摘要
目的分析Y_(2)O_(3)-Yb_(2)O_(3)-Gd_(2)O_(3)-ZrO_(2)热障陶瓷材料的稳定性及涂层的循环性能,探讨热循环失效机理。方法在1500℃下对Y_(2)O_(3)-Yb_(2)O_(3)-Gd_(2)O_(3)-ZrO_(2)陶瓷粉体和涂层进行24 h恒温热处理,并对粉末进行DT-DSC试验,用X射线衍射仪、扫描电子显微镜、能谱分析仪对涂层的物相、表面形貌、截面形貌、元素组成、元素分布进行表征,用Image J软件分析涂层的孔隙,对涂层进行结合强度拉伸试验,在1100℃下对涂层进行水淬试验,分析涂层的热循环寿命和失效行为。结果在室温至1500℃范围内Y_(2)O_(3)-Yb_(2)O_(3)-Gd_(2)O_(3)-ZrO_(2)陶瓷粉体和涂层的结构稳定,未发生相变。制备的Y_(2)O_(3)-Yb_(2)O_(3)-Gd_(2)O_(3)-ZrO_(2)热障涂层的平均孔隙率为17.8%,与基体的平均结合强度为43.1 MPa。在1100℃下对涂层进行水冷热循环处理,涂层的平均循环寿命次数为93。结论Y_(2)O_(3)、Yb_(2)O_(3)、Gd_(2)O_(3)等3种稀土的掺杂可以有效稳定ZrO_(2)晶体结构,抑制高温下ZrO_(2)的相变。在水冷热循环过程中,温度的剧烈变化使得陶瓷层内部产生了热应力,导致微裂纹的萌生、扩展,并最终形成裂纹。裂纹的形成和扩展可以释放热循环过程中产生的热应力,从而提高热障涂层的热循环寿命,但裂纹的不断扩展也降低了涂层内部的强度。随着热循环的进行,当热应力大于其内部结合强度时,涂层会加剧剥落,导致其失效。
To investigate the stability of Y_(2)O_(3)-Yb_(2)O_(3)-Gd_(2)O_(3)-ZrO_(2) thermal barrier ceramic material,the cyclic performance of coating,and their thermal cycling failure mechanisms,the work aims to prepare a thermal barrier coating through plasma spraying of Y_(2)O_(3)-Yb_(2)O_(3)-Gd_(2)O_(3)-ZrO_(2) ceramic powder.The ceramic powder and coating were subject to 24 h isothermal heat treatment at 1500℃.Differential thermal-thermogravimetric analysis(DT-DSC)was conducted on the powder,and X-ray diffraction(XRD)was utilized to analyze the phase stability of both the powder and the coating before and after heat treatment.Image J software was used to evaluate the coating porosity,while tensile tests were performed to characterize the bonding strength.Additionally,water-quenching thermal cycling tests were carried out on the prepared coating at 1100℃.Scanning electron microscopy(SEM)was employed to observe the surface and cross-sectional morphologies of the coating before and after failure,and energy-dispersive spectroscopy(EDS)was used to analyze the elemental composition and distribution on the cross section of the failed coating,thereby assessing the thermal cycling lifespan and failure behavior of the coating.The Y_(2)O_(3)-Yb_(2)O_(3)-Gd_(2)O_(3)-ZrO_(2) ceramic powder and the coating exhibited structural stability within the temperature range of room temperature to 1500℃,with no phase transitions observed.The doping of three rare-earth oxides(Y_(2)O_(3),Yb_(2)O_(3),and Gd_(2)O_(3))enabled rare-earth ions to substitute Zr4+in the lattice,effectively enhancing crystal structure stability and reducing lattice distortion.Simultaneously,oxygen vacancies were introduced into the original lattice,which stabilized the ZrO_(2) crystal structure and suppressed high-temperature phase transitions in ZrO_(2).Microstructural characterization revealed that the plasma-sprayed Y_(2)O_(3)-Yb_(2)O_(3)-Gd_(2)O_(3)-ZrO_(2) thermal barrier coating exhibited a substantial pore distribution with an average porosity of 17.8%,predominantly consisting of unmelted pores.The relatively high porosity contributed to reduced thermal conductivity,thereby enhancing the thermal insulation performance of the coating.The coating demonstrated excellent interfacial bonding characteristics,showing serrated,tightly interlocked interfaces both between the ceramic layer/bond coat and bond coat/substrate.With an average bonding strength of 43.1 MPa,this robust interfacial adhesion significantly improved the thermal cycling resistance of the coating under water-quenching conditions.During the 1100℃water-quenching thermal cycling tests,the coating demonstrated an average thermal cycling lifetime of 93 cycles,exhibiting favorable thermal cycling resistance.However,its service life remained constrained by progressive thermal stress accumulation and eventual coating spallation.The drastic temperature fluctuations during thermal cycling generated thermal stresses within the ceramic layer,promoting microcrack propagation and ultimately leading to the formation of larger cracks.While crack formation and expansion helped release thermal stresses and improved the thermal cycling lifespan of the coating,continuous crack propagation also weakened the internal strength.As thermal cycling progressed,once the thermal stress exceeded the internal bonding strength,the coating underwent accelerated spallation and failure.These findings provide critical insights into the complex relationship between microstructural evolution and mechanical performance in rare-earth-doped thermal barrier coatings under extreme thermal cycling conditions.The study demonstrates that the Y_(2)O_(3)-Yb_(2)O_(3)-Gd_(2)O_(3)-ZrO_(2) system exhibits exceptional high-temperature application potential due to its outstanding phase stability and thermal cycling resistance.The study outcomes offer valuable guidance for developing advanced thermal barrier coating systems,particularly in optimizing the balance between stress-relieving microcrack networks and maintaining sufficient structural cohesion to extend service life under severe thermal cycling conditions.
作者
周夏凉
徐群飞
骆仁智
袁阳
张健月
毛鹏展
陈利斌
左都云
ZHOU Xialiang;XU Qunfei;LUO Renzhi;YUAN Yang;ZHANG Jianyue;MAO Pengzhan;CHEN Libin;ZUO Duyun(Zhejiang Metallurgical Research Institute Co.,Ltd.,Hangzhou 310012,China;Hanggang Steel Metal Ceramics(Anji)Co.,Ltd.,Zhejiang Huzhou 313300,China)
出处
《表面技术》
北大核心
2025年第17期222-229,共8页
Surface Technology
基金
浙江省科技计划(2023C01052)
诸暨市“揭榜挂帅”专项(2024J04)。
关键词
等离子喷涂
热障涂层
结合强度
热循环性能
热应力
air plasma spraying
thermal barrier coating
bonding strength
thermal cycling property
thermal stress
