不同冷热循环条件下NiCrAlY涂层体系的微观组织演变规律及失效机理
来源期刊：中国有色金属学报2013年第2期
论文作者：李伟洲 李月巧 易丹青 刘会群 孙超
文章页码：417 - 426
关键词：NiCrAlY涂层；扩散阻挡层；循环氧化；界面；失效机理
Key words：NiCrAlY coating; diffusion barrier; cycled oxidation; interface; failure mechanism
摘 要：用空气缓冷和水快冷方式对加热至1 050 ℃的NiCrAlY单一涂层及含CrON扩散阻挡层的复合涂层冷却至室温，由此研究其抗循环氧化能力。结果表明：在缓冷情况下，经过200次循环氧化，无扩散阻挡层的NiCrAlY涂层明显退化，表面膜呈疏松多孔结构，以混合氧化物相为主，在涂层与基体界面附近出现Kirkendall孔穴；有扩散阻挡层的试样表面则以Al2O3膜为主，扩散阻挡层保持连续，无明显涂层退化或破坏现象，说明扩散阻挡层能明显提高NiCrAlY涂层的缓冷抗循环氧化能力。在快冷情况下，有或无扩散阻挡层的试样的表面涂层均较快发生破坏。40次循环氧化后，单一涂层表面出现鼓包突起；45次循环氧化后，鼓包处涂层脱落。而有扩散阻挡层的试样经40次循环氧化后于扩散阻挡层界面处开裂；45次循环氧化后，包覆涂层部分断落。利用Oxx公式能很好地解释涂层/基体或涂层/扩散阻挡层界面的破坏；对于快冷循环氧化，还要考虑在循环过程中的热应力累积效应。
Abstract: The cycled oxidation resistance abilities of single NiCrAlY coated sample and NiCrAlY/CrON duplex coating sample were studied by cooling from 1 050 ℃ to room temperature in air and water quenching. The results show that during slow cooling, the single NiCrAlY coating degrades after 200 cycles, with mixed-oxides of Al2O3, NiCr2O4 and TiO2 on the surface and Kirkendall voids formed closing to the NiCrAlY/DSM11 interface. On the surface of duplex coating sample with the diffusion barrier layer, an adhered Al2O3 scale is formed and no damage is detected at the coating/substrate interface. In the case of fast cooling, the two coating samples are fast damaged only after some cycles. After 40 cycles, some bulges are found on the single coating surface, and the interfacial delamination occurs in the duplex coating sample. After 45 cycles, the coatings in the bulge zone are spalled off from the single coated sample, while part of the overlayer is fractured in the duplex coating sample. By Oxx formula, the thermal stress formed during cycled oxidations can be used to explain the interfacial damage or coating failure, and the cumulative effects of stress should be considered during rapid cooling in water quenching.
李伟洲1, 2, 3，李月巧2，易丹青1，刘会群1，孙 超3
(1. 中南大学 材料科学与工程学院，长沙 410083；
2. 广西大学 材料科学与工程学院，南宁 530004；
3. 中国科学院 金属研究所 金属腐蚀与防护国家重点实验室，沈阳 110016)
摘 要：用空气缓冷和水快冷方式对加热至1 050 ℃的NiCrAlY单一涂层及含CrON扩散阻挡层的复合涂层冷却至室温，由此研究其抗循环氧化能力。结果表明：在缓冷情况下，经过200次循环氧化，无扩散阻挡层的NiCrAlY涂层明显退化，表面膜呈疏松多孔结构，以混合氧化物相为主，在涂层与基体界面附近出现Kirkendall孔穴；有扩散阻挡层的试样表面则以Al2O3膜为主，扩散阻挡层保持连续，无明显涂层退化或破坏现象，说明扩散阻挡层能明显提高NiCrAlY涂层的缓冷抗循环氧化能力。在快冷情况下，有或无扩散阻挡层的试样的表面涂层均较快发生破坏。40次循环氧化后，单一涂层表面出现鼓包突起；45次循环氧化后，鼓包处涂层脱落。而有扩散阻挡层的试样经40次循环氧化后于扩散阻挡层界面处开裂；45次循环氧化后，包覆涂层部分断落。利用Oxx公式能很好地解释涂层/基体或涂层/扩散阻挡层界面的破坏；对于快冷循环氧化，还要考虑在循环过程中的热应力累积效应。
关键词：NiCrAlY涂层；扩散阻挡层；循环氧化；界面；失效机理
LI Wei-zhou1, 2, 3, LI Yue-qiao2, YI Dan-qing1, LIU Hui-qun1, SUN Chao3
(1. School of Material Science and Engineering, Central South University, Changsha 410083, China;
2. School of Materials Science and Engineering, Guangxi University, Nanning 530004, China;
3.)
Abstract:The cycled oxidation resistance abilities of single NiCrAlY coated sample and NiCrAlY/CrON duplex coating sample were studied by cooling from 1 050 ℃ to room temperature in air and water quenching. The results show that during slow cooling, the single NiCrAlY coating degrades after 200 cycles, with mixed-oxides of Al2O3, NiCr2O4 and TiO2 on the surface and Kirkendall voids formed closing to the NiCrAlY/DSM11 interface. On the surface of duplex coating sample with the diffusion barrier layer, an adhered Al2O3 scale is formed and no damage is detected at the coating/substrate interface. In the case of fast cooling, the two coating samples are fast damaged only after some cycles. After 40 cycles, some bulges are found on the single coating surface, and the interfacial delamination occurs in the duplex coating sample. After 45 cycles, the coatings in the bulge zone are spalled off from the single coated sample, while part of the overlayer is fractured in the duplex coating sample. By Oxx formula, the thermal stress formed during cycled oxidations can be used to explain the interfacial damage or coating failure, and the cumulative effects of stress should be considered during rapid cooling in water quenching.
Key words:NiCrAlY coating; diffusion barrier; cycled oxidation; interface; failure mechanism
