Setting up the test rig for a study of the effect of magnetic fields on electrochemical behaviour of the metallic materials was completed, however it was not a simple task. The main issues when working with the effect of the magnetic field on electrochemical processes that involves very small currents and electrical cables is to clearly distinguish and ensure that the measurements of the phenomena are not confused with the effect of magnetism on the data collection system.The research direction concentrated on two areas that were study in presence of magnetic forces: (1) corrosion and (2) and formation of protective coatings by anodizing:
1) Magnetic field assisted corrosion.
From the test on low carbon ferritic steel in NaCl solution of different concentrations, the magnetic field have both positive effect and negative effect on the corrosion process. The Lorentz force will compel the directional migration of ions in the solution to some extent. Two distinguish areas (cathode and anode) clearly appeared at the sample surface when exposed to the electrolyte and the magnet. The formation of corrosion products on the cathodic areas and polishing effect at the anodic side could be clearly linked to the magnetic lines effect and the corrosion was classified as a galvanic corrosion, compared with uniform corrosion of the same material without the presence of magnet. The corrosion product formed in the presence of the magnet seems to have better adhesion and more compact structure and less pitting sides were identified, however more research is needed to make a final concussion.
2) Magnetic field assisted anodizing.
Anodic oxide films on aluminum, titanium, zirconium and its alloys can be produced in two types – barrier (dense) oxide and porous oxide. In this experiment we focused in formation of porous andic oxides on aluminum in phosphoric acid. Based on the experimental observations, it can be concluded that the application of a magnetic field during the anodizing process has an observable effect on the coating formation and its morphology and it depends on the direction of the magnetic field lines. When a parallel magnetic field is applied, the electric current flows perpendicularly to the magnetic field lines, inducing strong convection near the anode surface. This magnetohydrodynamic (MHD) effect most likely enhances the oxidation reaction and mass transfer, resulting in a faster initial increase in the voltage curve registered during galvanostatic anodizing, compared to the “non-magnetic” condition. However, when the magnetic field is applied perpendicularly to the sample, the expected acceleration in the anodizing reaction and pore formation does not occur, indicating a different mechanism at play. The results suggest that the orientation of the magnetic field relative to the sample surface plays a crucial role in determining the coating formation dynamics.
