Do Neodymium Magnets Rust
Yes, neodymium magnets can rust if the magnetic material is exposed to moisture. This is because neodymium magnets are made from an alloy of neodymium, iron and boron, and the iron content makes the material susceptible to oxidation and corrosion.
For this reason, neodymium magnets are commonly supplied with a protective coating that creates a barrier between the magnetic material and its surrounding environment.
With the right coating, careful handling and suitable operating conditions, corrosion can be managed effectively. However, the environment in which the magnet will be used should always be considered when choosing a magnet.
Why Do Neodymium Magnets Rust?
Neodymium magnets, also known as NdFeB magnets, are made primarily from:
- Neodymium
- Iron
- Boron
The combination creates an exceptionally strong permanent magnetic material, but its iron content also means the material needs protection from moisture.
If an unprotected neodymium magnet is exposed to water or humidity, oxidation can begin to affect the material. Over time, this can lead to visible corrosion and deterioration of the magnet.
Corrosion is not simply a cosmetic concern. If the magnetic material deteriorates, its physical condition and practical performance can also be affected.
You can learn more about the materials and processes involved in our guide to how neodymium magnets are made.
Why Are Neodymium Magnets Coated?
Most neodymium magnets have a protective surface coating because the underlying NdFeB material is vulnerable to corrosion.
The coating acts as a barrier, helping prevent moisture and other environmental factors from reaching the magnetic material underneath.
Nickel is a common choice. Jobmaster's neodymium range also includes magnets with protective finishes selected according to the product and intended use.
The important point is that the coating is part of the magnet's protection. A coated magnet should not automatically be treated as waterproof or suitable for every wet environment.
The correct coating depends on where and how the magnet will be used.
For more detail, read Jobmaster's complete guide to magnet coatings and adhesives.
What Happens if the Coating Is Damaged?
A protective coating is most effective when it remains intact.
Neodymium magnets are extremely strong, but the magnetic material itself is also hard and brittle. If two powerful magnets are allowed to snap together or a magnet strikes another hard surface, it can chip or crack.
Damage can also compromise the protective coating.
Once the underlying magnetic material is exposed, moisture has a more direct route to the iron-containing alloy. This can increase the risk of corrosion developing.
Signs that a magnet may have been damaged include:
- Chips or cracks
- Scratches through the coating
- Flaking or damaged plating
- Discolouration
- Visible signs of corrosion
Careful handling is therefore important not only for safety but also for helping protect the magnet over its working life.
Can Neodymium Magnets Be Used Around Water?
Whether a neodymium magnet is suitable for an application involving water or moisture depends on the specific magnet, its coating and the environment.
A standard coated neodymium magnet should not automatically be assumed to be waterproof.
Factors to consider include:
- How frequently the magnet will encounter moisture
- Whether it will be submerged or only occasionally exposed
- The condition and type of protective coating
- Whether chemicals or other substances are present
- How easily the magnet can be dried and maintained
- How important long-term corrosion resistance is to the application
This is a good example of why magnet selection should be based on the complete application rather than magnetic strength alone.
Planning to use a magnet around moisture, chemicals or other demanding conditions? Contact Jobmaster Magnets Canada to discuss the environment before choosing a product. A stock magnet may be suitable, or a custom magnetic solution may be more appropriate for unusual requirements.
Does Rust Affect Magnet Strength?
Corrosion can eventually affect how effectively a magnet performs.
As corrosion damages the magnetic material, the surface can become uneven and the magnet itself can begin to deteriorate. This can create additional space between the magnet and the surface it needs to attract.
Even a small air gap can influence practical holding performance. Severe corrosion can also damage the physical structure of the magnet itself, making it unsuitable for continued use.
This is why preventing corrosion is generally more effective than trying to address it after significant deterioration has already occurred.
How Can You Prevent Neodymium Magnets From Rusting?
The best approach is to select a magnet that is appropriate for its intended environment and then protect it during use. Steps that can help include:
- Choose a suitable protective coating for the application
- Avoid scratching or chipping the magnet's surface
- Do not allow powerful magnets to snap together unnecessarily
- Keep magnets dry where the product is not intended for wet environments
- Clean and dry magnets appropriately if they encounter moisture
- Inspect magnets periodically for coating damage or corrosion
- Consider the wider environment, including moisture and chemical exposure, before selecting a magnet
Our guide to how to properly maintain your magnets provides additional advice on protecting magnetic products during storage and use.
Are Some Magnet Materials More Corrosion Resistant?
Yes. Different permanent magnet materials respond differently to moisture and corrosion.
Neodymium provides exceptional magnetic strength in a compact size, but its iron content means corrosion protection is an important consideration.
Ceramic magnets, for example, are naturally more resistant to corrosion and may be worth considering in certain environments where maximum magnetic strength is not required.
However, that does not automatically make ceramic the better material for an application. Each type offers different advantages.
The right choice depends on factors including:
- Required holding force
- Available space
- Environmental conditions
- Operating temperature
- Magnet size and shape
- Cost
- Mounting requirements
Our guide to neodymium vs ceramic magnets provides a closer comparison of the two materials and where each may be useful.
Does the Neodymium Magnet Grade Affect Corrosion?
Neodymium magnets are available in different grades, including options such as N35, N40, N42 and N52.
Magnet grade is primarily used to describe magnetic performance. It should not be used by itself to determine whether a magnet will be suitable for a wet, corrosive or otherwise demanding environment.
For example, selecting a higher-strength grade does not remove the need to consider the magnet's coating or operating conditions.
When comparing grades, look at the complete application, including:
- Required magnetic strength
- Size restrictions
- Temperature
- Coating
- Moisture exposure
- Mounting method
- Intended use
Read our guide to magnet grades for more information on choosing between different neodymium grades.
Should You Use a Rusted Neodymium Magnet?
A small surface mark does not necessarily tell you how a magnet will perform, but visible corrosion should not be ignored.
If a neodymium magnet has substantial rust, damaged plating, cracking or other physical deterioration, it may no longer be appropriate for the application.
This is particularly important where the magnet is part of an industrial device, fixture or assembly in which reliable holding performance matters.
If you are unsure, replacing or professionally assessing the magnet may be more appropriate than assuming it will continue to perform as originally intended.
Choosing the Right Neodymium Magnet for Your Environment
Preventing rust starts before the magnet is installed.
When selecting a neodymium magnet, consider where it will actually be used rather than focusing only on strength and size.
Ask:
- Will the magnet encounter moisture?
- Is the environment indoors or outdoors?
- Could the coating be scratched or damaged?
- Are chemicals or other contaminants present?
- What holding force is required?
- What temperatures will the magnet encounter?
- Is an off-the-shelf magnet appropriate for the application?
These questions can help identify whether a standard neodymium magnet is suitable or whether the application needs a more specialised solution.
Need Help Choosing the Right Neodymium Magnet?
Jobmaster Magnets Canada supplies a range of neodymium magnets for industrial, commercial and personal applications across Canada.
If corrosion resistance, moisture exposure or unusual operating conditions are important to your project, the Jobmaster team can help you assess your requirements rather than relying on magnetic strength alone.
For non-standard applications, Jobmaster can also develop custom magnetic solutions based on the conditions in which the magnet or magnetic device will be used.
Contact Jobmaster Magnets Canada to discuss your application and find the right magnetic solution.