya ngokuya kuba buthaka futhi ekugcineni kuvame ukufana. Lokhu kungenxa yokuthi ukungezwa kwe-TiB2 kukhuthaza ukwabiwa kabusha kwe-solutes, futhi isici se-Ti sinokuthambekela okunamandla kokuhlukanisa emngceleni wokusanhlamvu. Lokhu kungafani kwendawo kubangela ukuthi isici se-Ti sihlukanise emngceleni wokusanhlamvu ngokuncamelayo kunesici sika-Si, esivimbela ukuhlukaniswa kwesici se-Si ngokwezinga elithile. Ukwengeza, lapho x = 2.5%, 5.0%, i-elementi B isatshalaliswa ngokulinganayo ekuhlanganiseni okuyinhlanganisela ngenxa yokuqukethwe kwayo okuncane. Ngokukhula kokuqukethwe kwe-TiB2, isici esingu-B sitholakala ngokuyinhloko ngendlela yokuhlukaniswa emngceleni wokusanhlamvu, okuqhubeka kunciphisa usayizi wokusanhlamvu.

2.3 Ubulukhuni obuncane

Ijika lokusabalalisa lobulukhuni obuncane bengubo eyinhlanganisela eduze kwesiqondiso sokujula kuboniswe kuMfanekiso 4. Ijika lokuqina lihlukaniswe izifunda ezintathu: indawo yokuvala, indawo ethinteke ukushisa kanye nendawo ye-substrate. Isifunda ngasinye sihlukaniswa ngomugqa wamachashazi ome mpo esithombeni. Ubulukhuni obuncane bendawo ethinteke ekushiseni buphezulu kakhulu ngenxa yokuthi ukuvala nge-laser kunezici zokupholisa okusheshayo nokuqiniswa ngokushesha. Inqubo yokupholisa ngokushesha evela esimweni sokushisa esiphezulu ilingana nokucisha, okungathuthukisa ubulukhuni. Isilinganiso sokuqina okuncane kwe-CoCrFeNiSi-xTiB2 (x = 2.5%, 5.0%, 7.5%, 10.0%) I-HEA eyinhlanganisela ye-HEA kanye ne-substrate engu-40Cr yi-HV342.98, HV404.13, HV460.51, HV547.11 kanye nokuqina, 201.23. yenhlanganisela ngayinye izikhathi 1.7, 2.0 izikhathi, 2.0 izikhathi, futhi 2.5 izikhathi kune substrate, ngokulandelana. 29 izikhathi kanye 2.72 izikhathi. Kungabonakala ngokucacile ku-Figure 4 ukuthi ngokwanda kokuqukethwe kwezinhlayiya ze-nano-TiB2, i-microhardness ye-coating eyinhlanganisela ikhula kancane kancane. Lapho x = 2.5%, 5.0%, ukuqina okuncane kokunamathela kuphansi. Izizathu zingase zihlanganise: ① Okuqukethwe kwe-TiB2 okwengezwe kuncane, amathuba okuthi ama-athomu e-Ti ancibilike esixazululweni esiqinile futhi athathele amanye ama-athomu noma ama-athomu B angena ezikhaleni ze-lattice mancane, ukuhlanekezela kwe-lattice kuncane, futhi ukuqiniswa kwesixazululo esiqinile okubangelwayo akubonakali; ② Uma x = 2.5%, 5.0%, okuqukethwe kwesigaba se-FCC kukukhulu kunalokho kwesigaba se-BCC, i-ductility yesigaba se-FCC iphakeme, kodwa amandla ako aphansi kunalawo esigaba se-BCC. Lapho x = 7.5%, 10.0%, ukuqina okuncane kokunamathela kuphansi. I-microhardness ye-coating iphansi kakhulu. Lapho x = 8.5%, 11.0%, 12.0%, 14.0%, 16.0%, 18.0%, 19.0%, 20.0%, 21.0%, 23.0%, 24.0%, 26.0%, 27.0%, 28.0%, 28.0%. 26.0%, 27.0%, 28 … Uma x = 0%, ubulukhuni obuncane bokunamathela okuyinhlanganisela buphezulu uma kuqhathaniswa. Lokhu kungenxa yokuthi ngokwanda kokuqukethwe kwe-nano-TiB2, isigaba se-FCC siguqulela esakhiweni sesigaba se-BCC, futhi okuqukethwe kwesakhiwo sesigaba se-BCC ekuhlanganiseni okuyinhlanganisela kuphakeme kakhulu; ngokwanda kwama-elementi e-Ti no-B, ama-athomu e-Ti anerediyasi enkulu ancibilika abe yisixazululo esiqinile futhi athathele amanye ama-athomu futhi athathe indawo ye-lattice, kuyilapho ama-athomu angu-B ethatha izikhala ze-interstitial ku-lattice njengama-athomu ahlanganayo. Umphumela ohlangene walokhu okubili uholela ekuhlanekeni kwe-lattice okunzima, okuthuthukisa izinga lokuqiniswa kwesisombululo esiqinile. Uma i-x = 10.0%, i-CrB ehlanganisiwe ye-intermetallic ikhiqizwa ekuhlanganiseni okuyinhlanganisela, okuholela ekuqinisweni kokuhlakazeka kwe-coating. Ukuqina okusheshayo ngesikhathi sokufakwa kwe-laser nakho kusiza ukuthuthukisa ukunyibilika nokuthuthukisa umphumela oqinile wokuqinisa isisombululo. Ukwengeza, ukwethulwa kwesici se-B kulawula usayizi wokusanhlamvu we-coating, kuhlanza okusanhlamvu, ukwandisa inani lemingcele yokusanhlamvu, futhi imingcele yokusanhlamvu idlala indima ekuvimbeleni ukunyakaza kokuhlukaniswa, ngakho-ke ukumboza kubonisa ubuncane be-microhardness. Ngokusho kwe-Hall-Petch equation Hg = H0 + kd1/2, ubulukhuni bokunamathela buhambisana ngokuphambene nosayizi wokusanhlamvu.

