| 摘要: |
| 在高温下长时间暴露，钢材表面的渗铝层与母材之间容易发生元素互扩散，对母材组织产生影响，影响母材的力学性能。为研究超超临界机组用 T92 钢表面铝化物涂层的抗蒸汽氧化性能及组织演化特性，采用低温粉末包埋渗铝法在 T92 钢锅炉管内壁制备铝化物涂层，并在 650 ℃饱和蒸汽环境中进行热暴露试验，结合扫描电镜(SEM)、透射电镜(TEM)观察及 X 射线衍射分析，研究铝化物涂层的氧化行为以及 T92 基体与铝化物涂层之间的扩散退化行为。研究结果表明：低温粉末包埋渗铝可在 T92 锅炉管内壁制备厚度约 30.4 μm 的双层结构铝化物涂层，各层结构连续均匀且组织稳定，与母材呈冶金结合。 在 650 ℃、3 000 h 饱和蒸汽氧化过程中，涂层表面生长厚度约 0.3 μm 的 α-Al2O3氧化膜。650 ℃长时热暴露过程中，Fe-Al 金属间化合物始终是涂层的主要物相，但涂层由 FeAl 相向 FeAl2相退化。铝化物涂层经长时间热暴露后组织退化，但仍具有优异的抗氧化性能，能够对 T92 钢提供很好的保护。 |
| 关键词: 锅炉管 铝化物涂层 T92 钢 蒸汽氧化 组织演化 |
| DOI：10.11933/j.issn.1007-9289.20211125001 |
| 分类号:TG178 |
| 基金项目:陕西省自然科学基础研究计划(2020JM-716)和中国华能集团有限公司科技(HNKJ20-H43)资助项目 |
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| Microstructure Evolution of Aluminide Coating on T92 Steel |
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Huang Chunlin1,2, Zhu Ming1, Lu Jintao2, Huang Zijing3, Huang Jinyang2, Zhou Yongli2, Yuan Yong2
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1.College of Material Science and Engineering, Xi’ an University of Science and Technology, Xi’ an 710054 , China;2.National Engineering Research Center of Integration and Maintenance of Clean and Low-carbon Thermal Power Generation System, Xi’ an Thermal Power Research Institute Co.Ltd, Xi’ an 710032 , China;3.College of Energy Resources, Xiamen University, Xiamen 361005 , China
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| Abstract: |
| It is known that the interdiffusion at the aluminide coating / matrix interface during the long time exposure at high temperature would change the microstructure of the matrix and deteriorate the mechanical properties of the matrix. To analyze the steam oxidation resistance and microstructure evolution of aluminide coating on T92 steel for ultra-supercritical unit, aluminide coating is prepared on the inner wall of T92 steel boiler tube by low temperature powder embedding method, and the heat exposure test is carried out in 650 ℃ saturated steam environment. The oxidation and diffusion degradation behaviors of T92 matrix and aluminide coating are studied by combining scanning electron microscope equipped with energy dispersive spectroscopy (SEM / EDS), transmission electron microscope (TEM) and X-ray diffraction analysis (XRD). The results show that the aluminide coating prepared on the inner wall of T92 boiler tube by low temperature powder embedding aluminizing, which is metallurgically combined with the matrix, has a double-layer structure, and each layer is continuous and uniform. The total thickness of the prepared aluminide coating is about 30.4 μm. A very thin α- Al2O3 oxide film with the thickness about 0.3 μm is formed on the surface of the aluminide coating after exploring in the 650 ℃ saturated steam for 3 000 h, which prevents the further oxidation of the coating. Fe-Al intermetallic compound is always the dominated phase of the coating, although the phase of the aluminide coating degenerated from FeAl to FeAl2. It can be concluded that even microstructure degradation of the aluminide coating occurres during the long-time thermal exposure process, it can still provide excellent protection for T92 steel to resistant water steam oxidation. |
| Key words: boiler tube aluminide coating T92 steel steam oxidation microstructure evolution |
