大气等离子喷涂热障涂层CMAS防护层成分及厚度优化
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摘要
目的优化热障涂层(TBCs)CMAS(CaO-MgO-Al_2O_3-SiO_2)阻抗层的成分和厚度,使其能有效阻抗CMAS沉积物的腐蚀,并同时与热障涂层有较高的结合力。方法首先利用多孔无压烧结陶瓷块体研究了不同含量Al_2O_3和8YSZ(8wt.%氧化钇稳定氧化锆)均匀混合后在高温(1250℃)条件下对CMAS沉积物的防护作用。采用扫描电子显微镜(SEM)、能谱仪(EDS)以及X射线衍射(XRD)仪,分析研究了CMAS腐蚀层的显微结构、腐蚀深度及反应产物。其次,基于最优成分,利用大气等离子喷涂(APS)制备了具有8YSZ/Al_2O_3陶瓷层的热障涂层。对CMAS腐蚀厚度进行分析测量,提出CMAS阻抗层的厚度。结果 Al_2O_3的添加可以有效地阻碍CMAS的渗入,并且Al_2O_3含量越多,防护效果越好。但是CMAS的渗入深度和氧化铝的添加量呈非线性关系。结合TBC陶瓷层的热学性能和力学性能的要求,本实验中最佳的TBCs复合陶瓷层组分为70wt%8YSZ+30wt%Al_2O_3。基于实验结果,提出YSZ/Al_2O_3复合陶瓷层(50μm)-YSZ陶瓷层(150μm)的双层TBC陶瓷层结构,并综合计算出复合陶瓷层的热膨胀系数为9.93×10-6℃-1以及双层TBC陶瓷层的热导率为2.4 W/(m·K)。最后对Al_2O_3减缓CMAS腐蚀的机理进行了量化分析。结论 YSZ/Al_2O_3复合阻抗层的最优成分为70wt%8YSZ+30wt%Al_2O_3,厚度为50μm,能有效阻碍高温下CMAS腐蚀。
The work aims to investigate composition and thickness of impedance layers on thermal barrier coatings(TBCs), so that the layers can effective impede corrosion of CMAS deposit and also easily adhere to thermal barrier coatings. Protection effects of uniformly blended different content of nano-sized Al_2O_3 and 8 YSZ on CMAS deposit were studied with porous pressureless sintered ceramic pellets at high temperature. Microstructure, corrosion depth and reaction product of the CMAS corro-sion layers was analyzed and studied with scanning electron microscope, energy dispersive spectrometer and X-ray diffractometer, respectively. Then thermal barrier coatings with 8 YSZ/Al_2O_3 ceramic layers were prepared by performing air plasma spraying(APS) based on optimal composition. Corrosion depth of CMAS was analyzed and measured, and thickness of CMAS impedance layers was proposed. Addition of Al_2O_3 can effectively prevent CMAS from infiltrating. Moreover, the higher the Al_2O_3 content was, the better the protection effects were. However, there was a nonlinear correlation between CMAS infiltration depth and Al_2O_3 addition. Concerning thermal properties and mechanical properties of the TBC ceramic layers, optimal composition of TBC composite ceramic layers was determined to be 70 wt%8 YSZ+30 wt%Al_2O_3. Based upon the experimental results, bilayer TBC ceramic layer structure consisting of YSZ/Al_2O_3 composite ceramic layers(50 μm) and YSZ ceramic layers was proposed. According to overall calculations, thermal expansion coefficient of the YSZ/Al_2O_3 composite ceramic layers was 9.93×10-6 ℃-1, and thermal conductivity of the bilayer TBC ceramic layers was 2.4 W/(m·K). Finally, the mechanism of CMAS corrosion being mitigated by Al_2O_3 was quantitatively analyzed. The optimal composition of YSZ/Al_2O_3 composite ceramic layers is 70 wt%8 YSZ+30 wt%Al_2O_3, and thickness is 50 μm, which can effectively prevent CMAS corrosion at high temperature.
