Oxidation behavior of porous Ni- 4 and 8 wt %Cr alloys in air at 1273K
Mohamed, L., Ghanem, W., El kady, O., Lotfy, M., Ahmed, H., Elrefaie, F. (2020). Oxidation behavior of porous Ni- 4 and 8 wt %Cr alloys in air at 1273K. EKB Journal Management System, 63(10), 3735-3745. doi: 10.21608/ejchem.2020.18068.2100
Lamiaa Mohamed; Wafaa A. Ghanem; Omayma A. El kady; Mohamed. M. Lotfy; Hafiz A. Ahmed; Fawzi A. Elrefaie. "Oxidation behavior of porous Ni- 4 and 8 wt %Cr alloys in air at 1273K". EKB Journal Management System, 63, 10, 2020, 3735-3745. doi: 10.21608/ejchem.2020.18068.2100
Mohamed, L., Ghanem, W., El kady, O., Lotfy, M., Ahmed, H., Elrefaie, F. (2020). 'Oxidation behavior of porous Ni- 4 and 8 wt %Cr alloys in air at 1273K', EKB Journal Management System, 63(10), pp. 3735-3745. doi: 10.21608/ejchem.2020.18068.2100
Mohamed, L., Ghanem, W., El kady, O., Lotfy, M., Ahmed, H., Elrefaie, F. Oxidation behavior of porous Ni- 4 and 8 wt %Cr alloys in air at 1273K. EKB Journal Management System, 2020; 63(10): 3735-3745. doi: 10.21608/ejchem.2020.18068.2100

Oxidation behavior of porous Ni- 4 and 8 wt %Cr alloys in air at 1273K

Egyptian Journal of Chemistry
Article 13, Volume 63, Issue 10, October 2020, Page 3735-3745  XML PDF (1.32 MB)
Document Type: Original Article
DOI: 10.21608/ejchem.2020.18068.2100
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Authors
Lamiaa Mohamed email orcid 1; Wafaa A. Ghanem2; Omayma A. El kady3; Mohamed. M. Lotfy1; Hafiz A. Ahmed1; Fawzi A. Elrefaie1
1Mining, Petroleum and Metallurgical Engineering Dept., Faculty of Engineering, Cairo University, Giza, 12613, Egypt
2Corrosion and Surface Protection, Central Metallurgical Research and Development Institute (CMRDI), Helwan, Egypt
3Powder Technology Division, Central Metallurgical Research and Development Institute (CMRDI), Helwan, Egypt
Abstract
Oxidation behavior of porous Ni-4 and 8 wt% Cr pellets prepared by conventional powder metallurgy was investigated. The pellets were oxidized in air at 1273K for 100 h. The oxidation kinetics were measured by using gravimetric method. The oxide layer morphology and, the surfaces topography and the cross-section microstructure of the oxidized pellets were investigated using X-ray diffraction, optical microscopy, scanning electron microscopy and X-ray energy dispersive analysis. The oxidation rate was initially rapid and then gradually decreased until realizing a constant rate after oxidation time of about 40 h for the 4 wt %Cr pellets with linear rate constant of about 8x10-8 (g/cm2)/sec. For the 8 wt %Cr pellets, the linear rate constant was about 20x10-8 (g/cm2).sec which was achieved after 72 h. Porous nickel oxide scales were formed on the 4 and 8 wt %Cr substrates. Finally, the growth of the oxide scale was explained on the basis of inward migration of molecular oxygen through the porous oxide scale; accordingly, the newly oxide atomic layers were added at the scale/metal interface.
Keywords
Porous Ni-4 and 8 wt%Cr alloys; High temperature oxidation; inward molecular oxygen migration; Linear kinetics; Porous oxide scale microstructure
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