發(fā)布時間：2018-05-31 19:23

  本文選題：熱障涂層 + EB-PVD　； 參考：《湘潭大學(xué)》2017年碩士論文

【摘要】：熱障涂層是航空發(fā)動機(jī)的關(guān)鍵材料,具有保護(hù)發(fā)動機(jī)熱端部件,提高發(fā)動機(jī)效率的作用。隨著工作溫度提高,TBCs的失效問題越來越突出。TBCs主要的失效形式有高溫氧化,CMAS腐蝕,沖蝕,燒結(jié)及相變等。其中CMAS高溫腐蝕是TBCs不可避免的、最復(fù)雜的失效形式。由于CMAS成分多種多樣、沉積量不確定,高溫腐蝕環(huán)境又非常復(fù)雜,導(dǎo)致CMAS腐蝕特征呈現(xiàn)多樣性,CMAS腐蝕熱化學(xué)機(jī)理非常復(fù)雜。文獻(xiàn)報道中主要研究的是硅多鈣少的CMAS腐蝕YSZ熱障涂層后的微結(jié)構(gòu)特征,而對富鈣的CMAS腐蝕研究較少。CMAS中氧化鈣含量的變化會導(dǎo)致YSZ熱障涂層的退化形式明顯不同。然而,在CMAS組分改變對YSZ熱障涂層微結(jié)構(gòu)特征和腐蝕機(jī)理影響方面的深入研究還非常缺乏。本文采用掃描電子顯微鏡(SEM)、X射線衍射(XRD)、拉曼光譜(Raman)和透射電鏡(TEM)等表征手段,深入細(xì)致地研究電子束物理氣相沉積(EB-PVD)法制備的YSZ熱障涂層在富鈣CMAS(組分為50CaO-10MgO-10AlO1.5-30SiO2(mol.%))腐蝕作用下的微結(jié)構(gòu)特征。主要研究內(nèi)容如下:第一、在實驗室條件下,人工制備了組分為50CaO-10MgO-10AlO1.5-30SiO2的富鈣CMAS粉末。根據(jù)研究目的并參考文獻(xiàn)中的實驗參數(shù),設(shè)計了CMAS涂覆量為10mg/cm2,在1400℃腐蝕EB-PVD 7YSZ熱障涂層4h的實驗方案。第二、運(yùn)用SEM和TEM對1400℃高溫CMAS腐蝕前后TBCs樣品微觀組織形貌進(jìn)行表征。結(jié)果表明,原始樣品陶瓷層呈柱狀晶結(jié)構(gòu),柱狀晶邊緣呈羽毛狀,柱狀晶之間存在間隙;腐蝕后樣品陶瓷層柱狀晶結(jié)構(gòu)坍塌,變成大塊等軸顆粒狀結(jié)構(gòu)。通過采用XRD、能量散射光譜儀(EDS)和選區(qū)電子衍射(SAED)分析,我們發(fā)現(xiàn)腐蝕后樣品陶瓷層除了原有的四方相氧化鋯外,有鎂鋁尖晶石(MgAl2O4)存在于大塊顆粒間隙和球形氧化鋯顆粒內(nèi)部,有些地方球形氧化鋯顆粒之間還存在有鈣長石(CaAl2Si2O8)和非晶CMAS。第三、運(yùn)用TEM對組分為Ca50Mg10Al10Si30的富鈣CMAS高溫腐蝕后的,EB-PVD 7YSZ熱障涂層微觀組織結(jié)構(gòu)進(jìn)行了詳細(xì)分析,并運(yùn)用TEM中的EDS并對陶瓷層上部、中部、下部進(jìn)行了詳細(xì)能譜分析。結(jié)果表明,鈣長石和鎂鋁尖晶石的生成和CMAS與YSZ相互反應(yīng)時的局部化學(xué)成分變化有關(guān)。當(dāng)達(dá)到它們生成所需要的環(huán)境條件,鈣長石和鎂鋁尖晶石便開始生成。通過對腐蝕機(jī)理分析,建立了富鈣CMAS高溫腐蝕機(jī)理模型。
[Abstract]:Thermal barrier coating is the key material of aero-engine. It can protect the hot end parts and improve the engine efficiency. The main failure forms of TBCs are high temperature oxidation, erosion, sintering and phase transformation. High temperature corrosion of CMAS is inevitable and the most complex failure form of TBCs. Because of the diversity of CMAS composition, the amount of deposition is uncertain, and the environment of high temperature corrosion is very complex, the corrosion characteristics of CMAS are diverse and the thermal chemical mechanism of CMAS corrosion is very complex. The microstructures of YSZ thermal barrier coatings were mainly studied by CMAS with more silicon, more calcium and less calcium. However, the changes of calcium oxide content in CMAS coatings with high calcium content would lead to different degradation forms of YSZ thermal barrier coatings. However, the effect of CMAS composition on the microstructure and corrosion mechanism of YSZ thermal barrier coatings is still lacking. In this paper, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the structure of the system. The microstructure of YSZ thermal barrier coatings prepared by electron beam physical vapor deposition (EB-PVD) method under the action of calcium rich CMAS-50 CaO-10MgO-10AlO1.5-30SiO2mol. The main contents are as follows: firstly, calcium rich CMAS powder with 50CaO-10MgO-10AlO1.5-30SiO2 composition was prepared under laboratory conditions. According to the experimental results and the experimental parameters in the literature, an experimental scheme of CMAS coating of 10 mg / cm ~ (2) was designed for 4 h after corrosion of EB-PVD 7YSZ thermal barrier coating at 1400 鈩，

本文編號：1960997