Ceramic magnets, also called ferrite magnets, were developed in the 1960s as a low-cost alternative to metallic magnets. They consist mainly of iron oxide and strontium carbonate. Ceramic magnets are corrosion-resistant and have a high resistance to demagnetization. They’re used in many industries because they’re cheap per pound and hold their magnetism in challenging environments. In this article, we’ll look at ceramic magnets, the different types, how they’re made, and how they’re used in today’s technology.
What Are Ceramic Magnets?
Ceramic magnets, also known as ferrite magnets, are hard and brittle permanent magnets made by mixing iron oxide with either barium or strontium carbonate. They’re popular because they’re cheap and resist corrosion and demagnetization. You can use ceramic magnets in many different industrial applications like DC motors, magnetic separators, and automotive sensors. By weight, ferrite magnets account for over 75% of the world’s magnet consumption.
Manufacturing Ceramic Magnets
Ceramic magnets are made using powder technology techniques. You mix the raw materials, which are usually iron oxide and strontium carbonate, and then heat them to around 1800-2000°F. This process causes a chemical reaction that produces ferrite material. The ferrite is then reduced to a fine powder using wet milling. The powder is dried for dry pressing or injected as a wet slurry into a die to shape it.
In wet pressing, you compact the slurry in a die, often with a magnetic field applied. This aligns the ferrite particles, so the magnet has the magnetic properties you want. The last step is to sinter the material at about 2000°F. This process removes any remaining water and forms a dense, solid magnet. The brittle magnet is then ground to size using diamond wheels because it’s so hard that normal tools can’t shape it.
Types of Ceramic Magnets
There are different types of ceramic magnets based on their magnetic properties and applications.
- Ferrite Permanent Magnets
These are the typical black ceramic magnets you’re used to seeing. They’re made from iron oxide and strontium carbonate or barium carbonate. Permanent ceramic magnets retain a strong magnetic field after you magnetize them. You’ll find these magnets in motors, loudspeakers, and generators.
- Soft Magnetic Materials
Soft ceramic magnets are made from a combination of iron oxide and other metal oxides like nickel or zinc. These magnets are not permanent. They don’t retain a magnetic field after you remove the external magnetizing force. You use these magnets in transformer cores, choke coils, and inductors.
- Gyromagnetic Materials
Gyromagnetic ceramic magnets have special properties when you expose them to a DC magnetic field perpendicular to the plane of the material or an electromagnetic wave field. You use these magnets in microwave communication systems to control the polarization of electromagnetic waves as they pass through.
- Moment Magnetic Materials
Moment magnetic materials are ferrite materials, like magnesium manganese ferrite. These materials have a rectangular hysteresis loop. That means they can retain the magnetization they achieve under a small external magnetic field. You use these magnets in memory elements for computers and other electronics.
- Piezomagnetic Materials
Piezomagnetic materials have a property called magnetostriction. When you magnetize these materials, they change shape. You use piezomagnetic materials in transducers that convert electromagnetic energy to mechanical energy. You’ll find these materials in sonar and ultrasound equipment.
Applications of Ceramic Magnets
Ceramic magnets are used in many different industrial and commercial applications. Here are a few examples:
Electroacoustic Devices: Loudspeakers, microphones, headphones, etc.
Motors and Generators: You’ll find ceramic magnets in DC motors and generators to create magnetic fields.
Magnetic Separators: You use ceramic magnets to separate ferrous contaminants in food, chemicals, and other industrial processes.
Automotive Sensors: Ceramic magnets are used in automotive applications like anti-lock braking systems and speed sensors.
Magnetic Storage: Hard drives and magnetic tapes used for audio, video, and data recording contain ceramic magnets.
Microwave Devices: Gyromagnetic materials for microwave communication systems.
Watt-Hour Meters: Ceramic magnets are used in utility meters to measure electricity consumption.
Magnetic Cards and Vouchers: Fare settlement systems, ID cards, and travel vouchers use ceramic magnets.
Benefits of Ceramic Magnets
Ceramic magnets have some advantages over other types of magnets, including:
Cost-Effectiveness: Ferrite magnets are one of the cheapest types of magnets you can buy. If you need magnets and cost is a big factor, these are the ones for you.
Corrosion Resistance: Ceramic magnets are resistant to rust and corrosion. You don’t have to put any protective coatings on them.
Demagnetization Resistance: Ceramic magnets have excellent resistance to demagnetization. They keep their magnetism over time.
Stability: Ceramic magnets work well over a range of temperatures. You can use them indoors or outdoors.
Availability: You can get ferrite magnets in many different shapes and sizes, so they work in lots of different industrial applications.
Conclusion
Ceramic magnets are a great, inexpensive, and reliable solution for many different industrial and commercial applications. They resist corrosion and demagnetization, and they’re cheap. That makes them perfect for everything from motors and sensors to magnetic separators and communication devices. With new developments in materials science, ceramic magnets will continue to be used in many of today’s technologies.
For more information on ceramic magnets, their properties, and their applications, visit NBAEM. We’ve been selling high-quality magnetic products since 2010.
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