摘要

熱障(zhang)涂(tu)(tu)層(thermal barrier coatings，TBCs)是(shi)航(hang)空發動(dong)機渦輪(lun)葉片(pian)的(de)關鍵核心技(ji)術之一(yi)，可顯著提高發動(dong)機工作(zuo)溫(wen)度，提升(sheng)發動(dong)機推力和(he)工作(zuo)效率；但(dan)另(ling)一(yi)方(fang)面，更高的(de)發動(dong)機工作(zuo)溫(wen)度使得(de)葉片(pian)及(ji)其表面TBCs遭(zao)受嚴(yan)重(zhong)的(de)環境(jing)沉積(ji)物(主要成分為CaO、MgO、Al2O3和(he)SiO2，簡(jian)稱CMAS)腐(fu)(fu)(fu)蝕(shi)，造成過早(zao)失效。CMAS腐(fu)(fu)(fu)蝕(shi)已(yi)成為限制TBCs工作(zuo)溫(wen)度和(he)服役壽命的(de)難題，抗腐(fu)(fu)(fu)蝕(shi)防(fang)護是(shi)目(mu)前TBCs領域研究的(de)重(zhong)點。本(ben)文首先(xian)綜述了(le)學者們(men)對TBCs CMAS腐(fu)(fu)(fu)蝕(shi)問題的(de)認識歷程以(yi)及(ji)CMAS本(ben)身(shen)特性，再簡(jian)述了(le)TBCs的(de)CMAS腐(fu)(fu)(fu)蝕(shi)機理(li)，重(zhong)點從TBCs的(de)表面防(fang)護層設計(ji)、涂(tu)(tu)層成分改性、新型抗腐(fu)(fu)(fu)蝕(shi)涂(tu)(tu)層材料(liao)開(kai)發以(yi)及(ji)涂(tu)(tu)層結構設計(ji)等方(fang)面闡述了(le)國(guo)際上(shang)目(mu)前TBCs的(de)抗CMAS腐(fu)(fu)(fu)蝕(shi)防(fang)護方(fang)法，最后對TBCs的(de)超高溫(wen)環境(jing)應用及(ji)腐(fu)(fu)(fu)蝕(shi)防(fang)護發展(zhan)方(fang)向進(jin)行了(le)展(zhan)望。

關鍵詞： 燃(ran)氣渦輪發動機 ; 熱障涂層 ; CMAS腐蝕 ; 失效機理 ; 防護方法(fa)

航空(kong)(kong)發(fa)(fa)(fa)動(dong)機的(de)(de)推(tui)重比是指發(fa)(fa)(fa)動(dong)機產生(sheng)的(de)(de)推(tui)力(li)與其自身重量的(de)(de)比值，高推(tui)重比是航空(kong)(kong)發(fa)(fa)(fa)動(dong)機的(de)(de)永恒追求(qiu)。但是，隨著(zhu)推(tui)重比的(de)(de)提(ti)高，發(fa)(fa)(fa)動(dong)機渦(wo)輪前進口溫度將大幅增加。單靠發(fa)(fa)(fa)展發(fa)(fa)(fa)動(dong)機葉(xie)片合金材料已難(nan)以滿(man)足高推(tui)重比航空(kong)(kong)發(fa)(fa)(fa)動(dong)機的(de)(de)發(fa)(fa)(fa)展需求(qiu)[1,2]，因此，熱障涂(tu)層(ceng)(thermal barrier coatings，TBCs)技(ji)術應運而(er)生(sheng)。TBCs是降(jiang)低高溫環境下合金表面溫度的(de)(de)一種(zhong)有效熱防護技(ji)術，可(ke)顯(xian)著(zhu)提(ti)高葉(xie)片承溫能力(li)，提(ti)升(sheng)發(fa)(fa)(fa)動(dong)機推(tui)重比和工作效率(lv)等(deng)，一般包括陶瓷層(ceng)、粘結層(ceng)以及(ji)(ji)熱生(sheng)長(chang)氧化物(thermal grown oxidation，TGO)[3,4]。目前，航空(kong)(kong)發(fa)(fa)(fa)動(dong)機中(zhong)最(zui)廣泛(fan)使用的(de)(de)陶瓷層(ceng)是Y2O3部分(fen)穩(wen)定ZrO2 (yttria partially stabilized zirconia，YSZ) TBCs，常用的(de)(de)制(zhi)備方法有大氣等(deng)離(li)子(zi)噴涂(tu)(air plasma spraying，APS)、電子(zi)束物理氣相沉(chen)積(ji)(electron beam physical vapor deposition，EB-PVD)以及(ji)(ji)近幾年迅(xun)速發(fa)(fa)(fa)展的(de)(de)等(deng)離(li)子(zi)物理氣相沉(chen)積(ji)技(ji)術(plasma spray-physical vapor deposition，PS-PVD)。

TBCs工作(zuo)環境(jing)惡劣，服役(yi)條件苛刻(ke)，失(shi)效機理復(fu)雜，長(chang)壽命TBCs的(de)(de)研(yan)發(fa)依然任重道遠。高(gao)溫的(de)(de)服役(yi)環境(jing)會(hui)導(dao)致YSZ涂(tu)(tu)(tu)層(ceng)發(fa)生亞穩四(si)方相(xiang)(xiang)(t′)分解，在(zai)隨后冷卻過(guo)程中相(xiang)(xiang)變形成單(dan)斜相(xiang)(xiang)(m)，并伴隨3%~4%的(de)(de)體積膨脹(zhang)，造成涂(tu)(tu)(tu)層(ceng)開裂(lie)；高(gao)溫還會(hui)加速涂(tu)(tu)(tu)層(ceng)燒結，破壞涂(tu)(tu)(tu)層(ceng)的(de)(de)微結構，減少(shao)孔隙率，降低(di)隔熱(re)性能(neng)和(he)涂(tu)(tu)(tu)層(ceng)的(de)(de)應變容限[5~7]。此外，由于氧化，粘結層(ceng)和(he)陶瓷(ci)涂(tu)(tu)(tu)層(ceng)之間會(hui)產(chan)生TGO；如果TGO生長(chang)過(guo)厚，其熱(re)膨脹(zhang)系數(shu)(coefficient of thermal expansion，CTE)與陶瓷(ci)涂(tu)(tu)(tu)層(ceng)失(shi)配產(chan)生較大內應力，加速涂(tu)(tu)(tu)層(ceng)剝(bo)落失(shi)效[8,9]。

除上(shang)述失效機(ji)(ji)(ji)(ji)理(li)(li)外，高溫(wen)(wen)腐蝕也(ye)是TBCs失效的(de)(de)(de)(de)一(yi)個重要(yao)原因。航空(kong)飛(fei)機(ji)(ji)(ji)(ji)執行任務的(de)(de)(de)(de)實際工況中(zhong)，發動(dong)機(ji)(ji)(ji)(ji)會攝(she)入(ru)大(da)量沙(sha)(sha)(sha)塵(chen)、火(huo)山灰、跑道碎屑以及各種環境污染物(wu)，這些(xie)吸入(ru)物(wu)在(zai)(zai)高溫(wen)(wen)下附著(zhu)(zhu)(zhu)于(yu)(yu)發動(dong)機(ji)(ji)(ji)(ji)熱端(duan)部(bu)件(如渦(wo)(wo)(wo)輪(lun)(lun)葉(xie)片(pian)、燃(ran)燒(shao)(shao)室壁等)；研(yan)究(jiu)發現(xian)沉積物(wu)的(de)(de)(de)(de)成(cheng)分(fen)主(zhu)要(yao)為(wei)(wei)CaO、MgO、Al2O3和(he)(he)SiO2，簡(jian)稱CMAS。CMAS的(de)(de)(de)(de)熔點隨(sui)成(cheng)分(fen)變(bian)化而變(bian)化，但(dan)一(yi)般來說，當工作溫(wen)(wen)度超過(guo)1200℃時，CMAS即開(kai)始熔化，高溫(wen)(wen)熔體會沿(yan)著(zhu)(zhu)(zhu)葉(xie)片(pian)表(biao)面(mian)TBCs中(zhong)微裂紋、孔隙(xi)內滲，同時與涂層(ceng)(ceng)組分(fen)反應，造成(cheng)涂層(ceng)(ceng)相成(cheng)分(fen)和(he)(he)微觀結構破壞，加速涂層(ceng)(ceng)失效，使得葉(xie)片(pian)合(he)金(jin)直面(mian)高溫(wen)(wen)燃(ran)氣，損害發動(dong)機(ji)(ji)(ji)(ji)性能[10]。此(ci)外，CMAS還(huan)會堵塞(sai)葉(xie)片(pian)冷(leng)(leng)(leng)卻通道，造成(cheng)局(ju)部(bu)過(guo)燒(shao)(shao)。Smialek等[11]在(zai)(zai)沙(sha)(sha)(sha)土(tu)聚集且(qie)夏季常(chang)有沙(sha)(sha)(sha)塵(chen)暴和(he)(he)霾(mai)的(de)(de)(de)(de)地區服役(yi)的(de)(de)(de)(de)直升機(ji)(ji)(ji)(ji)渦(wo)(wo)(wo)輪(lun)(lun)機(ji)(ji)(ji)(ji)葉(xie)片(pian)上(shang)發現(xian)了沉積的(de)(de)(de)(de)沙(sha)(sha)(sha)子，這些(xie)沙(sha)(sha)(sha)子粒徑小于(yu)(yu)10 μm，能夠繞過(guo)顆粒分(fen)離器進入(ru)冷(leng)(leng)(leng)卻和(he)(he)燃(ran)燒(shao)(shao)系統，在(zai)(zai)燃(ran)燒(shao)(shao)的(de)(de)(de)(de)氣體中(zhong)反應并(bing)主(zhu)要(yao)以CaSO4和(he)(he)其他結晶硅酸鹽的(de)(de)(de)(de)形式沉積到(dao)渦(wo)(wo)(wo)輪(lun)(lun)葉(xie)片(pian)上(shang)，并(bing)產(chan)生(sheng)冷(leng)(leng)(leng)卻孔堵塞(sai)問(wen)題，但(dan)是由于(yu)(yu)CaSO4熔點高，通常(chang)不會觀察到(dao)過(guo)度腐蝕。Borom等[12]研(yan)究(jiu)了在(zai)(zai)燃(ran)燒(shao)(shao)室、渦(wo)(wo)(wo)輪(lun)(lun)軸(zhou)發動(dong)機(ji)(ji)(ji)(ji)和(he)(he)渦(wo)(wo)(wo)輪(lun)(lun)螺旋槳發動(dong)機(ji)(ji)(ji)(ji)上(shang)TBC的(de)(de)(de)(de)剝落原因，發現(xian)都與高溫(wen)(wen)熔融相的(de)(de)(de)(de)沉積和(he)(he)滲透有關，而熔融相中(zhong)都存(cun)在(zai)(zai)CaO、MgO、Al2O3和(he)(he)SiO2，也(ye)就(jiu)是CMAS。Mercer等[13]研(yan)究(jiu)表(biao)明，當渦(wo)(wo)(wo)輪(lun)(lun)葉(xie)片(pian)表(biao)面(mian)溫(wen)(wen)度達到(dao)CMAS的(de)(de)(de)(de)熔點時，會激(ji)活(huo)一(yi)種冷(leng)(leng)(leng)沖擊分(fen)層(ceng)(ceng)的(de)(de)(de)(de)機(ji)(ji)(ji)(ji)制，這種機(ji)(ji)(ji)(ji)制會導(dao)致(zhi)涂層(ceng)(ceng)的(de)(de)(de)(de)分(fen)層(ceng)(ceng)和(he)(he)剝落。隨(sui)著(zhu)(zhu)(zhu)研(yan)究(jiu)深入(ru)，研(yan)究(jiu)者們意識到(dao)CMAS對TBC的(de)(de)(de)(de)危(wei)害極大(da)。發展至(zhi)今，CMAS腐蝕問(wen)題已成(cheng)為(wei)(wei)當前TBCs領域的(de)(de)(de)(de)研(yan)究(jiu)熱點和(he)(he)難點。因此(ci)，揭示(shi)CMAS腐蝕導(dao)致(zhi)的(de)(de)(de)(de)TBCs失效機(ji)(ji)(ji)(ji)理(li)(li)，建立(li)TBCs的(de)(de)(de)(de)CMAS腐蝕防護方(fang)法，研(yan)發抗(kang)CMAS腐蝕的(de)(de)(de)(de)TBCs新材(cai)料和(he)(he)新結構，是TBCs研(yan)究(jiu)亟待解決的(de)(de)(de)(de)難題，是提高發動(dong)機(ji)(ji)(ji)(ji)性能和(he)(he)壽(shou)命的(de)(de)(de)(de)迫切要(yao)求，是高性能航空(kong)發動(dong)機(ji)(ji)(ji)(ji)研(yan)制的(de)(de)(de)(de)關鍵保證(zheng)。

