Sintered ferrite magnet and motor provided therewith

Patent metadata

Field	Value
Publication number	US-9460835-B2
Application number	US-201314379012-A
Country	US
Kind code	B2
Filing date	Feb 20, 2013
Priority date	Feb 20, 2012
Publication date	Oct 4, 2016
Grant date	Oct 4, 2016

Abstract

Provided is a sintered ferrite magnet 10 that contains Sr ferrite having a hexagonal crystal structure, wherein the total amount of Na and K is 0.01 to 0.09% by mass in terms of Na 2 O and K 2 O, an amount of Si is 0.1 to 0.29% by mass in terms of SiO 2 , and the following Expression (1) is satisfied.

2.5≦(Sr F +Ba+Ca+2Na+2K)/Si≦5.4  (1)

[In Expression (1), Sr F represents an amount of Sr, on a molar basis, other than Sr which constitutes the Sr ferrite, and Ba, Ca, Na, and K represent amounts of respective elements on a molar basis.]

First claim

The invention claimed is:

1. A sintered ferrite magnet, containing:
M-type Sr ferrite having a hexagonal crystal structure,
wherein a total amount of Na and K is 0.01 to 0.09% by mass in terms of Na 2 O and K 2 O,
an amount of Si is 0.1 to 0.29% by mass in terms of SiO 2 , and
the following Expression (1) is satisfied:
2.5≦(Sr F +Ba+Ca+2Na+2K)/Si≦5.4  (1),

wherein in Expression (1), Sr F represents an amount of Sr, on a molar basis, other than Sr which constitutes the Sr ferrite, and Ba, Ca, Na, and K represent amounts of respective elements on a molar basis.

2. The sintered ferrite magnet according to claim 1 ,
wherein the following Expression (2) is satisfied:
3.2≦(Sr F Ba+Ca+2Na+2K)/Si≦3.5  (2),

wherein in Expression (2), Sr F represents an amount of Sr, on a molar basis, other than Sr which constitutes the Sr ferrite, and Ba, Ca, Na, and K represent amounts of respective elements on a molar basis.

3. The sintered ferrite magnet according to claim 1 ,
wherein the following Expression (3) is satisfied:
Br+⅓HcJ≧5.2  (3),

wherein in Expression (3), Br and HcJ represent a residual magnetic flux density (kG) and a coercive force (kOe), respectively.

4. The sintered ferrite magnet according to claim 1 ,
wherein an average grain size of crystal grains of the Sr ferrite is 1.0 μm or less, and
a ratio of the crystal grains, which have a grain size of 2.0 μm or more, on the number basis is 1% or less.

5. A motor, comprising:
the sintered ferrite magnet according to claim 1 .

Assignees

• Tdk Corp

Inventors

• Taguchi Hitoshi

Classifications

• H02K1/02

  characterised by the magnetic material · CPC title

• C04B2235/728

  Silicon content · CPC title

• C04B35/6262

  of calcined, sintered clinker or ceramics · CPC title

• C04B2235/3418

  Silicon oxide, silicic acids or oxide forming salts thereof, e.g. silica sol, fused silica, silica fume, cristobalite, quartz or flint · CPC title

• C04B2235/80

  Phases present in the sintered or melt-cast ceramic products other than the main phase · CPC title