2.4 Izakhiwo zokungqubuzana nokuguga

2.4.1 I-friction coefficient kanye nokuncipha kwesisindo somzimba

Umfanekiso 5 ubonisa ijika elihlanganisayo (i-COF) lenhlanganisela ye-CoCrFeNiSi-xTiB2 HEA, ebonisa izigaba ezimbili ezihlukene: isigaba sokugijima kanye nesiteji sokuguga esizinzile. Esigabeni sokugijima, i-friction pair i-Si3N4 ibhola le-ceramic iqala ngokuthinta ingaphezulu lesendlalelo sokuvala. Ngesikhathi sokungqubuzana nokuguga, kuzokwenziwa udoti ogqokile ebusweni bongqimba, futhi ukungqubuzana kwephoyinti kuzokwenzeka, okuzoholela ekuzinzeni nasekukhuleni kwe-coefficient yokungqubuzana. Ngokukhula kwesikhathi sokugqoka, indawo yokuxhumana ye-friction iyanda kancane kancane futhi iba yi-surface contact friction, okwenza uhlelo lwe-friction luvame ukuzinza futhi lungene esiteji sokugqoka esizinzile. Kulesi sigaba, i-COF ye-CoCrFeNiSi-xTiB2HEA eyinhlanganisela ye-coating iphakathi kuka-0.67 no-0.72, okubonisa ukuthi okuqukethwe kwezinhlayiya ze-nano-TiB2 kunomphumela omncane ku-COF ye-coating eyinhlanganisela esigabeni sokugqoka esizinzile. Izimo ezifanayo zitholakele emibikweni yangaphambilini. Umfanekiso 6a ubonisa isilinganiso se-coefficient yokungqubuzana phakathi kwe-substrate nenhlanganisela eyinhlanganisela. Kungatholakala ukuthi i-COF ye-coating eyinhlanganisela iphansi kunaleyo ye-substrate engu-40Cr. Umdwebo 6b ubonisa isisindo sokulahlekelwa ukuguga kwe-substrate kanye nenhlanganisela eyinhlanganisela. Kungabonakala ukuthi ukuhlanganiswa okuhlanganisiwe nokwengezwa kwezinhlayiya ze-nano-TiB2 kuthuthukisa kakhulu ukungqubuzana nokugqoka izakhiwo ze-substrate. Uma x = 10.0%, isisindo sokulahlekelwa kokugqokwa kwenhlanganisela yehliswe ngo-88% uma kuqhathaniswa ne-substrate.