1 CMAS腐蝕問題的發(fa)現

關于(yu)(yu)環境沉(chen)(chen)(chen)積(ji)(ji)物(wu)腐(fu)蝕的(de)(de)(de)(de)認識和(he)(he)(he)研(yan)(yan)(yan)究(jiu)(jiu)最早見于(yu)(yu)Smialek等(deng)(deng)[14]的(de)(de)(de)(de)報道。他們發(fa)(fa)現當(dang)一(yi)(yi)(yi)個(ge)地(di)區的(de)(de)(de)(de)空(kong)氣沙(sha)塵(chen)濃(nong)(nong)度較高、霧霾多發(fa)(fa)時，在(zai)(zai)(zai)(zai)此地(di)區服(fu)(fu)役的(de)(de)(de)(de)直升機(ji)(ji)(ji)(ji)(ji)(ji)的(de)(de)(de)(de)發(fa)(fa)動機(ji)(ji)(ji)(ji)(ji)(ji)葉(xie)(xie)(xie)片上存(cun)在(zai)(zai)(zai)(zai)玻璃狀沉(chen)(chen)(chen)積(ji)(ji)物(wu)，并認識到它對航空(kong)發(fa)(fa)動機(ji)(ji)(ji)(ji)(ji)(ji)運(yun)行(xing)的(de)(de)(de)(de)潛在(zai)(zai)(zai)(zai)危(wei)害。Shifler和(he)(he)(he)Choi[15]較早地(di)發(fa)(fa)現在(zai)(zai)(zai)(zai)服(fu)(fu)役溫度較低的(de)(de)(de)(de)船(chuan)舶發(fa)(fa)動機(ji)(ji)(ji)(ji)(ji)(ji)部(bu)件中(zhong)出(chu)現了類似(si)于(yu)(yu)航空(kong)發(fa)(fa)動機(ji)(ji)(ji)(ji)(ji)(ji)部(bu)件受(shou)CMAS腐(fu)蝕的(de)(de)(de)(de)后(hou)果(guo)。Toriz等(deng)(deng)[16]指出(chu)在(zai)(zai)(zai)(zai)渦(wo)輪導向葉(xie)(xie)(xie)片中(zhong)應(ying)用(yong)的(de)(de)(de)(de)TBC需要面臨極其(qi)(qi)惡劣的(de)(de)(de)(de)服(fu)(fu)役環境，其(qi)(qi)失(shi)效主要原因(yin)(yin)是熱(re)循(xun)環、粘結層(ceng)的(de)(de)(de)(de)氧化(hua)以及一(yi)(yi)(yi)些(xie)固體(ti)顆粒的(de)(de)(de)(de)沉(chen)(chen)(chen)積(ji)(ji)引(yin)發(fa)(fa)的(de)(de)(de)(de)腐(fu)蝕。為研(yan)(yan)(yan)究(jiu)(jiu)失(shi)效過程(cheng)和(he)(he)(he)機(ji)(ji)(ji)(ji)(ji)(ji)理，他們收(shou)集了一(yi)(yi)(yi)個(ge)飛(fei)機(ji)(ji)(ji)(ji)(ji)(ji)發(fa)(fa)動機(ji)(ji)(ji)(ji)(ji)(ji)葉(xie)(xie)(xie)片，這(zhe)架(jia)飛(fei)機(ji)(ji)(ji)(ji)(ji)(ji)長期飛(fei)行(xing)于(yu)(yu)沙(sha)塵(chen)濃(nong)(nong)度較高的(de)(de)(de)(de)國家。研(yan)(yan)(yan)究(jiu)(jiu)發(fa)(fa)現，高于(yu)(yu)1200℃時，這(zhe)些(xie)沉(chen)(chen)(chen)積(ji)(ji)物(wu)就(jiu)會熔(rong)化(hua)并撞擊在(zai)(zai)(zai)(zai)葉(xie)(xie)(xie)片表面，熔(rong)融的(de)(de)(de)(de)碎(sui)片可以進入多孔TBC結構，并腐(fu)蝕涂層(ceng)，或者通(tong)過熱(re)失(shi)配引(yin)起應(ying)力(li)增加(jia)，從而減少(shao)涂層(ceng)的(de)(de)(de)(de)熱(re)循(xun)環壽命。Kim等(deng)(deng)[17]使用(yong)Allison T56和(he)(he)(he)Whitney F-100發(fa)(fa)動機(ji)(ji)(ji)(ji)(ji)(ji)的(de)(de)(de)(de)燃燒室、點(dian)火器、燃料噴嘴(zui)和(he)(he)(he)第一(yi)(yi)(yi)級高壓渦(wo)輪葉(xie)(xie)(xie)片設計(ji)和(he)(he)(he)建造(zao)了2個(ge)熱(re)段實驗系(xi)統，以研(yan)(yan)(yan)究(jiu)(jiu)2種火山物(wu)質攝入燃氣渦(wo)輪發(fa)(fa)動機(ji)(ji)(ji)(ji)(ji)(ji)時的(de)(de)(de)(de)行(xing)為。他們發(fa)(fa)現，如果(guo)灰塵(chen)堵(du)塞(sai)(sai)噴頭冷卻孔，即使最初沒有沉(chen)(chen)(chen)積(ji)(ji)，也(ye)會對葉(xie)(xie)(xie)片造(zao)成(cheng)(cheng)損(sun)(sun)壞。這(zhe)種堵(du)塞(sai)(sai)會導致葉(xie)(xie)(xie)片在(zai)(zai)(zai)(zai)正常(chang)渦(wo)輪機(ji)(ji)(ji)(ji)(ji)(ji)入口(kou)溫度運(yun)行(xing)條件下損(sun)(sun)傷失(shi)效。Stott等(deng)(deng)[18]研(yan)(yan)(yan)究(jiu)(jiu)了服(fu)(fu)役于(yu)(yu)熱(re)帶沙(sha)漠氣候(hou)地(di)區的(de)(de)(de)(de)飛(fei)機(ji)(ji)(ji)(ji)(ji)(ji)發(fa)(fa)動機(ji)(ji)(ji)(ji)(ji)(ji)沉(chen)(chen)(chen)積(ji)(ji)物(wu)后(hou)指出(chu)：沉(chen)(chen)(chen)積(ji)(ji)物(wu)是一(yi)(yi)(yi)種具有透輝石型結構的(de)(de)(de)(de)鈣(gai)鎂鋁硅酸鹽玻璃，YSZ TBC在(zai)(zai)(zai)(zai)1300~1600℃的(de)(de)(de)(de)溫度下易(yi)受(shou)熔(rong)融砂和(he)(he)(he)玻璃碎(sui)片的(de)(de)(de)(de)腐(fu)蝕，其(qi)(qi)精確機(ji)(ji)(ji)(ji)(ji)(ji)理受(shou)熔(rong)體(ti)組成(cheng)(cheng)的(de)(de)(de)(de)影響(xiang)：含Ca量(liang)(liang)較低的(de)(de)(de)(de)沉(chen)(chen)(chen)積(ji)(ji)物(wu)腐(fu)蝕過程(cheng)主要消(xiao)耗(hao)穩定劑Y2O3；含Ca量(liang)(liang)較高的(de)(de)(de)(de)沉(chen)(chen)(chen)積(ji)(ji)物(wu)會消(xiao)耗(hao)Y2O3和(he)(he)(he)ZrO2造(zao)成(cheng)(cheng)相轉變。由于(yu)(yu)這(zhe)些(xie)沉(chen)(chen)(chen)積(ji)(ji)物(wu)的(de)(de)(de)(de)存(cun)在(zai)(zai)(zai)(zai)會導致飛(fei)機(ji)(ji)(ji)(ji)(ji)(ji)發(fa)(fa)動機(ji)(ji)(ji)(ji)(ji)(ji)葉(xie)(xie)(xie)片的(de)(de)(de)(de)失(shi)效，嚴重危(wei)害飛(fei)機(ji)(ji)(ji)(ji)(ji)(ji)服(fu)(fu)役的(de)(de)(de)(de)安全性。因(yin)(yin)此，研(yan)(yan)(yan)究(jiu)(jiu)者致力(li)于(yu)(yu)通(tong)過研(yan)(yan)(yan)究(jiu)(jiu)沉(chen)(chen)(chen)積(ji)(ji)物(wu)的(de)(de)(de)(de)一(yi)(yi)(yi)系(xi)列物(wu)理、化(hua)學性質以及其(qi)(qi)對發(fa)(fa)動機(ji)(ji)(ji)(ji)(ji)(ji)的(de)(de)(de)(de)危(wei)害機(ji)(ji)(ji)(ji)(ji)(ji)理，借此尋找相應(ying)的(de)(de)(de)(de)解(jie)決(jue)方法。

2 CMAS特性(xing)

CMAS化學(xue)成(cheng)分(fen)十分(fen)復雜，一些學(xue)者對其(qi)成(cheng)分(fen)進(jin)行了分(fen)析(xi)。TBC多(duo)應用于渦輪機葉片，Smialek等[11]分(fen)析(xi)了直升機渦輪葉片上(shang)非晶態沉積(ji)(ji)物(wu)后發現(xian)，其(qi)中SiO2、CaO、Al2O3、Fe2O3和(he)MgO含(han)量(liang)(liang)(liang)較高(gao)，同時也(ye)含(han)有少量(liang)(liang)(liang)Na和(he)K等。Borom等[12]研究(jiu)了TBC表面(mian)的環境沉積(ji)(ji)物(wu)后發現(xian)，無(wu)論(lun)操作條(tiao)件和(he)地理位置(zhi)(zhi)如(ru)何(he)，沉積(ji)(ji)物(wu)的組成(cheng)都很相似，主要為(wei)CaO、MgO、Al2O3和(he)SiO2。Aygun等[19]對所獲得的沙礫進(jin)行X射(she)線熒光譜分(fen)析(xi)后發現(xian)，其(qi)成(cheng)分(fen)為(wei)50SiO2-38CaO-5MgO-4Al2O3-FeO3-Na2O-K2O。通過對比不難發現(xian)，無(wu)論(lun)地理位置(zhi)(zhi)、服役環境如(ru)何(he)，沉積(ji)(ji)物(wu)始終含(han)有CaO、MgO、Al2O3和(he)SiO2，且含(han)量(liang)(liang)(liang)較高(gao)，其(qi)余除鐵氧化物(wu)以外的成(cheng)分(fen)會隨地點變化而變化，因此將沉積(ji)(ji)物(wu)簡稱(cheng)為(wei)CMAS。

CMAS的(de)(de)(de)熔(rong)點往往隨著成(cheng)分的(de)(de)(de)變化(hua)有差(cha)異(yi)，Smialek等[11]發現(xian)的(de)(de)(de)硅酸鹽沉(chen)積物(wu)熔(rong)點約(yue)為(wei)1135℃，Borom等[12]對(dui)環(huan)境沉(chen)積物(wu)進行差(cha)熱分析(xi)(xi)后(hou)得(de)出(chu)其熔(rong)點約(yue)為(wei)1200℃，Gledhill[20]分析(xi)(xi)了(le)(le)(le)褐煤(mei)灰和(he)火(huo)(huo)山(shan)(shan)灰發現(xian)，它(ta)們(men)(men)的(de)(de)(de)初(chu)始(shi)熔(rong)化(hua)溫(wen)度(du)分別(bie)約(yue)為(wei)1150和(he)1100℃。隨著研(yan)究深入(ru)，學者們(men)(men)得(de)出(chu)：CMAS的(de)(de)(de)熔(rong)點是一個區間，一般在1100~1250℃[21~23]，所以當(dang)溫(wen)度(du)超過1250℃時(shi)，CMAS會處于完全熔(rong)融狀態。作(zuo)為(wei)CMAS重要來源之一的(de)(de)(de)火(huo)(huo)山(shan)(shan)灰，其化(hua)學和(he)物(wu)理狀態更加復雜(za)。Song等[10]采集了(le)(le)(le)全球9座火(huo)(huo)山(shan)(shan)的(de)(de)(de)火(huo)(huo)山(shan)(shan)灰樣(yang)本，系統分析(xi)(xi)了(le)(le)(le)天(tian)然火(huo)(huo)山(shan)(shan)灰的(de)(de)(de)熔(rong)融過程(cheng)。Naraparaju等[24]比較了(le)(le)(le)合成(cheng)的(de)(de)(de)CMAS和(he)來自冰(bing)島埃亞菲亞德拉冰(bing)蓋(gai)冰(bing)川火(huo)(huo)山(shan)(shan)、日(ri)(ri)本櫻(ying)島火(huo)(huo)山(shan)(shan)的(de)(de)(de)火(huo)(huo)山(shan)(shan)灰熔(rong)點，發現(xian)合成(cheng)的(de)(de)(de)CMAS熔(rong)點最高，達1250℃；隨后(hou)是日(ri)(ri)本和(he)冰(bing)島火(huo)(huo)山(shan)(shan)灰，分別(bie)為(wei)1170和(he)1150℃。這說明在發動(dong)機(ji)工(gong)作(zuo)環(huan)境中，CMAS可能(neng)在較低溫(wen)度(du)下就開始(shi)熔(rong)化(hua)，因此熔(rong)融態持續時(shi)間更持久、滲透時(shi)間更長。

