What is a permanent magnet
A permanent magnet is made of material that has permanent magnetic properties, even if it is not in a magnetic field.
For the magnetism of the iron present is responsible. Many iron alloys exhibit magnetism. In addition to iron, for example have also nickel and cobalt on magnetic properties. There are natural and artificial magnets (z. B. Alnico, Fernico, ferrite).
One side of the magnet is the North Pole, called the other pole. North and south poles attract each other, which decreases as the square of distance between them. Like poles (North-North and South-South) repel. Field lines are imaginary lines which indicate the direction of the magnetic field at a particular location.They can be made visible when the magnet by a sheet of paper is placed on the magnet and fine iron dust is scattered thereon. The iron dust will align along the field lines, and make them visible. Under special conditions, a permanent magnet lose these magnetic properties, eg. As when heated (see Curie temperature), with shock loads or by degaussing with external magnetic fields.
Our magnets have a quality in which the loss of the magnetic properties can be neglected, if they are in accordance with the specification given as temperature range and external magnetic fields, used.
Originally permanent magnets made of steel were produced. Today there are a number of alloys that are ideally suited for this purpose.
A basic distinction in physics between diamagnetic, paramagnetic and ferromagnetic materials.
Diamagnetic weaken an applied magnetic field due to the Lenz’s law within the material. The atoms or molecules of a diamagnets have no unpaired electrons and thus no magnetic spin moment.
Paramagnetic substances consist of atoms or molecules, unpaired electrons and thus have a magnetic moment. Para magnets are permanent magnets bad.
Ferromagnets have as paramagnet atoms or molecules with permanent magnetic moment. The difference now is that the magnetic moments interact in this case and affect each other. Align spontaneously parallel to one another, even without applied external magnetic field. However, this arrangement takes place in so-called “White’s districts” whose direction is randomly distributed, so that overall no net magnetic field.
If now however, an external magnetic field on the alignment of all magnetic moments in the material succeeds simultaneously. This magnetization is maintained even after the decay of the magnetic field. Ferromagnets are so good permanent magnets.
Permanent magnets play an important role in many technically demanding applications.
In the electrical engineering , they are indispensable, inter alia, dynamos, motors and relays.
In the automotive industry , the use of permanent magnets has increased greatly in recent years. Hybrid drives, airbags, ABS systems, navigation and entertainment electronics, lane change warning systems and a variety of sensors
rising applications can be found in the field of renewable energy sources (wind, solar and hydropower).
also, the magnetic handling of steel sheets is in the production processes used in many cases. Spreading for separating stacked steel sheets, magnetic gripper for automatic handling of steel and aluminum parts, with or without the assistance of robots, as well as the quick and accurate placement of steel sheets in machines, that’s all possible with the help of magnets.
For a long time are AlNiCo and ferrite famous sorts, but the demand for ever smaller and more powerful magnet has led to the development of magnetic species on the basis of materials of rare earths. These include samarium cobalt (SmCo) and neodymium (NdFeB). These varieties develop a very strong magnetic force at very small dimensions and are available in many different versions.