Small round magnets

5.7 NdFeB (Neodymium magnet) also known as NdFeB magnets, of the formula Nd2Fe14B, the permanent magnet is an artificial, so far the strongest permanent magnets having a magnetic force. Known as magnetic king, we have extremely high magnetic its biggest energy product (BHmax) higher than the ferrite (Ferrite) more than 10 times. Machining performance itself is also very good. Operating temperature up to 200 degrees Celsius. And its hard, stable performance, good price, so its application is extremely broad. But because of its chemical activity is very strong, it must deal with its surface coating. (E.g. plating Zn, Ni, electrophoresis, passivation, etc.). Neodymium magnets are Sumitomo Special Metals Corporation Sagawa, who live invented in 1982, known by its chemical formula, etc. which is mainly composed of neodymium, iron and boron chemical element of the composition. In many areas it is possible to replace the traditional ferrite magnets, alnico and samarium cobalt magnets such as motors, equipment and instrumentation, automotive, petrochemical industry and magnetic health-care products. We can produce a variety of shapes: such as disc magnets, ring magnets, rectangle magnets, arc magnets, and other shapes of magnets. Neodymium magnet having a strong magnetic field has been widely used in electronic products, such as hard drives, mobile phones, headsets, and so on. Also known as the main ingredient magnet magnet refers to the presence of magnetic objects or materials in and around their own internal, is divided into two major categories of natural and man-made. Artificial magnets usually made of metal alloys having a ferromagnetic. It can be divided into a "permanent magnet" and "non-permanent magnet," or "hard magnetic" and "soft." Natural magnet main ingredients: iron oxide, the chemical formula Fe3O4, often referred to as "the magnetic iron oxide." Magnetic black crystals. Compound ferrous oxide and iron oxide can be seen as. Because the iron oxide crystals in the presence of two different valence states of ions, a third of Fe2 +, two-thirds of Fe3 +, is a complex compound. It is insoluble in water, it can not react with water. And an acid, alkali-insoluble. The main system for primer and topcoat, magnetic materials for the electronics industry, but also for anti-rust agent construction industry. 6 6.1 Defining performance magnet has the following three performance parameters to determine the performance of the magnet: remanence Br: permanent magnet technology magnetized to saturation, and after removing the external magnetic field, called the retained residual magnetic flux density Br. Coercive force Hc: to technical saturation magnetization of the permanent magnet B is reduced to zero, the need to add a reverse magnetic field strength is called magnetic induction coercive force, referred to as coercivity magnetic energy product BH: represents the magnet gap Space magnetic energy (magnetic poles of two spaces) established by the density, i.e., the static magnetic energy per unit volume of the air gap. As this energy is equal to the product of the magnet Bm and Hm, so called energy product. Magnetic field: generating a magnetic effect on the magnetic field space. Surface magnetic field: the magnetic induction of the permanent magnet surface to a specified location. 6.2 diamagnetism diamagnetic are some categories of substance, when in an external magnetic field, the magnetic field will produce a weak magnetic repulsion phenomenon. 6.3 paramagnetic paramagnetic, refers to a material's magnetic state. Some material may be affected by external magnetic fields, generating means characteristic with opposite magnetization vectors. Such a substance having a positive magnetic susceptibility. And paramagnetic contrast phenomenon is called diamagnetic. 6.4 ferromagnetism ferromagnetism, refers to a material's magnetic state with spontaneous magnetization. Each material to iron the most well known, hence the name. Some materials under the effect of external magnetic field and was magnetized, even if the external magnetic field disappears, still able to maintain its state of magnetization and magnetic, i.e., the so-called phenomenon of spontaneous magnetization. All of the permanent magnets have ferromagnetic or ferrimagnetic. This concept includes a ferromagnetic substantially any display in the absence of an external magnetic field matter. Someone still has to use this concept. But through the different display a magnetic substance and a deeper understanding of magnetism, scholars have made the concept more precise definition. Only a matter of primitive cell all the magnetic ions are pointing to its magnetic orientation is known to be ferromagnetic. If only part of the ions toward its magnetic field direction, called ferrimagnetic. If it refers to the direction of magnetic ions exactly cancel each other (although all the magnetic ions only two points to opposite directions) is called antiferromagnetic. There is a phenomenon of the magnetic substance critical temperature, it will occur at this temperature. For ferromagnetic and ferrimagnetic substances, this temperature is called the Curie temperature; for the antiferromagnetic material, this temperature is known as Neil temperature. Some people think that attraction between the magnet and the ferromagnetic material is magnetic earliest human understanding. 6.5 Select magnet before deciding to choose which one should be a clear need for magnet magnet What is the role? Major role: a moving object, fixed object or lifting objects. The desired shape of the magnet: disc-shaped, circular, square-shaped, tile-shaped or special shapes. Magnets required dimensions: length, width, height, diameter and tolerance and so on. Required suction magnet, expected price and quantity, and so on. Compass is based on the nature of the magnet invention.