CA1176814A - Method of improving magnets - Google Patents
Method of improving magnetsInfo
- Publication number
- CA1176814A CA1176814A CA000394598A CA394598A CA1176814A CA 1176814 A CA1176814 A CA 1176814A CA 000394598 A CA000394598 A CA 000394598A CA 394598 A CA394598 A CA 394598A CA 1176814 A CA1176814 A CA 1176814A
- Authority
- CA
- Canada
- Prior art keywords
- particles
- container
- particle charge
- alloy
- magnetic field
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
- H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
- H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
- H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
- H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
- H01F1/06—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys in the form of particles, e.g. powder
- H01F1/08—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys in the form of particles, e.g. powder pressed, sintered, or bound together
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
- H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
- H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
- H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
- H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
- H01F1/047—Alloys characterised by their composition
- H01F1/053—Alloys characterised by their composition containing rare earth metals
- H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
- H01F1/0555—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 pressed, sintered or bonded together
- H01F1/0557—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 pressed, sintered or bonded together sintered
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
- H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
- H01F41/0253—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets
- H01F41/0273—Imparting anisotropy
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Manufacturing Cores, Coils, And Magnets (AREA)
- Powder Metallurgy (AREA)
- Hard Magnetic Materials (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A method for producing magnets from powdered magnetic alloy, and magnets having improved remanence and good coercive force; the method comprises aligning a particle charge of magnet alloy within a container, which aligning may be achieved by use of a pulsating magnetic field; consolidating the charge after align-ment to a density in excess of 95% of theoretical density by cold or hot isostatic pressing, or a combination thereof.
A method for producing magnets from powdered magnetic alloy, and magnets having improved remanence and good coercive force; the method comprises aligning a particle charge of magnet alloy within a container, which aligning may be achieved by use of a pulsating magnetic field; consolidating the charge after align-ment to a density in excess of 95% of theoretical density by cold or hot isostatic pressing, or a combination thereof.
Description
117681`4 ******
It is conventional practice to produce magnets from powdered magnetic alloys, including rare earth cobalt magnets, by compacting as by die préssing a charge of aligned or oriented fine powder of a magnetic alloy of the desired magnet composition.
Thereafter, the compacted charge is heat treated at ~emperatures on the order of 2000 to 2090F. It is known that by increasing the density in the production of magnets of this type from particle charges of the magnetic material that remanence can be improved. Conventionally, density is increased by raising the sintering temperature after die pressing; however, this results in a corresponding lowering of coercive force.
It is accordingly an object of the present invention to provide a method for prodllcing from powdered magnetic alloy magnets with increased density, and thus improved remanence, with-out resorting to l~igher sintering temperatures that serve to lower coercive force.
Another object of the invention is in the production of magnets to provide for improved alignment or orientation to achieve higher remanence values.
These and other objects of the invention will be apparent from the following description and specific examples.
It has been determined broadly in accordance with the invention that improved remanence is a function of both the degree 1~76814 of alignment of the individual magnetic dipoles (powder particles)and density (the number of dipoles that are present in a given volume of the body of the magnet material). Accordingly, in the broader aspects of the invention it has been discovered tllat if one subjects a particle charge of magnet alloy, which may be one or more transition elements, e.g. nickel, cobalt, iron, chromium.
manganese, copper, zirconium and titanium, in combination with at least one rare earth element, e.g. samarium, to a temperature that is below the full density sintering temperature but above the temperature necessary to produce a close-pore structure and then subjects the material while at this temperature to isostatic compacting, increased density and thus improved remanence is achieved while maintaining good coercive force. Coercive force is maintained by maintaining the temperature below the full density sintering temperature. Additionally, remanence is improved by aligning or orienting the material by the use of a pulsating magnetic field within a container. The container may be collapsible within which the material can thereafter be isostatically compacted.
