The influence of powder morphology on the magnetic properties of FeNi50 magnetic powder cores
はじめに
The FeNi50 magnetic powder core is a new generation of soft magnetic material formed by pressing alloy powder after insulation coating. Compared with other soft magnetic materials, it has high magnetic permeability, low power loss and excellent DC superposition performance. In recent years, the FeNi50 magnetic powder core has broad application prospects in resonant power supplies, switching power supplies and filters. It is widely used in high-frequency power electronics, precision sensing, electromagnetic shielding, 3D printing / powder metallurgy, military and aerospace industries, etc., in the high-end fields.
The alloy powders prepared by the Gas Atomization process have gained popularity in the field of magnetic cores due to their high sphericality, narrow particle size distribution, and high bulk density. Currently, the research on magnetic cores based on Gas Atomized magnetic powders mainly focuses on the influence of powder alloy composition and coating processes on magnetic properties, while there is less research on the apparent properties of the powders. Generally, the particle size of the powders has a significant impact on the magnetic permeability of the magnetic cores, and the surface morphology affects the powder coating effect, thereby further influencing the magnetic permeability and power loss of the magnetic cores.
実験
FeNi50 alloy powders with different surface morphologies and particle size distributions was investigated through experiments, and focuses on studying the effects of powder morphology and particle size on the magnetic properties of FeNi50 magnetic cores.
Powder Information:
● Name: FeNi50 Soft Magnetic Powder
● Brand: TRUER
● Grade: 鉄ニッケル50
● Particle size: 15-45um
● 化学組成
TRUER Lot No. : 20260119-G
● Morphology:
The morphology of the FeNi50 alloy powder used in the experiment is shown in Figure 1.
● Permeability:
Figure 2 shows the relationship between the effective permeability of FeNi50 magnetic powder core and the powder morphology.
It can be seen that as the number of satellite ball particles in the powder decreases, the effective permeability increases. When the proportion of satellite balls is lower than 7.8%, the change in permeability gradually becomes more gradual. When the proportion of powder satellite balls increases, the surface smoothness of the powder decreases, and the specific surface area of the powder increases. During powder coating, there may be insufficient or incomplete coating; at the same time, during pressing, due to the irregularity of the powder surface, the coating film may rupture under the action of high pressure, thereby affecting the coating effect. When the proportion of satellite balls is lower than 7.8%, due to the low proportion of satellite balls, the influence on the forming of the magnetic core is relatively small, and therefore the change in effective permeability is not significant.
● Power loss
Figure 3 shows the relationship between power loss and powder morphology under the test conditions of 100 kHz/50 mT.
The power loss decreases as the number of satellite ball particles decreases. Although the number of satellite ball particles decreases, the possibility of bridge formation between powders decreases, and the powder particles are filled more densely. Due to the smoother surface of the powder particles with fewer satellite balls, it is easier to form a dense coating during powder coating, and less damage is caused to the coating during pressing, thus gradually reducing the power loss.