2.4.2 Gqoka umthamo nokuguga

Ukuze kuqhutshekwe kuhlolisiswe ukumelana nokugqokwa kwe-substrate kanye nokuhlanganisa okuhlanganisiwe, ukuhlaziywa kwephrofayela enezinhlangothi ezintathu kwamamaki okugqokwa kwamasampuli kwenziwa, futhi imephu yephrofayela ye-3D kanye nejika lephrofayili yokugqoka ye-substrate ne-coating kwakhishwa, njengoba kuboniswe kuMfanekiso 7. Uma kuqhathaniswa ne-substrate, ububanzi bokuguga nokujula kwe-varyno ye-coating kwehla ngamadigri e-varyno anciphile. Izindawo eziphambanayo zezibazi zokugqoka ze-substrate engu-40Cr kanye ne-CoCrFeNiSi-xTiB2 (x = 2.5%, 5.0%, 7.5%, 10.0%) i-coatings yayiyi-5 696.85, 1 250.10, 1 233 . μm2, ngokulandelana, okubonisa ukuthi indawo ephambanayo yezibazi zokugqokwa kwehle kancane kancane ngokwanda kokuqukethwe kwe-TiB2, futhi ivolumu yokugqoka ehambisanayo iqhubekile nokuncipha. Ukusebenzisa ifomula (2) ukubala izinga lokuguga le-coating, Umfanekiso 8 ubonisa ivolumu yokuguga kanye nezinga lokugqoka le-substrate engu-40Cr kanye ne-CoCrFeNiSi-xTiB2 (x = 2.5%, 5.0%, 7.5%, 10.0%) yokugqoka. Amavolumu abo okugqoka angu-0.056 97, 0.012 50, 0.012 33, 0.011 22, no-0.007 71 mm3, ngokulandelana, kanye namazinga okugqoka angu-39.561 5 × 10-6, 8.681 3 × 6 × 10-6 6. 8×10-6, kanye 5.352 4×10-6 mm3 · N-1·m-1, ngokulandelana. Ukuthambekela kokusebenza kokungqubuzana nokugqoka kwe-coating kuhambisana nokuthambekela kokuqina okuncane, okubonisa ukuthi ubulukhuni obukhulu ngokuvamile buhambisana nokumelana okuhle kakhulu kokugqoka. Uma i-x = 10.0%, i-coating inokujula okuncane kakhulu kokugqoka, ivolumu yokugqoka kanye nesilinganiso sokugqoka, okubonisa ukuthi ukugqoka kunokumelana okuhle kakhulu kokugqoka lapho x = 10.0%.
Bheka ifomula (2) emfanekisweni, lapho: W izinga lokuguga, i-Vloss ivolumu yokuguga, i-FN iwumthwalo, futhi u-H uyisamba sebanga lokushelela.