CMAS與TBCs的(de)(de)(de)相(xiang)互作(zuo)用行為還受CMAS的(de)(de)(de)熔(rong)(rong)體(ti)(ti)組成、黏(nian)(nian)(nian)度(du)以及(ji)其(qi)在(zai)涂層(ceng)(ceng)表(biao)(biao)面(mian)(mian)(mian)(mian)的(de)(de)(de)附著(zhu)、潤(run)(run)濕、擴散、鋪展和(he)(he)溫度(du)的(de)(de)(de)影(ying)響。涂層(ceng)(ceng)表(biao)(biao)面(mian)(mian)(mian)(mian)熔(rong)(rong)融CMAS在(zai)達到(dao)平(ping)衡狀態(tai)之(zhi)前會(hui)經歷一個(ge)(ge)較為短暫的(de)(de)(de)擴散過(guo)程和(he)(he)相(xiang)對(dui)較長的(de)(de)(de)液體(ti)(ti)流(liu)(liu)動(dong)(dong)階段，其(qi)中熔(rong)(rong)體(ti)(ti)流(liu)(liu)動(dong)(dong)是受熔(rong)(rong)體(ti)(ti)黏(nian)(nian)(nian)度(du)的(de)(de)(de)控(kong)制[25,26]，CMAS的(de)(de)(de)黏(nian)(nian)(nian)度(du)與其(qi)成分和(he)(he)環境(jing)溫度(du)密切相(xiang)關。作(zuo)用在(zai)TBCs表(biao)(biao)面(mian)(mian)(mian)(mian)熔(rong)(rong)融的(de)(de)(de)CMAS與涂層(ceng)(ceng)組分反應(ying)，隨著(zhu)SiO2的(de)(de)(de)消(xiao)(xiao)耗和(he)(he)熔(rong)(rong)體(ti)(ti)中稀土陽離子(zi)(zi)溶(rong)解(jie)量增(zeng)大，熔(rong)(rong)體(ti)(ti)的(de)(de)(de)黏(nian)(nian)(nian)度(du)會(hui)降(jiang)低；而CaO和(he)(he)MgO等氧(yang)化物的(de)(de)(de)消(xiao)(xiao)耗及(ji)ZrO2溶(rong)解(jie)量增(zeng)加(jia)(jia)，會(hui)使得熔(rong)(rong)體(ti)(ti)黏(nian)(nian)(nian)度(du)增(zeng)加(jia)(jia)[27,28]。同時(shi)，黏(nian)(nian)(nian)度(du)對(dui)溫度(du)的(de)(de)(de)變(bian)化也十分敏感，具體(ti)(ti)表(biao)(biao)現在(zai)黏(nian)(nian)(nian)度(du)會(hui)隨著(zhu)溫度(du)降(jiang)低而顯著(zhu)上升[29]。Song等[30]研究了(le)1040~1450℃溫度(du)范圍內CMAS在(zai)TBCs表(biao)(biao)面(mian)(mian)(mian)(mian)的(de)(de)(de)接(jie)觸(chu)角(jiao)(jiao)(jiao)，發現溫度(du)升高(gao)，熔(rong)(rong)融CMAS與涂層(ceng)(ceng)表(biao)(biao)面(mian)(mian)(mian)(mian)接(jie)觸(chu)角(jiao)(jiao)(jiao)減小(xiao)，表(biao)(biao)明(ming)熔(rong)(rong)體(ti)(ti)黏(nian)(nian)(nian)度(du)下降(jiang)。Li等[31]通(tong)過(guo)分子(zi)(zi)動(dong)(dong)力(li)學模擬(ni)了(le)CMAS在(zai)YSZ表(biao)(biao)面(mian)(mian)(mian)(mian)的(de)(de)(de)潤(run)(run)濕過(guo)程，通(tong)過(guo)分析接(jie)觸(chu)角(jiao)(jiao)(jiao)、黏(nian)(nian)(nian)合功、表(biao)(biao)面(mian)(mian)(mian)(mian)張力(li)和(he)(he)黏(nian)(nian)(nian)度(du)這幾個(ge)(ge)參數估計了(le)可潤(run)(run)濕性(xing)，結果表(biao)(biao)明(ming)YSZ表(biao)(biao)面(mian)(mian)(mian)(mian)的(de)(de)(de)氧(yang)離子(zi)(zi)分布是影(ying)響CMAS在(zai)涂層(ceng)(ceng)表(biao)(biao)面(mian)(mian)(mian)(mian)的(de)(de)(de)潤(run)(run)濕性(xing)的(de)(de)(de)關鍵，并指出CMAS熔(rong)(rong)體(ti)(ti)在(zai)YSZ(110)上最(zui)容易潤(run)(run)濕，因為氧(yang)陰離子(zi)(zi)的(de)(de)(de)濃度(du)增(zeng)加(jia)(jia)，容易被(bei)CMAS中的(de)(de)(de)陽離子(zi)(zi)吸引。

CMAS的(de)(de)(de)黏度(du)及其(qi)滲透行為同時還受自(zi)(zi)結(jie)晶(jing)的(de)(de)(de)影響。Guo等[32]研究了CMAS自(zi)(zi)結(jie)晶(jing)產物與(yu)加熱(re)、冷卻速(su)率(lv)(lv)和保(bao)溫溫度(du)之間的(de)(de)(de)關系，發(fa)現隨著冷卻速(su)率(lv)(lv)降(jiang)低(di)，結(jie)晶(jing)產物依次為透輝(hui)石(shi)、硅灰(hui)石(shi)和鈣(gai)長石(shi)，且結(jie)晶(jing)層(ceng)厚度(du)增加。當溫度(du)低(di)于1050℃時，結(jie)晶(jing)形成(cheng)透輝(hui)石(shi)和黃鐵礦相(xiang)；而在(zai)較高的(de)(de)(de)溫度(du)下(xia)，黃長石(shi)轉變為鈣(gai)長石(shi)和硅灰(hui)石(shi)，但與(yu)加熱(re)速(su)率(lv)(lv)無關。這些自(zi)(zi)結(jie)晶(jing)產物的(de)(de)(de)形成(cheng)將降(jiang)低(di)熔(rong)體(ti)的(de)(de)(de)黏度(du)，在(zai)一(yi)定程度(du)上可(ke)以減緩CMAS的(de)(de)(de)滲透。

3 熱障涂層CMAS腐蝕機理

TBCs中設計(ji)有一(yi)些微裂紋、孔隙，甚(shen)至柱狀微結構[33]，如圖1[34]所示(shi)，這有助于提高涂層的(de)應變容限(xian)，改善抗熱(re)震性(xing)能(neng)[35]。但是(shi)，這樣的(de)微結構也使得熔融CMAS極易滲入(ru)，加速涂層破壞和(he)失效。研究[36~38]表(biao)明，CMAS作(zuo)用下TBC的(de)失效一(yi)般是(shi)熱(re)化學和(he)熱(re)機械的(de)耦合作(zuo)用。

圖1  不同(tong)制備(bei)方法的氧化(hua)釔(yi)部分穩定氧化(hua)鋯(YSZ)涂(tu)層截面微(wei)觀結構[34]

為解析TBCs的(de)(de)(de)(de)(de)(de)CMAS腐(fu)蝕機(ji)理(li)，研究(jiu)者們開(kai)展了(le)大量(liang)(liang)的(de)(de)(de)(de)(de)(de)研究(jiu)工作。Mercer等(deng)[13]分(fen)(fen)析了(le)退役發(fa)動機(ji)的(de)(de)(de)(de)(de)(de)渦輪葉片，發(fa)現(xian)在最高的(de)(de)(de)(de)(de)(de)表(biao)(biao)面(mian)溫度(du)(du)下(xia)，沉積在表(biao)(biao)面(mian)的(de)(de)(de)(de)(de)(de)CMAS可以(yi)穿透TBCs，改變其近(jin)表(biao)(biao)面(mian)的(de)(de)(de)(de)(de)(de)力學性(xing)能(neng)，增(zeng)強層(ceng)裂傾(qing)向，并(bing)提(ti)出了(le)冷(leng)沖擊分(fen)(fen)層(ceng)和柱(zhu)晶斷(duan)裂失效機(ji)理(li)。Kr?mer等(deng)[39]評估了(le)航(hang)空發(fa)動機(ji)上(shang)(shang)具有較厚TBCs的(de)(de)(de)(de)(de)(de)固定部件(特別是護罩)，發(fa)現(xian)服役于最高溫度(du)(du)下(xia)的(de)(de)(de)(de)(de)(de)涂(tu)(tu)(tu)層(ceng)中(zhong)CMAS滲(shen)透深度(du)(du)約為涂(tu)(tu)(tu)層(ceng)厚度(du)(du)的(de)(de)(de)(de)(de)(de)一半(ban)；利用Raman位移(yi)法測量(liang)(liang)了(le)被滲(shen)透TBCs的(de)(de)(de)(de)(de)(de)橫(heng)截面(mian)殘余應力梯度(du)(du)，發(fa)現(xian)上(shang)(shang)表(biao)(biao)面(mian)是拉應力，底部為壓應力，這(zhe)有助于預測裂紋和層(ceng)裂現(xian)象。Wu等(deng)[40]研究(jiu)了(le)CMAS作用下(xia)YSZ的(de)(de)(de)(de)(de)(de)微觀結構及熱(re)物(wu)理(li)、機(ji)械性(xing)能(neng)，發(fa)現(xian)CMAS中(zhong)Si和Ca進(jin)入涂(tu)(tu)(tu)層(ceng)后(hou)會嚴重加(jia)劇涂(tu)(tu)(tu)層(ceng)燒(shao)結，相(xiang)互作用后(hou)還會導(dao)致t′相(xiang)轉變為m相(xiang)，縮短涂(tu)(tu)(tu)層(ceng)壽命；涂(tu)(tu)(tu)層(ceng)的(de)(de)(de)(de)(de)(de)孔隙率從25%降(jiang)低到5%；在1200℃下(xia)的(de)(de)(de)(de)(de)(de)熱(re)擴散率從0.3 mm2/s增(zeng)加(jia)到0.7 mm2/s，表(biao)(biao)明(ming)隔熱(re)效果顯著降(jiang)低，涂(tu)(tu)(tu)層(ceng)的(de)(de)(de)(de)(de)(de)顯微硬度(du)(du)也增(zeng)加(jia)了(le)約40%。

為更加(jia)深入(ru)、簡便(bian)地研究CMAS腐蝕熱障涂(tu)層(ceng)的(de)具體(ti)過程和(he)機(ji)理，研究人員建立(li)了(le)CMAS和(he)TBCs相(xiang)(xiang)互作(zuo)用(yong)的(de)實驗室模型并不(bu)斷(duan)完善。2者的(de)作(zuo)用(yong)與溫度密(mi)切相(xiang)(xiang)關：在(zai)較低的(de)溫度下(xia)，CMAS顆粒持續撞擊涂(tu)層(ceng)，造成磨損腐蝕和(he)涂(tu)層(ceng)的(de)局部脫落[41,42]；在(zai)較高的(de)溫度下(xia)，CMAS會(hui)轉(zhuan)變為熔(rong)融態并黏附、潤濕涂(tu)層(ceng)表面(mian)，沿著涂(tu)層(ceng)內部聯通的(de)孔(kong)隙和(he)裂(lie)紋滲入(ru)，同時與涂(tu)層(ceng)反應，破壞涂(tu)層(ceng)相(xiang)(xiang)組(zu)成和(he)微結構。

高溫(wen)下CMAS對TBCs的(de)(de)破壞主要分(fen)為熱化學(xue)(xue)和(he)(he)熱機械2方面(mian)，如圖2[13,43]所示。熱化學(xue)(xue)方面(mian)，有研究者[40,44]發現，反(fan)(fan)應(ying)初期在涂(tu)(tu)層(ceng)表(biao)面(mian)的(de)(de)CMAS中(zhong)(zhong)可(ke)(ke)以觀察到“起泡”現象，這可(ke)(ke)能是涂(tu)(tu)層(ceng)中(zhong)(zhong)本來存在的(de)(de)氣體(ti)由(you)于(yu)高溫(wen)向外擴散而被困在涂(tu)(tu)層(ceng)表(biao)面(mian)的(de)(de)CMAS中(zhong)(zhong)。反(fan)(fan)應(ying)過程中(zhong)(zhong)，Si、Ca和(he)(he)Al等(deng)元素進入涂(tu)(tu)層(ceng)，在CMAS和(he)(he)涂(tu)(tu)層(ceng)界面(mian)處開(kai)始反(fan)(fan)應(ying)，形(xing)成(cheng)尖(jian)晶(jing)石等(deng)產(chan)物；同時，YSZ涂(tu)(tu)層(ceng)中(zhong)(zhong)的(de)(de)Y2O3溶于(yu)CMAS中(zhong)(zhong)促使t‘相YSZ失穩(wen)、溶解，并(bing)重新(xin)沉淀形(xing)成(cheng)球狀m-ZrO2，此轉變(bian)通(tong)常伴隨(sui)3%~5%的(de)(de)體(ti)積膨脹，導致裂紋(wen)[12,45]。以上作用破壞了涂(tu)(tu)層(ceng)的(de)(de)相穩(wen)定性和(he)(he)微觀結(jie)構完整性，加速了涂(tu)(tu)層(ceng)的(de)(de)失效。

圖2  高溫下CMAS (CaO、MgO、Al2O3和SiO2)對(dui)熱障涂層(ceng)(TBCs)的破壞(huai)[13,43]