The pulsating magnetic field should have a pulse duration not exceeding one second per pulse and each pulse typically will be on the order of lS millisecond. At least one pulse and pre~erably two pulses at a power level of at ]east 50,000 Oe i9 sllitable f~r the purpose. Conventionally, highly oriente-l SmCoS magnets have been produced by the use of superconducting solenoids to generate the high-intensity magnetic fields. These superconducting solenoids must be operated at cryogenic temperatures (-450F) to pass the high-density current necessary to generate these high-intensity magnetic fields. In the practice of the invention, however, the required high-intensity magnetic fields are produced by discharging an i~76~14 assemblage of capacitors, e.g. four hundred to one thousand capacitors, thereby eliminating the need for superconducting solenoids. The container may be a rubber bag and prefera~ly after alignment the bag is evacuated in the presence of a constant DC
5 field which serves to maintain alignment. Alternately, the particles of magnet material may be aligned within a preformed container, which will be collapsible and of a material such as stainless steel. The step of subjecting the aligned material to a steady DC field in an evacuated container has been found to "lock 10 in" the alignment and thus insure improved remanence. The following constitutes specific examples with respect to the practice of the invention as described above and demonstrate its utility:
Example 1: SmCo5 powder was oriented in a die cavity with an 15 applied magnetic field and pressed. The applied field and the pressing direction being normal to each other. The pressed powder after sintering and post sintering had the properties as set forth in Table I.
The sintered magnet was loosely wrapped with stainless 20 steel foil (not pressure tight; for handling convenience only) and as-hot-isostatically pressed (~lIPed) at 1750F. The as-HlPed magnet had the properties as set forth in Table I.
The HIPed magnet was reheat treated at 1670F for three hours and quenched. The magnetic properties after HIPing and 25 heat treatment are set forth in Table I.
" ~1768~4 TABLE I
Br ~c ~Ic i B~nax Hk (~) (Oe) (Oe) MGOe Oe Pgm/Cm Die Pressed 5 and Sintered 8,900 8,60015,100 19.8 12,400 8.07 After HIP ~,400 9,10011,500 22.1 10,000 8.53 Heat Treatment after HIP 9,400 9,200>20,000 22.1 15,800 Example 2: Another magnet prepared according to the same 10 procedures prescribed as in Example 1 had the properties set forth on Table II.
TABLE II
Br HcHci BH~aX Hk 3 G OeOe MGOe Oe Pgm/Cm 15 Die Pressed and Sintered9,000 8,40014,000 19.0 9,400 8.07 Af~er HIP 9,400 8,80010,600 21.1 9,200 8.53 ExaMple 3: Another ma~net of SmCos from a batch other than in ~xamples 1 and 2 was prepared as described in Example 1. The 20 properties are recorded in Table III.
TABLE III
Br Hc Hci BHmax Hk G Oe Oe MGOe Oe Die Pressed 25 and Sintered9,200 8,800>20,000 21.0 9,400 After HIP 9,600 4,6007.,600 13.2 2,200 Heat Treatment 9,600 9,400>20,000 22.5 9,600 ~fter ~IIP
It may be seen from the magnetic property data that 30 remanence is improved by hot iso~tatic pressing after conventional aligning and cold pressing. Further improvement is achieved with respect to coercive force when after hot-isostatic pressing the magnet is subjected to post sintering heat treatment. The deterioration of the coerci.ve force after HIPing is believed to be 3sdue to phase separation.
~176~14 ExampLe 4: Using the powder from the same batch a~ in Example 3, a ma~,net was made by sintering SmCo5 powder that was previously oriented and cold isostatically pressed. The magnet had the properties set forth in Table IV.
TABLE IV
Br Hc Hci BHmaX Hk 3 G Oe Oe MGOe Oe Pgm/Cm Cold Isostatically Pressed and 10 Sintered 9,700 9,00017,700 23.59,600 8.31 After HIP 9,800 6,000 7,000 22.05,200 8.49 Heat Treatment 9,800 9,200>20,000 24.012,400 After HIP
With the magnet alloy of Example 4 the theoretical 15 maximum density is 8.6 gm/C~ e specific magnet had a density of 8.31 gm/Cm3 be~ore hot isostatic pressing and the density increase a~ter hot isostatic pressing was only about 2~/~, which accounts for small improvement in remanence reported in the example. It is anticipated that if the theoretical maximum 20 d~nsity had been achieved during hot isostatic pressing about a 3% increase in remanence would result.
Example 5: SmCo5 alloy was loaded into a stainless container and hydrogen admitted into the container. The pressure was built up to 30 atmospheres; hydrogen absorption by the alloy results in a 25 disintegration of the alloy to ab~ut -~0 mesh pow~er. The dehydrided powder was jet milled to about 41l partlcle size.