2.4.3 Gqoka i-morphology

I-wear surface morphology yesampula ikhonjiswe kuMfanekiso 9, ophinde ubonise inqubo yokuguga engase ibe khona ehlobene ne-substrate kanye nokuhlanganisa okuyinhlanganisela. Umfanekiso 9a yi-morphology yezibazi ze-40Cr substrate. I-deformation yepulasitiki esobala iboniswa phezu kwe-substrate. Inani elikhulu lemigodi exebukayo kanye nezingqimba zokunamathela zingabonwa eduze nendawo yokushelela. Imfucumfucu esetshenzisiwe inamathela endaweni egugile. Ngesikhathi esifanayo, ngesenzo samandla okulayisha, isendlalelo sokunamathela sakhiwe endaweni yesibazi sokugqoka. Ngenxa yokuqina okuphansi kwe-substrate, lapho uslayida ngokuhlobene nokupheya kokungqubuzana, amandla okulayisha abangela ukuwohloka kwe-shear plastic endaweni yesampula eduze nendawo yokuslayida. I-deformation yepulasitiki idala ukuthi ama-microcracks avele ngaphansi kwesibazi esigqokile se-substrate. Ama-microcracks ayanda futhi aphule, okuholela ekuxebukeni kwemigodi kanye ne-delamination ebusweni be-substrate. Ngesikhathi esifanayo, kunenombolo encane yemisele endaweni ye-substrate, ebonisa ukuthi i-substrate idlula ukugqoka okunamathelayo okuhambisana nenani elincane lokugqoka kwe-abrasive.

Umfanekiso 9b-e ubonisa ukuguga kwesibazi sezingubo eziyinhlanganisela ezinokuqukethwe okuhlukile kwe-nano-TiB2. Kungabonakala ukuthi isibazi sokugqoka sihlukaniswe izingxenye ezimbili: indawo empunga emnyama kanye nendawo empunga ekhanyayo. Umfanekiso we-10 ubonisa ukuhlaziywa kwe-spectrum yamandla kwesampula ye-CoCrFeNiSi-10.0%TiB2 (indawo yokuqala ngakwesokunxele kwesibazi sokuguga). Kungatholakala ukuthi umkhuba wokusabalalisa wezakhi ze-Si no-O endaweni empunga emnyama iyahambisana, futhi kungabonakala ukuthi indawo empunga emnyama iyi-oxide eyakhiwe inhlanganisela yezinto ze-Si ne-O. Lapho i-friction pair iphindaphinda, imfucumfucu ye-oxide wear ikhiqizwa ngokuqhubekayo ebusweni benhlanganisela eyinhlanganisela. Le mfucumfucu yokugqokwa ikhishwa eduze kwesikhombisi-ndlela sokungqubuzana okuphindaphindiwe, kodwa enye imfucumfucu ayikwazi ukuchithwa ngokuphelele futhi ihlanganiswe ngokuqhubekayo emiseleni noma ezinhlangothini zombili zamamaki okuguga, yenze ungqimba lwe-oxide ebusweni bengubo eyinhlanganisela. Njengoba kuboniswe ku-Figure 9b no-c, lapho i-x = 2.5% no-5.0%, imisele ebanzi kanye nenani elikhulu lezingqimba ze-oxide zivela ebusweni be-coating, ehambisana nenani elincane lemigodi egobileyo, kanye namazinga ahlukene okuguqulwa kwepulasitiki kungatholakala, okubonisa ukuthi indlela yokugqoka i-abrasive igugile kakhulu kanye nokugqoka kwe-oxidation, okuhambisana ne-adhesive. Lapho x = 7. Uma x = 5%, kungatholwa Emfanekisweni 9f ukuthi indawo enamathelayo inemisele yokushona okuhlukahlukene, okuwumkhuba ojwayelekile wokugqoka okuhuzuka. Inani lezendlalelo ze-oxide endaweni empunga emnyama nalo lehle kakhulu, okubonisa ukuthi izinga lokuguga kwe-oxidation lehlile. Ngesikhathi esifanayo, kuphinde kuqashelwe ukuthi ngenxa yokunyakaza okuphindaphindiwe kwe-friction pair, ukushisa okukhulu kwe-friction kukhiqizwa ukuze kushiselwe ubuso, futhi ukuxhuma okuncane okwakhiwa kuyadatshulwa ukuze kukhiqizwe imigodi enamathelayo kanye nokuxebuka, okubonisa ukuthi ukunamathela nakho kunokugqoka okunamathelayo. Kuyaphawuleka ukuthi ngesikhathi sokungqubuzana nokugqoka inqubo, umbhangqwana we-friction ucindezela ingxenye yongqimba lwe-oxide, okwenza ungqimba lwe-oxide luphule futhi lukhiqize inani elikhulu lemfucumfucu yokugqoka. Ngenxa yobulukhuni obuncane bento enamathelayo, inani elikhulu lemfucumfucu egugileyo libangela ukunyakaza okuhlobene kwendawo egugileyo ukuthi kushintshe ukusuka ku-sliding friction kuya ku-rolling friction, ngaleyo ndlela kunciphisa i-coefficient yokungqubuzana kwentolo enamathelayo ngokwezinga elithile. Kungabonakala ku-Figure 9e ukuthi lapho i-x = 10.0%, inani lezingqimba ze-oxide liqhubeka nokuncipha, indawo yokumboza ibushelelezi, futhi kuvela imisele engajulile futhi emincane, ehambisana nenani elincane lemigodi yokucwenga, ebonisa ukuthi ukugqoka kunokugqoka okuncane kwe-abrasive kanye nokugqoka kwe-oxidation, okuhambisana nenani elincane lokugqoka okunamathelayo. Kusukela ekubukeni okunwetshiwe ngakwesokudla soMfanekiso 9e, kungabonakala ukuthi imfucumfucu egqokwayo echithwe endaweni egqokile incane ngosayizi futhi incane ngenani, ngakho-ke ukunyakaza okuhlobene kwendawo yokugqoka kuguqulwa kube ukungqubuzana okuslayidayo, okwandisa i-coefficient ye-friction ye-coefficient, ehambisana nokuthambekela kwesilinganiso se-friction coefficient ku-Figure coefficient. Kafushane, ngokukhuphuka kokuqukethwe kwe-nano-TiB2, indlela yokugqokwa eyinhloko yenhlanganisela yenhlanganisela iyashintsha kusukela ekugugeni okunzima nokugqokwa kwe-oxidation kuya ekugqokeni okuncane nokugqokwa kwe-oxidation, okubonisa ukuthi ukungezwa kwe-nano-TiB2 kuthuthukisa kakhulu ukumelana nokugqokwa kwenhlanganisela eyinhlanganisela.

