| LI Qing-yu,ZENG Xian,CHENG Xu-dong.Study on Thermal Properties of Ceramic Layer/Metal Layer/Ceramic Layer Composite Coating with Low Infrared Emissivity[J],49(5):299-307 |
| Study on Thermal Properties of Ceramic Layer/Metal Layer/Ceramic Layer Composite Coating with Low Infrared Emissivity |
| Received:July 08, 2019 Revised:May 20, 2020 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2020.05.036 |
| KeyWord:CAIP composite coating AlCrN Ni-based K424 alloy infrared emissivity oxidation resistance diffusion resistance |
| Author | Institution |
| LI Qing-yu |
a.State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan , china |
| ZENG Xian |
b.School of Material Science and Engineering, Wuhan University of Technology, Wuhan , china |
| CHENG Xu-dong |
a.State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan , china |
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| Abstract: |
| This work aims to investigate the effects of annealing duration on low infraed emissivity property of ceramic layer/metallic layer/ceramic layer composite coatings, and analyze its effective operating temperature. The AlCrN/Cr/AlCrN and AlCrSiN/Cr/AlCrSiN compsite coatings were prepared by multi-arc ion plating technology on Ni-based K424 alloy substrate. The microstructure, chemical composition and surface radiation characteristics of the samples were analyzed by X-ray diffractometer, field emission high resolution transmission electron microscope, X-ray photoelectron spectrometer, electron probe microanalyzer, glow discharge mass spectrometer and Fourier transform infrared spectrometer. The oxidation resistance and diffusion resistance of samples were compared by modeling and calculating its oxidation activation energy and diffusion coefficient. The ceramic layer presented a nanocrystalline-amouphous characteristic, and the nanocrystalline in AlCrN and AlCrSiN ceramic layers were hcp-Cr2N and hcp-AlN, respectively. Amorphous AlCrN matrix would crystallize into face-centered cubic phase Cr(Al)N at 750 ℃. The addition of Si elements could increase the crystallization temperature to 850 ℃. In the early oxidation stage, Cr rich and Al richoxides was formed on the surface of AlCrN and AlCrSiN ceramic layer, respectively, which was due to the difference of nanocrystals. Then, a mixed oxide layer of aluminum and chromium was observed on the surface of the sample, which resulted from the formation of fcc-Cr(Al)N and the extremely high solubility between chromium oxide and alumina. When amorphous AlCrN media crystallized, the further penetration of O element through crystal boundaries led to a sharp increase in the infrared emissivity, resulting in the failure of its low emissivity property. Meanwhile, after the crystallization of ceramic layer, its oxidation activation energy decreased, and the diffusion coefficient of Ni element increased. Nanocrystalline-amorphous ceramic layer showed more excellent oxidation resistance and diffusion resistance. The addition of Si elements could improve the oxidation resistance of the sample. The AlCrSiN/Cr/AlCrSiN composite coating could be applied for low infrared emissivity applications under the temperature of 850 ℃. |
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