1) iron powder core Ordinary iron powder core consists of carbon-based iron magnetic powder and resin carbon-based iron magnetic powder. The price is the lowest among the powder cores. The saturation magnetic induction intensity is about1.4t; The range of permeability is 22 ~100; The initial permeability μi has good stability with frequency; DC current superposition performance is good; But the loss is high at high frequency. Variation of initial permeability of iron powder core with DC magnetic field strength. Variation of initial magnetic permeability of iron powder core with frequency (2) Permalloy powder core Permalloy powder core mainly includes molybdenum permalloy powder core (MPP) and Qualcomm powder core. MPP consists of 8 1%Ni, 2%Mo and Fe powders. The main features are: the saturation magnetic induction intensity is about 7500Gs, and the permeability range is large, from 14 to 550; It has the lowest loss in the powder core; Excellent temperature stability, widely used in aerospace equipment, outdoor equipment and so on. The magnetostrictive coefficient is close to zero, and there is no noise when working at different frequencies. It is mainly used for high quality factor Q filters below 300kHz, inductive load coils, resonant circuits, LC circuits requiring high temperature stability, output inductors, power factor compensation circuits, etc. Commonly used in AC circuits, powder core is the most expensive. Qualcomm powder core HF consists of 50%Ni and 50%Fe powder. The main features are: the saturation magnetic induction intensity is about15000 GS; The range of permeability is14 ~160; It has the highest magnetic induction intensity and the highest DC bias ability in the powder core; The size of the magnetic core is very small. Mainly used in line filters, AC inductors, output inductors, power factor correction circuits, etc. It is usually used in DC circuits, mostly for high DC bias, high DC and low AC. The price is lower than MPP. (3) The iron, silicon and aluminum cores of Kool mμ magnetic core consist of 9% Al, 5% Si and 85% Fe powder. Mainly replacing iron powder core, the loss is 80% lower than that of iron powder core, so it can be used at frequencies above 8kHz. The saturation magnetic induction intensity is about1.05t; The permeability is from 26 to125; The magnetostrictive coefficient is close to 0, and no noise is generated when working at different frequencies; It has higher DC bias ability than MPP; It has the best cost performance. Mainly used in AC inductors, output inductors, line filters, power factor correction circuits, etc. Sometimes it is used to replace ferrite with air gap as transformer core. 2. Ferrite soft ferrite soft ferrite is a kind of ferrimagnetic oxide with Fe2O3 as the main component, which is produced by powder metallurgy. There are several types, such as manganese zinc, copper zinc, nickel zinc and so on. Among them, the output and consumption of Mn-Zn ferrite is the largest, and the resistivity of Mn-Zn ferrite is low, which is 1 ~ 10 ohm-m, and it is generally used at frequencies below 100kHZ. The resistivity of Cu-Zn and Ni-Zn ferrites is 102 ~ 104 ohm-m, and the loss is very small in the radio frequency range of 100 kHz ~ 10 MHz, so they are mostly used in radio antenna coils and radio intermediate frequency transformers. There are many kinds of magnetic cores, such as E, I, U, EC, ETD, square (RM, EP, PQ), can (PC, RS, ds) and round. This is a very convenient application. Because soft ferrite can obtain high permeability without using scarce materials such as nickel, powder metallurgy method is suitable for mass production, so the cost is low, and because sintered materials are hard and insensitive to stress, it is very convenient in application. Moreover, the change of magnetic permeability with frequency is relatively stable, and it remains basically unchanged below 150kHz. With the appearance of soft ferrite, the output of magnetic powder core is greatly reduced, and many places where magnetic powder core was originally used have been replaced by soft ferrite. There are many manufacturers of ferrite at home and abroad. Here, the application of Mn-Zn ferrite produced by Magnetics Company in the United States is introduced. It is divided into three basic materials: telecom basic materials, broadband and EMI materials and power supply materials. The magnetic permeability of communication ferrite ranges from 750 to 2300, with low loss factor, high quality factor Q and stable relationship between magnetic permeability and