2.5 Ukugqwala kwe-Electrochemical

2.5.1 Ijika elinamandla le-polarization

Umfanekiso we-11 ubonisa amajika aguqukayo we-polarization we-40Cr matrix kanye ne-CoCrFeNiSi-xTiB2 (x = 2.5%, 5.0%, 7.5%, 10.0%) i-HEA eyinhlanganisela ye-HEA kusixazululo se-3.5% se-NaCl. I-substrate ne-composite coating ibonisa izifunda ezifanayo esifundeni se-cathode, okubonisa ukuthi ukuguqulwa kokuqukethwe kwezinhlayiya ze-nano-TiB2 ze-ceramic akunawo umthelela engxenyeni ye-cathode yejika le-polarization. Iplathifomu evamile yokudlula ivela endaweni ye-anode. Umthambeka wejika lezoni yokwedlula uhlobene nezinga lokuvikelwa kwefilimu ye-passivation. Uma i-x = 7.5%, i-slope ye-coating passivation zone curve inkulu kakhulu, futhi i-passivation yesibili iyenzeka ngesikhathi esifanayo, okubonisa ukuthi ukugqoka kukhiqiza ifilimu ye-denser passivation ngesikhathi senqubo yokugqwala, okuthuthukisa ukumelana nokugqwala kwefilimu ye-passivation.

