Assessing Corrosion in NdFeB Rails of a Superconducting MagLev Prototype

TL;DR

This paper studies how corrosion affects neodymium magnets in a superconducting maglev system and how it progresses over time.

Contribution

The study introduces a detailed corrosion progression model for NdFeB magnets in maglev rails through field inspections and lab simulations.

Findings

Corrosion in NdFeB magnets forms a passivating layer after 45 days of immersion.

The passivating layer detaches after 60 days, restarting corrosion and causing material loss.

Rainwater analysis and electrochemical tests were used to simulate and study exposure conditions.

Abstract

This study aims to evaluate the progression of the corrosion
process
in Neodymium–Iron–Boron (NdFeB) magnets that constitute
the rails of the Superconducting Magnetic Levitation Vehicle. Periodic
inspections were carried out on the tracks, including collecting corrosion
product samples detached from the structure and rainwater samples,
to determine the main constituents of the electrolyte to which the
magnets are exposed. These rainwater samples were characterized by
using ion chromatography, pH measurements, and conductivity analysis.
In addition to sample collection, the inspections included temperature
measurements of the metallic structure and a visual analysis of the
rails. Based on the collected data, bench tests, electrochemical polarization,
and immersion tests were conducted to simulate exposure conditions.
The samples of NdFeB magnets subjected to immersion tests were analyzed
using Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray
Spectroscopy (EDS), revealing that the corrosion process progresses
gradually, forming a uniform passivating layer after 45 days of immersion.
However, this layer detaches entirely after 60 days, restarting the
corrosion process and leading to a loss of solid material from the
structure.

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