Theoretical and experimental comparisons of nearfield electrogalvanic fields due to nonlinear polarization layers
Abstract
Based on completed experimental electric-field scans and the corresponding finite-element field predictions, it appears that the finite-element numerical technique presents a strong analytical tool in calculating the nearfield (within 650 micrometers electric-field distributions about active microcells. This was analytically achieved with the new double membrane finite-element configuration representing nonlinear polarization and by using a local tangent slope (impedance) definition dependent on the local potential difference. The experimental determination of the normal current was realized with a newly developed scanning vibrating electrode technique. The finite-element model utilizes a priori measured uncoupled polarization curves for pure iron and pure copper. The current densities and the electric field intensity was calculated for all the grid points within the electrolyte and on its boundaries. Results appear to indicate that first order anodic mass loss can be predicted using finite-element predicted current density distributions on the anodic surface and the imposition of Faraday's law. The electric-field correlation established for the normal current-density vector provides the confidence to proceed in the evaluation of electric fields associated with pitting and crevice corrosion.
- Publication:
-
NASA STI/Recon Technical Report N
- Pub Date:
- February 1985
- Bibcode:
- 1985STIN...8527149K
- Keywords:
-
- Electric Fields;
- Electrochemical Corrosion;
- Finite Element Method;
- Mathematical Models;
- Near Fields;
- Polarization (Charge Separation);
- Coordinates;
- Copper;
- Correlation;
- Current Density;
- Density Distribution;
- Electric Field Strength;
- Electric Potential;
- Electrical Measurement;
- Electrodes;
- Electrolytes;
- Faraday Effect;
- Iron;
- Nonlinearity;
- Prediction Analysis Techniques;
- Predictions;
- Purity;
- Scanning;
- Surface Cracks;
- Surface Layers;
- Vibration;
- Electronics and Electrical Engineering