Amandla okuzi-corrosion (Ecorr) kanye ne-corrosion current density (Icorr) ye-CoCrFeNiSi-xTiB2 (x = 2.5%, 5.0%, 7.5%, 10.0%) i-HEA eyinhlanganisela ye-HEA itholwe ngokusebenzisa indlela ye-Tafeel polarization curve extrapolation, njengoba kuboniswe ku-Table corporate i-thedynamic ekhombisa indlela yokukhuluma i-corrosion trend kanye nokwenzeka kwezinto ezibonakalayo, kuyilapho ipharamitha ye-kinetic i-Icorr ingabonisa izinga lokugqwala kwezinto [46-47]. Uma i-x = 7.5%, i-Icorr (1.252 × 10-4 A/cm2) ye-coating eyinhlanganisela iphansi kunezinye izigqoko, futhi i-Ecorr (-0.816 V) inkulu kakhulu, iphakeme kune-substrate nezinye izigqoko, okubonisa ukuthi i-CoCrFeNiSi-7.5% inokumelana okungcono kakhulu kwe-TiB2. Ngokuqhathanisa i-Icorr ne-Ecorr yezinye izigqoko, kungatholakala ukuthi ukumelana nokugqwala kwe-CoCrFeNiSi-10.0%TiB2 yokugqoka kungcono kune-CoCrFeNiSi-2.5%TiB2 kanye ne-CoCrFeNiSi-5.0%TiB2. Phakathi kwalezi ezimbili zokugcina, inani le-Ecorr le-CoCrFeNiSi-2.5%TiB2 likhudlwana kunele-CoCrFeNiSi-5.0%TiB2, kuyilapho amanani e-Icorrr elingana nobukhulu obufanayo, ngakho ukumelana nokugqwala kwe-CoCrFeNiSi-2.5%TiB2 kungcono kancane. Kuyaphawuleka ukuthi ukumelana nokugqwala kwazo zonke izintambo ze-CoCrFeNiSi-xTiB2 kungcono kunaleyo ye-40Cr, okubonisa ukuthi izimbobo ze-CoCrFeNiSi-xTiB2 zithuthukise ikhono lokumelana ne-Cl- intrusion futhi zibe nokuphikiswa okuhle kokugqwala. Ukumelana nokugqwala kwe-substrate kanye ne-coating ngayinye ibalwa njenge-CoCrFeNiSi-7.5%TiB2 > CoCrFeNiSi-10.0%. 0%TiB2>CoCrFeNiSi-2. 5%TiB2>CoCrFeNiSi-5. 0%TiB2>40Cr.

