Behavior of air plasma sprayed thermal barrier coatings, subject to intense thermal cycling
Behavior of air plasma sprayed thermal barrier coatings, subject to intense thermal cycling
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DOI：
10.1016/s0257-8972(02)00740-5
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发表时间：
2003-03
影响因子：
5.4
通讯作者：
A. N. Khan;Jian Lu
中科院分区：
文献类型：
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作者：
A. N. Khan;Jian Lu
研究了空气等离子喷涂(APS)制备的热障涂层(TBC)在1020℃下随热循环次数的变化、损伤萌生和层裂的变化。TBC由ZrO2-7wt.%Y2O3、(YSZ)热生长氧化物(TGO)、MCrAlY粘结层和镍基高温合金Hastelloy-X组成。首先，热循环包括直接插入样品至1020°C，然后保温5min，水淬火。在另一种循环方式中，采用强制空气进行淬火或冷却。用扫描电子显微镜和光学显微镜对其微观结构进行了表征，用X射线衍射仪对其进行了物相分析。YSZ涂层在水冷50次后开始剥落，并持续到220次，以20%的剥落为试验标准。在空气淬火至1000次循环的情况下，只有10%的样品剥落。在这两种情况下，在整个循环过程中都没有观察到垂直裂缝。在水淬样品中，220次循环后，顶层厚度是其原始厚度的一半，而在空冷样品中，没有观察到这种表面劣化。在对水淬态样品进行X射线衍射研究时，发现了氧化锆钙(CaZrO_3)的峰。鼓包导致YSZ/TGO界面微裂纹和空洞的形成，降低了TGO和YSZ之间的韧性。
Microstructural changes, damage initiation and spallation of thermal barrier coatings (TBC), which were deposited by air plasma spraying (APS) and consisting of ZrO2–7 wt.% Y2O3; (YSZ) thermally grown oxide (TGO); MCrAlY bond coat; and a nickel base super alloy, Hastelloy-X, were examined as a function of thermal cycles at 1020 °C. Two types of thermal shock testing were adopted. Firstly, thermal cycling consisted of a directly inserting samples to 1020 °C and then 5 min holding and water quenching. In the other cycling method, forced air was applied for quenching or cooling. Microstructural characterization was carried out by scanning electron microscopy (SEM) and optical microscopy whereas phase analysis was carried out by X-ray diffractrometry (XRD). Spallation of YSZ coatings was initiated by edge cracking after 50 cycles in water quenching and sustained upto 220 cycles, 20% spalling was adopted the criteria for this test. In case of air quenching up to 1000 cycles only 10% of the sample spalled. In both cases, no vertical cracking was observed throughout the cycling. In the water-quenched samples, after 220 cycles the thickness of the top coating was half of its original thickness, while in case of air-quenched samples no such surface deterioration was observed. Peaks for calcium zirconium oxide (CaZrO3) were found during XRD studies for water-quenched samples. Rumpling-induced micro-cracking at the YSZ/TGO interface and the formation of voids decreasing the toughness between the TGO and YSZ.