Thermal shock resistance of ZrO2-CeO2/Al2O3 composite ceramic coating on superalloy GH3039 by sol-gel method
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摘要: 基于溶胶-凝胶技术制备Al2O3溶胶及ZrO2和CeO2陶瓷粉末,将ZrO2和CeO2陶瓷粉末掺杂在Al2O3溶胶中形成复合浆料并在高温合金GH3039表面分别制备Al2O3、ZrO2/Al2O3和ZrO2-CeO2/Al2O3复合陶瓷涂层,通过XRD、SEM、EDS、DSC等检测手段研究不同陶瓷粉末的加入对复合陶瓷涂层在900℃抗热震性能的影响。结果表明:未添加任何陶瓷粉末的纯Al2O3陶瓷涂层在烧结过程中会产生大量的宏观裂纹,涂层表面质量差且易剥落;在Al2O3溶胶中掺杂ZrO2陶瓷粉末后,ZrO2/Al2O3复合陶瓷涂层的结构致密无明显宏观裂纹且涂层与基体的附着力明显增加;当掺杂粉末为CeO2:ZrO2=1:10(摩尔比)时,CeO2可稳定高温下易发生相变的ZrO2,阻止其由t-ZrO2向m-ZrO2的转变,陶瓷颗粒在Al2O3网络膜中分散均匀并呈现出纳米Al2O3颗粒包覆ZrO2-CeO2大颗粒的结构,这种结构使ZrO2-CeO2/Al2O3涂层的抗热震性能和抗剥落较ZrO2/Al2O3复合陶瓷涂层更优异。ZrO2-CeO2/Al2O3复合陶瓷涂层能够缓解纯Al2O3陶瓷涂层与基体之间热膨胀系数不匹配而造成易剥落的问题,从而延长了涂层寿命,进一步提高基体的抗热震性能。Abstract: Preparation of Al2O3 sol and ZrO2 and CeO2 ceramic powder based on sol-gel method were prepared. The ceramic powders were dispersed in Al2O3 sol to form the composite slurry, then ZrO2/Al2O3 and ZrO2-CeO2/Al2O3 composite ceramic coatings were prepared on the surface of superalloy GH3039 substrate by XRD, SEM, EDS and DSC to study the influence of different ceramic powder on thermal shock resistance of composite sol-gel coating at 900℃. The results indicate that the pure Al2O3 coating without any ceramic powder has a large number of macro crack, bad surface integrity and easy peeling during the process of sintering; when the ZrO2 ceramic powder is added into the Al2O3 sol, the structure of the ZrO2/Al2O3 composite ceramic coating has no obvious macro crack and the adhesion between the coating and the substrate increases significantly; when CeO2:ZrO2=1:10 (molar ratio), CeO2 can stabilize the phase transition under high temperature, which can prevent the transition from t-ZrO2 to m-ZrO2. The ceramic particles are dispersed homogeneously in the Al2O3 network film and present the structure of coated ZrO2-CeO2 particles covered with nano Al2O3 particles. This structure makes the thermal shock resistance and spalling resistance of Al2O3 composite ceramic coating more excellent than the ZrO2/Al2O3 composite ceramic coating. ZrO2-CeO2/Al2O3 composite ceramic coatings can solve the thermal coefficient mismatch problem between matrix and Al2O3 coating so as to further improve the performance of matrix thermal shock and prolongs lifetime of the superalloy GH3039.
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Key words:
- sol-gel /
- superalloy /
- nano-powders /
- composite ceramic coatings /
- thermal shock resistance
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