Studies on the Surface Chemistry of Oxide Films Formed on IN-738LC Superalloy at Elevated Temperatures in Dry Air
Studies on the Surface Chemistry of Oxide Films Formed on IN-738LC Superalloy at Elevated Temperatures in Dry Air
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DOI：
10.1023/a:1012569803467
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发表时间：
2001-12
影响因子：
2.2
通讯作者：
S. Seal;S. Kuiry;L. Bracho
中科院分区：
文献类型：
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作者：
S. Seal;S. Kuiry;L. Bracho
研究了IN-738LC的氧化行为，以开发低成本、高效的涡轮系统的高温材料。本文研究了in - 738lc高温合金在1123 ~ 1223 K的干燥空气中等温氧化过程中形成的氧化膜的动力学和表面化学性质。氧化动力学遵循抛物线规律。氧化活化能为264 kJ mol−1。结垢过程主要受铬离子通过结垢中间铬层的扩散控制。采用SEM、XRD、EDS等方法对其表面形貌和氧化相进行了表征。XRD分析结果表明，样品表面存在NiO、NiAl2O4、nicr2o4尖晶石、Al2O3和cr2o3等杂质。利用x射线光电子能谱（XPS）进一步表征了氧化膜表面和横截面，发现氧化膜表面存在NiO、Ni2O3、NiAl2O4、Al2O3和tio2。色度层位于最上层的下方。铬层还含有nicr2o4和nial2o4尖晶石以及Al2O3。从in - 738lc在高温下的氧化生长机理来看，XPS的应用是成功的。
The oxidation behavior of IN-738LC was studied to develop high-temperature materials for low cost and highly efficient turbine systems. The present study was undertaken to investigate the kinetics and the surface chemistry of the oxide films formed during isothermal oxidation of IN-738LC superalloy in the temperature range 1123–1223 K in dry air. The oxidation kinetics followed the parabolic law. The activation energy of oxidation was 264 kJ mol−1. The scaling process is controlled mainly by the diffusion of chromium ions through the intermediate chromia layer in the scale. The surface morphology and the oxide phases of the scale were characterized by SEM, XRD, and EDS studies. XRD analysis revealed the presence of NiO, NiAl2O4, NiCr2O4spinel, Al2O3, and Cr2O3on the top-scale surface. The scale surface and cross section were further characterized using X-ray photoelectron spectroscopy (XPS), which revealed the presence of NiO, Ni2O3, NiAl2O4, Al2O3, and TiO2on the top-oxide surface. The chromia layer was found to be underneath the top scale. The chromia layer also contains NiCr2O4and NiAl2O4spinels along with Al2O3. Application of XPS was found to be successful to understand the oxide-scale chemistry in terms of the oxide-growth mechanism of IN-738LC at elevated temperatures.