ࡱ> 796a (bjbj[[ A,9bE\9bE\%::8 4b>>"```;U aZ9i;;ii``i``i`0;X}^20bId iiiiiiiiiibiiiiiiiiiiiii:> x: AN INVESTIGATION OF NANO-PHASE GOETHITE AND ITS ROLE IN PROTECTIVE RUST FORMATION by Jonathan Wood A Senior Thesis submitted to the Faculty of the Department of Physics 鶹ý in Partial Fulfillment of the Requirement for the Degree of BACHELOR OF SCIENCE OLD DOMINION UNIVERSITY MAY 2005 Approved by: ______________________________ Dr. Desmond C. Cook (Advisor) ______________________________ Dr. Gary Copeland ______________________________ Dr. Charles I. Sukenik ABSTRACT AN INVESTIGATION OF NANO-PHASE GOETHITE AND ITS ROLE IN PROTECTIVE RUST FORMATION Jonathan Wood 鶹ý, April 2005 Advisor: Dr. Desmond C. Cook Recent research in corrosion science has revealed that goethite (a-FeOOH) is an important iron oxide in the formation of protective, adherent rust layers on exposed steel. Moreover, these adherent properties seem to be attributed to small particle, nano-phase goethite. The investigation of goethite includes particles ranging in sizes between 10-200nm, both pure and chromium substituted, using Mssbauer spectroscopy at 300K, 77K, and 4K. The analysis of these spectra produced a reliable means of quickly identifying particle size and magnetic properties. A 15nm particle at 300K has an average hyperfine interaction of 13.28T while a 50nm particle has an average interaction of 35.10T. Similarly, differences between chromium substituted and pure goethite were found using Mssbauer spectroscopy. A 15nm pure particle at 4K has an average hyperfine interaction of 49.69T while a 15nm Chromium substituted particle as an interaction of 49.84T. Acknowledgments I would like to express my gratitude to Dr. Cook for being my mentor and providing me important insight into the corrosion process throughout the entire project. I would also like to thank 鶹ý for providing funding through the Undergraduate Research Program (2005) to make this research possible. Table of Contents Page 1. Introduction 1 1.1 Types of Steel 1 1.2 Research Motivation 2 1.3 Current and Past Research 3 2. Sample and Analytical Techniques 8 2.1 Samples 8 2.2 X-ray Diffraction 9 2.3 Mssbauer Spectroscopy 13 2.3.1 Isomer Shift 14 2.3.2 Electric Quadrupole Interaction 15 2.3.3 Magnetic Zeeman Effect 16 2.3.4 Laboratory Equipment 16 2.3.5 Methodology 19 2.3.6 Magnetic Relaxation 19 3. Results 21 3.1 Pure Goethite Mssbauer Data 21 3.2 Chromium Substituted Mssbauer Data 22 3.3 4K Analysis of Pure and Chromium Substituted Goethite 31 4. Conclusion 33 4.1 Research Findings 33 4.2 Future Research 33 5. Bibliography 34 Table of Figures and Tables Page Figure 1(a): EPMA Photograph of a cross section of exposed steel 5 Figure 1(b): EPMA Cross-section from exposed steel sample 5 Figure 2: TEM Photographs of Cr substituted samples 6 Figure 3: Particle size vs Cr concentration for YAM samples 10 Figure 4: XRD spectra of Al2O3 11 Figure 5: XRD spectra of common iron oxides 12 Figure 6: Illustration of Mssbauer splitting in Fe 17 Figure 7: Mssbauer instrumentation 18 Figure 8: Overlay of Mssbauer spectra of goethite at 300K and 77K 20 Figure 9(a): Comparison of pure goethite magnetic field at 300K and 77K 21 Figure 9(b): Comparison of pure goethite magnetic field at 77K 22 Figure 10(a): Comparison of Cr goethite magnetic field at 300K and 77K 23 Figure 10(b): Comparison of Cr goethite magnetic field at 77K 23 Figure 11: Cr goethite Mssbauer spectra at 300K 24 Figure 12: Pure goethite Mssbauer spectra at 300K 25 Figure 13: Cr goethite Mssbauer spectra at 77K 26 Figure 14: Pure goethite Mssbauer spectra at 77K 27 Figure 15: Cr goethite Mssbauer spectra at 4K 28 Figure 16: Pure goethite Mssbauer spectra at 4K 29 Figure 17: Magnetic field distribution at 300K 30 Figure 18: Magnetic field distribution at 77K 30 Figure 19: Overlay of Mssbauer spectra in 15nm Cr and pure 31 Figure 20: Comparison of magnetic fields in Cr and pure goethite at 4K 32 Table 1: Common iron oxides 3 Table 2: Goethite sample dimensions 8     RU.  yd(((( ( ((((((((h6666666666666666666666666666666666666666666666666hH66666666666666666666666666666666666666666666666666666666666666666p62&6FVfv2(&6FVfv&6FVfv&6FVfv&6FVfv&6FVfv&6FVfv8XV~ 0@ 0@ 0@ 0@ 0@ 0@ 0@ 0@ 0@ 0@ 0@ 0@ 0@ 0@_HmH nH sH tH @`@ NormalCJ_HaJmH sH tH >@>  Heading 1$$@&a$CJ DA`D Default Paragraph FontViV 0 Table Normal :V 44 la (k ( 0No List >B@>  Body Text$a$ 5CJ$\4@4 Header  !4 4 Footer  !.)@!.  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