Thermal barrier coatings on γ-TiAl protected by the halogen effect
Thermal barrier coatings on γ-TiAl protected by the halogen effect
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DOI：
10.1016/j.surfcoat.2012.09.021
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发表时间：
2012-11-01
影响因子：
5.4
通讯作者：
Schuetze, Michael
中科院分区：
文献类型：
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作者：
Friedle, Simone;Niessen, Nadine;Schuetze, Michael
通过形成薄氧化铝膜，γ-TiAl合金表面的氟处理可以在热障涂层（TBC）系统中用作粘合涂层，消除与传统粘合涂层类型的厚度和化学相容性相关的问题。在目前的工作中，氧化钇部分稳定氧化锆（YSZ）涂层沉积在两个最近开发的γ-TiAl合金，两相TNB-V5和β-稳定的TNM-B1，使用电子束物理气相沉积（EB-PVD）。沉积温度为900 ℃和1000 ℃。在TBC沉积之前，通过在稀氢氟酸中浸渍或喷涂有机含氟化合物来用氟处理衬底材料，然后通常在空气中在900 ℃下进行24小时的预氧化步骤。对于一些样品，省略了后面的预氧化步骤。扫描电子显微镜显示，无论氟化技术、TBC沉积温度和预氧化处理如何，沉积的氧化锆面漆都与两种氟处理合金紧密粘附。在循环氧化条件下，在900摄氏度的空气中测定涂层试样的氧化行为。循环短期氧化测试表明，预氧化步骤是至关重要的，以保持氧化保护后EB-PVD TBC应用的卤素效应。而一个连续的氧化铝层被发现下的氧化锆面漆上预氧化的样品，一个混合的层状氧化物规模的TiO 2和Al 2 O 3形成的试样上没有预氧化。当在900摄氏度下热循环时，通过氢氟酸氟处理的基板上的TBC系统在高温下表现出超过500个循环的1小时停留时间的寿命。对于TNB-V5和TNM-B1合金，均未观察到氧化锆顶涂层的剥落。因此，YSZ热障涂层结合氟效应为γ-TiAl基合金的热保护提供了一个很有前途的概念。(C)2012爱思唯尔有限公司版权所有。
Establishing the formation of a thin alumina scale, fluorine-treatment of the surface of gamma-TiAl alloys can function as a bond coat in thermal barrier coating (TBC) systems, eliminating problems associated with thickness and chemical compatibility of conventional bond coat types. In the present work, yttria partially stabilized zirconia (YSZ) coatings were deposited on two recently developed gamma-TiAl alloys, two-phase TNB-V5 and beta-stabilized TNM-B1, using electron-beam physical vapor deposition (EB-PVD). The deposition temperature was 900 degrees C and 1000 degrees C. Prior to TBC deposition, the substrate materials were treated with fluorine by dipping in dilute hydrofluoric acid or spraying of an organic fluorine-containing compound, followed, in general, by a pre-oxidation step at 900 degrees C for 24 h in air. With some of the samples, the latter pre-oxidation step was omitted. As revealed by scanning electron microscopy, the as-deposited zirconia topcoats were tightly adherent to both fluorine treated alloys, regardless of the fluorination technique, the TBC deposition temperature and the pre-oxidation treatment. The oxidation behavior of the coated specimens was determined under cyclic oxidation conditions at 900 degrees C in air. Cyclic short-term oxidation tests revealed that the pre-oxidation step was crucial to maintain the oxidation protection by the halogen effect after EB-PVD TBC application. Whereas a continuous alumina layer was found beneath the zirconia topcoat on pre-oxidized samples, a mixed layered oxide scale of TiO2 and Al2O3 formed on specimens without pre-oxidation. When thermally cycled at 900 degrees C, the TBC system on substrates fluorine-treated by hydrofluoric acid exhibited lifetimes exceeding 500 cycles of 1 h dwell time at high temperature. No spallation of the zirconia topcoat was observed for both TNB-V5 and TNM-B1 alloys. Therefore, YSZ TBCs offer a promising concept to thermally protect -gamma-TiAl based alloys in combination with the fluorine effect. (C) 2012 Elsevier B.V. All rights reserved.