在熱機械方面，冷卻后(hou)的(de)(de)熔融CMAS填充涂(tu)(tu)(tu)層(ceng)的(de)(de)孔隙和微(wei)(wei)裂紋，會(hui)導(dao)(dao)(dao)致涂(tu)(tu)(tu)層(ceng)變(bian)得(de)更加(jia)致密，顯著降低(di)陶瓷涂(tu)(tu)(tu)層(ceng)的(de)(de)應變(bian)容(rong)限(xian)；CMAS中(zhong)的(de)(de)Si會(hui)擴散至涂(tu)(tu)(tu)層(ceng)中(zhong)而加(jia)速YSZ的(de)(de)燒結(jie)，增(zeng)大(da)涂(tu)(tu)(tu)層(ceng)的(de)(de)彈(dan)(dan)性模量、降低(di)應變(bian)容(rong)限(xian)和隔熱效果。此外，CMAS滲入涂(tu)(tu)(tu)層(ceng)后(hou)還(huan)會(hui)改變(bian)涂(tu)(tu)(tu)層(ceng)的(de)(de)CTE，導(dao)(dao)(dao)致涂(tu)(tu)(tu)層(ceng)中(zhong)反應區(qu)和未反應區(qu)CTE失配，CMAS滲透深(shen)度的(de)(de)差異會(hui)導(dao)(dao)(dao)致涂(tu)(tu)(tu)層(ceng)不同(tong)部位的(de)(de)彈(dan)(dan)性模量和CTE變(bian)化不一(yi)致。這一(yi)系列的(de)(de)涂(tu)(tu)(tu)層(ceng)微(wei)(wei)結(jie)構(gou)、熱力學性能參量的(de)(de)變(bian)化會(hui)加(jia)大(da)熱循環(huan)過程(cheng)中(zhong)TBCs的(de)(de)應力，最終導(dao)(dao)(dao)致涂(tu)(tu)(tu)層(ceng)剝落[46~48]。

4 熱障(zhang)涂(tu)層的CMAS腐(fu)蝕防(fang)護方法

由于CMAS引起TBCs損傷和(he)(he)失效的(de)(de)(de)(de)(de)(de)原因(yin)非(fei)(fei)常復雜，因(yin)此針對CMAS腐(fu)蝕的(de)(de)(de)(de)(de)(de)防護(hu)方(fang)法(fa)(fa)也各不相(xiang)同。Rai等[49]較早總結(jie)了TBCs的(de)(de)(de)(de)(de)(de)3種(zhong)(zhong)CMAS腐(fu)蝕防護(hu)方(fang)法(fa)(fa)，可分為：非(fei)(fei)滲(shen)(shen)(shen)透性(xing)(xing)(xing)(xing)(xing)涂(tu)(tu)(tu)(tu)(tu)層(ceng)(ceng)(ceng)(ceng)(ceng)、犧(xi)牲(sheng)性(xing)(xing)(xing)(xing)(xing)防護(hu)涂(tu)(tu)(tu)(tu)(tu)層(ceng)(ceng)(ceng)(ceng)(ceng)以及多(duo)層(ceng)(ceng)(ceng)(ceng)(ceng)復合的(de)(de)(de)(de)(de)(de)防護(hu)涂(tu)(tu)(tu)(tu)(tu)層(ceng)(ceng)(ceng)(ceng)(ceng)(通常是非(fei)(fei)滲(shen)(shen)(shen)透性(xing)(xing)(xing)(xing)(xing)涂(tu)(tu)(tu)(tu)(tu)層(ceng)(ceng)(ceng)(ceng)(ceng)、犧(xi)牲(sheng)性(xing)(xing)(xing)(xing)(xing)涂(tu)(tu)(tu)(tu)(tu)層(ceng)(ceng)(ceng)(ceng)(ceng)以及不潤濕(shi)涂(tu)(tu)(tu)(tu)(tu)層(ceng)(ceng)(ceng)(ceng)(ceng)的(de)(de)(de)(de)(de)(de)復合涂(tu)(tu)(tu)(tu)(tu)層(ceng)(ceng)(ceng)(ceng)(ceng))。非(fei)(fei)滲(shen)(shen)(shen)透性(xing)(xing)(xing)(xing)(xing)涂(tu)(tu)(tu)(tu)(tu)層(ceng)(ceng)(ceng)(ceng)(ceng)是一種(zhong)(zhong)致密、無裂(lie)紋(wen)、無孔的(de)(de)(de)(de)(de)(de)層(ceng)(ceng)(ceng)(ceng)(ceng)，包(bao)括(kuo)氧化物、非(fei)(fei)氧化物或金(jin)屬(shu)涂(tu)(tu)(tu)(tu)(tu)層(ceng)(ceng)(ceng)(ceng)(ceng)等，沒(mei)有反(fan)應(ying)過程；而犧(xi)牲(sheng)性(xing)(xing)(xing)(xing)(xing)防護(hu)涂(tu)(tu)(tu)(tu)(tu)層(ceng)(ceng)(ceng)(ceng)(ceng)內某些(xie)成(cheng)分會與(yu)環境沉積(ji)物反(fan)應(ying)，生成(cheng)更難(nan)滲(shen)(shen)(shen)透的(de)(de)(de)(de)(de)(de)物質(zhi)(zhi)(zhi)；不潤濕(shi)的(de)(de)(de)(de)(de)(de)防護(hu)層(ceng)(ceng)(ceng)(ceng)(ceng)著重改進涂(tu)(tu)(tu)(tu)(tu)層(ceng)(ceng)(ceng)(ceng)(ceng)的(de)(de)(de)(de)(de)(de)表(biao)面(mian)(mian)質(zhi)(zhi)(zhi)量，使熔融的(de)(de)(de)(de)(de)(de)物質(zhi)(zhi)(zhi)無法(fa)(fa)潤濕(shi)涂(tu)(tu)(tu)(tu)(tu)層(ceng)(ceng)(ceng)(ceng)(ceng)表(biao)面(mian)(mian)，從而減緩了熔體滲(shen)(shen)(shen)透。這(zhe)3種(zhong)(zhong)方(fang)法(fa)(fa)旨在減緩CMAS的(de)(de)(de)(de)(de)(de)滲(shen)(shen)(shen)入和(he)(he)化學反(fan)應(ying)以及減少CMAS在表(biao)面(mian)(mian)的(de)(de)(de)(de)(de)(de)附著，本質(zhi)(zhi)(zhi)上(shang)是在表(biao)面(mian)(mian)制(zhi)備一層(ceng)(ceng)(ceng)(ceng)(ceng)防護(hu)層(ceng)(ceng)(ceng)(ceng)(ceng)，直接阻擋CMAS滲(shen)(shen)(shen)入，屬(shu)于物理方(fang)法(fa)(fa)[48,50~53]。同時，近年來出現了很多(duo)其他抗CMAS的(de)(de)(de)(de)(de)(de)腐(fu)蝕方(fang)法(fa)(fa)，比如：改性(xing)(xing)(xing)(xing)(xing)YSZ涂(tu)(tu)(tu)(tu)(tu)層(ceng)(ceng)(ceng)(ceng)(ceng)(促使環境沉積(ji)物結(jie)晶或與(yu)其反(fan)應(ying)直至消(xiao)耗完沉積(ji)物)、新(xin)型(xing)的(de)(de)(de)(de)(de)(de)熱障涂(tu)(tu)(tu)(tu)(tu)層(ceng)(ceng)(ceng)(ceng)(ceng)材(cai)料和(he)(he)TBC的(de)(de)(de)(de)(de)(de)結(jie)構設計。以上(shang)所(suo)述的(de)(de)(de)(de)(de)(de)方(fang)法(fa)(fa)各有優劣(lie)，但改性(xing)(xing)(xing)(xing)(xing)YSZ涂(tu)(tu)(tu)(tu)(tu)層(ceng)(ceng)(ceng)(ceng)(ceng)和(he)(he)開發新(xin)型(xing)熱障涂(tu)(tu)(tu)(tu)(tu)層(ceng)(ceng)(ceng)(ceng)(ceng)體系的(de)(de)(de)(de)(de)(de)方(fang)法(fa)(fa)更受研究者青睞，更具發展潛力。

4.1 表面防護層

非滲(shen)(shen)透性(xing)(xing)涂(tu)(tu)(tu)層(ceng)(ceng)(ceng)的(de)(de)(de)(de)(de)(de)(de)主要特征有(you)連續、致(zhi)密(mi)、無裂(lie)(lie)紋，它(ta)可(ke)以(yi)(yi)包含氧化(hua)物(wu)(wu)、非氧化(hua)物(wu)(wu)或(huo)金(jin)屬(shu)涂(tu)(tu)(tu)層(ceng)(ceng)(ceng)，是通(tong)(tong)過材料的(de)(de)(de)(de)(de)(de)(de)物(wu)(wu)理特征直接阻(zu)(zu)擋(dang)熔(rong)(rong)(rong)體滲(shen)(shen)透。根據Hasz等(deng)[52,53]的(de)(de)(de)(de)(de)(de)(de)專利(li)，阻(zu)(zu)止熔(rong)(rong)(rong)融CMAS最有(you)效(xiao)的(de)(de)(de)(de)(de)(de)(de)非滲(shen)(shen)透涂(tu)(tu)(tu)層(ceng)(ceng)(ceng)有(you)Pd-Ag (80%~20%，質量分數)、Pd、Pt、SiC、SiO2、Ta2O5、CaZrO3、MgAlO4、SiOC及其(qi)(qi)混合物(wu)(wu)。Wang等(deng)[54]比較了(le)(le)表(biao)面鍍(du)Pt層(ceng)(ceng)(ceng)和(he)(he)EB-PVD制備Gd2Zr2O7 (GZO)層(ceng)(ceng)(ceng)對YSZ涂(tu)(tu)(tu)層(ceng)(ceng)(ceng)CMAS腐(fu)蝕的(de)(de)(de)(de)(de)(de)(de)防護(hu)效(xiao)果(guo)(guo)，發(fa)現(xian)(xian)Pt層(ceng)(ceng)(ceng)的(de)(de)(de)(de)(de)(de)(de)非滲(shen)(shen)透特性(xing)(xing)可(ke)以(yi)(yi)顯(xian)著(zhu)阻(zu)(zu)止熔(rong)(rong)(rong)體滲(shen)(shen)入(ru)，但(dan)GZO的(de)(de)(de)(de)(de)(de)(de)效(xiao)果(guo)(guo)較差，可(ke)能(neng)原(yuan)因(yin)是體系的(de)(de)(de)(de)(de)(de)(de)熱膨脹不匹(pi)配致(zhi)使涂(tu)(tu)(tu)層(ceng)(ceng)(ceng)微裂(lie)(lie)紋和(he)(he)孔(kong)隙擴大，如圖3[54]所(suo)示。Liu等(deng)[55]發(fa)現(xian)(xian)鍍(du)Pt的(de)(de)(de)(de)(de)(de)(de)YSZ涂(tu)(tu)(tu)層(ceng)(ceng)(ceng)雖然可(ke)以(yi)(yi)阻(zu)(zu)止CMAS熔(rong)(rong)(rong)體滲(shen)(shen)入(ru)，但(dan)是Pt層(ceng)(ceng)(ceng)的(de)(de)(de)(de)(de)(de)(de)穩定(ding)性(xing)(xing)較差，隨著(zhu)熱處理時間延長，Pt層(ceng)(ceng)(ceng)部分溶解在熔(rong)(rong)(rong)融CMAS中(zhong)，厚(hou)度(du)減小。因(yin)此(ci)，鍍(du)Pt層(ceng)(ceng)(ceng)雖然對TBCs的(de)(de)(de)(de)(de)(de)(de)抗(kang)CMAS腐(fu)蝕有(you)積(ji)(ji)極作用，但(dan)是Pt層(ceng)(ceng)(ceng)與(yu)熔(rong)(rong)(rong)融CMAS之間的(de)(de)(de)(de)(de)(de)(de)熱化(hua)學相容(rong)性(xing)(xing)有(you)待提(ti)(ti)(ti)高(gao)。何箐等(deng)[50]在孔(kong)隙率(lv)為12.9%的(de)(de)(de)(de)(de)(de)(de)8YSZ涂(tu)(tu)(tu)層(ceng)(ceng)(ceng)表(biao)面制備厚(hou)度(du)為10~20 ?m的(de)(de)(de)(de)(de)(de)(de)致(zhi)密(mi)Al2O3防護(hu)層(ceng)(ceng)(ceng)后，涂(tu)(tu)(tu)層(ceng)(ceng)(ceng)的(de)(de)(de)(de)(de)(de)(de)熱沖擊壽命提(ti)(ti)(ti)高(gao)了(le)(le)4.4倍；同(tong)時，致(zhi)密(mi)度(du)的(de)(de)(de)(de)(de)(de)(de)提(ti)(ti)(ti)高(gao)以(yi)(yi)及Al2O3防護(hu)層(ceng)(ceng)(ceng)的(de)(de)(de)(de)(de)(de)(de)制備均能(neng)改(gai)善(shan)表(biao)面粗糙度(du)，有(you)效(xiao)緩解了(le)(le)CMAS的(de)(de)(de)(de)(de)(de)(de)黏附(fu)、滲(shen)(shen)入(ru)以(yi)(yi)及提(ti)(ti)(ti)高(gao)接觸界面CMAS的(de)(de)(de)(de)(de)(de)(de)穩定(ding)性(xing)(xing)。Zhang等(deng)[56~59]采用直流磁控(kong)濺射法(fa)在TBCs表(biao)面沉積(ji)(ji)了(le)(le)柱狀Al膜(mo)，真(zhen)空熱處理后通(tong)(tong)過Al和(he)(he)ZrO2的(de)(de)(de)(de)(de)(de)(de)反應(ying)原(yuan)位(wei)生成(cheng)了(le)(le)α-Al2O3層(ceng)(ceng)(ceng)。結(jie)果(guo)(guo)表(biao)明，真(zhen)空熱處理后的(de)(de)(de)(de)(de)(de)(de)Al沉積(ji)(ji)TBCs具有(you)更(geng)好(hao)的(de)(de)(de)(de)(de)(de)(de)抗(kang)CMAS腐(fu)蝕性(xing)(xing)，其(qi)(qi)中(zhong)原(yuan)因(yin)可(ke)能(neng)是α-Al2O3填充了(le)(le)部分YSZ涂(tu)(tu)(tu)層(ceng)(ceng)(ceng)中(zhong)的(de)(de)(de)(de)(de)(de)(de)孔(kong)隙和(he)(he)裂(lie)(lie)紋，阻(zu)(zu)止熔(rong)(rong)(rong)融CMAS的(de)(de)(de)(de)(de)(de)(de)滲(shen)(shen)透。同(tong)時，CMAS與(yu)α-Al2O3反應(ying)形(xing)成(cheng)CaAl2Si2O8和(he)(he)MgAl2O4層(ceng)(ceng)(ceng)，其(qi)(qi)結(jie)構致(zhi)密(mi)，有(you)抑制CMAS進一(yi)步滲(shen)(shen)透的(de)(de)(de)(de)(de)(de)(de)作用。此(ci)外，Zhang等(deng)[60,61]還(huan)比較了(le)(le)CMAS在原(yuan)始(shi)態TBCs和(he)(he)Al改(gai)性(xing)(xing)TBCs上的(de)(de)(de)(de)(de)(de)(de)吸附(fu)性(xing)(xing)和(he)(he)鋪展(zhan)(zhan)性(xing)(xing)；結(jie)果(guo)(guo)表(biao)明，與(yu)原(yuan)始(shi)態TBCs相比，Al改(gai)性(xing)(xing)TBCs具有(you)較低的(de)(de)(de)(de)(de)(de)(de)吸附(fu)質量和(he)(he)較小的(de)(de)(de)(de)(de)(de)(de)鋪展(zhan)(zhan)面積(ji)(ji)。此(ci)外，Guo等(deng)[62]比較了(le)(le)APS和(he)(he)PS-PVD方法(fa)在YSZ涂(tu)(tu)(tu)層(ceng)(ceng)(ceng)上沉積(ji)(ji)Al2O3的(de)(de)(de)(de)(de)(de)(de)性(xing)(xing)能(neng)，通(tong)(tong)過對比發(fa)現(xian)(xian)PS-PVD沉積(ji)(ji)的(de)(de)(de)(de)(de)(de)(de)Al2O3層(ceng)(ceng)(ceng)熱循環和(he)(he)抗(kang)CMAS腐(fu)蝕性(xing)(xing)能(neng)更(geng)好(hao)。