The fine powder was loaded into a rubber bag of 3/4"
diameter an~ the bag was contained in a stainless or plastic sheath. The bag was then pressurized and the powder ori.ente~l by 30 placing the rubber bag along with the sheatll i.nside a ~oil, and pulsing the coil, at least three times, wi.th eno~1~h power to generate 60,000 Oe within the coil.
~i768~
Tlle oriented powder was then placed in a sLeady D~
field of ~10 kOe and the bag evacuated to lock the alignment. The evacuated bag containing the powder was then placed in an isostatic press chamber and compressed with a pressure up to 100,000 psi.
5 The green compact was subsequently sintered between 1000-1200C and post sinter aged between 870-930C.
The magnets prepared from these four batches of powder in the manner described above had the properties set forth in Table V, which Table also shows magnetic properties of conventional 10 commercial magnets.
TABLE V
Br Hc Hci BHmax ~k G Oe Oe MGOe Oe Batch #I 10,000 9,600 11,800 24 8,600 15 Batch #II10,200 10,200 18,000 26 14,800 Batch #III10,600 9,800 17,000 28 10,400 Batch #IV10,200 9,600 15,300 25 10,800 Commercial)8,800 B,600 15,000 19 10,000 ~agnets )9,200 8,800 20,000 21 10,000 20Example 6: Powder of SmCoS was loaded in a rubber bag and oriented in the poles of an electromagnet in a field of 25 kOe. The oriented powder was then evacuated maintaining the steady DC field. The evacuated bag containing the oriented powder was isostatically pressed followed by sintering and heat treatmenc. The magnet had 2sthe following properties shown in Table VI.
~a~7~
TABLE VI
Br Hc Hci B~lax G Oe Oe MGOe ~agnet Prepared Without a 5 Pulsating d.c. Field 8,900 6,400 7,200 19.0 ~xample 7: A fourth batch of SmCo5 was processed into magnets by procedures as described in Example 1 except for a change in the compaetion method. The powder contained in the bag after align-ment was initially compacted inside the bag by placing the bag towards the end of the coil and employing the field gradient present in the coil during pulsing to bring forth an initial compaction to an intermediate density by additional pulsing. The oriented compacted powder placed in a steady DC field was evacuated, isostatically pressed and sintered. The sintered sample was of 15 uniform diameter and had a flat top and bottom contrary to the samples prepared without the field gradient packing which had a pyramidal top. The magnetic properties oi the sintered magnet prepared as per this example are shown in Table VII.
TABLE VII
20 Br ~ Hc H~i BHmax Hk G Oe Oe M~;Oe Oe 10,000 9,800 ~20,000 25.0 13,000 Example 8: A reetangular preform which has the dimensions o~ a die cavity was loaded with powder and the pow~ler was oriented in 25 a pul5e coil. The oriented powder in the preform was transferred to a die press and placed between the upper and ]ower p~nches.
After all the powder has transferred into the die cavi~y ~he powder was pressed between the upper and lower punches under Lhe application of a DC field. The die pressed part was sintered and 30 post sintered. The magnet prepared in this manner had the follow-ing properties set forth on Table VIII.
1176~14 Example 9. From the same batch of powder one magnet was pressed by directly feeding the powder into the die cavity, applying the DC field, and pressing. l'he properties of ~hese two magnets are set forth in Table VIII.
S TABLE VIII
7~
Br Hc Hci BHmax Hk G Oe Oe MGOe Oe Premagnetized powder in a preform before 10 transferring into the die cavity 9,750 8,700 ~10,000 23.7 8,800 Direct location oE powder in the die cavity 8,800 7,400 >10,000 19.0 6,000 It may be seen from the data reported in Examples 5 through 9 that aligning by the use of a pulsating magnetic field in accordance with the practice of the invention, as opposed to the conventional practice of aligning by the use of a steady-state magnetic field, resulted in improvement in remanence and energy 20 product.
It is conventional practice to produce magnets from powdered magnetic alloys, including rare earth cobalt magnets, by compacting as by die préssing a charge of aligned or oriented fine powder of a magnetic alloy of the desired magnet composition.
