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Journal Of Chemistry And Material Sciences Vol.2(1) pp.037 - 048 November 2012
Available online http://www.globalresearchjournals.org/?a=journal&id=jcms
Copyright ©2012 Global Research Journals
Full Length Research.
CORROSION RESISTANCE OF TYPE 444 FERRITIC STAINLESS STEEL IN ACIDIC CHLORIDE MEDIA
J.H. Potgieter1, F.V. Adams1, N. Maledi1, J. Van Der Merwe 1,2 and P. A. Olubambi3
1. School of Chemical and Metallurgical Engineering, University of the Witwatersrand, Private Bag 3, Wits, 2050, Johannesburg, South Africa.
2. NRF/DST Centre of Excellence in Strong Materials, University of the Witwatersrand, Private Bag 3,Wits, 2050, Johannesburg, South Africa.
3. Department of Chemical and Metallurgical Engineering, Tshwane University of Technology, Pretoria, South Africa.
Corresponding Authors E-mail: salojohope@yahoo.com
Abstract.
The pitting corrosion resistance of the alloy 444 was studied by means of immersion tests and electrochemical techniques, including cyclic potentiodynamic polarization, open circuit corrosion potential measurements and chronoamperometry. All the corrosion measurements were carried out at room temperature and at varying concentrations of the electrolytes. The alloys were also characterized prior and after corrosion tests using a scanning electron microscope, and the corroded or passivated surfaces with a Raman spectrometer. The alloy displayed similar corrosion behaviour with slight differences in their corrosion resistance in all the solutions. The passivity of the alloy remained stable with none/little breakdown and pitting in 0.1 M of all the investigated solutions. Alloy 444 was better corrosion resistant in chloride environments than in the sulphuric acid. This was corroborated by SEM analysis, and 444 had more corrosion pits in sulphuric acid than in the chloride environments investigated.
Key words: Ferritic stainless steel, acidic chloride media, corrosion resistance, mass loss tests, Raman spectra