圖3  CMAS作用下1250℃熱處(chu)理4 h后(hou)鍍Pt YSZ涂層(ceng)的截面微觀結構和Si元(yuan)素(su)EDS結果[54]

不潤濕涂(tu)層(ceng)是通過提(ti)供(gong)對熔(rong)融(rong)CMAS不潤濕的(de)(de)(de)表面(mian)，使涂(tu)層(ceng)與(yu)熔(rong)體(ti)之間的(de)(de)(de)接(jie)觸達到最小化。這(zhe)種材料(liao)旨在降低熔(rong)融(rong)沉積物通過毛(mao)細作用穿透TBCs的(de)(de)(de)能力，并增強(qiang)高溫下涂(tu)層(ceng)的(de)(de)(de)完(wan)整性。Rai等(deng)[49]制備了(le)幾乎無(wu)裂紋的(de)(de)(de)Pd涂(tu)層(ceng)，在簡(jian)短的(de)(de)(de)等(deng)溫(1260℃、10 min)實驗(yan)中，Pd層(ceng)提(ti)供(gong)了(le)非常優越的(de)(de)(de)抗(kang)CMAS腐蝕性能和(he)不潤濕性，但其多(duo)孔結(jie)構(gou)并不能完(wan)全阻止(zhi)CMAS滲透。

可(ke)以(yi)發現(xian)，只追求(qiu)材(cai)(cai)(cai)料(liao)(liao)的(de)(de)(de)非(fei)(fei)滲透(tou)(tou)、不(bu)潤(run)(run)濕(shi)(shi)性(xing)(xing)是(shi)不(bu)太現(xian)實的(de)(de)(de)，2種特(te)性(xing)(xing)在(zai)(zai)一(yi)種材(cai)(cai)(cai)料(liao)(liao)上(shang)很難(nan)兼得。同時，理(li)想的(de)(de)(de)非(fei)(fei)滲透(tou)(tou)材(cai)(cai)(cai)料(liao)(liao)多是(shi)致(zhi)密(mi)無孔隙，雖然可(ke)以(yi)阻止(zhi)熔體滲透(tou)(tou)，但其(qi)隔熱(re)性(xing)(xing)和應變容(rong)限(xian)較低(di)。在(zai)(zai)8YSZ涂層(ceng)(ceng)上(shang)制備(bei)致(zhi)密(mi)防護(hu)(hu)層(ceng)(ceng)如Al膜(mo)(mo)、Pt層(ceng)(ceng)等(deng)，阻止(zhi)CMAS滲透(tou)(tou)效(xiao)果突出。然而(er)，沉積(ji)(ji)后(hou)的(de)(de)(de)涂層(ceng)(ceng)與(yu)8YSZ涂層(ceng)(ceng)的(de)(de)(de)結(jie)合(he)(he)沒有詳細研(yan)究(jiu)；沉積(ji)(ji)的(de)(de)(de)Al膜(mo)(mo)勢必(bi)影響(xiang)(xiang)8YSZ熱(re)障(zhang)涂層(ceng)(ceng)的(de)(de)(de)熱(re)應力釋放；Al膜(mo)(mo)由于致(zhi)密(mi)性(xing)(xing)良好(hao)，對(dui)涂層(ceng)(ceng)的(de)(de)(de)抗(kang)熱(re)震性(xing)(xing)能(neng)(neng)、熱(re)循(xun)環壽(shou)命性(xing)(xing)能(neng)(neng)也(ye)會造成不(bu)良影響(xiang)(xiang)，同時Al膜(mo)(mo)較薄，熱(re)循(xun)環過程(cheng)中(zhong)容(rong)易(yi)剝落(luo)，影響(xiang)(xiang)腐(fu)蝕(shi)(shi)(shi)防護(hu)(hu)效(xiao)果。而(er)在(zai)(zai)追求(qiu)材(cai)(cai)(cai)料(liao)(liao)表(biao)(biao)面(mian)的(de)(de)(de)不(bu)潤(run)(run)濕(shi)(shi)特(te)性(xing)(xing)時要結(jie)合(he)(he)具體的(de)(de)(de)材(cai)(cai)(cai)料(liao)(liao)，如Ye等(deng)[63]發現(xian)CMAS對(dui)m-YTaO4的(de)(de)(de)潤(run)(run)濕(shi)(shi)性(xing)(xing)比YSZ差，有利于提(ti)高其(qi)耐腐(fu)蝕(shi)(shi)(shi)性(xing)(xing)，而(er)m-YTaO4本(ben)身也(ye)具有良好(hao)的(de)(de)(de)抗(kang)CMAS腐(fu)蝕(shi)(shi)(shi)性(xing)(xing)能(neng)(neng)。Guo等(deng)[64]研(yan)究(jiu)了表(biao)(biao)面(mian)粗(cu)糙度對(dui)YSZ、GdPO4和LaPO4塊(kuai)體抗(kang)CMAS腐(fu)蝕(shi)(shi)(shi)性(xing)(xing)能(neng)(neng)的(de)(de)(de)影響(xiang)(xiang)，發現(xian)經過表(biao)(biao)面(mian)拋光處理(li)后(hou)，熔融CMAS在(zai)(zai)這些(xie)塊(kuai)材(cai)(cai)(cai)表(biao)(biao)面(mian)的(de)(de)(de)潤(run)(run)濕(shi)(shi)性(xing)(xing)更低(di)、鋪展面(mian)積(ji)(ji)更小(xiao)，表(biao)(biao)明適當(dang)的(de)(de)(de)表(biao)(biao)面(mian)處理(li)可(ke)以(yi)賦予涂層(ceng)(ceng)更好(hao)的(de)(de)(de)抗(kang)CMAS腐(fu)蝕(shi)(shi)(shi)性(xing)(xing)能(neng)(neng)。因此，在(zai)(zai)現(xian)有的(de)(de)(de)材(cai)(cai)(cai)料(liao)(liao)基礎上(shang)進行(xing)改(gai)性(xing)(xing)使其(qi)具備(bei)一(yi)定的(de)(de)(de)非(fei)(fei)滲透(tou)(tou)、不(bu)潤(run)(run)濕(shi)(shi)特(te)性(xing)(xing)，同時結(jie)合(he)(he)其(qi)他防護(hu)(hu)方法是(shi)未(wei)來(lai)TBCs抗(kang)CMAS腐(fu)蝕(shi)(shi)(shi)研(yan)究(jiu)重點探索(suo)的(de)(de)(de)方向。

4.2 改性YSZ涂(tu)層(ceng)材料促使CMAS結晶

熔融CMAS的(de)(de)結(jie)晶會(hui)影響熔體的(de)(de)成(cheng)分、黏度以及滲透動力學(xue)，研究(jiu)CMAS的(de)(de)結(jie)晶行為(wei)和(he)機理可為(wei)探究(jiu)CMAS在涂層內(nei)的(de)(de)滲入以及與涂層的(de)(de)相互(hu)作用(yong)(yong)規律提供(gong)基礎和(he)指導。CMAS熔體的(de)(de)結(jie)晶行為(wei)由溫度梯度和(he)成(cheng)分共同決定。在沒有與涂層相互(hu)作用(yong)(yong)但存在溫度梯度的(de)(de)情況下，CMAS會(hui)產(chan)生(sheng)(sheng)“自結(jie)晶”行為(wei)；當CMAS與TBCs相互(hu)作用(yong)(yong)時(shi)，熔體就可能發生(sheng)(sheng)“反應性結(jie)晶”行為(wei)。

Guo等[32]的(de)(de)(de)研究表(biao)明(ming)，CMAS熔體自(zi)(zi)結(jie)晶行(xing)為(wei)和(he)產(chan)物受(shou)加(jia)熱、冷卻(que)速率(lv)以及溫度的(de)(de)(de)影響較(jiao)大。在空冷過(guo)程中，CMAS自(zi)(zi)結(jie)晶被抑制(zhi)；隨著冷卻(que)速率(lv)的(de)(de)(de)降低，透(tou)輝(hui)石(shi)(shi)、硅灰(hui)石(shi)(shi)和(he)鈣(gai)長(chang)石(shi)(shi)依次生成晶相，結(jie)晶層厚(hou)度增加(jia)。在停留(liu)(liu)溫度不高(gao)于1050℃的(de)(de)(de)加(jia)熱過(guo)程中，形成透(tou)輝(hui)石(shi)(shi)和(he)磷灰(hui)石(shi)(shi)相等自(zi)(zi)結(jie)晶產(chan)物；在較(jiao)高(gao)的(de)(de)(de)停留(liu)(liu)溫度(1150和(he)1250℃)下，透(tou)輝(hui)石(shi)(shi)仍然存在，而鈣(gai)長(chang)石(shi)(shi)轉變(bian)為(wei)鈣(gai)長(chang)石(shi)(shi)和(he)硅灰(hui)石(shi)(shi)。研究[32]還指出，盡管(guan)自(zi)(zi)結(jie)晶可以減(jian)緩(huan)CMAS在TBCs中的(de)(de)(de)滲入，但保護TBCs免受(shou)CMAS腐(fu)蝕的(de)(de)(de)效果卻(que)有限，需要發展其他的(de)(de)(de)CMAS腐(fu)蝕防(fang)護方法(fa)。

通(tong)(tong)過(guo)對YSZ涂層進行成分改性，促使(shi)與CMAS的(de)(de)反應結(jie)晶是(shi)(shi)一種減(jian)緩熔融(rong)CMAS滲(shen)入的(de)(de)有(you)(you)效方法(fa)[65]。有(you)(you)報道[66~68]稱TiO2、Cr2O3、ZrO2是(shi)(shi)熔融(rong)CMAS結(jie)晶的(de)(de)有(you)(you)效形(xing)核劑。Webster等[69]研究了TiO2對CMAS結(jie)晶行為的(de)(de)影(ying)響，發現TiO2添(tian)加量為12.5%~20% (質量分數)時可作(zuo)為CMAS熔體中的(de)(de)形(xing)核劑，有(you)(you)助于黃長石、白云(yun)母以(yi)及含Ti透輝(hui)石的(de)(de)結(jie)晶。Shi等[66]在CMAS基玻璃(li)陶瓷(ci)中加入了Cr2O3，有(you)(you)效降低了結(jie)晶溫度(du)并促使(shi)透輝(hui)石結(jie)晶，同時還細化了透輝(hui)石晶粒(li)。通(tong)(tong)過(guo)CMAS的(de)(de)反應結(jie)晶，可降低CMAS熔體的(de)(de)黏度(du)，而(er)且(qie)TBCs中已滲(shen)入的(de)(de)CMAS的(de)(de)結(jie)晶可阻塞后續CMAS繼續滲(shen)入的(de)(de)通(tong)(tong)道，降低CMAS的(de)(de)持續腐蝕能力。

