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Development and Characterization of High Emittance and Low-Thickness Plasma Electrolytic Oxidation Coating on Ti6Al4V for Spacecraft Application

Development and Characterization of High Emittance and Low-Thickness Plasma Electrolytic... Plasma electrolytic oxidation (PEO) or microarc oxidation process has been carried out on Ti6Al4V substrate in electrolytic bath containing sodium silicate and sodium hypophosphate. The phase composition, microstructure and roughness of the PEO coating are examined by x-ray diffraction, scanning electron microscopy and profilometry techniques, respectively. Wavelength-dependent thermo-optical properties viz. solar absorptance (αs\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$\alpha_{s}$$\end{document}) and IR emittance (εir) are recorded by UV-VIS-NIR and FTIR spectrophotometer, respectively. Nanomechanical properties such as nanohardness (H) and Young’s modulus (E) are evaluated by well-established nanoindentation technique. The PEO coating is found to be hydrophobic (contact angle ~108°) and possesses low thickness of 5-9 μ\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$\upmu$$\end{document}m. Average εir is obtained to be 85% while average αs\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$\alpha_{s}$$\end{document} is recorded as 76%. The characteristics H and E values are 2.59 GPa and 81.45 GPa, respectively. The PEO coating is also characterized with respect to potentiodynamic polarization and impedance spectroscopy to evaluate corrosion resistance. The total impedance and corrosion current density (icorr) are in the order of 1 MΩ and 10-8 µA.cm-2, respectively. The results indicate superior corrosion resistance of the present PEO coating compared to similar coatings reported in the literature. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Materials Engineering and Performance Springer Journals

Development and Characterization of High Emittance and Low-Thickness Plasma Electrolytic Oxidation Coating on Ti6Al4V for Spacecraft Application

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Publisher
Springer Journals
Copyright
Copyright © ASM International 2021
ISSN
1059-9495
eISSN
1544-1024
DOI
10.1007/s11665-021-05862-6
Publisher site
See Article on Publisher Site

Abstract

Plasma electrolytic oxidation (PEO) or microarc oxidation process has been carried out on Ti6Al4V substrate in electrolytic bath containing sodium silicate and sodium hypophosphate. The phase composition, microstructure and roughness of the PEO coating are examined by x-ray diffraction, scanning electron microscopy and profilometry techniques, respectively. Wavelength-dependent thermo-optical properties viz. solar absorptance (αs\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$\alpha_{s}$$\end{document}) and IR emittance (εir) are recorded by UV-VIS-NIR and FTIR spectrophotometer, respectively. Nanomechanical properties such as nanohardness (H) and Young’s modulus (E) are evaluated by well-established nanoindentation technique. The PEO coating is found to be hydrophobic (contact angle ~108°) and possesses low thickness of 5-9 μ\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$\upmu$$\end{document}m. Average εir is obtained to be 85% while average αs\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$\alpha_{s}$$\end{document} is recorded as 76%. The characteristics H and E values are 2.59 GPa and 81.45 GPa, respectively. The PEO coating is also characterized with respect to potentiodynamic polarization and impedance spectroscopy to evaluate corrosion resistance. The total impedance and corrosion current density (icorr) are in the order of 1 MΩ and 10-8 µA.cm-2, respectively. The results indicate superior corrosion resistance of the present PEO coating compared to similar coatings reported in the literature.

Journal

Journal of Materials Engineering and PerformanceSpringer Journals

Published: May 20, 2021

Keywords: contact angle; corrosion; IR emittance; nanoindentation; PEO coating

References