Thereafter, the compacted charge is heat treated at ~emperatures on the order of 2000 to 2090F. It is known that by increasing the density in the production of magnets of this type from particle charges of the magnetic material that remanence can be improved. Conventionally, density is increased by raising the sintering temperature after die pressing; however, this results in a corresponding lowering of coercive force.
It is accordingly an object of the present invention to provide a method for prodllcing from powdered magnetic alloy magnets with increased density, and thus improved remanence, with-out resorting to l~igher sintering temperatures that serve to lower coercive force.
Another object of the invention is in the production of magnets to provide for improved alignment or orientation to achieve higher remanence values.
These and other objects of the invention will be apparent from the following description and specific examples.
It has been determined broadly in accordance with the invention that improved remanence is a function of both the degree 1~76814 of alignment of the individual magnetic dipoles (powder particles)and density (the number of dipoles that are present in a given volume of the body of the magnet material). Accordingly, in the broader aspects of the invention it has been discovered tllat if one subjects a particle charge of magnet alloy, which may be one or more transition elements, e.g. nickel, cobalt, iron, chromium.
manganese, copper, zirconium and titanium, in combination with at least one rare earth element, e.g. samarium, to a temperature that is below the full density sintering temperature but above the temperature necessary to produce a close-pore structure and then subjects the material while at this temperature to isostatic compacting, increased density and thus improved remanence is achieved while maintaining good coercive force. Coercive force is maintained by maintaining the temperature below the full density sintering temperature. Additionally, remanence is improved by aligning or orienting the material by the use of a pulsating magnetic field within a container. The container may be collapsible within which the material can thereafter be isostatically compacted.
The pulsating magnetic field should have a pulse duration not exceeding one second per pulse and each pulse typically will be on the order of lS millisecond. At least one pulse and pre~erably two pulses at a power level of at ]east 50,000 Oe i9 sllitable f~r the purpose. Conventionally, highly oriente-l SmCoS magnets have been produced by the use of superconducting solenoids to generate the high-intensity magnetic fields. These superconducting solenoids must be operated at cryogenic temperatures (-450F) to pass the high-density current necessary to generate these high-intensity magnetic fields. In the practice of the invention, however, the required high-intensity magnetic fields are produced by discharging an i~76~14 assemblage of capacitors, e.g. four hundred to one thousand capacitors, thereby eliminating the need for superconducting solenoids. The container may be a rubber bag and prefera~ly after alignment the bag is evacuated in the presence of a constant DC
5 field which serves to maintain alignment. Alternately, the particles of magnet material may be aligned within a preformed container, which will be collapsible and of a material such as stainless steel. The step of subjecting the aligned material to a steady DC field in an evacuated container has been found to "lock 10 in" the alignment and thus insure improved remanence. The following constitutes specific examples with respect to the practice of the invention as described above and demonstrate its utility:
Example 1: SmCo5 powder was oriented in a die cavity with an 15 applied magnetic field and pressed. The applied field and the pressing direction being normal to each other. The pressed powder after sintering and post sintering had the properties as set forth in Table I.
The sintered magnet was loosely wrapped with stainless 20 steel foil (not pressure tight; for handling convenience only) and as-hot-isostatically pressed (~lIPed) at 1750F. The as-HlPed magnet had the properties as set forth in Table I.
The HIPed magnet was reheat treated at 1670F for three hours and quenched. The magnetic properties after HIPing and 25 heat treatment are set forth in Table I.
" ~1768~4 TABLE I
Br ~c ~Ic i B~nax Hk (~) (Oe) (Oe) MGOe Oe Pgm/Cm Die Pressed 5 and Sintered 8,900 8,60015,100 19.8 12,400 8.07 After HIP ~,400 9,10011,500 22.1 10,000 8.53 Heat Treatment after HIP 9,400 9,200>20,000 22.1 15,800 Example 2: Another magnet prepared according to the same 10 procedures prescribed as in Example 1 had the properties set forth on Table II.
TABLE II
Br HcHci BH~aX Hk 3 G OeOe MGOe Oe Pgm/Cm 15 Die Pressed and Sintered9,000 8,40014,000 19.0 9,400 8.07 Af~er HIP 9,400 8,80010,600 21.1 9,200 8.53 ExaMple 3: Another ma~net of SmCos from a batch other than in ~xamples 1 and 2 was prepared as described in Example 1. The 20 properties are recorded in Table III.
