Magnetic refrigeration material and manufacturing method of magnetic refrigeration material

Patent metadata

Field	Value
Publication number	US-9824803-B2
Application number	US-201214344269-A
Country	US
Kind code	B2
Filing date	Sep 12, 2012
Priority date	Sep 14, 2011
Publication date	Nov 21, 2017
Grant date	Nov 21, 2017

Abstract

A magnetic refrigeration material includes an alloy represented by a composition formula of La(Fe, Si) 13 H, and the alloy includes α-Fe by a weight ratio lower than 1 wt % and a plurality of pores so that a packing fraction of the alloy is within a range from 85% to 99%.

First claim

What is claimed is:

1. A magnetic refrigeration material comprising:
an alloy represented by a composition formula of La(Fe, Si) 13 H,
wherein the alloy further includes α-Fe by a weight ratio lower than 1 wt % and a plurality of pores so that a packing fraction of the alloy is within a range from 85% to 99%, and
wherein a maximum dimension of each of the plurality of pores is within a range from 1 μm to 200 μm, and
wherein the packing fraction is based on an actually measured density and a theoretical density of the alloy, and
wherein the packing fraction increases as an average grain diameter increases, and
wherein the alloy is made of a fine powder having a NaZn 13 crystal structure and a grain diameter equal to or lower than 214 micrometers, the fine powder prepared by:
combining La, Fe, and Si at respective predetermined ratios;
melting and rapidly cooling the powder raw material to obtain a sheet having the NaZn 13 crystal structure; and
powderizing the sheet to obtain the fine powder.

2. A manufacturing method of the magnetic refrigeration material of claim 1 comprising:
preparing powder raw material by combining La, Fe, and Si at respective predetermined ratios;
melting and rapidly cooling the powder raw material to obtain a sheet having a NaZn 13 crystal structure;
powderizing the sheet to obtain a fine powder having the NaZn 13 crystal structure and a grain diameter equal to or lower than 214 micrometers;
sintering the fine powder represented by a composition formula of La(Fe, Si) 13 at a temperature within a range from 950° C. to 1200° C. by a spark plasma sintering method to generate a sintered body; and
carrying out a hydrogen absorption to the sintered body after sintering the fine powder;
wherein the sintered body has a packing fraction within a range from 85% to 99% and includes α-Fe by a weight ratio lower than 1 wt %,
wherein the packing fraction is based on an actually measured density and a theoretical density of the sintered body, and
wherein the packing fraction increases as an average grain diameter increases.

3. The magnetic refrigeration material according to claim 1 , wherein a generation of a crack can be restricted by the packing fraction being within the range of 85% to 99% and the α-Fe weight ratio being lower than 1 wt %.

4. The manufacturing method according to claim 2 , wherein a difference in a degree of expansion by the absorption of hydrogen between the La(Fe, Si) 13 H and the α-Fe restricts a generation of a crack.

5. The manufacturing method according to claim 2 , wherein the average grain diameter is equal to or less than 214 micrometers.

6. The magnetic refrigeration material according to claim 1 , wherein a sintering temperature is in a range between 950° C. and 1200° C.

7. The manufacturing method according to claim 5 , wherein a difference in a degree of expansion by the absorption of hydrogen between the La(Fe, Si) 13 H and the α-Fe restricts a generation of a crack.

Assignees

• Fujinaka Tomonori
• Sakakibara Nobuyoshi
• Denso Corp

Inventors

• Fujinaka Tomonori
• Sakakibara Nobuyoshi

Classifications

• C22C33/0278

  with at least one alloying element having a minimum content above 5% · CPC title

• C22C38/02

  containing silicon · CPC title

• B22F3/11

  Making porous workpieces or articles · CPC title

• B22F2202/13

  Use of plasma · CPC title

• C22C38/005

  containing rare earths, i.e. Sc, Y, Lanthanides · CPC title