Among metals, there are those that have magnetization properties. These include iron, nickel and cobalt. Gadolinium acquires ferromagnetic properties at temperatures below 0 ° C. When these elements are added to the alloy, magnetic steel is obtained. In addition, they are characterized by the presence of residual induction and coercive force.
Magnetic steels and alloys
All alloys with magnetism can be divided into 2 types:
- hard magnetic;
- soft magnetic.
Solid steels comply with GOST 6862-71 and permanent magnets are produced from them. For this, high-carbon substances doped with chromium or chromium and cobalt are used.
Iron-based alloys can also be used to produce dc magnets. An example is alnico material, where 54% is iron.
Soft magnetic - so in a different way called electrical steel. They must comply with GOST 21427-75. Such magnetic steels are used to work in variable fields, where magnetization occurs without interruption. Hard magnetic materials possess significant residual induction, high coercive force. Low magnetic permeability becomes an additional property of the alloy.
The material is used to make the cores of coils of electromagnets and transformers. Silicon and low-carbon alloys are suitable for this.
Magnetic steel is marked with a four-digit number. The first number determines the structure and type of rolling. The second is the silicon content. The third number determines the heat loss, the fourth - the code of the normalized parameter.
To work in alternating fields, you can use magnetic steel based on iron or nickel. An example of such a material is alsifer.
Ferrites
To reduce electrical losses, an increase in resistivity is used. Magnetic steel plays an important role in modern manufacturing. Magnetic materials, ferrites, have great resistance.
Ferrites are obtained from oxides by powder metallurgy. Such materials have the properties of a ferromagnet and dielectric, which allows them to be used where high and ultrahigh frequencies are used.
The cost of ferrite cores is lower than the rest due to automation of production. Alloys can be divided into 4 groups:
- sintered;
- deformable;
- cast;
- press magnets.
Alloys
Magnetic steel for a permanent magnet must have a sufficient amount of carbon that is in the solid solution. Such alloys are called deformable. High carbon materials are considered the simplest and cheapest. The addition of cobalt increases the magnetic properties of steel.
Alloys include alloys based on Fe — Ni — A1. More than 80% of magnets are made of such a material. The highest quality alloys of this group have very powerful magnetism. They differ from carbon and chrome magnetic steel.
Small magnets are produced by sintering. This will require nickel, aluminum and high purity iron. They are famous for their high hardness. This method creates magnets from magnetically solid ferrites. The most popular were barium ferrites due to the high magnetic properties and reasonable prices.