Related Experiment Video
Updated: Jul 20, 2026

Magnetometric Characterization of Intermediates in the Solid-State Electrochemistry of Redox-Active Metal-Organic Frameworks
Published on: June 9, 2023
Magnetic strength and corrosion of rare earth magnets
Khalid A Ahmad1, James L Drummond, Thomas Graber
1Department of Orthodontics, College of Dentistry, University of Illinois at Chicago, IL 60612-7212, USA.
Introduction:
Rare earth magnets have been used in orthodontics, but their corrosion tendency in the oral cavity limits long-term clinical application. The aim of this project was to evaluate several; magnet coatings and their effects on magnetic flux density.
Methods:
A total of 60 neodymium-iron-boron magnets divided into 6 equal groups--polytetrafluoroethylene-coated (PTFE), parylene-coated, and noncoated--were subjected to 4 weeks of aging in saline solution, ball milling, and corrosion testing.
Results:
A significant decrease in magnet flux density was recorded after applying a protective layer of parylene, whereas a slight decrease was found after applying a protective layer of PTFE. After 4 weeks of aging, the coated magnets were superior to the noncoated magnets in retaining magnetism. The corrosion-behavior test showed no significant difference between the 2 types of coated magnets, and considerable amounts of iron-leached ions were seen in all groups.
Conclusions:
Throughout the processes of coating, soaking, ball milling, and corrosion testing, PTFE was a better coating material than parylene for preserving magnet flux density. However, corrosion testing showed significant metal leaching in all groups.
Related Concept Videos
Ferromagnetism
Magnetic Susceptibility and Permeability
When diamagnetic materials are placed under an external magnetic field, the moments opposite to the field are induced. Hence, the susceptibility for diamagnets has a minimal negative value of 10-5–10-6. Since...
Magnetic Fields
A magnetic field is defined by the force that a charged particle experiences...
Magnetism
An individual magnetic pole cannot be isolated. No matter how small, every piece of a magnet contains a north pole and a south...
Eddy Currents
Other major applications of eddy currents appear in metal detectors and the braking systems of trains and roller...
Paramagnetism

