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Theoretical approach to oxygen atom degradation of silver
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Fromhold Jr., Albert T. Beshears, Ronald Whitaker, Ann F. Noh, Seung Little, Sally A. |
| Copyright Year | 1987 |
| Description | Based on available Rutherford backscattering spectrometry (RBS), proton induced X-ray emission (PIXE) and ellipsometry data obtained on silver specimens subjected to atomic oxygen attack in low Earth orbit STS flight 41-G, a theory was developed to model the oxygen atom degradation of silver. The diffusion of atomic oxygen in a microscopically nonuniform medium is an essential constituent of the theory. The driving force for diffusion is the macroscopic electrochemical potential gradient developed between the specimen surface exposed to the ambient and the bulk of the silver specimen. The longitudinal electric effect developed parallel to the gradient is modified by space charge of the diffusing charged species. Lateral electric fields and concentration differences also exist due to the nonuniform nature of the medium. The lateral concentration differences are found to be more important than the lateral electric fields in modifying the diffusion rate. The model was evaluated numerically. Qualitative agreement exists between the kinetics predicted by the theory and kinetic data taken in ground-based experiments utilizing a plasma asher. |
| File Size | 82936 |
| Page Count | 1 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_19870016766 |
| Archival Resource Key | ark:/13960/t4sj6cc9n |
| Language | English |
| Publisher Date | 1987-06-01 |
| Access Restriction | Open |
| Subject Keyword | Inorganic And Physical Chemistry Silver Earth Orbital Environments Oxygen Atoms Low Earth Orbits Metal Surfaces Surface Reactions Reaction Kinetics Electrochemistry Mathematical Models Surface Diffusion Electric Fields Gas-metal Interactions Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Article |
