Posts
Micro-structure-influence research on the double phase nano-composite permanent magnet
Micro-structure-influence research on the double phase nano-composite permanent magnet
As new permanent magnets, double-phase nanocomposite permanent magnets have recently attracted considerable attention. This type of alloys integrates advantages of hard magnetic phase??s high magnetocrystalline anisotropy and soft magnetic phase??s high saturation magnetization, and obtains the excellent magnetic properties through exchange-coupled interaction on a scale of the order nm. Theoretical estimation indicates that double-phase nanocomposite permanent magnet material??s energy product may reach as high as 800kJ/m3, higher than any kind of single-phase permanent-magnet material. This kind of material also has characteristics of low rare earth content and good chemical stability, Therefore, it is of great practical value and to be the new generation of low price caking permanent-magnet material, it will have promising application prospect.
Firstly, this author studied the take-shape craft of double-phase nanocomposite permanent magnet material, including the performance by pressure and time??s maintenance to magnet??s density and the magnetism.
The result indicates that the magnet density increases along with the pressure and time. The magnet density reaches the biggest one when pressure is 600MPa and time is 150s. When the pressure or the time is continually increased, the magnet density will no longer increase, there is possibility to create break interior and reduce the production efficiency. This suppressed craft was still used in following experiments.
Optimization Design of Permanent Magnetic Mechanism in High Magnetic Field
Optimization Design of Permanent Magnetic Mechanism in High Magnetic Field
The permanent magnets with high field intensity are used in medical systems,military affair and high-energy physics fields.They are usually electromagnets or superconductor magnets at present.If we design the size of the permanent magnetic mechanism properly,there will be much higher magnetic field than its remanence in the center,and it can replace the superconductor magnet and electromagnet.So with the development of properties about permanent magnetic material,the optimization design of the permanent magnetic mechanism with high magnetic field must develop well in the future in the magnetic field.
There is a kind of special permanent magnetic mechanism permanent magic ring which is made up of permanent magnet blocks.Their magnetized direction changes equably.In the assembly complex process, the permanent magnet blocks with different magnetized direction will impact each other, and might bring the local demagnetization or saturation.So the work point of permanent magnetic material might be at the whole hysteresis loop including minor hysteresis loop.The traditional method only considers the demagnetized curve of the magnetic material, so inevitably there are some errors in simulating the magnetic characteristic in the high magnetic field.
What is the magnets?
A magnet is a material or object that produces a magnetic field. This magnetic field is invisible but is responsible for the most notable property of a magnet: a force that pulls on other ferromagnetic materials, such as iron, and attracts or repels other magnets.
A permanent magnet is an object made from a material that is magnetized and creates its own persistent magnetic field. An everyday example is a refrigerator magnet used to hold notes on a refrigerator door. Materials that can be magnetized, which are also the ones that are strongly attracted to a magnet, are called ferromagnetic (or ferrimagnetic). These include iron, nickel, cobalt, some alloys of rare earth metals, and some naturally occurring minerals such as lodestone. Although ferromagnetic (and ferrimagnetic) materials are the only ones attracted to a magnet strongly enough to be commonly considered magnetic, all other substances respond weakly to a magnetic field, by one of several other types of magnetism.
Ferromagnetic materials can be divided into magnetically “soft” materials like annealed iron, which can be magnetized but do not tend to stay magnetized, and magnetically “hard” materials, which do. Permanent magnets are made from “hard” ferromagnetic materials such as alnico and ferrite that are subjected to special processing in a powerful magnetic field during manufacture, to align their internal microcrystalline structure, making them very hard to demagnetize. To demagnetize a saturated magnet, a certain magnetic field must be applied, and this threshold depends on coercivity of the respective material. “Hard” materials have high coercivity, whereas “soft” materials have low coercivity.
An electromagnet is made from a coil of wire that acts as a magnet when an electric current passes through it but stops being a magnet when the current stops. Often, an electromagnet is wrapped around a core of ferromagnetic material like steel, which enhances the magnetic field produced by the coil.
The overall strength of a magnet is measured by its magnetic moment or, alternately, the total magnetic flux it produces. The local strength of the magnetism in a material is measured by its magnetization.
