Periodic Reporting for period 1 - MagniFiCor (Magnetism for the Functionalization of Metallic Materials Surfaces and its effect on Corrosion Phenomena)
Okres sprawozdawczy: 2022-09-01 do 2024-08-31
The mechanisms of material degradation are determined by environmental factors such as chemical composition of the solution in contact with the surface of the material, mechanical stress, temperature or presence of magnetic fields. The effect of a magnetic field on surface phenomena of metallic materials and specifically on corrosion is an unusual and not very well understood variable, particularly important when material contains magnetic phases. The issues of electrochemical processes assisted by magnetism are of interest to a wide range of industries: from magnetically confined fusion reactors to water splitting technologies.
The overall chemistry of an electrolyte in many cases is harmless to the material, but locally ions concentration inside the pit and thus the pH of the electrolyte within the pit decreases, which causes acceleration of corrosion process. For some cases the Lorentz force induced due to interaction between the anodic and cathodic currents from corrosion process and magnetic field might be significant. The possible impact of enhanced mass transfer by Lorentz force might be twofold and contradictory: (i) to enhance corrosion product transport away from an active site (accelerated corrosion) and (ii) to remove the aggressive species away from the pit and thereby result in re-passivation (prevention of further corrosion).
The MagniFiCor project examines the effect of varied intensities and shapes of magnetic fields on electrochemical behaviour of materials surfaceA study of electrochemical processes at the surface of metallic materials under effect of DC or AC magnetic fields is not a trivial tasks and is a subject of many, but relatively random study. Some experimental observations have led to confusion and speculation rather than clarification, primarily due to uncertainties in the experimental control setup's ability. One of the significant challenge is to identify and separate overlapping signals coming from the phenomena itself and the appropriate shielding of the electrochemical setup to avoid artifacts that may falsify the results or lead to incorrect conclusions. The topic is very interesting from the point of view of fundamental research and applications. Considering that charged particles move along magnetic lines, it feels evident that magnetism influences redox reactions and the transport of electrons and protons between metals and conductive liquid environment, but may also affect the polarize sub-surface of the solid material and electric double layer properties, including polar molecules alignment.
The overall chemistry of an electrolyte in many cases is harmless to the material, but locally ions concentration inside the pit and thus the pH of the electrolyte within the pit decreases, which causes acceleration of corrosion process. For some cases the Lorentz force induced due to interaction between the anodic and cathodic currents from corrosion process and magnetic field might be significant. The possible impact of enhanced mass transfer by Lorentz force might be twofold and contradictory: (i) to enhance corrosion product transport away from an active site (accelerated corrosion) and (ii) to remove the aggressive species away from the pit and thereby result in re-passivation (prevention of further corrosion).
The MagniFiCor project examines the effect of varied intensities and shapes of magnetic fields on electrochemical behaviour of materials surfaceA study of electrochemical processes at the surface of metallic materials under effect of DC or AC magnetic fields is not a trivial tasks and is a subject of many, but relatively random study. Some experimental observations have led to confusion and speculation rather than clarification, primarily due to uncertainties in the experimental control setup's ability. One of the significant challenge is to identify and separate overlapping signals coming from the phenomena itself and the appropriate shielding of the electrochemical setup to avoid artifacts that may falsify the results or lead to incorrect conclusions. The topic is very interesting from the point of view of fundamental research and applications. Considering that charged particles move along magnetic lines, it feels evident that magnetism influences redox reactions and the transport of electrons and protons between metals and conductive liquid environment, but may also affect the polarize sub-surface of the solid material and electric double layer properties, including polar molecules alignment.
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.
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.
Understanding the complex relationships between magnetism and electrochemical phenomena and materials performance, longevity, and stability under varying application conditions is a challenging and meticulous task. However, with the support of machine learning (ML), it will be possible to identify dependencies or sequences that are difficult for experimenters to detect in dispersed experimental data. The main risk is a too far reaching simplification of the model and ignoring significance of the atomic scales phenomena on the macroscale behaviour, thus a constant dialog with the modelling groups is essential. The MagniFiCor project become a corner stone for creating a platform to facilitate a dialog with a modelling groups of the host institution at Nomaten CoE at National Center for Nuclear Reearch.
The basis of this project and future plans are in line with specific research topics, with an emphasis on reducing damage caused by environmental factors (corrosion, radiation, high temperatures) and internal factors (optimized composition and surface treatments/coatings of new materials), are directly related to the "reduce" and "rethink" principles of the 6R environmental strategy. The MagniFiCor and the future planned work to optimise the protective coatings for materials exposed to corrosive environment and magnetic fields are also fully consistent with the Polish Smart Specializations (https://smart.gov.pl/en/ ).
The basis of this project and future plans are in line with specific research topics, with an emphasis on reducing damage caused by environmental factors (corrosion, radiation, high temperatures) and internal factors (optimized composition and surface treatments/coatings of new materials), are directly related to the "reduce" and "rethink" principles of the 6R environmental strategy. The MagniFiCor and the future planned work to optimise the protective coatings for materials exposed to corrosive environment and magnetic fields are also fully consistent with the Polish Smart Specializations (https://smart.gov.pl/en/ ).