TABLE III
Br Hc Hci BHmax Hk G Oe Oe MGOe Oe Die Pressed 25 and Sintered9,200 8,800>20,000 21.0 9,400 After HIP 9,600 4,6007.,600 13.2 2,200 Heat Treatment 9,600 9,400>20,000 22.5 9,600 ~fter ~IIP
It may be seen from the magnetic property data that 30 remanence is improved by hot iso~tatic pressing after conventional aligning and cold pressing. Further improvement is achieved with respect to coercive force when after hot-isostatic pressing the magnet is subjected to post sintering heat treatment. The deterioration of the coerci.ve force after HIPing is believed to be 3sdue to phase separation.
~176~14 ExampLe 4: Using the powder from the same batch a~ in Example 3, a ma~,net was made by sintering SmCo5 powder that was previously oriented and cold isostatically pressed. The magnet had the properties set forth in Table IV.
TABLE IV
Br Hc Hci BHmaX Hk 3 G Oe Oe MGOe Oe Pgm/Cm Cold Isostatically Pressed and 10 Sintered 9,700 9,00017,700 23.59,600 8.31 After HIP 9,800 6,000 7,000 22.05,200 8.49 Heat Treatment 9,800 9,200>20,000 24.012,400 After HIP
With the magnet alloy of Example 4 the theoretical 15 maximum density is 8.6 gm/C~ e specific magnet had a density of 8.31 gm/Cm3 be~ore hot isostatic pressing and the density increase a~ter hot isostatic pressing was only about 2~/~, which accounts for small improvement in remanence reported in the example. It is anticipated that if the theoretical maximum 20 d~nsity had been achieved during hot isostatic pressing about a 3% increase in remanence would result.
Example 5: SmCo5 alloy was loaded into a stainless container and hydrogen admitted into the container. The pressure was built up to 30 atmospheres; hydrogen absorption by the alloy results in a 25 disintegration of the alloy to ab~ut -~0 mesh pow~er. The dehydrided powder was jet milled to about 41l partlcle size.
The fine powder was loaded into a rubber bag of 3/4"
diameter an~ the bag was contained in a stainless or plastic sheath. The bag was then pressurized and the powder ori.ente~l by 30 placing the rubber bag along with the sheatll i.nside a ~oil, and pulsing the coil, at least three times, wi.th eno~1~h power to generate 60,000 Oe within the coil.
~i768~
Tlle oriented powder was then placed in a sLeady D~
field of ~10 kOe and the bag evacuated to lock the alignment. The evacuated bag containing the powder was then placed in an isostatic press chamber and compressed with a pressure up to 100,000 psi.
5 The green compact was subsequently sintered between 1000-1200C and post sinter aged between 870-930C.
The magnets prepared from these four batches of powder in the manner described above had the properties set forth in Table V, which Table also shows magnetic properties of conventional 10 commercial magnets.
TABLE V
Br Hc Hci BHmax ~k G Oe Oe MGOe Oe Batch #I 10,000 9,600 11,800 24 8,600 15 Batch #II10,200 10,200 18,000 26 14,800 Batch #III10,600 9,800 17,000 28 10,400 Batch #IV10,200 9,600 15,300 25 10,800 Commercial)8,800 B,600 15,000 19 10,000 ~agnets )9,200 8,800 20,000 21 10,000 20Example 6: Powder of SmCoS was loaded in a rubber bag and oriented in the poles of an electromagnet in a field of 25 kOe. The oriented powder was then evacuated maintaining the steady DC field. The evacuated bag containing the oriented powder was isostatically pressed followed by sintering and heat treatmenc. The magnet had 2sthe following properties shown in Table VI.
~a~7~
TABLE VI
Br Hc Hci B~lax G Oe Oe MGOe ~agnet Prepared Without a 5 Pulsating d.c. Field 8,900 6,400 7,200 19.0 ~xample 7: A fourth batch of SmCo5 was processed into magnets by procedures as described in Example 1 except for a change in the compaetion method. The powder contained in the bag after align-ment was initially compacted inside the bag by placing the bag towards the end of the coil and employing the field gradient present in the coil during pulsing to bring forth an initial compaction to an intermediate density by additional pulsing. The oriented compacted powder placed in a steady DC field was evacuated, isostatically pressed and sintered. The sintered sample was of 15 uniform diameter and had a flat top and bottom contrary to the samples prepared without the field gradient packing which had a pyramidal top. The magnetic properties oi the sintered magnet prepared as per this example are shown in Table VII.
