Thermal barrier coatings muab "heat-insulating armor" ntawm cov khoom hlau.
Nyob rau hauv lub teb ntawm aero engines thiab roj turbines, muaj ib tug nyob mus ib txhis nrhiav: siab dua turbine inlet kub. Vim li no, cov kws tshawb fawb cov ntaub ntawv tseem niaj hnub tshawb nrhiav txoj hauv kev los txhim kho qhov siab - qhov kub thiab txias tsis kam ntawm turbines, thiab ib txoj hauv kev zoo tshaj plaws yog muab tso rau ntawm "cov khaub ncaws tiv thaiv"- txheej txheej turbine nrog cov txheej txheej uas muaj cov haujlwm sib txawv, yog li ua tiav cov kev pabcuam zoo dua qub, kev ntseeg siab dua, thiab kev pabcuam lub neej ntev dua.
Thermal barrier coatings in aero engine (GP7200) and the cross-sectional morphology of a typical thermal barrier coating system
Tam sim no, thermal barrier coatings tau dhau los ua cov cuab yeej txhawb nqa tseem ceeb rau kev rhuav tshem cov kev pabcuam ntawm cov khoom siv hlau.
Thermal barrier coatings (TBCs) yog ib hom txheej txheej insulating uas ua ke nrog cov qauv kev ua haujlwm thiab cov yam ntxwv ua haujlwm. Lawv muaj ntau txheej txheej zoo li "sandwich," uas muaj cov txheej txheem thermal rwb thaiv tsev, lub tsho hlau nplaum, thiab cov khoom siv superalloy substrate. Ntawm cov no, cov txheej txheem ceramic sab saum toj yog cov txheej txheem tseem ceeb ntawm cov txheej txheem thermal barrier txheej, ncaj qha coj cov thermal shock, yaig, thiab tshuaj lom neeg corrosion ntawm siab -kub roj. Kev xaiv cov khoom siv thiab cov qauv tsim ntawm cov txheej txheem no ncaj qha txiav txim siab thermal rwb thaiv tsev nyhuv thiab kev pabcuam lub neej ntawm cov txheej.
Thermal barrier txheej txheej
Zirconium-raws li cov ntaub ntawv yog cov khoom siv zoo tshaj plaws rau txheej ceramic ntawm siab - kub thermal barrier txheej.
Vim tias zirconium-raws li cov ntaub ntawv muaj kev ua haujlwm zoo thermal rwb thaiv tsev, siab -kub oxidation tsis kam, siab -kub corrosion kuj, thiab kuj muaj zog, lawv tau dhau los ua cov khoom nyiam rau cov txheej txheem ceramic ntawm siab - kub thermal barrier coatings.
Thawj theem ntawm kev txhim kho zirconium-raws li thermal barrier coatings yog siv ncaj qha ntawm zirconium oxide (ZrO2) raws li cov khoom siv ceramic. Kev hloov pauv sai ntawm ZrO2 thaum lub sijhawm cua sov txwv nws qhov kev pabcuam kub, ua rau lub neej luv luv rau cov txheej txheem thermal barrier txheej. Qhov thib ob theem yog siv 6 wt% ~ 8 wt% Y2O3 ib nrab stabilized ZrO2 (YSZ) ceramic txheej. Doping nrog lub ntiaj teb tsis tshua muaj oxide Y2O3 nce qib kev hloov pauv kub ntawm ZrO2, txhim kho qhov siab -kub theem stability ntawm cov ceramic system, thiab YSZ tseem yog cov feem ntau siv thermal barrier txheej ceramic khoom thoob ntiaj teb.
Txawm li cas los xij, raws li kev pabcuam kub maj mam nce ntxiv, YSZ system tau maj mam nthuav tawm nws cov kev txwv hauv theem kev ruaj ntseg, sintering tsis kam, thiab thermal cycling qaug zog ua haujlwm. Tshwj xeeb tshaj yog nyob rau hauv siab - qhov kub thiab txias ib puag ncig siab tshaj 1200 degree, YSZ yog nquag mus rau theem transformation, ua rau structural embrittlement thiab txheej tsis ua hauj lwm. Txhawm rau daws cov teeb meem no, cov kws tshawb fawb tau pib tshawb nrhiav cov khoom siv ceramic tshiab.
Zirconium-raws li hmoov: thawj qhov teeb meem rau "heat-insulating armor" ntawm thermal barrier coatings.
Nyob rau hauv thermal barrier txheej daim ntaub ntawv, coatings npaj los ntawm "nano zirconium oxide hmoov thiab hollow spherical zirconium oxide hmoov" muaj kev ua tau zoo tshaj li cov tsoos microstructured txheej.