The work aims to investigate composition and thickness of impedance layers on thermal barrier coatings(TBCs), so that the layers can effective impede corrosion of CMAS deposit and also easily adhere to thermal barrier coatings. Protection effects of uniformly blended different content of nano-sized Al_2O_3 and 8 YSZ on CMAS deposit were studied with porous pressureless sintered ceramic pellets at high temperature. Microstructure, corrosion depth and reaction product of the CMAS corro-sion layers was analyzed and studied with scanning electron microscope, energy dispersive spectrometer and X-ray diffractometer, respectively. Then thermal barrier coatings with 8 YSZ/Al_2O_3 ceramic layers were prepared by performing air plasma spraying(APS) based on optimal composition. Corrosion depth of CMAS was analyzed and measured, and thickness of CMAS impedance layers was proposed. Addition of Al_2O_3 can effectively prevent CMAS from infiltrating. Moreover, the higher the Al_2O_3 content was, the better the protection effects were. However, there was a nonlinear correlation between CMAS infiltration depth and Al_2O_3 addition. Concerning thermal properties and mechanical properties of the TBC ceramic layers, optimal composition of TBC composite ceramic layers was determined to be 70 wt%8 YSZ+30 wt%Al_2O_3. Based upon the experimental results, bilayer TBC ceramic layer structure consisting of YSZ/Al_2O_3 composite ceramic layers(50 μm) and YSZ ceramic layers was proposed. According to overall calculations, thermal expansion coefficient of the YSZ/Al_2O_3 composite ceramic layers was 9.93×10-6 ℃-1, and thermal conductivity of the bilayer TBC ceramic layers was 2.4 W/(m·K). Finally, the mechanism of CMAS corrosion being mitigated by Al_2O_3 was quantitatively analyzed. The optimal composition of YSZ/Al_2O_3 composite ceramic layers is 70 wt%8 YSZ+30 wt%Al_2O_3, and thickness is 50 μm, which can effectively prevent CMAS corrosion at high temperature.
引文
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[3]郭巍,马壮,刘玲,等.航空发动机用热障涂层的CMAS侵蚀及防护[J].现代技术陶瓷,2017,38(3):159-175.GUO Wei,MA Zhuang,LIU Ling,et al.CMAS Corrosion and Protection of Thermal Barrier Coatings for Aeroengines[J].Advanced Ceramics,2017,38(3):159-175.
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[13]何箐,汪瑞军,邹晗,等.不同结构8YSZ热障涂层对CMAS沉积物的防护作用[J].中国表面工程,2016,29(4):86-95.HE Qing,WANG Rui-jun,ZOU Han,et al.Protective Effects of 8YSZ TBCs with Different Microstructures against CMAS Deposits[J].China Surface Engineering,2016,29(4):86-95.
[14]WANG Lu,GUO Lei,LI Zhuo-min,et al.Protectiveness of Pt and Gd2Zr2O7 Layers on EB-PVD YSZ Thermal Barrier Coatings against Calcium-Magnesium-AluminaSilicate(CMAS)Attack[J].Ceramics International,2015,41:11662-11669.
[15]ZHANG X F,ZHOU K S,XU W,et al.In Situ Synthesis ofα-Alumina Layer on Thermal Barrier Coating for Protection against CMAS(Ca O-Mg O-Al2O3-Si O2)Corrosion[J].Surface&Coatings Technology,2015,261:54-59.
[16]ZHANG X F,ZHOU K S,LIU M,et al.Adsorbability and Spreadability of Calcium-Magnesium-Alumino-Silicate(CMAS)on Al-modified 7YSZ Thermal Barrier Coating[J].Ceramics International,2016,261:54-59.
[17]AHLBORG N L,ZHU D.Calcium-Magnesium-AluminoSilicate(CMAS)Reactions and Degradation Mechanisms of Advanced Environmental Barrier Coatings[J].Surface&Coatings Technology,2013,237:79-87.
[18]SHAN Xiao,ZOU Zhong-hua,GU Li-jian,et al.Buckling Failure in Air-Plasma Sprayed Thermal Barrier Coatings Induced by Molten Silicate Attack[J].Scripta Materialia,2016,113:71-74.
[19]BOROM M P,JOHNSON C A,PELUSO L A.Role of Environmental Deposits and Operating Surface Temperature in Spallation of Air Plasma Sprayed Thermal Barrier Coatings[J].Surface&Coatings Technology,1996,86-87:116-126.
