Magnetics Business & Technology - July/August 2024 - 11

FEATURE ARTICLE
Grain boundary diffusion process
It is a technology in which heavy rare earth elements powder
is applied to the surface of a rare earth permanent magnet and
then heated at a high temperature, and heavy rare earths are diffused
inside along with the interface of magnet grains, and finally
a HRE2Fe14B (= core shell) diffusion layer is formed with high
isotropic magnetic field, thus increasing the strength of the saw.
It is the most effective technology to improve the magnetization
of rare earth permanent magnets because expensive heavy earth
elements are selectively used for crystal grain interfaces. (It is possible
to reduce the use of heavy earth elements by 80% compared
to conventional technologies).
Neodymium voice coil motor magnets for providing the torque
needed to move the head stack assembly to a specific location. SDI
has been a long-time supplier of magnets for hard disk drives and
voice coil motors to Samsung Electronics, Seagate and Western
Digital.
Split magnet
As the development trend of the motor industry progresses in the
direction of high-speed and high-output, SGI has developed a split
magnet as a way to reduce the eddy current of rare earth permanent
magnets generated in motors rotating at high speed. Splitting
and bonding rare earth permanent magnets can reduce the
electrical conductivity of permanent magnets, which can effectively
reduce eddy current generated within permanent magnets. This
reduction in eddy current means that the heating of the motor can
be controlled, which means that it can reduce the number of rare
earth elements used in rare earth permanent magnets. SGI has an
optimal solution for a number of magnets, the shape, and direction
of the division of rare earth permanent magnets.
For more info, see www.sgtech.co.kr.
Linear motor magnets
Wind generator magnets from Star
Group
According to the company, it Is the only producer
of rare earth magnets in South Korea. SGI holds a
number of patents, including heavy earth element
powder manufacturing technology and uniform diffusion
technology, through years of research and
development. Its Production Technology Research
Institute cooperates with leading domestic and foreign
research institutes and companies in pursuit of
developing high magnetic force permanent magnets
that stably exhibit their magnetic performance even
at high temperatures. Below are examples of some
of its key technologies, as presented by the company
on its website.
Particle refinement technology
Generally, in the alloy manufacturing stage, the addition
of rare earth elements dysprosium (Dy) and
terbium (Tb) improves the magnetic force. However,
SGI has developed a technology to refine particles
and suppress grain growth as much as possible during
the sintering process when manufacturing rare
earth permanent magnet powders without adding
expensive heavy earth elements.
As a result, we have secured a technology for manufacturing
rare earth sintered magnets with improved
magnetic strength of 1.5 kOe compared to conventional
rare earth permanent magnets. In addition,
the reduction in residual magnetic flux density (Br)
was minimized because the cloth strength was improved
without adding heavy rare earth elements.
Precision Instruments for Professionals
Hemholtz Coil
Systems
FVM400 Vector
Magnetometer
* Turnkey 1, 2, 3 and 4
meter
* 3-Axis
* Range: ±200,000 nT
(2 Gauss)
* Resolution: 0.4 nT
* Accuracy: ±0.05% of
setting
* PC control through serial
COM port
MEDA.COM
SALES@MEDA.COM
703.996.8990
* 3-Axis
* ±100,000 nT Range
* ±0.25% Accuracy
* 1 nT Resolution
* RS232 Interface
RM100 Nanotesla
Meter
* ±200,000 nT Range
* ±0.01% Accuracy
* 0.1 nT Resolution
* RS232 & Ethernet
Connectivity
* Ambient Field
Cancellation
FAX: 703.996.8770
www.MagneticsMag.com
July/August 2024 * Magnetics Business & Technology 11
http://www.sgtech.co.kr http://www.MEDA.COM http://www.MagneticsMag.com
Magnetics Business & Technology - July/August 2024

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