Observation on void formed in oxide scale of Fe-Cr-Ni alloy at 1073K in dry and humid environments

Kaderi, Akbar and Mohd Zainal, Ahmad Zaki and Ani, Mohd Hanafi and Othman, Raihan (2011) Observation on void formed in oxide scale of Fe-Cr-Ni alloy at 1073K in dry and humid environments. IIUM Engineering Journal, 12 (5). pp. 69-78. ISSN 1511-788X

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Abstract

Void formation in oxide scale during high temperature oxidation is a common phenomenon. Over a long period of time voids will affect the mechanical property of scales by influencing the cracking and spalling. Voids formed in dry environment are different than that of formed in humid environment. With the presence of water vapor in humid environment the formation of void will increase, thus greater number of void compared to that in dry environment. Fe-Cr-Ni alloy samples were exposed isothermally at 1073 K in air (P_(O_2)= 0.21atm = 2.1 x? 10 5 Pa) and humid (air + steam) environments. XRD analysis done to all samples confirms that Fe2O3, Fe3O4, NiCr2O4, FeCr2O4, Cr2O3 and NiO phases exist in the scale. EDX analysis done shows varying compositions of Fe,Cr,Ni and O in outer and inner oxide scale, oxide scale/metal interface and metal. Field emission scanning electron microscope (FE-SEM) was used to investigate voids formed in the cross sections of the oxidized samples. Volume fraction of voids in the oxide scale was calculated in accordance to the cross sectional area fraction of voids in the scale. It shows that Fe-Cr-Ni alloy samples exposed in humid environment has as high as 71% more voids than that exposed in dry environment. It is concluded that the humid environment increased the number of void formed in the oxide scale, thus facilitates the exfoliation of protective scale during the high temperature oxidation.

Item Type:	Article (Journal)
Additional Information:	4583/16790
Uncontrolled Keywords:	high temperature oxidatio;, Fe-Cr-Ni alloy; void formation; quantitative analysis of voi;, dry environment; humid environment
Subjects:	T Technology > TN Mining engineering. Metallurgy
Kulliyyahs/Centres/Divisions/Institutes (Can select more than one option. Press CONTROL button):	Kulliyyah of Engineering > Department of Manufacturing and Materials Engineering
Depositing User:	Dr Mohd Hanafi Ani
Date Deposited:	23 Jan 2012 00:39
Last Modified:	21 Sep 2012 18:19
URI:	http://irep.iium.edu.my/id/eprint/16790

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