[20]ZALESKI E M,ENSSLEN C,LEVI C G.Melting and Crystallization of Silicate Systems Relevant to Thermal Barrier Coating Damage[J].Journal of the American Ceramic Society,2015,98:1642-1649.
[21]MUNRO M.Evaluated Material Properties for a Sintered Alpha-Alumina[J].Journal of the American Ceramic Society,1997,80:1919-1928.
[22]YANG Fan,ZHAO Xiao-feng,XIAO Pin.Thermal Conductivities of YSZ/Al2O3 Composites[J].Journal of the European Ceramic Society,2010,30:3111-3116.
[23]陈则韶,钱军.复合材料等效导热系数的理论推算[J].中国科学技术大学学报,1992,22(4):416-424.CHEN Ze-shao,QIAN Jun.Predicting Theory of Effective Thermal Conductivity of Complex Material[J].Journal of China University of Science and Technology,1992,22(4):416-424.
[24]VASCONCELOS P V,LABRINCHA J A,FERREIRA J M F.Porosity Development of Diatomite Layers Processed by Tape Casting[J].Ceramics International,1998,24:447-454.
[25]IYI C B.CMAS Reactivity with Candidate Ceramic Oxides Applicable in Thermal Barrier Coatings[J].Dissertations&Theses Gradworks,2012,157:9672.
[26]WU Jing,GUO Hong-bo,GAO Yu-zhi,et al.Microstructure and Thermo-physical Properties of Yttriastabilized Zirconia Coatings with CMAS Deposits[J].Journal of the European Ceramic Society,2011,31:1881-1888.
[2]PADTURE N P,GELL M,JORDAN E H.Thermal Barrier Coatings for Gas-turbine Engine Applications[J].Science,2002,296:280-284.
[3]郭巍,马壮,刘玲,等.航空发动机用热障涂层的CMAS侵蚀及防护[J].现代技术陶瓷,2017,38(3):159-175.GUO Wei,MA Zhuang,LIU Ling,et al.CMAS Corrosion and Protection of Thermal Barrier Coatings for Aeroengines[J].Advanced Ceramics,2017,38(3):159-175.
[4]WELLMAN R,WHITMAN G,NICHOLLS J R.CMAS Corrosion of EB PVD TBCs:Identifying the Minimum Level to Initiate Damage[J].International Journal of Refractory Metals&Hard Materials,2010,28:124-132.
[5]KRAUSE A R,GARCES H F,DWIVEDI G,et al.Calcia-Magnesia-Alumino-Silicate(CMAS)-Induced Degradation and Failure of Air Plasma Sprayed Yttriastabilized Zirconia Thermal Barrier Coatings[J].Acta Materialia,2016,105:355-366.
[6]STOTT F H,WET D J D,TAYLOR R.The Degradation Resistance of Thermal Barrier Coatings to Molten Deposits at Very High Temperatures[J].Advanced Materials I,1994,93:135-140.
[7]MERCER C,FAULHABER S,EVANS A G,et al.A Delamination Mechanism for Thermal Barrier Coatings Subject to Calcium-Magnesium-Alumino-Silicate(CMAS)Infiltration[J].Acta Materialia,2005,53:1029-1039.
[8]KR?MER S,FAULHABER S,CHAMBERS M,et al.Mechanisms of Cracking and Delamination within Thick Thermal Barrier Systems in Aero-engines Subject to Calcium-Magnesium-Alumino-Silicate(CMAS)Penetration[J].Materials Science&Engineering A,2008,490:26-35.
[9]KRAUSE A R,LI X,PADTURE N P.Interaction Between Ceramic Powder and Molten Calcia-MagnesiaAlumino-Silicate(CMAS)Glass,and Its Implication on CMAS-resistant Thermal Barrier Coatings[J].Scripta Materialia,2016,112:118-122.
[10]AYGUN A,VASILIEV A L,PADTURE N P,et al.Novel Thermal Barrier Coatings That are Resistant to High-temperature Attack by Glassy Deposits[J].Acta Materialia,2007,55:6734-6745.
