In situ X-ray Reflectivity Study of Oxidation Kinetics in Iron and Stainless steel
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flectivity Study of Oxidation Kinetics in Iron and Stainless steel D. H. Kim, S. S. Kim, H. H. Lee, H. W. Jang, J. W. Kim, M. Tang, K. S. Liang, S. K. Sinha and D. Y. Noh MRS Proceedings / Volume 840 / 2004 DOI: 10.1557/PROC840Q4.8
Link to this article: http://journals.cambridge.org/abstract_S1946427400081331 How to cite this article: D. H. Kim, S. S. Kim, H. H. Lee, H. W. Jang, J. W. Kim, M. Tang, K. S. Liang, S. K. Sinha and D. Y. Noh (2004). In situ Xray Reflectivity Study of Oxidation Kinetics in Iron and Stainless steel. MRS Proceedings,840, Q4.8 doi:10.1557/PROC840Q4.8 Request Permissions : Click here
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In situ X-ray Reflectivity Study of Oxidation Kinetics in Iron and Stainless steel D. H. Kim, S. S. Kim, H. H. Lee, H. W. Jang, J. W. Kim, M. Tang1, K. S. Liang1, S. K. Sinha2 and D. Y. Noh Department of Materials Science and Engineering, Gwangju Institute of Science & Technology (K-JIST), Gwangju 500-712, Republic of Korea 1 Synchrotron Radiation Research Center, Hsinchu, Taiwan 300, Taiwan 2 Department of Physics, University of California at San Diego, CA 92093, USA ABSTRACT In situ specular x-ray reflectivity was applied to study the growth kinetics of passive oxide films on iron and stainless steel substrates in pH 8.4 borate buffer solution. Under electrical potential from 0 to 800 mV, the growth rate of oxide films decreases exponentially in thickness following the direct logarithmic growth law predicted in the point defect model. The electric field in the oxide on iron is independent of the applied potentials consistent with the point defect model. In stainless steel, however, the electric field depends strongly on the applied potential indicating that the oxide properties change as the applied potential varies. INTRODUCTION The growth kinetics of passive films has been the subject of intense research for many decades [1-8]. This interest has arisen because of the technical importance of thin oxide films that passivate and protect metals from corrosive environments. Several growth models have been proposed to describe the oxidation [1-5]. Experimental data have shown that the growth kinetics obey one of the two models; the high field model predicting inverse logarithmic growth and the point defect model predicting direct logarithmic growth. The experimental data obtained up to now, however, can fit both growth laws equally well, and it is difficult to distinguish between the models. This is mainly due to the difficulty in measuring in situ the growth kinetics of very thin passive oxide films of a few nm thick. In particular, there have been relatively few experimental data on alloys. Goswami et. al. observed the growth kinetics of passive Fe and Fe-based alloy films using ellipsometry. Their data were described better by the inverse logarithmic law. They, however, suggested that it was not definitive [6]. On the other hand, Sil
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