Working with neodymium magnets requires protecting them from corrosion.
Over time, exposure to moisture and corrosive elements can degrade the magnet’s performance.
It can also shorten its lifespan.
That’s where zinc plating comes in.
It is a common and economical protective coating.
It offers several key benefits for your magnets.
Let’s dive into what zinc plating is.
What is Zinc Plating?
Zinc plating involves applying a thin layer of zinc onto the surface of a neodymium magnet.
This is done through an electroplating process.
The magnets are cleaned, dried, and then submerged in a zinc electrolyte solution.
An electric current is applied.
- This causes the zinc to adhere to the magnet’s surface.
- It creates a uniform protective coating.
Advantages of Zinc Plating
Corrosion resistance
As the zinc begins to oxidize, it forms a layer of zinc oxide.
This helps protect the underlying magnet from corrosion.
- This sacrificial layer allows the zinc to corrode preferentially.
- It delays corrosion of the magnet itself.
Cost-effectiveness
Zinc is an abundant and economical metal.
This makes zinc plating a cheaper option compared to other protective coatings like nickel.
Ease of application
The zinc electroplating process is relatively simple.
It doesn’t require extensive equipment.
This makes it an accessible option for many manufacturers.
Decent appearance
While not as shiny as nickel, zinc plating still provides a smooth, professional-looking metallic finish.
Environmental friendliness
Zinc plated magnets are highly recyclable.
This makes them an eco-friendly choice.
Zinc Plating Specifications
When considering zinc plating for your magnets, here are some key properties and specifications to keep in mind:
Coating thickness
Zinc plating is typically thinner than nickel plating.
- White zinc coatings usually measure around 5-10μm thick.
Adhesion properties
Zinc plating exhibits good adhesion.
This is when the magnets are glued onto steel using a magnet-rated adhesive or epoxy.
Temperature resistance
Zinc coated magnets are best suited for applications with low working temperatures.
- Zinc has lower temperature resistance compared to nickel.
- Zinc plating is recommended for applications with temperatures up to 80°C due to its mechanical stability limitations.
Magnetic strength impact
The zinc plating process can slightly reduce the magnetic properties of NdFeB magnets.
- One study found that producing a 12 μm thick zinc coating reduced the remanence by 40 mT.
- It also reduced the coercivity by 40 kA/m.
However, the protective benefits often outweigh this minor trade-off.
Zinc vs. Nickel Plating
When choosing a protective coating for your neodymium magnets, you might wonder how zinc plating compares to nickel plating.
Here’s a quick comparison:
Cost
Zinc plating is generally much cheaper than nickel plating.
This is thanks to zinc’s abundance and the simpler plating process involved.
Durability
Nickel plating offers superior wear resistance and corrosion protection.
Especially in harsh environments with exposure to acids, alkalis, or sulfides.
- Nickel’s strong passivation ability creates a hard, uniform coating.
- It maintains its luster and integrity for a long time.
Corrosion resistance
Zinc plating provides good general corrosion resistance.
- But it is more susceptible to corrosion from acids, alkalis, and sulfides compared to nickel.
- Additional passivation treatments can enhance zinc’s corrosion protection.
Appearance
Nickel plating provides a shinier, more polished look compared to zinc’s slightly duller finish.
When to Choose Zinc Plating?
So, when might you choose zinc plating over nickel?
- Zinc can be a great choice for cost-sensitive applications.
- Or projects requiring bonding to steel.
- Or products where a non-magnetic coating is needed.
- Industries like consumer goods, education, jewelry making, and those producing items with prolonged skin contact may prefer zinc.
This is because of its economical price point, decorative qualities, or reduced nickel allergy risks.
Long-Term Effects on Magnet Performance
Zinc plating offers good initial corrosion protection.
And, it’s important to consider its long-term effects on magnet performance.
Coating degradation
Over time, the zinc coating is more prone to falling off, chipping, or wearing down compared to nickel.
This can expose the underlying magnet to corrosion.
It can affect its magnetic strength and overall performance.
- The service life of zinc plated magnets is generally lower than nickel plated magnets.
- This is due to these differences in durability and corrosion resistance.
Limited service life
Due to the differences in durability and corrosion resistance, zinc plated magnets generally have a shorter service life compared to nickel plated ones.
As the zinc coating deteriorates over time, it can no longer protect the magnet effectively.
- This leads to oxidation and loss of magnetic performance.
Re-plating challenges
Once the zinc coating wears off and the magnet starts corroding, it cannot be re-plated effectively.
The degradation will continue.
- It will irreversibly impact the magnet’s long-term performance.
Despite these limitations, the economical price point and good initial protection offered by zinc plating still make it a valuable option for many applications.
In Summary
Zinc plating offers a cost-effective solution for protecting neodymium magnets from corrosion.
So, if you’re looking for an economical way to extend the life and performance of your magnets, zinc plating might just be the solution you need.
If you are looking for zinc plated magnets, make sure to contact Osenc!