[11]ZHENG C,WU N Q,SINGH J,et al.Effect of Al2O3Overlay on Hot-corrosion Behavior of Yttria-stabilized Zirconia Coating in Molten Sulfate-vanadate Salt[J].Thin Solid Films,2003,443:46-52.
[12]DREXLER J M,ORTIZ A L,PADTURE N P.Composition Effects of Thermal Barrier Coating Ceramics on Their Interaction with Molten Ca-Mg-Al-Silicate(CMAS)Glass[J].Acta Materialia,2012,60:5437-5447.
[13]何箐,汪瑞军,邹晗,等.不同结构8YSZ热障涂层对CMAS沉积物的防护作用[J].中国表面工程,2016,29(4):86-95.HE Qing,WANG Rui-jun,ZOU Han,et al.Protective Effects of 8YSZ TBCs with Different Microstructures against CMAS Deposits[J].China Surface Engineering,2016,29(4):86-95.
[14]WANG Lu,GUO Lei,LI Zhuo-min,et al.Protectiveness of Pt and Gd2Zr2O7 Layers on EB-PVD YSZ Thermal Barrier Coatings against Calcium-Magnesium-AluminaSilicate(CMAS)Attack[J].Ceramics International,2015,41:11662-11669.
[15]ZHANG X F,ZHOU K S,XU W,et al.In Situ Synthesis ofα-Alumina Layer on Thermal Barrier Coating for Protection against CMAS(Ca O-Mg O-Al2O3-Si O2)Corrosion[J].Surface&Coatings Technology,2015,261:54-59.
[16]ZHANG X F,ZHOU K S,LIU M,et al.Adsorbability and Spreadability of Calcium-Magnesium-Alumino-Silicate(CMAS)on Al-modified 7YSZ Thermal Barrier Coating[J].Ceramics International,2016,261:54-59.
[17]AHLBORG N L,ZHU D.Calcium-Magnesium-AluminoSilicate(CMAS)Reactions and Degradation Mechanisms of Advanced Environmental Barrier Coatings[J].Surface&Coatings Technology,2013,237:79-87.
[18]SHAN Xiao,ZOU Zhong-hua,GU Li-jian,et al.Buckling Failure in Air-Plasma Sprayed Thermal Barrier Coatings Induced by Molten Silicate Attack[J].Scripta Materialia,2016,113:71-74.
[19]BOROM M P,JOHNSON C A,PELUSO L A.Role of Environmental Deposits and Operating Surface Temperature in Spallation of Air Plasma Sprayed Thermal Barrier Coatings[J].Surface&Coatings Technology,1996,86-87:116-126.
[20]ZALESKI E M,ENSSLEN C,LEVI C G.Melting and Crystallization of Silicate Systems Relevant to Thermal Barrier Coating Damage[J].Journal of the American Ceramic Society,2015,98:1642-1649.
[21]MUNRO M.Evaluated Material Properties for a Sintered Alpha-Alumina[J].Journal of the American Ceramic Society,1997,80:1919-1928.
[22]YANG Fan,ZHAO Xiao-feng,XIAO Pin.Thermal Conductivities of YSZ/Al2O3 Composites[J].Journal of the European Ceramic Society,2010,30:3111-3116.
[23]陈则韶,钱军.复合材料等效导热系数的理论推算[J].中国科学技术大学学报,1992,22(4):416-424.CHEN Ze-shao,QIAN Jun.Predicting Theory of Effective Thermal Conductivity of Complex Material[J].Journal of China University of Science and Technology,1992,22(4):416-424.
[24]VASCONCELOS P V,LABRINCHA J A,FERREIRA J M F.Porosity Development of Diatomite Layers Processed by Tape Casting[J].Ceramics International,1998,24:447-454.
[25]IYI C B.CMAS Reactivity with Candidate Ceramic Oxides Applicable in Thermal Barrier Coatings[J].Dissertations&Theses Gradworks,2012,157:9672.
[26]WU Jing,GUO Hong-bo,GAO Yu-zhi,et al.Microstructure and Thermo-physical Properties of Yttriastabilized Zirconia Coatings with CMAS Deposits[J].Journal of the European Ceramic Society,2011,31:1881-1888.