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Oxidation Resistance Behavior of NiAl Coating on NiCrW-based Superalloy by Pack Cementation
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1.State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China;2.State Key Laboratory for System Integration of High Power AC Drive Electric Locomotive, Zhuzhou 412001, China

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Natural Science Foundation of Hunan Province (2018JJ2524)

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    Abstract:

    The NiAl coating was prepared on the surface of NiCrW-based superalloy by pack cementation method with CaCl2 as an activator. The surface and cross-section of the coated specimens were analyzed via X-ray diffraction and scanning electron microscopy coupled with energy dispersive spectroscopy. Results show that CaCl2 can replace NH4Cl as an effective activator. The NiAl coating with an almost single phase structure and a thickness of 30 μm can be obtained after pack cementation at 950 °C for 4 h. A chromium-rich interlayer can be observed between the NiAl coating and the substrate. When the filling ratio of the pack powder is less than 100%, the needle-like θ-Al2O3 phase is formed on the NiAl layer surface. During the constant temperature air oxidation test at 1000 °C, the NiAl coating suffers from high speed oxidation to slow speed oxidation, which is in agreement with the phase transformation from needle-like metastable θ-Al2O3 to irregular granular stable α-Al2O3. The final stable α-Al2O3 provides a good oxidation resistance for the substrate.

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[Gao Shan, Zou Jianpeng. Oxidation Resistance Behavior of NiAl Coating on NiCrW-based Superalloy by Pack Cementation[J]. Rare Metal Materials and Engineering,2022,51(3):814~820.]
DOI:10.12442/j. issn.1002-185X.20210016

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History
  • Received:January 07,2021
  • Revised:March 01,2021
  • Adopted:March 17,2021
  • Online: March 30,2022
  • Published: March 30,2022