temperature/time. It is the type with the slowest decline in permeability in operation, with a decrease of 3% to 4% every 10 year. Widely used in high Q filters, tuned filters, load coils, impedance matching transformers and proximity sensors. Broadband ferrite, also known as high permeability ferrite, has permeability of 5000, 10000 and 15000 respectively. It is characterized by low loss factor, high permeability and high impedance/frequency characteristics. Widely used in * * * mode filters, saturation inductors, current transformers, leakage protectors, insulation transformers, signal and pulse transformers, and widely used in broadband transformers and EMI. Power ferrite has a high saturation magnetic induction intensity of 4000~5000Gs. In addition, it has low loss/frequency relationship and low loss/temperature relationship. That is to say, with the increase of frequency, the loss does not increase much; With the increase of temperature, the loss does not change much. Widely used in power chokes, shunt filters, switching power supply transformers, switching power supply inductors and power factor correction circuits. (2) Belt wound iron 1. Silicon steel sheet iron core Silicon steel sheet is an alloy, and the iron-silicon alloy formed by adding a small amount of silicon (generally below 4.5%) to pure iron is called silicon steel. The saturation magnetic induction intensity of this iron core can reach up to 20000Gs；; Because of its good magnetoelectric performance, easy mass production, low price and little influence by mechanical stress, it is widely used in power electronics industry, such as power transformers, distribution transformers, current transformers and other iron cores. It is the material with the largest output and consumption in soft magnetic materials. It is also the most used magnetic material for power transformers. Especially at low frequency and high power. Commonly used are cold-rolled silicon steel sheet DG3, cold-rolled non-oriented electrical steel strip DW and cold-rolled oriented electrical steel strip DQ, which are suitable for small and medium power low-frequency transformers, choke coils, reactors and inductive cores in various electronic systems and household appliances. This kind of alloy has good toughness, and can be used for punching and cutting, core lamination and winding. However, the loss increases sharply at high frequency, and the general use frequency is less than 400Hz. From the application point of view, the selection of silicon steel should consider two factors: magnetism and cost. For small motors, reactors and relays, pure iron or low silicon steel sheets can be selected; For large motors, high-silicon hot-rolled silicon steel sheets and unidirectional or non-oriented cold-rolled silicon steel sheets can be selected; Single-oriented cold-rolled silicon steel sheets are often used in transformers. When used at power frequency, the thickness of ordinary steel strip is 0.2~0.35 mm; When used at 400Hz, the thickness of 0. 1 mm is usually selected. The thinner the thickness, the higher the price. 2.Permo alloy Permo alloy iron core Permo alloy often refers to iron-nickel alloy, and the nickel content is in the range of 30~90%. It is a very widely used soft magnetic alloy. The magnetic properties can be effectively controlled by proper technology, such as the initial permeability exceeding 105, the maximum permeability exceeding 106, the coercivity as low as 2‰ Oster, and the rectangular coefficient approaching 1 or approaching 0. Permo alloy with face-centered cubic crystal structure has good plasticity, and can be processed into ultra-thin strip with 65,438+0 micron and various use forms. Commonly used alloys are 1J50, 1J79, 1J85, etc. The saturated magnetic induction of 1J50 is slightly lower than that of silicon steel, but its magnetic permeability is several times higher and its iron loss is 2~3 times lower than that of silicon steel. The transformer with higher frequency (400~8000Hz) has small no-load current, and is suitable for making small-sized transformer with higher frequency below 100W. 1J79 has good comprehensive performance, and is suitable for high and low voltage transformers, leakage protection switch cores, * * * mode inductor cores and current transformer cores. The initial permeability of 1J85 can reach more than 100000 105, which is suitable for low-frequency or high-frequency input-output transformers, * * * mode inductors and high-precision current transformers with weak signals. 