TABLE VII
20 Br ~ Hc H~i BHmax Hk G Oe Oe M~;Oe Oe 10,000 9,800 ~20,000 25.0 13,000 Example 8: A reetangular preform which has the dimensions o~ a die cavity was loaded with powder and the pow~ler was oriented in 25 a pul5e coil. The oriented powder in the preform was transferred to a die press and placed between the upper and ]ower p~nches.
After all the powder has transferred into the die cavi~y ~he powder was pressed between the upper and lower punches under Lhe application of a DC field. The die pressed part was sintered and 30 post sintered. The magnet prepared in this manner had the follow-ing properties set forth on Table VIII.
1176~14 Example 9. From the same batch of powder one magnet was pressed by directly feeding the powder into the die cavity, applying the DC field, and pressing. l'he properties of ~hese two magnets are set forth in Table VIII.
S TABLE VIII
7~
Br Hc Hci BHmax Hk G Oe Oe MGOe Oe Premagnetized powder in a preform before 10 transferring into the die cavity 9,750 8,700 ~10,000 23.7 8,800 Direct location oE powder in the die cavity 8,800 7,400 >10,000 19.0 6,000 It may be seen from the data reported in Examples 5 through 9 that aligning by the use of a pulsating magnetic field in accordance with the practice of the invention, as opposed to the conventional practice of aligning by the use of a steady-state magnetic field, resulted in improvement in remanence and energy 20 product.
Claims (14)
1. A method for improving the remanence of magnets produced by consolidating a particle charge of a transition metal-rare earth magnet alloy to form a magnet article, said method comprising applying a magnetic field to said particle charge within a container to magnetically align said particles, said magnetic field being applied as a plurality of pulses with each said pulse having a duration not exceeding one second and a power level of at least 50,000 oersted and thereafter con-solidating said particle charge to a final density.
2. The method of claim 1 wherein said particles are loaded into a collapsible container for magnetic alignment and subsequent consolidation.
3. The method of claim 2 wherein said container is a rubber bag.
4. The method of claim 1 wherein said container is preformed to the desired shape of the particle charge after consolidation.
5. The method of claim 2 wherein said container is evacuated in the presence of a DC electric field after alignment of said particles.
6. The method of claim 1 wherein said alloy contains cobalt as at least one transition element.
7. The method of claim 1 wherein said alloy contains samarium as at least one rare earth element.
8. The method of claim 1 wherein after magnetic alignment of said particles, said particles are compacted to an inter-mediate density by additional pulsing.
9. The method of claim 1 wherein consolidation is by die pressing plus sintering.
10. The method of claim 1 wherein consolidation is by cold isostatic compaction plus sintering.
11. A method for improving the remanence of magnets produced by consolidating a particle charge of a transition metal-rare earth alloy to form a magnet article, said method comprising applying a magnetic field to said particle charge within a container to magnetically align said particles, said magnetic field being applied as a plurality of pulses with each pulse having a duration not exceeding one second and a power level of at least 50,000 oersted and thereafter hot isostatically pressing said particles to consolidate the same to full density.
12. The method of claim 11 wherein said container is evacuated in the presence of a DC electric field after alignment of said particles.
