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Showa Denko Develops Dysprosium-free Magnetic Alloy
for Factory Automation Applications

Showa Denko K.K.
Nov 26, 2013

Showa Denko (SDK) (TOKYO:4004) has developed a new grade of neodymium-based magnetic alloy for factory automation (FA) applications, which alloy does not contain dysprosium (element symbol: Dy) but gives the same performance as conventional products in which Dy is added to increase heat resistance. SDK has started commercial production of the new product.

While SDK has already commercialized Dy-free magnetic alloys for HDD voice coil motor and wind-power generation motor applications, the company this time has developed a new Dy-free magnetic alloy for FA applications, in which higher levels of Dy is usually added. The new technology will enable SDK to further reduce the levels of added Dy for more demanding applications such as electrically-assisted power steering and electric vehicles. Thus, the new technology will contribute toward solving the future problem of resource limitations.

1. Reductions in levels of added Dy, as realized in SDK’s magnetic alloys

The magnetic force of a magnet is in inverse proportion to its coercive force (resistance to a magnetic field on the outside), and magnetic force weakens as the temperature rises. While neodymium-based magnets with high magnetic force are used in electric motors for industrial products, cars, and industrial machinery, Dy is added to these magnets to increase their heat resistance. However, Dy is especially scarce among all rare earth minerals, occurring only in very limited areas in the world, such as Jiangxi, Guandong, and Fujian provinces, of China. Although demand for high-performance neodymium-based magnets is expected to grow for energy conservation purposes, there is concern about the availability of raw materials in the future.

SDK has therefore been promoting R&D on Dy-free magnetic alloys, succeeding this time in developing a Dy-free magnetic alloy that gives the same performance as conventional products in which 4% by weight of Dy is added. (SDK is already mass-producing a Dy-free alloy comparable to conventional products in which 2% by weight of Dy is added.)

Comparison, by magnet application, of levels of added Dy (in terms of ratio by weight)
Conventional
products
SDK’s products Main applications of magnets
1% 0% Motors and speakers of communication equipment
2% 0% Voice coil motors for HDDs; wind-power generation motors
4% 0%
Realized this time
Factory automation
6% 2% Electrically-assisted power steering for vehicles
8% 4% Motors and power generators for hybrid cars and electric vehicles
2. Outline of the new technology

Neodymium-based magnets generally have two phases, namely, the main phase (with magnetism) and the grain boundary phase. However, a “third phase,” consisting mainly of iron, arises in magnets produced by using the new Dy-free magnetic alloy developed by SDK. This third phase is considered to be effective in increasing coercive force.

There is no need on the part of magnet producers to introduce a new facility or additional process in producing magnets using the new magnetic alloy developed by SDK. Furthermore, magnet producers can use other Dy-conserving technologies in combination to further reduce the levels of added Dy.

Based on the new technology, SDK is working to further reduce the levels of added Dy. Next year, SDK will develop another new grade of Dy-free magnetic alloy that gives the same performance as conventional products in which 6% by weight of Dy is added. Thus, SDK will continue contributing toward further energy conservation.

[Reference]

Scanning electron microscopy (SEM) image of ordinary neodymium-based magnet (cross-section) 

Scanning electron microscopy (SEM) image of the new neodymium-based magnet (cross-section) 

 

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