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

Akhbar, Kaderi and Ani, Mohd Hanafi and Othman, Raihan and Mohd Zainal, Ahmad Zaki (2011) Observation on void formed in oxide scale of Fe-Cr-Ni alloy at 1073K in dry and humid environments. In: 2nd International Conference on Mechanical and Manufacturing Engineering 2011 (ICME 2011), 6-7th June 2011, Perbadanan Putrajaya Complex, Putrajaya. (Unpublished)

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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 ((POO2=0.21atm = 2.1 × 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 oxidation.

Item Type:	Conference or Workshop Item (Full Paper)
Additional Information:	4583/4128
Uncontrolled Keywords:	high temperature oxidation, Fe-Cr-Ni alloy, void formation,quantitative analysis of void, dry environment, humid environment
Subjects:	T Technology > TA Engineering (General). Civil engineering (General) > TA401 Materials of engineering and construction
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:	17 Oct 2011 13:43
Last Modified:	21 Nov 2011 11:24
URI:	http://irep.iium.edu.my/id/eprint/4128

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