Core level and valence band XPS investigations of the corrosion of common metals and strategies for their potential protection

The studies presented here are the results of a three stage investigation designed to provide a detailed understanding of the corrosion of metal systems. The primary objectives and thus the three stages of the project were (1) to continue improvement of the application of valence band X-ray photoelectron spectroscopy (XPS) to extract high confidence chemical information from corrosion surfaces often containing multilayer films of subtle chemical difference; (2) to develop methods to study metal electrodes which are highly reactive upon removal of their native oxide; and (3) to provide new strategies for the potential protection of commercially important metals.; Previous studies in our group measured the valence band XPS spectra of {dollar}alpha{dollar}-Al{dollar}sb2{dollar}O{dollar}sb3{dollar}, {dollar}gamma{dollar}-Al{dollar}sb2{dollar}O{dollar}sb3{dollar}, bayerite, Gibbsite, nordstrandite, boehmite, and diaspore excited with achromic Al K{dollar}alpha{dollar} radiation and interpreted the data with cluster type multiple scatter wave X{dollar}alpha{dollar} calculations. This study has involved the excitation of the valence band XPS spectra of these alumina compounds with monochromatic Al K{dollar}alpha{dollar} radiation. The monochromatic valence band data was interpreted by modification of the original X{dollar}alpha{dollar} cluster calculations and new band structure calculations which have been performed due to additional structure observed in the monochromatic spectra.; It is well known that oxide free surfaces of common metals such as Mo, Ni, Fe, and Al will immediately react in atmosphere with oxygen and water to reform the native oxide. The instantaneous nature of the reaction presents a considerable challenge in the oxidation study of these materials. A method to study the controlled oxidation and to perform the electrochemical treatment of highly reactive electrodes was developed.; These efforts have resulted in the development of novel surface film technology currently under patent pending status. The formation of potentially protective air stable phosphate films directly adjacent to the metal surface in the absence of metal oxide represents a unique state of matter opening an exciting range of new research opportunities and potential industrial applications. These phosphate films have been successfully formed directly adjacent to surfaces of aluminum, iron, and copper. Conclusive evidence regarding the chemical identity of the surface films and the lack of metal oxide is provided by valence band photoemission and supported by core level XPS studies.