In this article we will discuss about:- 1. Introduction to Magnetic Materials 2. Magnetic Parameters 3. Classification of Magnetic Materials 4. Paramagnetism 5. Diamagnetism 6. Feebly Magnetic Materials 7. Cast and Cermet Permanent Magnets 8. Metal Ceramic Technique of making Magnets 9. Ageing of a Permanent Magnet. Introduction to Magnetic Materials: Magnetic materials are those materials in which a state [...]
The magnetically soft materials are characterised as follows: (i) They have high permeability. (ii) The magnetic energy stored is not high. (iii) They have negligible coercive force (due to which these are not suitable for making permanent magnets). (iv) They have low remanence. The different magnetically soft materials are considered below: 1. Pure or Ingot Iron: It has high permeability [...]
For certain applications of soft or non-retentive materials, special alloys and other materials have been developed which, after proper fabrication and heat treatment, have superior properties in certain ranges of magnetisation. Several of these alloys will be described. 1. Nickel-Iron Alloys: i. Nickel: Nickel alloyed with iron in various proportions produces a series of alloys with a wide range of [...]
When magnetic materials are subjected to an alternating flux, two types of losses occur which are: 1. Hysteresis Loss 2. Eddy Current Loss The above losses comprise the total core loss. Type # 1. Hysteresis Loss: Below curie temperature (it is the rising temperature at which the given material ceases to be ferromagnetic, or the falling temperature at which it [...]
The B-H curve of a single crystal of ferromagnetic material depends on the crystal orientation relative to the field. Fig. 4.8 shows B-H curves for single crystal of iron and nickel, with the applied field along (111), (110), and (100) directions. In each case, one direction is more easily magnetized than the others. Saturation occurs at a lower field in [...]
In this article we will discuss about the phenomenon of magnetic hysteresis and why it occurs in ferromagnetic materials. The transition metals Fe, Co, and Ni, rare earth metals such as Gd, and a few oxides such as CrO2 and ErO display very large and permanent magnetization. In fact, these substances remain magnetized even when the field is removed. Their [...]
In this article we will discuss about the types of soft magnetic materials and its applications in electrical engineering. Types of Soft Magnetic Materials: 1. Soft Iron-Silicon Alloys: The most widely used type of soft magnetic material is the iron-silicon alloy. Before 1900, ordinary low-carbon steel was used for low frequency power applications, in transformers, generators, and motors. Today iron-silicon [...]
Just as dielectrics change their length when they are polarized (electrostriction), so do most magnetic materials change their length when they are magnetized. This is because of the fact that when the magnetic electron spins dipole moments of the atoms in a solid are rotated into alignment, the length of the bonds between the atoms changes. The fields of the [...]
Many solids that have small but positive magnetic susceptibilities are called paramagnetic. A magnetic dipole can minimize its potential energy by lining up with the magnetic field. Such alignment makes a positive contribution to the magnetization. The atoms in a solid may have permanent magnetic moments. Since paramagnetism depends upon magnetic moments of atoms or ions, the origin of these [...]
In this article we will discuss about:- 1. Meaning of Hard Magnetic Materials 2. Types of Hard Magnetic Materials 3. Applications. Meaning of Hard Magnetic Materials: Materials having the highest possible saturation magnetization, remanance, and coercive force are used as permanent magnets. The usefulness of a permanent magnet is determined by the magnetic energy it can deliver at various flux [...]