3. Amorphous and nanocrystalline soft magnetic alloy silicon steel and permalloy soft magnetic materials are crystalline materials. Atoms are regularly arranged in three-dimensional space, forming a periodic lattice structure, and there are defects such as crystal grains, grain boundaries, dislocations, interstitial atoms and magnetocrystalline anisotropy, which are unfavorable to soft magnetic properties. In magnetic physics, the amorphous structure with irregular arrangement of atoms, no periodicity and grain boundaries is very ideal for obtaining excellent soft magnetic properties. Amorphous metals and alloys are a new material field that appeared in 1970s. Its preparation process is completely different from the traditional method, but it adopts the ultra-fast cooling and solidification technology with the cooling rate of about one million degrees per second, which reduces many intermediate processes from molten steel to finished thin strip products compared with the general cold-rolled metal thin strip manufacturing process. This new process is called the revolution of traditional metallurgical technology. Due to ultra-rapid solidification, atoms cannot be arranged and crystallized in order when the alloy is solidified. The obtained solid alloy has a long-range disordered structure, and there are no grains and grain boundaries of crystalline alloy. Known as amorphous alloy, it is called a revolution in metallurgical materials science. This amorphous alloy has many unique properties, such as excellent magnetism, corrosion resistance, wear resistance, high strength, hardness and toughness, high resistivity and electromechanical coupling performance. Because of its excellent performance and simple technology, it has become a research hotspot in the field of materials science at home and abroad since 1980s. At present, the United States, Japan and Germany have perfect production scale, and a large number of amorphous alloy products have gradually replaced silicon steel, permalloy and ferrite to enter the market. China has been researching and developing amorphous alloys since 1970s. After the completion of major scientific and technological key projects during the Sixth Five-Year Plan, the Seventh Five-Year Plan and the Eighth Five-Year Plan, * * has achieved scientific research achievements 134, 2 national invention awards, and 0/6 patents, and nearly 100 alloy varieties. Iron and Steel Research Institute now has four amorphous alloy strip production lines and one amorphous alloy component iron core production line. Production of various iron-based, iron-nickel-based, cobalt-based, nanocrystalline tapes and magnetic cores, suitable for inverter power supply, switching power supply, power transformer, leakage protector and inductive magnetic core components, with an annual output value of nearly 20 million yuan. During the Ninth Five-Year Plan period, the1000t iron-based amorphous production line is under construction, which has reached the international advanced level. At present, the best single performance level of amorphous soft magnetic alloy is: initial permeability μo = 14 × 104, maximum permeability micron of cobalt-based amorphous = 220 × 104, and coercivity HC of cobalt-based amorphous = 0.001OE magnetic material.
Cobalt-based amorphous rectangle ratio Br/Bs = 0.995 Co-based amorphous saturation magnetization 4πMs = 18300Gs Iron-based amorphous resistivity ρ = 270μ Ω/cm Commonly used amorphous alloys are: iron-based, iron-nickel-based, cobalt-based amorphous alloys and iron-based nanocrystalline alloys. See table and figure for its national brand and performance characteristics. For comparison, the corresponding properties of crystalline alloy silicon steel sheet, permalloy 1J79 and ferrite are also listed. These materials have different characteristics and are used in different aspects. The basic composition and characteristics of the brand:1k10/Fe-Si-B rapidly quenched soft magnetic base alloy 102 Fe-Si-B-C rapidly quenched soft magnetic base alloy 1K 103 Fe-Si-B-Ni rapidly quenched alloy. -Si-B-Ni Mo fast-quenched soft magnetic base alloy 1K 105 Fe-Si-B-Cr (and other elements) 1K 106 fast-quenched soft magnetic base alloy1k/Kloc-0. Rapidly quenched soft magnetic cobalt-based alloy and quenched soft magnetic cobalt-based alloy 1K203 high magnetic induction low loss fast quenched soft magnetic cobalt-based alloy 1K204 high frequency low loss fast quenched soft magnetic cobalt-based alloy 1K205 high initial magnetic permeability fast quenched soft magnetic cobalt-based alloy 1K50 1 Fe-Ni-P-B system.