Types, characteristics, and application scope of soft magnetic materials

Soft magnetic materials refer to materials that undergo magnetization at Hc not exceeding 1000A/m, and are called soft magnets. A typical soft magnetic material can achieve maximum magnetization with the smallest external magnetic field. Soft magnetic materials are magnetic materials with low coercivity and high permeability. Soft magnetic materials are easy to magnetize and demagnetize, and are widely used in electrical and electronic equipment. The most commonly used soft magnetic materials are iron silicon alloys (silicon steel sheets) and various soft magnetic ferrite materials. It has the characteristics of narrow and steep hysteresis loop, nearly reversible magnetization process, low hysteresis loss, high permeability, and low coercive force. Such as silicon steel sheets, industrial pure iron, pure carbon steel, etc.

Magnetic materials with low coercivity, also known as high conductivity magnetic materials. Iron cores used in the manufacturing of electrical equipment such as motors and transformers in the power industry. Used in the electronics industry to manufacture various magnetic components, widely used in television, broadcasting, and communication. This type of material has characteristics such as high saturation magnetic flux density, high magnetic permeability, narrow hysteresis loops, small area, low hysteresis loss, and low residual magnetism and coercive force. When used in communication situations, low eddy current and hysteresis losses are required. Commonly used include pure iron, low-carbon steel, silicon steel sheet, permalloy, ferrite, etc.

(1) Pure iron and low-carbon steel: high magnetic permeability and good processing performance. However, due to high eddy current loss, it is only suitable for DC iron cores.

(2) Silicon steel sheet and strip: high resistivity and low eddy current loss. But the texture is brittle and the processing performance is poor. Laminate or roll into a circular shape for use, with insulating paint or an oxide layer formed between the sheets to reduce eddy current losses.

(3) Permalloy: A general term for iron nickel alloys, which have high magnetic permeability. Used for precision instruments, recording heads, and other applications where small volume is required.

(4) Ferrite: With Fe2O3 as the main component, mixed with Mn Zn or Ni Zn, it is pressed into manganese zinc ferrite or nickel zinc ferrite using powder metallurgy method. It has high resistivity and low high-frequency loss. The former is used for frequencies below 1MHz, while the latter is used for microwave frequencies. The higher the operating frequency, the lower its magnetic permeability. Ferrites belong to ferrous magnetic materials, with lower magnetic permeability than ferromagnetic materials.

A typical soft magnetic material can achieve maximum magnetization with the smallest external magnetic field. Soft magnetic materials can be divided into three categories: metal soft magnetic materials, ferrite soft magnetic materials, and magnetic media. Metal soft magnetism can be further divided into four categories: electromagnetic pure iron, silicon steel sheet, iron nickel alloy, and iron aluminum alloy.