富钙CMAS高温腐蚀EB-PVD热障涂层微结构特征的研究

发布时间：2018-05-31 19:23

  本文选题：热障涂层 + EB-PVD　； 参考：《湘潭大学》2017年硕士论文

【摘要】：热障涂层是航空发动机的关键材料,具有保护发动机热端部件,提高发动机效率的作用。随着工作温度提高,TBCs的失效问题越来越突出。TBCs主要的失效形式有高温氧化,CMAS腐蚀,冲蚀,烧结及相变等。其中CMAS高温腐蚀是TBCs不可避免的、最复杂的失效形式。由于CMAS成分多种多样、沉积量不确定,高温腐蚀环境又非常复杂,导致CMAS腐蚀特征呈现多样性,CMAS腐蚀热化学机理非常复杂。文献报道中主要研究的是硅多钙少的CMAS腐蚀YSZ热障涂层后的微结构特征,而对富钙的CMAS腐蚀研究较少。CMAS中氧化钙含量的变化会导致YSZ热障涂层的退化形式明显不同。然而,在CMAS组分改变对YSZ热障涂层微结构特征和腐蚀机理影响方面的深入研究还非常缺乏。本文采用扫描电子显微镜(SEM)、X射线衍射(XRD)、拉曼光谱(Raman)和透射电镜(TEM)等表征手段,深入细致地研究电子束物理气相沉积(EB-PVD)法制备的YSZ热障涂层在富钙CMAS(组分为50CaO-10MgO-10AlO1.5-30SiO2(mol.%))腐蚀作用下的微结构特征。主要研究内容如下:第一、在实验室条件下,人工制备了组分为50CaO-10MgO-10AlO1.5-30SiO2的富钙CMAS粉末。根据研究目的并参考文献中的实验参数,设计了CMAS涂覆量为10mg/cm2,在1400℃腐蚀EB-PVD 7YSZ热障涂层4h的实验方案。第二、运用SEM和TEM对1400℃高温CMAS腐蚀前后TBCs样品微观组织形貌进行表征。结果表明,原始样品陶瓷层呈柱状晶结构,柱状晶边缘呈羽毛状,柱状晶之间存在间隙;腐蚀后样品陶瓷层柱状晶结构坍塌,变成大块等轴颗粒状结构。通过采用XRD、能量散射光谱仪(EDS)和选区电子衍射(SAED)分析,我们发现腐蚀后样品陶瓷层除了原有的四方相氧化锆外,有镁铝尖晶石(MgAl2O4)存在于大块颗粒间隙和球形氧化锆颗粒内部,有些地方球形氧化锆颗粒之间还存在有钙长石(CaAl2Si2O8)和非晶CMAS。第三、运用TEM对组分为Ca50Mg10Al10Si30的富钙CMAS高温腐蚀后的,EB-PVD 7YSZ热障涂层微观组织结构进行了详细分析,并运用TEM中的EDS并对陶瓷层上部、中部、下部进行了详细能谱分析。结果表明,钙长石和镁铝尖晶石的生成和CMAS与YSZ相互反应时的局部化学成分变化有关。当达到它们生成所需要的环境条件,钙长石和镁铝尖晶石便开始生成。通过对腐蚀机理分析,建立了富钙CMAS高温腐蚀机理模型。
[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，

本文编号：1960997