Fang等(deng)[70]將莫來石(shi)(shi)(shi)(shi)、Al2O3-SiO2分別與YSZ以不同的(de)比例預混合，發現(xian)引入莫來石(shi)(shi)(shi)(shi)、Al2O3-SiO2促使(shi)CMAS形成(cheng)鈣長石(shi)(shi)(shi)(shi)可(ke)以減少熔(rong)(rong)體(ti)(ti)滲入涂層。Aygun等(deng)[19]提出(chu)YSZ + Al2O3 + TiO2的(de)涂層組分，并(bing)成(cheng)功制(zhi)備了(le)該涂層，展現(xian)出(chu)了(le)良好(hao)的(de)抗(kang)CMAS腐(fu)蝕性(xing)能(neng)：CMAS溶(rong)(rong)解涂層組分后引起熔(rong)(rong)體(ti)(ti)中(zhong)(zhong)Al、Ti含量(liang)升高(gao)，其(qi)中(zhong)(zhong)Al改變了(le)原始CMAS的(de)成(cheng)分，Ti作(zuo)為(wei)(wei)(wei)形核劑，導致熔(rong)(rong)體(ti)(ti)加(jia)速析出(chu)CaAl2Si2O8、MgAl4O4結晶(jing)(jing)相；這些(xie)結晶(jing)(jing)產(chan)物熔(rong)(rong)點高(gao)，構成(cheng)的(de)結晶(jing)(jing)層結構致密，能(neng)夠有效阻止CMAS的(de)滲入。Guo等(deng)[71]研究發現(xian)，MAX相化(hua)(hua)(hua)合物(“Mn + 1AXn相”簡(jian)稱MAX相，其(qi)中(zhong)(zhong)M為(wei)(wei)(wei)過(guo)渡族金屬(shu)元(yuan)素(su)，A為(wei)(wei)(wei)主族元(yuan)素(su)，X為(wei)(wei)(wei)C或(huo)者N) Ti2AlC可(ke)高(gao)度抵抗(kang)CMAS侵蝕，并(bing)進一步指出(chu)經過(guo)預氧(yang)化(hua)(hua)(hua)處理后Ti2AlC促使(shi)CMAS結晶(jing)(jing)、抑制(zhi)熔(rong)(rong)體(ti)(ti)滲透的(de)能(neng)力更佳[72]，因為(wei)(wei)(wei)預氧(yang)化(hua)(hua)(hua)在Ti2AlC表面形成(cheng)連續(xu)的(de)Al2O3層和TiO2粒子，Al2O3與熔(rong)(rong)融的(de)CMAS反(fan)應形成(cheng)鈣長石(shi)(shi)(shi)(shi)相，而TiO2以富(fu)Ti顆(ke)粒或(huo)Ti溶(rong)(rong)解(存在含量(liang)閾(yu)值)的(de)形式作(zuo)為(wei)(wei)(wei)形核劑促使(shi)結晶(jing)(jing)，如圖4[72]所示(shi)。

圖(tu)4  熱處理后Ti2AlC的(de)截面(mian)和(he)元素的(de)EDS結果[72]

4.3 抗(kang)CMAS腐蝕TBCs新材料(liao)

新(xin)一代(dai)先進航空發動機的(de)(de)推重比顯著提高(gao)，渦輪前(qian)進口溫(wen)(wen)度大幅增加，使得YSZ涂層(ceng)面臨嚴重的(de)(de)燒結(jie)、相變等問(wen)題(ti)，造成涂層(ceng)功(gong)能退化和過(guo)早失(shi)效(xiao)。因此，新(xin)型超高(gao)溫(wen)(wen)高(gao)隔熱(re)TBCs的(de)(de)研發勢(shi)在必行[73]。當在更高(gao)的(de)(de)服役(yi)溫(wen)(wen)度下工作，TBCs的(de)(de)CMAS腐(fu)蝕問(wen)題(ti)將(jiang)更為嚴重，因此新(xin)型TBCs的(de)(de)CMAS腐(fu)蝕行為和抗腐(fu)蝕機理引(yin)起關注[74]。

4.3.1 鈣鈦礦

鈣(gai)(gai)(gai)(gai)鈦(tai)(tai)礦(kuang)具有(you)高熔(rong)點、高熱(re)膨脹系數以及低熱(re)導(dao)等(deng)優點。Vassen等(deng)[75]研究鈣(gai)(gai)(gai)(gai)鈦(tai)(tai)礦(kuang)型材(cai)料SrZrO3和BaZrO3發(fa)現(xian)，SrZrO3會于(yu)730℃發(fa)生(sheng)相變(bian)并伴隨體積膨脹；BaZrO3則顯示出(chu)相對較差的(de)(de)(de)(de)熱(re)穩定性(xing)(xing)(xing)和化學穩定性(xing)(xing)(xing)，不宜直接作為TBCs材(cai)料。但是(shi)，鈣(gai)(gai)(gai)(gai)鈦(tai)(tai)礦(kuang)的(de)(de)(de)(de)晶體結(jie)構(gou)可以容納其(qi)他(ta)(ta)離子，該(gai)(gai)特點為其(qi)提(ti)(ti)供(gong)了(le)(le)便(bian)于(yu)改性(xing)(xing)(xing)的(de)(de)(de)(de)結(jie)構(gou)基礎。Ma等(deng)[76]采用Yb2O3和Gd2O3摻(chan)雜SrZrO3，改善了(le)(le)SrZrO3的(de)(de)(de)(de)缺(que)陷，提(ti)(ti)高了(le)(le)其(qi)作為TBCs應用材(cai)料的(de)(de)(de)(de)潛力；他(ta)(ta)們還研究了(le)(le)SrZrO3和YSZ形(xing)成的(de)(de)(de)(de)雙陶瓷層(ceng)TBCs，發(fa)現(xian)其(qi)1250℃熱(re)循(xun)環壽(shou)命是(shi)SrZrO3涂層(ceng)的(de)(de)(de)(de)2倍以上(shang)[77]。Guo等(deng)[78]和Yu等(deng)[79]研究了(le)(le)新型鈣(gai)(gai)(gai)(gai)鈦(tai)(tai)礦(kuang)TBCs材(cai)料BaLn2Ti3O10 (Ln = La、Nd)的(de)(de)(de)(de)CMAS腐(fu)(fu)蝕(shi)行(xing)為，發(fa)現(xian)該(gai)(gai)材(cai)料中(zhong)的(de)(de)(de)(de)Ba能進入CMAS中(zhong)并促使結(jie)晶出(chu)鋇長石；BaLn2Ti3O10與CMAS反應形(xing)成由磷灰(hui)石和CaTiO3組成的(de)(de)(de)(de)連續致密結(jie)晶層(ceng)，可有(you)效阻(zu)擋熔(rong)融CMAS滲入，其(qi)抗CMAS腐(fu)(fu)蝕(shi)性(xing)(xing)(xing)能非常優越。Ba2REAlO5是(shi)鈦(tai)(tai)礦(kuang)結(jie)構(gou)的(de)(de)(de)(de)一種(zhong)變(bian)體，由于(yu)其(qi)結(jie)構(gou)中(zhong)缺(que)少1/6的(de)(de)(de)(de)O原子，點陣中(zhong)O空(kong)位濃(nong)度大，具有(you)超低的(de)(de)(de)(de)熱(re)導(dao)率和彈(dan)性(xing)(xing)(xing)模量，且抗CMAS腐(fu)(fu)蝕(shi)性(xing)(xing)(xing)能優異(yi)，其(qi)中(zhong)Ba2DyAlO5與熔(rong)融CMAS的(de)(de)(de)(de)反應結(jie)晶速率最(zui)(zui)快(kuai)，抗CMAS腐(fu)(fu)蝕(shi)能力最(zui)(zui)強[80~82]。

4.3.2 稀土鋯(gao)酸(suan)鹽

稀(xi)(xi)土(tu)鋯(gao)(gao)酸(suan)(suan)(suan)鹽(yan)(yan)具(ju)有(you)燒綠石和缺(que)陷(xian)型螢石2種晶體(ti)(ti)(ti)結構，熔點(dian)高(gao)(gao)、相穩定性(xing)(xing)(xing)(xing)好(hao)、熱(re)導率(lv)低，是一(yi)種極富應用前景的(de)(de)(de)超(chao)高(gao)(gao)溫TBCs材(cai)料(liao)，具(ju)有(you)代(dai)表性(xing)(xing)(xing)(xing)的(de)(de)(de)是Gd2Zr2O7和La2Zr2O7[83~85]。特別地，稀(xi)(xi)土(tu)鋯(gao)(gao)酸(suan)(suan)(suan)鹽(yan)(yan)的(de)(de)(de)抗CMAS腐(fu)蝕性(xing)(xing)(xing)(xing)能(neng)非(fei)常(chang)好(hao)，如熔融CMAS在Gd2Zr2O7表面(mian)，2者(zhe)可(ke)在數(shu)十(shi)秒內(nei)(nei)快(kuai)速(su)反應，形成(cheng)高(gao)(gao)熔點(dian)的(de)(de)(de)磷灰石相，并且促(cu)使(shi)熔體(ti)(ti)(ti)結晶，在2者(zhe)的(de)(de)(de)界面(mian)形成(cheng)連續致(zhi)密反應層(ceng)(ceng)(ceng)(ceng)，有(you)效(xiao)抑制(zhi)CMAS持(chi)續內(nei)(nei)滲(shen)[86]。但是，稀(xi)(xi)土(tu)鋯(gao)(gao)酸(suan)(suan)(suan)鹽(yan)(yan)的(de)(de)(de)斷裂韌(ren)(ren)性(xing)(xing)(xing)(xing)不(bu)高(gao)(gao)，使(shi)得涂層(ceng)(ceng)(ceng)(ceng)的(de)(de)(de)熱(re)循(xun)環壽命不(bu)理想，因此增韌(ren)(ren)是稀(xi)(xi)土(tu)鋯(gao)(gao)酸(suan)(suan)(suan)鹽(yan)(yan)作為TBCs材(cai)料(liao)的(de)(de)(de)研究重點(dian)。Wang等[87]在稀(xi)(xi)土(tu)鋯(gao)(gao)酸(suan)(suan)(suan)鹽(yan)(yan)中(zhong)摻(chan)雜(za)(za)Sc2O3，研究了摻(chan)雜(za)(za)量(liang)(liang)對材(cai)料(liao)力學性(xing)(xing)(xing)(xing)能(neng)和熱(re)膨(peng)脹系數(shu)的(de)(de)(de)影響規律(lv)，優(you)化(hua)出(chu)的(de)(de)(de)摻(chan)雜(za)(za)量(liang)(liang)為10% (摩爾分數(shu)，下(xia)同)；他們[87~89]還采用成(cheng)分的(de)(de)(de)非(fei)化(hua)學計量(liang)(liang)比(bi)設計改善了稀(xi)(xi)土(tu)鋯(gao)(gao)酸(suan)(suan)(suan)鹽(yan)(yan)的(de)(de)(de)熱(re)膨(peng)脹系數(shu)和韌(ren)(ren)性(xing)(xing)(xing)(xing)。此外(wai)，Wang等[90]還在稀(xi)(xi)土(tu)鋯(gao)(gao)酸(suan)(suan)(suan)鹽(yan)(yan)中(zhong)摻(chan)雜(za)(za)LaPO4第(di)二(er)相，顯著(zhu)提高(gao)(gao)了韌(ren)(ren)性(xing)(xing)(xing)(xing)，不(bu)僅闡明了韌(ren)(ren)化(hua)機理，還指(zhi)出(chu)最優(you)摻(chan)雜(za)(za)量(liang)(liang)為30%，并采用等離子噴涂方法制(zhi)備了納米結構Gd2Zr2O7-30%LaPO4 TBCs；研究了其CMAS腐(fu)蝕行(xing)為，發(fa)現該(gai)涂層(ceng)(ceng)(ceng)(ceng)的(de)(de)(de)抗CMAS腐(fu)蝕性(xing)(xing)(xing)(xing)能(neng)優(you)于Gd2Zr2O7 TBCs，原因在于P可(ke)加速(su)涂層(ceng)(ceng)(ceng)(ceng)與CMAS的(de)(de)(de)反應形成(cheng)致(zhi)密阻擋層(ceng)(ceng)(ceng)(ceng)。CMAS作用下(xia)，Gd2Zr2O7-30%LaPO4涂層(ceng)(ceng)(ceng)(ceng)表面(mian)形成(cheng)的(de)(de)(de)致(zhi)密反應層(ceng)(ceng)(ceng)(ceng)可(ke)分為2個(ge)亞層(ceng)(ceng)(ceng)(ceng)，下(xia)層(ceng)(ceng)(ceng)(ceng)由Gd-La-P磷灰石組(zu)成(cheng)，而上層(ceng)(ceng)(ceng)(ceng)由Gd-La-P磷灰石、鈣長石、尖(jian)晶石和四方ZrO2相組(zu)成(cheng)，在長時間的(de)(de)(de)熱(re)處(chu)理中(zhong)該(gai)反應層(ceng)(ceng)(ceng)(ceng)能(neng)保(bao)持(chi)良好(hao)的(de)(de)(de)穩定性(xing)(xing)(xing)(xing)，可(ke)有(you)效(xiao)阻止熔融CMAS持(chi)續內(nei)(nei)滲(shen)[91]。

