The emergence of high-performance core materials has improved equipment performance such as motors and transformers, promoting the development of emerging industries like new energy vehicles and photovoltaic energy storage. In addition to amorphous alloys, commonly used high-performance core materials include 6.5% silicon steel, cobalt iron, nickel iron, and metal soft magnetic powder cores.
Core Materials: Amorphous Alloy
Compared to traditional silicon steel sheet motors, amorphous alloy motors have significant advantages in power density and energy efficiency. In terms of the material itself, amorphous alloys have lower density, smaller volume, and lighter weight. From a magnetic performance perspective, amorphous alloys exhibit high magnetic permeability, high electrical resistivity, low losses, and low coercivity.
This means that for the same power and speed, amorphous alloy motors are smaller and lighter. In medium to high-frequency applications, the iron loss of amorphous alloys is only about 1/8 to 1/10 that of ordinary silicon steel sheets, with this trend becoming more pronounced at higher frequencies. Motors using amorphous alloy nanocrystalline cores can achieve a power density of up to 12 kW/kg while reducing core losses by 50%, effectively lowering the motor’s energy loss.
However, the brittle and hard physical properties of amorphous alloy materials make them highly sensitive to processing techniques, making it difficult to process amorphous alloy into complex shapes, which poses challenges for the industrialization of amorphous alloy materials.
6.5% Silicon Steel
As the silicon content increases, the magnetostriction coefficient of silicon steel decreases, iron loss decreases, and magnetic permeability increases. When the silicon content reaches 6.5%, the magnetic permeability of silicon steel reaches its maximum, exhibiting excellent magnetic properties. However, 6.5% silicon steel is brittle and has poor processing performance, making it difficult to make complicated shapes. In terms of applications, 6.5% silicon steel is an ideal core material for high-frequency motors.
Cobalt Iron
Alloyed with iron, cobalt reaches extremely high saturation magnetization at room temperature. However, cobalt iron is usually expensive due to its high cobalt content. Typical applications include airborne motors, oil field motors, and specialized electric and hybrid systems in motorsports.
Nickel Iron
It is primarily composed of nickel and iron. Also, it contains other elements such as Cr, Si, S, P, and C. Nickel iron’s main advantages are high magnetic permeability and low coercivity. Its limitations are low saturation and maximum flux density. Nickel iron is mainly used in low-loss motors, such as those required in aerospace for low-loss.
Metal Soft Magnetic Powder
Magnetic particles are uniformly dispersed in a non-magnetic medium, which can reduce high-frequency eddy current losses and increase application frequency. It has advantages such as low density, lightweight, high production efficiency, low cost, and good product consistency. However, because magnetic particles are separated by non-magnetic materials, some magnetic circuits are interrupted. Currently, metal soft magnetic powder cores can be used as stator materials for axial flux motors.
Overall, through methods such as optimizing alloy formulations, improving preparation processes, and controlling grain structures, the magnetic performance of core materials can be enhanced, and hysteresis and eddy current losses reduced, thereby improving motor efficiency and power density. As motor technology continues to advance, the use of high-performance core materials will become increasingly widespread.
High-Performance Cores Materials Provider
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Image Source: Jfe-steel & Researchgate & Nanoshel & Samaterials & Vacuumschmelze
