Method of manufacture of permanent magnets
AssigneeNamiki Precision Jewel Co., Ltd.
InventorNobuo Imaizumi
Life of this patent
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Abstract
This invention concerns a heat treatment method for rare earth type permanent magnets which are primarily of the Nd-Fe-B type. With regard to these permanent magnets, which oxidize rather easily in the air, the alloy is crushed, and either compression formed in a magnetic a non-magnetic field, sintered at 900.degree. to 1,200.degree. C., and then machined into the shape desired, and then solution treated in an atmosphere of oxygen and/or nitrogen at a temperature of 900.degree. to 1,200.degree. C., and then aged at 300.degree. to 900.degree. C. in order that an oxide and/or nitride protective layer of 0.001 to 10 .mu. be formed on the surface of the permanent magnet to prevent corrosion and in order to relieve machining strain.
Claims21
A method for the manufacture of a permanent magnet from a permanent magnet alloy powder having the composition R(T,M).sub.z, wherein R is at least one rare earth element selected from the group consisting of Nd, Pr, La and Dy;
- T is a transition metal selected from the group consisting of Fe and a mixture of Fe and Co;
- M is boron;
- and z=4 to 9, including the steps of:
- (a) pressure forming said powder to form a green body;
- (b) sintering said green body at a temperature in the range 900.degree. to 1200.degree. C.;
- (c) machining the sintered green body into a utilizable shape;
- (d) solution treating the machined body formed in step (c) at a temperature in the range of 900.degree. to 1200.degree. C. in an atmosphere of a gas selected from the group consisting of nitrogen, oxygen and mixtures of nitrogen and oxygen at a pressure in the range of 10.sup.-8 to 1.0 Torr;
- and
- (e) aging the solution treated machined body formed in step (d) at a temperature in the range of 300.degree. to 900.degree. C. to form a corrosion resistant permanent magnet.
A method for the manufacture of a permanent magnet from a permanent magnet alloy powder having the composition R(T, M).sub.z, wherein R is at least one rare earth element selected from the group consisting of Nd, Pr, La and Dy;
- T is a transition metal selected from the group consisting of Fe and a mixture of Fe and Co;
- M is boron;
- and z=4 to 9, including the steps of:
- (a) pressure forming said powder to form a green body;
- (b) sintering said green body at a temperature in the range of 900.degree. to 1200.degree. C.;
- (c) solution treating the sintered green body formed in step (b) at a temperature in the range of 900.degree. to 1200.degree. C.;
- (d) machining the solution treated body formed in step (c) into a utilizable shape;
- and
- (e) aging the solution treated machined body formed in step (d) at a temperature in the range of 300.degree. to 900.degree. C. in an atmosphere of a gas selected from the group consisting of nitrogen, oxygen and mixtures of nitrogen and oxygen at a pressure in the range of 10.sup.-8 to 1.0 Torr to form a permanent magnet.
A method for the manufacture of a permanent magnet from a permanent magnet alloy powder having the composition R(T, M).sub.z, wherein R is at least one rare earth element selected from the group consisting of Nd, Pr, La and Dy;
- T is a transition metal selected from the group consisting of Fe and a mixture of Fe and Co;
- M is boron;
- and z=4 to 9, including the steps of:
- (a) pressure forming said powder to form a green body;
- (b) sintering said green body at a temperature in the range 900.degree. to 1200.degree. C.;
- (c) machining the sintered green body into a utilizable shape;
- and
- (d) re-sintering said machined sintered green body at a temperature in the range of 900.degree. to 1200.degree. C. in an atmosphere of a gas selected from the group consisting of nitrogen, oxygen and mixtures of nitrogen and oxygen at a pressure in the range of 10.sup.-8 to 1.0 Torr to form a permanent magnet.
Dependencies are inferred from the claim text.