13. The method of claim 11 wherein said alloy contains cobalt as at least one transition element.
14. The method of claim 11 wherein said alloy contains samarium as at least one rare earth element.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000446774A CA1195814A (en) | 1981-05-11 | 1984-02-03 | Method of improving magnets |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US26227081A | 1981-05-11 | 1981-05-11 | |
| US262,270 | 1981-05-11 |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000446774A Division CA1195814A (en) | 1981-05-11 | 1984-02-03 | Method of improving magnets |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1176814A true CA1176814A (en) | 1984-10-30 |
Family
ID=22996852
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000394598A Expired CA1176814A (en) | 1981-05-11 | 1982-01-21 | Method of improving magnets |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0066348B1 (en) |
| JP (1) | JPS57194512A (en) |
| CA (1) | CA1176814A (en) |
| DE (1) | DE3266728D1 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA1216623A (en) * | 1983-05-09 | 1987-01-13 | John J. Croat | Bonded rare earth-iron magnets |
| US5080731A (en) * | 1988-08-19 | 1992-01-14 | Hitachi Metals, Ltd. | Highly oriented permanent magnet and process for producing the same |
| JP3554604B2 (en) * | 1995-04-18 | 2004-08-18 | インターメタリックス株式会社 | Compact molding method and rubber mold used in the method |
| US9952513B2 (en) | 2014-03-31 | 2018-04-24 | Asml Netherlands B.V. | Undulator |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3919003A (en) * | 1971-12-17 | 1975-11-11 | Gen Electric | Sintered cobalt-rare earth intermetallic product |
| JPS5646245B2 (en) * | 1973-06-23 | 1981-10-31 | ||
| CH603802A5 (en) * | 1975-12-02 | 1978-08-31 | Bbc Brown Boveri & Cie | |
| JPS52155124A (en) * | 1976-06-18 | 1977-12-23 | Hitachi Metals Ltd | Permanent magnetic alloy |
| JPS5941840B2 (en) * | 1978-12-28 | 1984-10-09 | 株式会社井上ジャパックス研究所 | Magnetic field press device |
| JPS5923446B2 (en) * | 1979-03-22 | 1984-06-02 | ティーディーケイ株式会社 | Plastic magnets and their manufacturing method |
-
1982
- 1982-01-21 CA CA000394598A patent/CA1176814A/en not_active Expired
- 1982-02-01 EP EP19820300510 patent/EP0066348B1/en not_active Expired
- 1982-02-01 DE DE8282300510T patent/DE3266728D1/en not_active Expired
- 1982-05-10 JP JP57078057A patent/JPS57194512A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| EP0066348A2 (en) | 1982-12-08 |
| JPH0318329B2 (en) | 1991-03-12 |
| EP0066348B1 (en) | 1985-10-09 |
| JPS57194512A (en) | 1982-11-30 |
| EP0066348A3 (en) | 1983-03-30 |
| DE3266728D1 (en) | 1985-11-14 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP0125752B1 (en) | Bonded rare earth-iron magnets | |
| US4902361A (en) | Bonded rare earth-iron magnets | |
| JPH07307211A (en) | Hot press magnet formed of anisotropic powder | |
| US4076561A (en) | Method of making a laminated rare earth metal-cobalt permanent magnet body | |
| US5026438A (en) | Method of making self-aligning anisotropic powder for magnets | |
| Schultz et al. | Preparation and properties of mechanically alloyed rare earth permanent magnets | |
| EP0516264A1 (en) | Producing method for high coercive rare earth-iron-boron magnetic particles | |
| CA1176814A (en) | Method of improving magnets | |
| ES372993A1 (en) | Method of densifying magnetically anisotropic powders | |
| Chin et al. | Compaction and sintering behaviors of a Nd‐Fe‐B permanent magnet alloy | |
| EP0474730B1 (en) | Magnetic alloy compositions and permanent magnets | |
| KR101804313B1 (en) | Method Of rare earth sintered magnet | |
| US5536334A (en) | Permanent magnet and a manufacturing method thereof | |
| US4564400A (en) | Method of improving magnets | |
| CA1195814A (en) | Method of improving magnets | |
| JPS6181603A (en) | Preparation of rare earth magnet | |
| US3933535A (en) | Method for producing large and/or complex permanent magnet structures | |
| Falk et al. | Recent Developments in the Field of Elongated Single‐Domain Iron and Iron‐Cobalt Permanent Magnets | |
| US3821034A (en) | High-density high-energy anisotropically permanent magnet | |
| Korent et al. | Magnetic properties and microstructure evolution of hot-deformed Nd-Fe-B magnets produced by low-pressure spark-plasma sintering | |
| EP0455718A4 (en) | Method and apparatus for making polycrystaline flakes of magnetic materials having strong grain orientation | |
| Tawara et al. | Sintered magnets of copper-and iron-modified cerium cobalt | |
| JPH02156038A (en) | Making of permanent magnet | |
| US4869869A (en) | Method of consolidating FeNdB magnets | |
| US3682715A (en) | Sintered cobalt-rare earth intermetallic product including samarium and lanthanum and permanent magnets produced therefrom |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEC | Expiry (correction) | ||
| MKEX | Expiry |