Sintered ferrite magnet and motor provided therewith

Patent metadata

Field	Value
Publication number	US-9514871-B2
Application number	US-201314379667-A
Country	US
Kind code	B2
Filing date	Feb 20, 2013
Priority date	Feb 20, 2012
Publication date	Dec 6, 2016
Grant date	Dec 6, 2016

Abstract

Provided is a sintered ferrite magnet 10 that comprises Sr ferrite having a hexagonal crystal structure, wherein the total amount of Na and K is 0.004 to 0.31% by mass in terms of Na 2 O and K 2 O, an amount of Si is 0.3 to 0.94% by mass in terms of SiO 2 , and the following Expression (1) is satisfied.

1.3≦(Sr F +Ba+Ca+2Na+2K)/Si≦5.7  (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, comprising:
M-type Sr ferrite having a hexagonal crystal structure,
wherein a total amount of Na and K is 0.004 to 0.169% by mass in terms of Na 2 O and K 2 O,
an amount of Si is 0.3 to 0.94% by mass in terms of SiO 2 , and
the following Expression (1) is satisfied:
1.3(Sr F +Ba+Ca+2Na+2K)/Si≦5.7  (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,
wherein the following Expression (3) is satisfied:
Br+1/3HcJ≧5.3  (3),

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

2. A sintered ferrite magnet, comprising:
M-type Sr ferrite having a hexagonal crystal structure,
wherein a total amount of Na and K is 0.004 to 0.169% by mass in terms of Na 2 O and K 2 O,
an amount of Si is 0.3 to 0.94% by mass in terms of SiO 2 , and
the following Expression (1) is satisfied:
1.3≦(Sr F +Ba+Ca+2Na+2K)/Si≦5.7  (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,
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.

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

4. A motor, comprising:
the sintered ferrite magnet according to claim 2 .

Assignees

• Tdk Corp

Inventors

• Taguchi Hitoshi

Classifications

• C04B2235/5409

  expressed by specific surface values · 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

• C04B2235/3208

  Calcium oxide or oxide-forming salts thereof, e.g. lime · CPC title

• C04B2235/785

  Submicron sized grains, i.e. from 0,1 to 1 micron · CPC title

• H01F1/11 Primary

  in the form of particles {(for magnetic record carriers G11B5/70626)} · CPC title