2.5.2 Ukuhlaziywa kwe-Electrochemical impedance

I-Electrochemical impedance spectroscopy (EIS) iyithuluzi elisebenzayo lokufunda ukusebenza kokugqwala kanye nendlela yokugqwala. Ibonisa izici zesakhiwo se-electrode interface ngokuqhathanisa ulwazi lwayo lwe-kinetic kanye nejika le-polarization. Izibalo 12a kanye no-12b ziyimidwebo yeNyquist kanye neBhodi ye-substrate kanye nenhlanganisela ye-CoCrFeNiSi-xTiB2 HEAs eyinhlanganisela. Njengoba kungabonwa kuMfanekiso 12a, ijika le-Nyquist lesampula liyisiyingi, okubangelwa ukudluliswa kwenkokhiso endaweni ehlukahlukene. Ucwaningo luye lwabonisa ukuthi uma ubukhulu be-semicircle bukhulu, kuba ngcono ukumelana nokugqwala. Ububanzi be-semicircle bomdwebo we-Nyquist ngu-x = 7.5%, x = 10.0%, x = 2.5%, x = 5. 0%, 40Cr, okubonisa ukuthi inani elifanele lezinhlayiya ze-TiB2 lingathuthukisa ngempumelelo ukumelana nokugqwala kwengubo ku-3.5% yesisombululo se-NaCl. Kumdwebo we-Bode, i-impedance modulus Z ingabonisa izinga lokuhlasela kwe-Cl. Uma likhulu inani le-Z, liba lincane izinga le-Cl- invasion. Esifundeni se-mid-frequency (1-103 Hz) yoMfanekiso 12, i-logarithm ye-impedance modulus kanye nefrikhwensi ibonisa ubudlelwano bomugqa nomthambeka ongaphansi kuka -1. Ku-frequency engashintshi engu-0.1 Hz, inani lika-Z licishe lilingane nenani lokumelana ne-polarization (RP). Uma i-RP iba ​​nkulu, kuba nzima nakakhulu ukuthi isampula igqwale [51]. Njengoba kuboniswe kuMfanekiso 12b, ku-f = 10-2 Hz, inani le-Z le-coating eline-x = 7.5% likhulu kunawo wonke, okubonisa ukuthi ukumelana nokugqwala kwefilimu ye-passive endaweni yokwemboza kuphezulu kakhulu uma x = 7.5%. Esifundeni semvamisa ephezulu ye-104-105 Hz, i-engeli yesigaba isondele ku-zero, okubonisa ukuthi ukumelana nesixazululo kuphansi. Ebangeni lemvamisa emaphakathi, i-engeli yesigaba yazo zonke izimbotshana ayifinyeleli ku-90 °, okubonisa ukuthi ukumboza kunesici "se-semi-adaptive", okubonisa ukuthi ifilimu ye-passivation endaweni yokwemboza kancane kancane ishintsha ibe isendlalelo se-capacitance ehlanzekile ngokusebenza okuhle kokufakwa, okunomthelela omuhle wokuvikela ekuhlanganiseni. Ukuze kuhlolwe inqubo yokugqwala kwentonga, i-spectrum ye-EIS ihlaziywa kusetshenziswa isekethe efanayo. Njengoba kuboniswe kuMdwebo 12c, ama-Rs ukumelana nesixazululo, i-Rf iwukumelana nefilimu yomkhiqizo wokugqwala, i-Rct iwukumelana nokushajwa kokudluliselwa kwe-electrode, futhi isici sesigaba esingaguquki (CPE) sisetshenziselwa ukunxephezela ukungafanani kwesistimu (ukuhwalala kobuso kanye nokukhubazeka kwendawo), okuyi-CPE1 ne-CPE2 ngokulandelana. Kungabonakala ngokucacile kuThebula lesi-4 ukuthi uma x = 7.5%, i-Rct ne-Rf inkulu kakhulu, okubonisa ukuthi ukugqoka nge-x = 7.5% kunokumelana nokugqwala okungcono kakhulu. Kafushane, i-substrate ne-coating ngayinye inokumelana nokugqwala okuhle ku-3.5%. Ukumelana nokugqwala kusixazululo se-NaCl esingu-5% sibalwa njenge-CoCrFeNiSi-7.5% TiB2 > CoCrFeNiSi-10.0% TiB2 > CoCrFeNiSi-2.5% TiB2 > CoCrFeNiSi-5.0% TiB2 > 40Cr, okuhambisana nemiphumela yokuhlaziywa kwe-polar potentiodynamic.

2.5.3 I-Corrosion surface morphology

Umfanekiso we-13 ubonisa i-electrochemical corrosion morphology ye-40Cr substrate kanye nenhlanganisela eyinhlanganisela. Kungabonakala ngokucacile ukuthi ingaphezulu lika-40Cr lukhuni, izinga lokugqwala liyingozi kakhulu, futhi kuvela imigodi yokugoba. Lokhu kungenxa yokuthi kunezinto eziningi ze-Cr ngaphezulu kwe-40Cr, ifilimu ye-passivation eyakhiwe ayilingani, i-Cl- ithinta ingxenye ebuthakathaka yefilimu ye-passivation, futhi yakhe ama-chloride ancibilikayo endaweni yefilimu, okuholela ekubukeni kwemigodi yokugoba. x = 2.5%, 5.0%. Uma u-x = 0.0% no-10.0%, ingaphezulu lenhlanganisela eyinhlanganisela lishelela kunalelo le-substrate engu-40Cr, futhi inani elincane lemigodi yokugqwala yamazinga ahlukahlukene ivela kuzo zombili izindawo. Uma i-x = 7.5%, i-coating surface ibushelelezi futhi ayikho imigodi yokugqwala evelayo, okubonisa ukuthi i-CoCrFeNiSi-7.5%TiB2 yokugqoka inokumelana nokubola okuhle. Kuyaphawuleka ukuthi lapho okuqukethwe kwe-TiB2 kwenyukela ku-10.0%, ukumelana nokugqwala kwento enamathelayo kuncipha esikhundleni salokho. Lokhu kungenxa yokuthi ukwengezwa ngokweqile kwe-TiB2 kuholela ezingxenyeni eziningi ze-B ekuhlanganisweni. Kusukela ekuhlaziyweni kwe-XRD ku-Figure 1, kungabonakala ukuthi i-intermetallic compound CrB ikhiqizwa embozweni nge-x = 10.0%, okwandisa ukungafani kwefilimu ye-passivation futhi kunciphisa ukumelana nokugqwala kwefilimu ye-passivation kusixazululo se-NaCl; i-intermetallic compound CrB izokwakha i-microbattery ku-coating, ibangele ukugqwala kwe-galvanic. Ngakho-ke, ukumelana nokugqwala kokugqoka nge-x = 10.0% kungcono kunokwemboza nge-x = 7.5%. I-5% yokugqoka iyancipha.