Vim tias lawv "tsim microstructure," nanostructured thermal barrier coatings feem ntau muaj ntau dua sintering tsis kam thiab zoo strain kam rau ua, li no ho txhim kho lub neej kev pab cuam ntawm txheej. Hollow spherical structured thermal barrier coatings, vim lawv "cov yam ntxwv ntxeem tau," tuaj yeem txo cov thermal conductivity ntawm txheej thiab muab thermal rwb thaiv tsev zoo dua, thaum tseem muaj kev ruaj ntseg zoo dua thiab lwm yam ntxwv. Cov yam ntxwv ntawm thawj zaug zirconium oxide hmoov muaj kev txiav txim siab ntawm txheej txheej. Yog li ntawd, kev ua kom zoo dua cov hmoov uas twb muaj lawm- ua cov txheej txheem lossis tshawb nrhiav cov khoom zoo dua qub, thiab tsim cov hmoov tshiab nrog kev ua tau zoo dua, yog txoj hauv kev tseem ceeb rau kev txhim kho cov txheej txheem thermal barrier coatings thiab ua tau raws li qhov yuav tsum tau ua ntawm kev ua haujlwm siab thiab sophisticated.
Cov txheej txheem kev npaj rau cov hmoov siv zirconium-raws li siab- kub thermal barrier txheej muaj xws li vapor deposition, molten ntsev txoj kev, sol-gel method, homogeneous nag lossis daus txheej txheem, hydrothermal method, template method, thiab lwm yam. Ntawm lawv, qhov tshwj xeeb tseem ceeb "hydrothermal method," raws li kev npaj tshuaj lom neeg nrog kev txhim kho zoo, qhia tau zoo heev hauv kev npaj cov ntshiab / doped nano zirconium oxide hmoov. Cov txheej txheem template tuaj yeem tswj cov kab thiab phab ntsa tuab ntawm hollow spheres los ntawm kev xaiv cov neeg ua haujlwm templates ntawm ntau qhov sib txawv, thiab yog ib txoj hauv kev ua tau zoo ntawm kev ua tiav kev npaj ntawm cov hollow kheej kheej. Cov tshuaj tsuag pyrolysis yog qhov tsim nyog rau qhov loj - teev ntau lawm, tsim cov qauv hollow kheej kheej nyob rau hauv ib kauj ruam los ntawm atomization, ziab, thiab pyrolysis txheej txheem ntawm precursor- tswj kua.
Kev sib piv ntawm cov txheej txheem kev npaj tseem ceeb rau zirconium-raws li cov ntaub ntawv hmoov
Qhia txog lub ntiaj teb tsis tshua muaj los tsim cov zirconium tshiab-raws li thermal barrier ceramic txheej.
Ntawm ib sab, kev txhim kho cov ntaub ntawv thermal thaiv txheej uas twb muaj lawm thaum tib lub sijhawm doping nrog ntau lub ntiaj teb tsis tshua muaj oxides -ytterbium oxide, scandium oxide, gadolinium oxide, cerium oxide- tuaj yeem tsim cov teebmeem sib txawv.
Ntawm qhov tod tes, tsim tshiab zirconium-raws li cov hmoov sib xyaw (xws li cov txheej txheem sib xyaw ntawm zirconium oxide thiab cov ntsev hauv ntiaj teb tsawg) kuj tau dhau los ua ib qho kev tshawb fawb tseem ceeb.
Piv nrog YSZ, tsis tshua muaj lub ntiaj teb zirconate (RE2Zr2O7) cov ntaub ntawv nthuav tawm qis thermal conductivity, siab dua theem stability, thiab zoo sintering tsis kam, ua rau lawv cov tub ntxhais sib tw rau tiam tom ntej ntawm TBC ceramic cov ntaub ntawv. Cov kev tshawb fawb pom tau tias cov khoom zoo heev ntawm lub ntiaj teb tsis tshua muaj zirconates tuaj yeem txhim kho cov thermal shock kev ua tau zoo thiab thermal cycling lub neej ntawm coatings. Piv txwv li, nyob rau hauv ob chav - txheej txheej txheej txheej ntawm La2Zr2O7 thiab 8YSZ, cov khoom La2Zr2O7 sab nrauv tuaj yeem txo cov thermal conductivity thiab ua kom cov thermal shocks thiab thermal oxidation lub neej, ua kom pom qhov zoo ntawm "tsis muaj thermal conductivity-siab stability."
Tsis tas li ntawd, nyob rau hauv xyoo tas los no, lub ntiaj teb tsis tshua muaj tantalates (RE2Ta2O7) thiab tsis tshua muaj ntiaj teb niobates (RE2Nb2O7), raws li cov ntaub ntawv nrog ultra- thermal conductivity thiab thermal stability zoo heev, tau dhau los ua cov kev tshawb fawb tshiab. Vim yog lawv cov tawv tawv tsis zoo, lawv daim ntawv thov raws li cov ntaub ntawv txheej yog txwv. Kev tshawb fawb tam sim no feem ntau tsom mus rau kev ua tiav kev ua tiav ntawm cov khoom siv los ntawm cov txheej txheem sib xyaw ua ke lossis cov qauv gradient.