Cyclic oxidation behavior of Pt-modified aluminide coating treated with ultrasonic nanocrystal surface modification (UNSM) on Ni-based superalloy
Cyclic oxidation behavior of Pt-modified aluminide coating treated with ultrasonic nanocrystal surface modification (UNSM) on Ni-based superalloy
复制标题
镍基高温合金超声纳米晶表面改性（UNSM）处理的Pt改性铝化物涂层的循环氧化行为
DOI：
10.1016/j.surfcoat.2010.09.039
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发表时间：
2011
影响因子：
5.4
通讯作者：
S. G. Kang
中科院分区：
文献类型：
--
作者：
S. J. Hong;Gil;Won;S. G. Kang
研究了超声辐照对镍基高温合金表面铂改性铝化物涂层的影响。UNSM的应用，使晶粒尺寸更细，并通过降低表面粗糙度释放压应力的Al氧化物膜。在高温合金表面镀上一层厚度为10-11μm的Pt层，经1050°C退火3 h，得到Ni-Pt合金层。在固体渗铝前，对Ni-Pt合金层表面进行UNSM冲击处理。该UNSM冲击的Ni-Pt合金层的晶粒尺寸比未处理的试样上的晶粒尺寸更细。在固体渗铝过程中，处理的Pt改性的铝化物涂层有更多的Al吸收和更大的厚度比未经处理的Pt改性的铝化物涂层，因为许多晶界和体积增加引起的UNSM。此外，处理后的涂层显示出更光滑的表面之前，和之后，包铝。处理后的涂层具有上级抗循环氧化性能。涂层表面粗糙度的减小降低了压应力，导致热生长氧化物（TGO）的析出和Al的快速耗尽，导致由β-NiAl向γ′-Ni 3Al的相变，进而导致合金元素Cr的体积和溶解度的变化。表面和界面粗糙度的增加是体积变化以及TGO和涂层之间的应力和应变增加的结果。此外，合金元素Cr在涂层中的溶解度增加，导致形成大量的Cr和Ni相关的氧化物，其在循环氧化期间在TGO中是不稳定的。TGO的喷涂导致未处理涂层中Al耗尽的速率加快，并且比处理涂层中的降解速率更快。
The effect of ultrasonic nanocrystal surface modification (UNSM) on Pt-modified aluminide coatings on Ni-based superalloy was investigated. UNSM was applied to make the grain size finer and to release compressive stress on the Al oxide film by reducing surface roughness. A Pt layer, with a thickness of 10–11μm, was coated on a superalloy and transformed to a Ni-Pt alloy layer by annealing, at 1050°C for 3h. Before pack aluminizing, the surface of the Ni-Pt alloy layer was shocked by UNSM. The grain size of this UNSM-shocked Ni-Pt alloy layer was finer than the grain size on the untreated specimen. During pack aluminizing, the treated Pt-modified aluminide coating had more Al uptake and greater thickness than the untreated Pt-modified aluminide coating, because many grain boundaries and volume increase were incurred by UNSM. Furthermore, the treated coating displayed a smoother surface before, and after, pack aluminizing. The treated coating showed superior cyclic oxidation resistance. The decrease of surface roughness in the treated coatings diminished compressive stress, which caused spallation of the thermally grown oxide (TGO) and faster depletion of Al. Faster Al depletion in the untreated coating led to a phase transformation, from β-NiAl to γ′-Ni3Al, and then to changes in volume and solubility of the alloying element, Cr. The increase of the surface and interface roughness was a result of the change in volume as well as the increased stress and strain between the TGO and the coating. Additionally, the increasing solubility of the alloying element, Cr, in the coating, resulted in the formation of a large amount of Cr- and Ni-related oxides, which are unstable in the TGO during cyclic oxidation. Spallation of the TGO caused an accelerated rate of Al depletion in the untreated coating, and a faster degradation rate than in the treated coatings.