EB-PVD热障涂层TGO三维结构分析
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摘要
热生长氧化物(TGO)的厚度及形貌是影响热障涂层热应力的关键因素。首先开展了电子束物理气相沉积(EB-PVD)热障涂层1 050℃恒温氧化实验,采用聚焦离子束-扫描电子显微镜(FIB-SEM)实现了EB-PVD热障涂层三维成像,获得了576幅热障涂层高温氧化48 h后的SEM图像;其次,通过EB-PVD热障涂层三维结构的分割与提取,得到了真实TGO三维结构和柱间孔隙三维分布,实现了TGO层的厚度测量;最后建立了基于TGO三维结构和柱间孔隙三维分布的EB-PVD热障涂层有限元热应力分析模型,分析了真实TGO三维结构和柱间孔隙三维分布对EB-PVD热障涂层热应力的影响。结果表明,TGO层的平均厚度为2.37μm,有限元模型中最大拉应力为403 MPa,最大压应力为-282 MPa,最大拉应力与最大压应力均出现在陶瓷层中的柱间孔隙处。
The thickness and morphology of thermally grown oxide( TGO) are key factors which affect the thermal stress of thermal barrier coatings( TBCs). Firstly,an isothermal oxidation experiment is performed at 1050 ℃ for TBCs generated by electron beam physical vapor deposition( EB-PVD). The three-dimensional( 3 D) imaging of EB-PVD thermal barrier coatings is realized by the focused ion beam-scanning electron microscopy( FIB-SEM),and 576 SEM images of TBCs after high temperature oxidation for48 h are obtained. Secondly,the real 3 D structure of TGO and 3 D distribution of inter-column pores are obtained based on the 3 D structure segmentation and the extraction of EB-PVD thermal barrier coatings. The thickness of the TGO layer is measured.Finally,a finite element thermal stress analysis model of EB-PVD thermal barrier coatings based on the 3 D structure of TGO and3 D distribution of inter-column pores is established. The influence of the real 3 D structure of TGO and 3 D distribution of intercolumn pores on the thermal stress of EB-PVD thermal barrier coatings is analyzed. Experimental results indicate that the average thickness of TGO layer is 2. 37 μm,the maximum tensile stress in the finite element model is 403 MPa,and the maximum compressive stress is-282 MPa,both the maximum tensile stress and the maximum compressive stress appeared in the intercolumn pores in the top coat.
The thickness and morphology of thermally grown oxide( TGO) are key factors which affect the thermal stress of thermal barrier coatings( TBCs). Firstly,an isothermal oxidation experiment is performed at 1050 ℃ for TBCs generated by electron beam physical vapor deposition( EB-PVD). The three-dimensional( 3 D) imaging of EB-PVD thermal barrier coatings is realized by the focused ion beam-scanning electron microscopy( FIB-SEM),and 576 SEM images of TBCs after high temperature oxidation for48 h are obtained. Secondly,the real 3 D structure of TGO and 3 D distribution of inter-column pores are obtained based on the 3 D structure segmentation and the extraction of EB-PVD thermal barrier coatings. The thickness of the TGO layer is measured.Finally,a finite element thermal stress analysis model of EB-PVD thermal barrier coatings based on the 3 D structure of TGO and3 D distribution of inter-column pores is established. The influence of the real 3 D structure of TGO and 3 D distribution of intercolumn pores on the thermal stress of EB-PVD thermal barrier coatings is analyzed. Experimental results indicate that the average thickness of TGO layer is 2. 37 μm,the maximum tensile stress in the finite element model is 403 MPa,and the maximum compressive stress is-282 MPa,both the maximum tensile stress and the maximum compressive stress appeared in the intercolumn pores in the top coat.
引文
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[18]TANG W Z,YANG L,ZHU W,et al.Numerical simulation of temperature distribution and thermal-stress field in a turbine blade with multilayer-structure TBCs by a fluid-solid coupling method[J].Journal of Materials Science&Technology,2016,32(5):452-458.
[19]PADTURE N,GELL M,JORDAN E H.Thermal barrier coatings for gas-turbine engine applications[J].Science,2002,296(5566):280-284.
[2]WRIGHT P K.Influence of cyclic strain on life of a PVD TBC[J].Materials Science and Engineering:A,1998,245(2):191-200.
