Method of producing phosphate-coated SmFeN-based anisotropic magnetic powder and phosphate-coated SmFeN-based anisotropic magnetic powder

Patent metadata

Field	Value
Publication number	US-12462958-B2
Application number	US-202218146752-A
Country	US
Kind code	B2
Filing date	Dec 27, 2022
Priority date	Dec 27, 2021
Publication date	Nov 4, 2025
Grant date	Nov 4, 2025

Abstract

A method of producing a phosphate-coated SmFeN-based anisotropic magnetic powder, the method including performing a phosphate treatment including adding an inorganic acid to a slurry containing a raw material SmFeN-based anisotropic magnetic powder, water, a phosphate compound, and a rare earth compound so that the slurry is adjusted to have a pH of at least 1 and not higher than 4.5 to obtain a phosphate-coated SmFeN-based anisotropic magnetic powder having a surface coated with a phosphate.

First claim

What is claimed is:

1 . A method of producing a phosphate-coated SmFeN-based anisotropic magnetic powder, the method comprising
performing a phosphate treatment comprising adding an inorganic acid to a slurry containing a SmFeN-based anisotropic magnetic powder, water, a phosphate compound, and a rare earth compound containing a rare earth element so that the slurry is adjusted to have a pH of at least 1 and not higher than 4.5 to obtain a phosphate-coated SmFeN-based anisotropic magnetic powder having a surface coated with a phosphate, and after the phosphate treatment, heat-treating the phosphate-coated SmFeN-based anisotropic magnetic powder at a temperature of at least 150° C. but not higher than 330° C. in an oxygen-containing atmosphere, wherein the rare earth compound is at least one compound selected from the group consisting of a rare earth hydroxide, a rare earth chloride, a rare earth sulfate, a rare earth nitrate, a rare earth acetate, and a combination thereof, and wherein the solvent of the slurry is water.

2 . The method according to claim 1 ,
wherein an amount of the rare earth element contained in the rare earth compound is 0.25% by mass or less relative to the mass of the phosphate-coated SmFeN-based anisotropic magnetic powder.

3 . The method according to claim 1 ,
wherein the rare earth compound comprises a rare earth hydroxide represented by the following formula (1):
R—(OH) x   (1),

wherein R is Ce, Nd, Sm, or Dy, and x is 1, 2, 3, or 4.

4 . The method according to claim 3 ,
wherein the rare earth hydroxide is at least one selected from the group consisting of Ce(OH) 3 , Nd(OH) 3 , Sm(OH) 3 , and Dy(OH) 3 .

5 . The method according to claim 1 ,
wherein the phosphate-coated SmFeN-based anisotropic magnetic powder has a phosphate content of higher than 0.5% by mass.

6 . The method according to claim 3 ,
wherein the phosphate-coated SmFeN-based anisotropic magnetic powder has a phosphate content of higher than 0.5% by mass.

7 . The method according to claim 1 ,
wherein in the phosphate treatment, the slurry is adjusted to have the pH of at least 1 and not higher than 4.5 for at least 10 minutes.

8 . The method according to claim 3 ,
wherein in the phosphate treatment, the slurry is adjusted to have the pH of at least 1 and not higher than 4.5 for at least 10 minutes.

9 . The method according to claim 1 ,
wherein in the phosphate treatment, the slurry is adjusted to have the pH of at least 1.6 and not higher than 3.9.

10 . The method according to claim 3 ,
wherein in the phosphate treatment, the slurry is adjusted to have the pH of at least 1.6 and not higher than 3.9.

11 . The method according to claim 1 ,
wherein in the phosphate treatment, the phosphate compound includes an inorganic phosphate compound.

12 . The method according to claim 3 ,
wherein in the phosphate treatment, the phosphate compound includes an inorganic phosphate compound.

13 . The method according to claim 1 ,
comprising mixing the SmFeN-based anisotropic magnetic powder, water, and the rare earth compound to obtain a mixture, and then adding an aqueous phosphate solution containing the phosphate compound to the mixture to prepare the slurry, prior to the phosphate treatment.

14 . The method according to claim 1 ,
wherein the inorganic acid is added to the slurry as needed so that the slurry is adjusted to have a pH of at least 1 and not higher than 4.5 during the phosphate treatment.

15 . The method according to claim 1 ,
wherein the rare earth element contained in the rare earth compound is at least one selected from the group consisting of Ce, Sm, Nd, and Dy.

16 . A method of producing a phosphate-coated SmFeN-based anisotropic magnetic powder, the method comprising
performing a phosphate treatment comprising adding an inorganic acid to a slurry containing a SmFeN-based anisotropic magnetic powder, water, a phosphate compound, and a rare earth compound containing a rare earth element so that the slurry is adjusted to have a pH of at least 1 and not higher than 4.5 to obtain a phosphate-coated SmFeN-based anisotropic magnetic powder having a surface coated with a phosphate, and after the phosphate treatment, heat-treating the phosphate-coated SmFeN-based anisotropic magnetic powder at a temperature of at least 150° C. but not higher than 330° C. in an oxygen-containing atmosphere, wherein the rare earth compound is at least one compound that can generate rare earth ions in a slurry containing water as a solvent, or a combination thereof, and wherein the solvent of the slurry is water.

17 . The method according to claim 16 ,
wherein the rare earth element contained in the rare earth compound is at least one selected from the group consisting of Ce, Sm, Nd, and Dy.

Assignees

• Nichia Corp

Inventors

• Abe Masahiro
• Yamanaka Satoshi
• Tada Shuichi
• Iwai Kenta

Classifications

• B22F1/142

  Thermal or thermo-mechanical treatment · CPC title

• B22F2301/45

  Rare earth metals, i.e. Sc, Y, Lanthanides (57-71) · CPC title

• B22F2302/45

  Others, including non-metals · CPC title

• B22F2201/03

  Oxygen · CPC title

• B22F2998/10

  Processes characterised by the sequence of their steps · CPC title