Magnetic Materials and Applications
- [Rare-earth Magnets: Tetrataenite - a ‘cosmic magnet’ that takes millions of years to develop naturally in meteorites - Cambridge University]
- Overview
A magnet is a material or object that produces a magnetic field. This magnetic field is invisible, but is responsible for the most striking property of magnets: a force that pulls on other ferromagnetic materials (such as iron, steel, nickel, cobalt, etc.) and attracts or repels other magnets. Permanent magnets are objects made of materials that are magnetized and produce their own persistent magnetic field.
Magnetic alloys are the single most important material underpinning the new green economy. They are active in electric motors, transformers, generators, magnetic sensors, data storage and many electronic components.
Magnetic materials underpin an international industry worth trillions of dollars each year. More than 99% of electrical energy is generated using a motor made of magnetic material that passes through at least two transformers before reaching the user. About 10% of the power generation is being lost, the largest part of which is in the magnetic core.
The 2015 EU Ecodesign Regulation imposed efficiency limits on all new equipment and required a further 10% reduction in losses by 2021. This can only be achieved with the best commercially available electrical steel grades. These developments will also reduce electricity demand for electric vehicles, industry and households.
The steps taken will expand the ability to optimize the role of magnetic materials in key elements such as design, end-use and end-of-life to optimize current processes and drive future innovations.
- Magnetic Materials
Materials that can be magnetized, that is, materials that are strongly attracted by magnets, are called ferromagnetic materials (or ferrimagnetic materials). These include the elements iron, nickel and cobalt and their alloys, some rare earth metal alloys, and some naturally occurring minerals such as magnetite.
Traditionally, only those materials that exhibit ferromagnetism (or ferrimagnetism) have been called "magnetic". Only nine elements are ferromagnetic. All are metals, of which three (Fe, Co, Ni) are iron group metals and the other six (Gd, Tb, Dy, Ho, Er, Tm) are rare earth metals.
The transition metals Fe and Co are essential elements for the preparation of alloys and compounds with large Curie temperatures (TC) and large spontaneous magnetization (Ms). Some intermetallic compounds with rare earth metals are characterized by very high values of magnetocrystalline anisotropy and magnetostriction.
- The Fabrication of Magnetic Materials
The fabrication of magnetic materials is a long-standing topic, and today magnetic materials are used in a variety of applications, including magnetic recording, magnetic sensor technology, magnetic levitation, magnetic cooling, spintronics, and more. However, modern challenges of ecological, resource-friendly, and environmental concerns place more stringent requirements on the study of magnetic materials.
Much effort has been put into producing environmentally friendly materials to reduce energy consumption in use, improve cost-effectiveness, reduce the weight of equipment, and consume fewer resources such as expensive rare earth materials or rare lithium. In addition, material recycling issues must also be considered.
[More to come ...]