3 Iziphetho

(1) Ukwengeza izinhlayiya ze-nano-TiB2 ku-CoCrFeNiSi HEA yokugqoka kunganciphisa ngokuphumelelayo usayizi ojwayelekile wokusanhlamvu we-coating futhi kucwengisise isakhiwo sokusanhlamvu se-coating eyinhlanganisela. Ukwakhiwa kwesigaba sokuhlanganisa i-CoCrFeNiSi-xTiB2 HEA isigaba se-FCC, isigaba se-BCC kanye ne-CrB boride. Ama-athomu e-Ti no-B ayancibilika esixazululweni esiqinile, futhi isenzo esihlangene salokhu okubili siholela ekuhlanekeni okunzima kwe-lattice. Kusukela ku-microstructure, kungabonakala ukuthi ngokwanda kokuqukethwe kwe-TiB2, ukuguqulwa kwesakhiwo sokumboza sisuka kumakristalu alinganayo siye kuma-columnar dendrites. Ngesikhathi esifanayo, ukungezwa kwe-TiB2 kuvimbela ukuhlukaniswa kwezakhi ze-Si emingceleni yokusanhlamvu.

(2) I-microhardness ye-coating ihlotshaniswa kahle nokuqukethwe kwe-TiB2. Uma u-x = 10. 0%, ubulukhuni obuncane obumaphakathi bokwemboza bufinyelela inani eliphakeme le-HV547. 11, okungaba izikhathi ezi-2.72. Ukuthuthukiswa kokuqina kwe-microhardness kuwumphumela womphumela ohlangene wokuqinisa isisombululo esiqinile, ukuqinisa ukuhlakazeka kanye nokuqinisa okusanhlamvu okuhle. Ukumelana nokugqoka kwe-coating kukhuphuka ngokwanda kokuqukethwe kwe-TiB2. Uma x = 10.0%, isisindo sokulahlekelwa kokuguga sincane kakhulu, sifinyelela ku-0.13 mg, okungaphansi ngo-88% kuneso se-substrate. Izinga lokugqoka le-coating liyancipha ngokunyuka kwe-TiB2. Ukwenyuka kwe-TiB2 kushintsha indlela yokuguga eyinhloko ye-coating ukusuka ekugugeni okunzima nokuguga kwe-oxidation kuye ekugugeni okuncane nokuguga kwe-oxidation.

(3) Ngokusho kwe-polarization curve kanye nemiphumela efanelekile ye-EIS, ukwanda kokuqukethwe kwezinhlayiyana ze-TiB2 kungathuthukisa ngokuphumelelayo ukumelana nokugqwala kokugqoka. Ukuthuthukiswa kokumelana nokugqwala kwe-corrosion kubangelwa ikakhulukazi ukudlula kwesibili kwe-coating ngesikhathi senqubo yokugqwala, okukhiqiza ifilimu e-denser passivation futhi ithuthukise ikhono lokumelana ne-Cl- invasion. Phakathi kwazo, i-CoCrFeNiSi-7.5% TiB2 yokugqoka inokumelana nokugqwala okungcono kakhulu.