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Showa Denko's Patents for Rare Earth Magnetic Alloys

Showa Denko's Patents for Rare Earth Magnetic Alloys

Showa Denko K.K. (SDK) began developing rare earth magnetic alloys in 1987 using its metal refining technologies accumulated over many years.  As a result of such development efforts, SDK applied for patents: 77 in Japan and approximately 80 in foreign countries.  The following are typical examples of patents we have obtained so far:

Japanese Patents: 20

JP 2817624 JP 2880428 JP 3121577 JP 3234741
JP 3242818 JP 3267133 JP 3449166 JP 3536943
JP 3561692 JP 3721831 JP 4040571 JP 4048568
JP 4213417 JP 4219390 JP 4263366 JP 4305600
JP 4318204 JP 4366015 JP 4366360 JP 4406963

United States Patents: 9

US 5908513 US 5948179 US 5963774 US 6328825 US 6045629
US 7014718 US7431070 US 7442262 US 7571757

European Patents: 3

EP 0801402  EP 0886284  EP 1118601

Chinese Patents: 8

ZL97111284.3 ZL99809914.7 ZL99816359.7 ZL02800585.6
ZL02805097.5 ZL02817079.2 ZL200580010040.3 ZL200610168974.6

These patents pertain to the structure of quenched and solidified magnetic alloys, and its manufacturing process.  The patents cover a wide range of R-T-B rare earth magnetic alloys* produced mainly by the Strip-cast method**.  Because SDK highly values intellectual property, the company will take strong measures against any infringement on its patent rights. 


When you produce, use, transfer, export or import rare earth magnetic alloys inside and outside Japan, please pay your full attention to SDK's patents. 

Meanwhile, SDK grants a license under appropriate conditions to contribute to the growth of the industry.  Please contact the following in case you are interested in obtaining the license:

1. Strip-cast (SC) method

This refers to a metal casting method in which molten rare earth material is poured on a water-cooling roll, quenched, and solidified into a sheet.


Illustration of Strip-cast method



2. R-T-B rare earth magnetic alloys

(R: rare earth elements, including yttrium; T: transition metals; B: boron)

R-T-B alloys mainly consist of ferromagnetic R2T14B-phase crystals, which contribute to magnetization.  In the alloys, non-magnetic R-rich phase with a low melting point coexists.  The alloys are used in such applications as hard disk (HD) media, magnetic resonance imager (RMI), and various motors. 


Cross-section photo of an R-T-B rare earth magnetic alloy produced by the Strip-cast method

Intellectual Property Office

Research & Development Headquarters

Showa Denko K.K.

(Phone: 81-3-5470-3195)

The inquiry form is here.

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