Mitigation of damage from molten fly ash to air-plasma-sprayed thermal barrier coatings
Mitigation of damage from molten fly ash to air-plasma-sprayed thermal barrier coatings
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DOI：
10.1016/j.msea.2011.06.041
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发表时间：
2011-09-15
期刊：
影响因子：
6.4
通讯作者：
Padture, Nitin P.
中科院分区：
文献类型：
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作者：
Gledhill, Andrew D.;Reddy, Kongara M.;Padture, Nitin P.
燃气轮机发动机中使用的陶瓷热障涂层 (TBC) 可提供更高的工作温度，从而提高效率和性能。然而，在合成气发动机的情况下，合成气中可能存在的飞灰颗粒杂质会在较热的 TBC 表面熔化并形成玻璃状沉积物。这些沉积物可以穿透热障涂层，导致其失效。在使用褐煤飞灰模拟这些条件的实验中，我们表明使用空气等离子喷涂（APS）工艺制造的成分为 93 wt% ZrO2 + 7 wt% Y2O3 (7YSZ) 的传统热障涂层被熔融飞灰完全破坏。发现熔融飞灰渗透了 TBC 的整个厚度。发生这种情况的机制似乎与在熔融钙镁铝硅酸盐 (CMAS) 砂和飞机发动机中熔融火山灰降解 7YSZ TBC 时观察到的机制相似。相比之下，Gd2Zr2O7 成分的 APS TBC 在相同条件下对熔融褐煤飞灰的侵蚀具有很强的抵抗力，其中熔融灰渗透大约为 TBC 厚度的 25%。这种损害减轻似乎是由于在飞灰/Gd2Zr2O7 TBC 界面处形成了不渗透的稳定结晶层，阻止了穿透的熔融飞灰前沿。 (C) 2011 Elsevier B.V. 保留所有权利。
Ceramic thermal barrier coatings (TBCs) used in gas-turbine engines afford higher operating temperatures, resulting in enhanced efficiencies and performance. However, in the case of syngas-fired engines, fly ash particulate impurities that may be present in syngas can melt on the hotter TBC surfaces and form glassy deposits. These deposits can penetrate the TBCs leading to their failure. In experiments using lignite fly ash to simulate these conditions we show that conventional TBCs of composition 93 wt% ZrO2 + 7 wt% Y2O3 (7YSZ) fabricated using the air plasma spray (APS) process are completely destroyed by the molten fly ash. The molten fly ash is found to penetrate the full thickness of the TBC. The mechanisms by which this occurs appear to be similar to those observed in degradation of 7YSZ TBCs by molten calcium-magnesium-alumino-silicate (CMAS) sand and by molten volcanic ash in aircraft engines. In contrast, APS TBCs of Gd2Zr2O7 composition are highly resistant to attack by molten lignite fly ash under identical conditions, where the molten ash penetrates similar to 25% of TBC thickness. This damage mitigation appears to be due to the formation of an impervious, stable crystalline layer at the fly ash/Gd2Zr2O7 TBC interface arresting the penetrating molten-fly-ash front. (C) 2011 Elsevier B.V. All rights reserved.