IntermediateTopic 53 of 100Materials & Chemical
Magnetic materials
Soft and hard magnets for transformers and permanent magnets.
In depth
Soft magnets (silicon steel, ferrites, permalloy) have high permeability and low loss for transformers and inductors; hard magnets (NdFeB, SmCo, alnico, ferrite) have high coercivity for permanent magnets. Hysteresis loop, Curie temperature, saturation and core loss characterise them.
Key points
- B-H curve
- Eddy current loss reduced by lamination
- Rare-earth supply issues
ExampleWind turbine generators use NdFeB magnets.
Magnetic materials are used in motors, transformers and sensors, and choosing soft or hard magnets controls efficiency and performance.
What is Magnetic materials?
Soft and hard magnets for transformers and permanent magnets.
Why is it important to understand magnetic materials?
Magnetic materials are used in motors, transformers and sensors, and choosing soft or hard magnets controls efficiency and performance.
What distinguishes soft and hard magnets?
Soft magnets are easy to magnetise and demagnetise, which suits transformers, while hard magnets keep their magnetisation and suit permanent magnets.
What causes hysteresis loss?
Repeated magnetisation and demagnetisation dissipates energy as heat in the material, which matters for AC machines.
How is Magnetic materials used in practice?
Typical applications include using a soft iron core for a transformer to reduce losses, choosing a neodymium magnet for a compact motor and selecting a ferrite magnet for a low-cost loudspeaker.
What should I learn before Magnetic materials?
Study "Semiconductor materials" first (topic 52 of 100 in Materials & Chemical). It covers the groundwork this topic builds on.
What are the key points of Magnetic materials?
B-H curve. Eddy current loss reduced by lamination. Rare-earth supply issues.
Can you give an example of Magnetic materials?
Wind turbine generators use NdFeB magnets.
What comes after Magnetic materials?
The next topic is "Superconductors", which builds directly on this one.
How difficult is Magnetic materials?
It is classed as Intermediate in Materials & Chemical (topic 53 of 100). It is an intermediate topic. Work through the beginner topics in Materials & Chemical first.