[3]EVANS H E.Oxidation failure of TBC systems:An assessment of mechanisms[J].Surface&Coatings Technology,2011,206(7):1512-1521.
[4]BARGRASER C,MOHAN P,LEE K,et al.Life approximation of thermal barrier coatings via quantitative microstructural analysis[J].Materials Science and Engineering:A,2012,549(7):76-81.
[5]INKSON B J,MULVIHILL M,MBUS G.3D determination of grain shape in a Fe Al-based nanocomposite by 3D FIB tomography[J].Scripta Materialia,2001,45(7):753-758.
[6]BANSAL R K,KUBIS A,HULL R,et al.Highresolution three-dimensional reconstruction:A combined scanning electron microscope and focused ion-beam approach[J].Journal of Vacuum Science&Technology B Microelectronics&Nanometer Structures,2006,24(2):554-561.
[7]SONG X M,MENG F L,KONG M G,et al.Thickness and microstructure characterization of TGO in thermal barrier coatings by 3D reconstruction[J].Materials Characterization,2016,120(10):244-248.
[8]何存富,杨玉娥,吴斌.反射系数法微波检测热障涂层厚度的实验研究[J].仪器仪表学报,2011,32(11):2590-2595.HE C F,YANG Y E,WU B.Experimental study on thickness detection of thermal barrier coatings using microwave[J].Chinese Journal of Scientific Instrument,2011,32(11):2590-2595.
[9]杨玉娥,赵东,安延涛,等.微波检测热障涂层孔隙率的可行性研究[J].仪器仪表学报,2015,36(6):1215-1220.YANG Y E,ZHAO D,AN Y T,et al.Feasibility study for detecting the porosity of thermal barrier coating using microwave[J].Chinese Journal of Scientific Instrument,2015,36(6):1215-1220.
[10]MAUREL V,HELFEN L,N'GUYEN F,et al.Threedimensional investigation of thermal barrier coatings by synchrotron-radiation computed laminography[J].Scripta Materialia,2012,66(7):471-474.
[11]MAUREL V,HELFEN L,SOULIGNAC R,et al.Threedimensional damage evolution measurement in EB-PVD TBCs using synchrotron laminography[J].Oxidation of Metals,2013,79(3-4):313-323.
[12]敖波,何深远,邓翠贞.热障涂层X射线显微镜三维成像[J].稀有金属材料与工程,2016,45(12):3306-3312.AO B,HE SH Y,DENG C ZH.Three-dimensional imaging of thermal barrier coatings by X-ray microscopy[J].Rare Metal Materials and Engineering,2016,45(12):3306-3312.
[13]SLAME CKA K,SKALKA P,POKLUDA J,et al.Finite element simulation of stresses in a plasma-sprayed thermal barrier coating with an irregular top-coat/bondcoat interface[J].Surface&Coatings Technology,2016,304(10):574-583.
[14]WANG L L,FAN Q B,LIU Y B,et al.Simulation of damage and failure processes of thermal barrier coatings subjected to a uniaxial tensile load[J].Materials&Design,2015,86(12):89-97.
[15]LI C,ZHANG X,CHEN Y,et al.Understanding the residual stress distribution through the thickness of atmosphere plasma sprayed(APS)thermal barrier coatings(TBCs)by high energy synchrotron XRD;digital image correlation(DIC)and image based modelling[J].Acta Materialia,2017,132(6):1-12.
[16]ROSLER J,BAKER M,AUFZUG K.A parametric study of the stress state of thermal barrier coatings:Part I:Creep relaxation[J].Acta Materialia,2004,52(16):4809-4817.
[17]YU Q M,HE Q.Effect of material properties on residual stress distribution in thermal barrier coatings[J].Ceramics International,2018,44(3):3371-3380.
[18]TANG W Z,YANG L,ZHU W,et al.Numerical simulation of temperature distribution and thermal-stress field in a turbine blade with multilayer-structure TBCs by a fluid-solid coupling method[J].Journal of Materials Science&Technology,2016,32(5):452-458.
[19]PADTURE N,GELL M,JORDAN E H.Thermal barrier coatings for gas-turbine engine applications[J].Science,2002,296(5566):280-284.