4.3.3 稀土磷酸鹽(yan)

稀(xi)(xi)土(tu)(tu)(tu)磷(lin)酸鹽(yan)(yan)(yan)(LnPO4，Ln = 稀(xi)(xi)土(tu)(tu)(tu)元(yuan)素(su))的(de)(de)(de)(de)(de)熱導率(lv)低(di)、高(gao)溫(wen)(wen)相(xiang)穩定(ding)性(xing)好、抗(kang)熔(rong)(rong)鹽(yan)(yan)(yan)和CMAS腐蝕(shi)(shi)能(neng)(neng)(neng)力強(qiang)，而(er)且相(xiang)比(bi)其(qi)他(ta)超高(gao)溫(wen)(wen)TBCs候選(xuan)材料(liao)(如稀(xi)(xi)土(tu)(tu)(tu)鋯酸鹽(yan)(yan)(yan))，它的(de)(de)(de)(de)(de)韌(ren)性(xing)更(geng)高(gao)，因(yin)(yin)此(ci)LnPO4被認為(wei)(wei)有成(cheng)為(wei)(wei)新一代(dai)超高(gao)溫(wen)(wen)熱障涂(tu)層(ceng)(ceng)的(de)(de)(de)(de)(de)巨大潛(qian)質[92,93]。Wang等(deng)(deng)[94]比(bi)較(jiao)了(le)(le)LnPO4 (Ln = Nd、Sm、Gd)、YSZ在(zai)(zai)1250℃下(xia)CMAS腐蝕(shi)(shi)行為(wei)(wei)后發(fa)現(xian)，相(xiang)比(bi)于YSZ與(yu)CMAS生(sheng)成(cheng)的(de)(de)(de)(de)(de)松散反應層(ceng)(ceng)，LnPO4與(yu)CMAS的(de)(de)(de)(de)(de)反應層(ceng)(ceng)更(geng)為(wei)(wei)致密(mi)無裂紋，能(neng)(neng)(neng)抑制CMAS進一步滲透(tou)。Guo等(deng)(deng)[95]和Zhang等(deng)(deng)[96]采用等(deng)(deng)離子噴涂(tu)方法成(cheng)功制備了(le)(le)LaPO4/YSZ涂(tu)層(ceng)(ceng)并(bing)研究(jiu)了(le)(le)其(qi)CMAS腐蝕(shi)(shi)行為(wei)(wei)，發(fa)現(xian)LaPO4/YSZ涂(tu)層(ceng)(ceng)的(de)(de)(de)(de)(de)抗(kang)CMAS腐蝕(shi)(shi)性(xing)能(neng)(neng)(neng)與(yu)溫(wen)(wen)度(du)相(xiang)關，具體(ti)(ti)(ti)表(biao)現(xian)為(wei)(wei)：在(zai)(zai)1250℃時，涂(tu)層(ceng)(ceng)具有極強(qiang)的(de)(de)(de)(de)(de)阻(zu)止(zhi)熔(rong)(rong)融CMAS滲透(tou)能(neng)(neng)(neng)力，但是(shi)在(zai)(zai)1300和1350℃時，CMAS滲入涂(tu)層(ceng)(ceng)較(jiao)為(wei)(wei)明顯，主要原因(yin)(yin)是(shi)更(geng)高(gao)溫(wen)(wen)度(du)下(xia)CMAS熔(rong)(rong)體(ti)(ti)(ti)的(de)(de)(de)(de)(de)黏度(du)很低(di)，使得CMAS在(zai)(zai)涂(tu)層(ceng)(ceng)內的(de)(de)(de)(de)(de)滲入速率(lv)大于其(qi)與(yu)涂(tu)層(ceng)(ceng)發(fa)生(sheng)化(hua)學反應的(de)(de)(de)(de)(de)速率(lv)，因(yin)(yin)此(ci)涂(tu)層(ceng)(ceng)內很難形成(cheng)有效的(de)(de)(de)(de)(de)結(jie)(jie)晶產物(wu)(wu)阻(zu)止(zhi)熔(rong)(rong)體(ti)(ti)(ti)持續內滲。如圖(tu)5a[95]所(suo)示(shi)，在(zai)(zai)1250℃，CMAS侵蝕(shi)(shi)2 h后，在(zai)(zai)LaPO4/YSZ涂(tu)層(ceng)(ceng)表(biao)面(mian)觀(guan)察到(dao)厚(hou)度(du)約為(wei)(wei)85 ?m的(de)(de)(de)(de)(de)殘余CMAS層(ceng)(ceng)；該層(ceng)(ceng)嵌有許多(duo)晶體(ti)(ti)(ti)，這是(shi)熔(rong)(rong)融CMAS自結(jie)(jie)晶的(de)(de)(de)(de)(de)結(jie)(jie)果。圖(tu)5c[95]顯示(shi)了(le)(le)在(zai)(zai)1250℃下(xia)CMAS侵蝕(shi)(shi)10 h后涂(tu)層(ceng)(ceng)的(de)(de)(de)(de)(de)橫截(jie)面(mian)微(wei)觀(guan)結(jie)(jie)構。與(yu)CMAS侵蝕(shi)(shi)2 h的(de)(de)(de)(de)(de)情況相(xiang)比(bi)，在(zai)(zai)這種(zhong)情況下(xia)觀(guan)察到(dao)一些明顯的(de)(de)(de)(de)(de)特征：界(jie)面(mian)處的(de)(de)(de)(de)(de)反應層(ceng)(ceng)變得更(geng)加連續和致密(mi)，在(zai)(zai)此(ci)之上剩余的(de)(de)(de)(de)(de)CMAS層(ceng)(ceng)厚(hou)度(du)沒有變化(hua)，但是(shi)沉淀出更(geng)多(duo)的(de)(de)(de)(de)(de)針(zhen)狀化(hua)合物(wu)(wu)。值得注意的(de)(de)(de)(de)(de)是(shi)，LaPO4涂(tu)層(ceng)(ceng)在(zai)(zai)CMAS作(zuo)用下(xia)的(de)(de)(de)(de)(de)腐蝕(shi)(shi)產物(wu)(wu)幾乎與(yu)溫(wen)(wen)度(du)無關，主要由磷(lin)灰石、鈣長石和尖晶石相(xiang)組成(cheng)，如圖(tu)5b和d[95]所(suo)示(shi)。此(ci)外，LnPO4還可(ke)作(zuo)為(wei)(wei)第二相(xiang)添加到(dao)稀(xi)(xi)土(tu)(tu)(tu)鋯酸鹽(yan)(yan)(yan)中，細化(hua)母相(xiang)晶粒(li)、強(qiang)化(hua)晶界(jie)，改善材料(liao)的(de)(de)(de)(de)(de)韌(ren)性(xing)，提高(gao)抗(kang)CMAS腐蝕(shi)(shi)和熔(rong)(rong)鹽(yan)(yan)(yan)腐蝕(shi)(shi)性(xing)能(neng)(neng)(neng)[90,91,97,98]。

圖5  LaPO4/YSZ涂層(ceng)在1250℃下(xia)CMAS腐蝕2和10 h后的截面微觀(guan)形貌[95]

4.4 抗CMAS腐蝕(shi)的TBCs結(jie)構設計

采(cai)用激(ji)(ji)光(guang)(guang)方法改(gai)(gai)(gai)(gai)性(xing)(xing)(xing)(xing)TBCs表(biao)面(mian)(mian)(mian)結(jie)(jie)(jie)構是(shi)一種提高涂(tu)層(ceng)(ceng)(ceng)(ceng)(ceng)抗CMAS腐(fu)蝕(shi)性(xing)(xing)(xing)(xing)能的(de)(de)(de)有(you)(you)效方法[99,100]。有(you)(you)研究(jiu)者(zhe)通過飛秒(miao)激(ji)(ji)光(guang)(guang)作用制(zhi)備出具有(you)(you)微(wei)棒狀結(jie)(jie)(jie)構的(de)(de)(de)涂(tu)層(ceng)(ceng)(ceng)(ceng)(ceng)表(biao)面(mian)(mian)(mian)，降(jiang)(jiang)低(di)了(le)(le)與熔(rong)(rong)融CMAS的(de)(de)(de)接觸(chu)面(mian)(mian)(mian)積，涂(tu)層(ceng)(ceng)(ceng)(ceng)(ceng)呈(cheng)現出超疏(shu)液(ye)性(xing)(xing)(xing)(xing)，表(biao)現出良(liang)好的(de)(de)(de)抗CMAS腐(fu)蝕(shi)性(xing)(xing)(xing)(xing)能[101~103]。郭(guo)磊(lei)等[104]研究(jiu)了(le)(le)激(ji)(ji)光(guang)(guang)功(gong)率、掃描(miao)速率以及光(guang)(guang)束(shu)長(chang)(chang)(chang)度(du)等工藝(yi)參數對YSZ改(gai)(gai)(gai)(gai)性(xing)(xing)(xing)(xing)層(ceng)(ceng)(ceng)(ceng)(ceng)微(wei)觀(guan)結(jie)(jie)(jie)構的(de)(de)(de)影(ying)響，指出改(gai)(gai)(gai)(gai)性(xing)(xing)(xing)(xing)層(ceng)(ceng)(ceng)(ceng)(ceng)厚度(du)與激(ji)(ji)光(guang)(guang)功(gong)率成(cheng)正(zheng)比(bi)，與光(guang)(guang)束(shu)長(chang)(chang)(chang)度(du)成(cheng)反比(bi)，受(shou)掃描(miao)速率影(ying)響較(jiao)小。通過激(ji)(ji)光(guang)(guang)改(gai)(gai)(gai)(gai)性(xing)(xing)(xing)(xing)，TBCs由層(ceng)(ceng)(ceng)(ceng)(ceng)片(pian)狀、高孔(kong)隙率的(de)(de)(de)結(jie)(jie)(jie)構轉變為致密(mi)的(de)(de)(de)柱狀微(wei)觀(guan)結(jie)(jie)(jie)構，如圖(tu)6a和(he)b所(suo)示；同時(shi)(shi)，從圖(tu)6c和(he)d中可觀(guan)察到涂(tu)層(ceng)(ceng)(ceng)(ceng)(ceng)的(de)(de)(de)表(biao)面(mian)(mian)(mian)粗(cu)糙度(du)降(jiang)(jiang)低(di)。Yan等[43]比(bi)較(jiao)了(le)(le)激(ji)(ji)光(guang)(guang)改(gai)(gai)(gai)(gai)性(xing)(xing)(xing)(xing)涂(tu)層(ceng)(ceng)(ceng)(ceng)(ceng)和(he)原始(shi)涂(tu)層(ceng)(ceng)(ceng)(ceng)(ceng)的(de)(de)(de)CMAS腐(fu)蝕(shi)行為，發現改(gai)(gai)(gai)(gai)性(xing)(xing)(xing)(xing)涂(tu)層(ceng)(ceng)(ceng)(ceng)(ceng)在(zai)CMAS作用下(xia)的(de)(de)(de)相(xiang)穩定性(xing)(xing)(xing)(xing)更好，其中改(gai)(gai)(gai)(gai)性(xing)(xing)(xing)(xing)層(ceng)(ceng)(ceng)(ceng)(ceng)受(shou)CMAS腐(fu)蝕(shi)后依然能保持較(jiao)好的(de)(de)(de)結(jie)(jie)(jie)構完整性(xing)(xing)(xing)(xing)，如圖(tu)7a[43]所(suo)示；但是(shi)，長(chang)(chang)(chang)時(shi)(shi)間的(de)(de)(de)熱(re)處理(li)會使(shi)得(de)熔(rong)(rong)融CMAS沿著改(gai)(gai)(gai)(gai)性(xing)(xing)(xing)(xing)層(ceng)(ceng)(ceng)(ceng)(ceng)中的(de)(de)(de)縱向(xiang)裂紋內滲(shen)，并(bing)腐(fu)蝕(shi)下(xia)方未改(gai)(gai)(gai)(gai)性(xing)(xing)(xing)(xing)的(de)(de)(de)涂(tu)層(ceng)(ceng)(ceng)(ceng)(ceng)，如圖(tu)7c和(he)d[43]所(suo)示。激(ji)(ji)光(guang)(guang)改(gai)(gai)(gai)(gai)性(xing)(xing)(xing)(xing)層(ceng)(ceng)(ceng)(ceng)(ceng)中不(bu)可避免會產生縱向(xiang)裂紋，它(ta)們可提高改(gai)(gai)(gai)(gai)性(xing)(xing)(xing)(xing)涂(tu)層(ceng)(ceng)(ceng)(ceng)(ceng)的(de)(de)(de)抗熱(re)震性(xing)(xing)(xing)(xing)能，但也是(shi)CMAS熔(rong)(rong)體滲(shen)透的(de)(de)(de)通道[105]。針對此，郭(guo)磊(lei)等[104]設計了(le)(le)多層(ceng)(ceng)(ceng)(ceng)(ceng)激(ji)(ji)光(guang)(guang)表(biao)面(mian)(mian)(mian)改(gai)(gai)(gai)(gai)性(xing)(xing)(xing)(xing)層(ceng)(ceng)(ceng)(ceng)(ceng)，旨在(zai)通過多次的(de)(de)(de)激(ji)(ji)光(guang)(guang)改(gai)(gai)(gai)(gai)性(xing)(xing)(xing)(xing)方法，使(shi)得(de)改(gai)(gai)(gai)(gai)性(xing)(xing)(xing)(xing)層(ceng)(ceng)(ceng)(ceng)(ceng)中的(de)(de)(de)縱向(xiang)裂紋不(bu)連貫(guan)，延緩(huan)(huan)或阻止(zhi)熔(rong)(rong)融CMAS內滲(shen)，初期的(de)(de)(de)結(jie)(jie)(jie)構設計效果如圖(tu)6e和(he)f所(suo)示。同時(shi)(shi)，在(zai)使(shi)激(ji)(ji)光(guang)(guang)改(gai)(gai)(gai)(gai)性(xing)(xing)(xing)(xing)后涂(tu)層(ceng)(ceng)(ceng)(ceng)(ceng)內裂紋不(bu)連續的(de)(de)(de)思路中，Rai等[49]提出，除了(le)(le)制(zhi)備更為致密(mi)的(de)(de)(de)TBCs外，還可以將EB-PVD TBCs中幾乎垂直的(de)(de)(de)柱狀結(jie)(jie)(jie)構改(gai)(gai)(gai)(gai)變成(cheng)Z字形柱狀結(jie)(jie)(jie)構，這種結(jie)(jie)(jie)構有(you)(you)望減緩(huan)(huan)CMAS滲(shen)入速率，延長(chang)(chang)(chang)反應時(shi)(shi)間，從而(er)生成(cheng)黏度(du)、熔(rong)(rong)點更高的(de)(de)(de)結(jie)(jie)(jie)晶相(xiang)來抑制(zhi)進一步滲(shen)透。

圖6  激(ji)光(guang)改性涂層后單(dan)層斷(duan)面形貌(mao)(mao)和雙層的表面及斷(duan)面形貌(mao)(mao)

圖7  激光處理后的涂層在1250℃下CMAS腐蝕(shi)0.5 h截(jie)面和(he)斷面形(xing)貌(mao)，以及腐蝕(shi)4 h的截(jie)面形(xing)貌(mao)[43]

一些(xie)新(xin)型(xing)超高溫TBCs材料，如Gd2Zr2O7、LaCe2O7、GdPO4等，它們(men)雖然具(ju)有(you)TBCs應用(yong)的(de)(de)潛力(li)，且(qie)抗(kang)(kang)CMAS腐(fu)蝕(shi)性(xing)能優異，但(dan)由于一些(xie)問題，比如熱膨脹系數較小、韌性(xing)差等，使得(de)這(zhe)些(xie)新(xin)型(xing)涂層(ceng)(ceng)的(de)(de)抗(kang)(kang)熱震性(xing)能不理(li)想，特別(bie)是(shi)在CMAS、溫度梯(ti)度耦合作用(yong)的(de)(de)熱循環條件下，涂層(ceng)(ceng)壽命較低，容(rong)易過早剝(bo)落失效(xiao)。通過TBCs的(de)(de)結構設計(ji)，人們(men)提出了(le)雙(shuang)陶(tao)(tao)瓷(ci)(ci)層(ceng)(ceng)TBCs，即頂(ding)層(ceng)(ceng)陶(tao)(tao)瓷(ci)(ci)層(ceng)(ceng)為這(zhe)些(xie)新(xin)型(xing)TBCs材料，底(di)層(ceng)(ceng)陶(tao)(tao)瓷(ci)(ci)層(ceng)(ceng)為YSZ。這(zhe)一方法調和了(le)涂層(ceng)(ceng)系統與基(ji)體(ti)(ti)之(zhi)間(jian)的(de)(de)熱膨脹不匹配和應力(li)過大問題，且(qie)兼顧了(le)涂層(ceng)(ceng)的(de)(de)隔熱、抗(kang)(kang)CMAS腐(fu)蝕(shi)性(xing)能。與單(dan)陶(tao)(tao)瓷(ci)(ci)層(ceng)(ceng)的(de)(de)Gd2Zr2O7、LaCe2O7、GdPO4等TBCs以及YSZ TBCs相比，它們(men)對應的(de)(de)雙(shuang)陶(tao)(tao)瓷(ci)(ci)層(ceng)(ceng)TBCs的(de)(de)熱循環壽命顯著(zhu)提升，且(qie)具(ju)有(you)更佳的(de)(de)抗(kang)(kang)CMAS腐(fu)蝕(shi)性(xing)能[92,98,106~108]。

近來，Motoren and Turbinen-Union Friedrichshafen GmbH (MTU)航空(kong)發(fa)動機公司(si)研究(jiu)人員指出(chu)，熔融CMAS會給飛機發(fa)動機葉(xie)片造(zao)成巨大(da)損壞(huai)，未(wei)應用TBCs技術的(de)(de)(de)部件與有涂層(ceng)保護的(de)(de)(de)部件的(de)(de)(de)抗腐(fu)蝕性(xing)能相差(cha)較大(da)。MTU中的(de)(de)(de)Dilba[109]給出(chu)的(de)(de)(de)解決方案是在(zai)YSZ層(ceng)上再加一層(ceng)，頂層(ceng)與熔融CMAS發(fa)生反應，從(cong)而(er)保持(chi)YSZ的(de)(de)(de)結(jie)構和性(xing)能穩定。隨后，其開(kai)發(fa)人員設計了一種(zhong)多涂層(ceng)保護系(xi)統，即將(jiang)2種(zhong)硬、軟涂層(ceng)交替涂覆(fu)在(zai)葉(xie)片上，形成共(gong)約(yue)15層(ceng)、層(ceng)厚10 μm以內(nei)、順序相同(先金屬氮(dan)化物，后金屬)的(de)(de)(de)涂層(ceng)體(ti)系(xi)。這種(zhong)設計有效(xiao)降低了涂層(ceng)磨損程度，并且(qie)解決了因涂層(ceng)過厚導(dao)致裂紋幾率(lv)增(zeng)大(da)的(de)(de)(de)問題。

5 總(zong)結與展望

經過(guo)多年的(de)發(fa)展和國家的(de)大力支持，我國的(de)TBCs研究水平與國外的(de)差(cha)(cha)距越來越小，但在應(ying)用方(fang)面(mian)(mian)依然有不(bu)(bu)小的(de)差(cha)(cha)距，特別是涂層的(de)長壽命(ming)、可靠性和穩定性。同時(shi)，隨著(zhu)(zhu)航空發(fa)動機向著(zhu)(zhu)高(gao)(gao)(gao)性能、高(gao)(gao)(gao)推重比發(fa)展，渦輪(lun)進口(kou)溫度不(bu)(bu)斷提升，TBCs的(de)工作溫度也(ye)越來越高(gao)(gao)(gao)，再加(jia)上環境污(wu)染加(jia)劇，使得TBC的(de)CMAS腐蝕問題愈(yu)加(jia)突出。因此，下(xia)一代航空發(fa)動機對(dui)TBCs抗高(gao)(gao)(gao)溫腐蝕能力提出了(le)更高(gao)(gao)(gao)的(de)要求，這篇綜(zong)述對(dui)CMAS認識歷程、CMAS降解熱障涂層機理以及現有幾種主流抗CMAS腐蝕方(fang)法做(zuo)了(le)較(jiao)為全面(mian)(mian)總結：

首(shou)先，探究CMAS的(de)(de)成分、熔點(dian)、黏度、結(jie)晶行(xing)為等自(zi)身特征(zheng)是(shi)研究CMAS與涂(tu)(tu)層相互作(zuo)用行(xing)為的(de)(de)基礎(chu)。CMAS的(de)(de)成分復雜(za)，受(shou)地(di)理(li)位(wei)置、發動(dong)機工況、氣候(hou)變化(hua)等影(ying)響，使(shi)得(de)CMAS的(de)(de)熔化(hua)行(xing)為、結(jie)晶特征(zheng)以(yi)及黏度、鋪展性、滲入動(dong)力學、熱物理(li)性能(neng)(neng)、力學性能(neng)(neng)等復雜(za)多變，掌握上述特征(zheng)、性能(neng)(neng)的(de)(de)變化(hua)規律，了解透徹CMAS，方能(neng)(neng)清楚CMAS對涂(tu)(tu)層的(de)(de)作(zuo)用行(xing)為和(he)機理(li)。

其(qi)次，揭示(shi)CMAS對TBC的(de)(de)腐(fu)蝕(shi)損傷機(ji)理(li)是(shi)(shi)開展CMAS防(fang)護(hu)的(de)(de)前(qian)提。雖然關于(yu)TBC的(de)(de)CMAS腐(fu)蝕(shi)已(yi)經研究多(duo)年，腐(fu)蝕(shi)機(ji)理(li)也較為(wei)(wei)明晰，但(dan)是(shi)(shi)研究涉及的(de)(de)條件較為(wei)(wei)理(li)想化(hua)，對環(huan)境沉積物的(de)(de)成分復雜性考慮不夠。比如，海洋環(huan)境下，鹽類的(de)(de)存在會(hui)與(yu)CMAS發(fa)生耦(ou)合(he)作用，改變CMAS本身特征，如降低熔點、減小黏度，使得TBC的(de)(de)腐(fu)蝕(shi)復雜化(hua)、嚴重化(hua)，但(dan)是(shi)(shi)這(zhe)些多(duo)元復雜高溫腐(fu)蝕(shi)環(huan)境下TBC的(de)(de)損傷行(xing)為(wei)(wei)研究較少，涂(tu)層失效機(ji)理(li)仍不清(qing)楚。

最后，研發抗(kang)(kang)CMAS腐(fu)(fu)蝕的(de)TBC材(cai)料和(he)涂(tu)(tu)層結構設(she)計是(shi)(shi)發展(zhan)抗(kang)(kang)腐(fu)(fu)蝕長(chang)壽(shou)命(ming)(ming)TBC的(de)支撐。第(di)一(yi)代的(de)YSZ TBC已(yi)被證實(shi)不(bu)(bu)能(neng)(neng)(neng)抵抗(kang)(kang)CMAS腐(fu)(fu)蝕，而且工(gong)作(zuo)溫度(du)越高，受(shou)腐(fu)(fu)蝕越嚴重(zhong)，涂(tu)(tu)層服役壽(shou)命(ming)(ming)直線下降；一(yi)些新型的(de)TBC材(cai)料如(ru)GdPO4和(he)Gd2Zr2O7，雖然在(zai)抗(kang)(kang)CMAS腐(fu)(fu)蝕、高溫穩定性、隔熱性能(neng)(neng)(neng)等方面表現(xian)優秀，但(dan)是(shi)(shi)力(li)學性能(neng)(neng)(neng)(如(ru)韌性)不(bu)(bu)理想，影響(xiang)涂(tu)(tu)層的(de)抗(kang)(kang)熱震(zhen)性能(neng)(neng)(neng)，因此對(dui)這些涂(tu)(tu)層材(cai)料的(de)增(zeng)韌研究是(shi)(shi)重(zhong)點(dian)。此外，激光表面改(gai)性已(yi)被證明能(neng)(neng)(neng)提高TBC的(de)抗(kang)(kang)高溫腐(fu)(fu)蝕性能(neng)(neng)(neng)，但(dan)是(shi)(shi)改(gai)性涂(tu)(tu)層的(de)結構設(she)計和(he)界面匹配相容性值得深入研究。

基于(yu)以上(shang)總結，為推動發展(zhan)新一代長壽(shou)命高(gao)可靠性(xing)TBCs，對制(zhi)約TBCs服役壽(shou)命的CMAS腐蝕的防護方(fang)法(fa)做以下展(zhan)望：

(1) 研發抗CMAS腐蝕(shi)的TBC新材料(liao)。這些材料(liao)一方面需要(yao)迅速與CMAS反應形成反應層(ceng)，且(qie)反應層(ceng)需結構致(zhi)密、化學穩定，能有效阻止(zhi)熔融CMAS持續內(nei)滲；另一方面，這些涂(tu)(tu)層(ceng)材料(liao)需具(ju)有熱導率低(di)、熱膨脹系數(shu)大、韌性好等(deng)特(te)性。目(mu)前來看，尚(shang)未發現完全符合上述要(yao)求的新型抗CMAS腐蝕(shi)涂(tu)(tu)層(ceng)材料(liao)，相對較(jiao)理想的有稀土磷酸(suan)鹽，特(te)別是GdPO4，極具(ju)進一步(bu)研究的價值。

(2) 設計(ji)抗CMAS腐蝕的(de)涂層結構(gou)(gou)。激(ji)(ji)光表(biao)面(mian)(mian)改性、施(shi)加表(biao)面(mian)(mian)防(fang)護(hu)(hu)層以及(ji)納米(mi)結構(gou)(gou)設計(ji)是值(zhi)得(de)研究(jiu)的(de)方法。在進行(xing)激(ji)(ji)光表(biao)面(mian)(mian)改性時，改性層的(de)結構(gou)(gou)設計(ji)和結構(gou)(gou)精確控制是關(guan)鍵；施(shi)加表(biao)面(mian)(mian)防(fang)護(hu)(hu)層時，防(fang)護(hu)(hu)層與涂層的(de)界面(mian)(mian)結合以及(ji)防(fang)護(hu)(hu)層的(de)結構(gou)(gou)穩定性是重點；納米(mi)結構(gou)(gou)設計(ji)時，納米(mi)結構(gou)(gou)的(de)高溫穩定性是難題。

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