GB2058845A - Method of producing fine metal particles - Google Patents
Method of producing fine metal particles Download PDFInfo
- Publication number
- GB2058845A GB2058845A GB8026454A GB8026454A GB2058845A GB 2058845 A GB2058845 A GB 2058845A GB 8026454 A GB8026454 A GB 8026454A GB 8026454 A GB8026454 A GB 8026454A GB 2058845 A GB2058845 A GB 2058845A
- Authority
- GB
- United Kingdom
- Prior art keywords
- metal particles
- temperature
- fine metal
- oxidizing
- particles
- 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.)
- Granted
Links
- 239000002923 metal particle Substances 0.000 title claims abstract description 47
- 229910001111 Fine metal Inorganic materials 0.000 title claims abstract description 28
- 238000000034 method Methods 0.000 title claims abstract description 13
- 238000010438 heat treatment Methods 0.000 claims abstract description 13
- 230000005294 ferromagnetic effect Effects 0.000 claims abstract description 12
- 230000001590 oxidative effect Effects 0.000 claims abstract description 11
- 230000009467 reduction Effects 0.000 claims abstract description 10
- 238000001035 drying Methods 0.000 claims abstract description 6
- 239000002904 solvent Substances 0.000 claims abstract description 5
- 239000010419 fine particle Substances 0.000 claims abstract description 3
- 230000001681 protective effect Effects 0.000 claims abstract description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 8
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 6
- 229910045601 alloy Inorganic materials 0.000 claims description 5
- 239000000956 alloy Substances 0.000 claims description 5
- 229910052742 iron Inorganic materials 0.000 claims description 4
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 3
- 239000007789 gas Substances 0.000 claims description 3
- 229910052757 nitrogen Inorganic materials 0.000 claims description 2
- 239000001569 carbon dioxide Substances 0.000 claims 1
- 229910002092 carbon dioxide Inorganic materials 0.000 claims 1
- JCXJVPUVTGWSNB-UHFFFAOYSA-N nitrogen dioxide Inorganic materials O=[N]=O JCXJVPUVTGWSNB-UHFFFAOYSA-N 0.000 claims 1
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 15
- 230000005291 magnetic effect Effects 0.000 description 12
- 239000002245 particle Substances 0.000 description 10
- 230000005415 magnetization Effects 0.000 description 8
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 4
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 4
- 230000004907 flux Effects 0.000 description 4
- 238000011282 treatment Methods 0.000 description 4
- ZWEHNKRNPOVVGH-UHFFFAOYSA-N 2-Butanone Chemical compound CCC(C)=O ZWEHNKRNPOVVGH-UHFFFAOYSA-N 0.000 description 3
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000012279 sodium borohydride Substances 0.000 description 3
- 229910000033 sodium borohydride Inorganic materials 0.000 description 3
- 239000007858 starting material Substances 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 description 2
- 229910000359 iron(II) sulfate Inorganic materials 0.000 description 2
- 150000002576 ketones Chemical class 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 229910017061 Fe Co Inorganic materials 0.000 description 1
- 229910001030 Iron–nickel alloy Inorganic materials 0.000 description 1
- 229910017709 Ni Co Inorganic materials 0.000 description 1
- 229910003267 Ni-Co Inorganic materials 0.000 description 1
- 229910003262 Ni‐Co Inorganic materials 0.000 description 1
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 150000001491 aromatic compounds Chemical class 0.000 description 1
- 235000011089 carbon dioxide Nutrition 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 229940044175 cobalt sulfate Drugs 0.000 description 1
- 229910000361 cobalt sulfate Inorganic materials 0.000 description 1
- KTVIXTQDYHMGHF-UHFFFAOYSA-L cobalt(2+) sulfate Chemical compound [Co+2].[O-]S([O-])(=O)=O KTVIXTQDYHMGHF-UHFFFAOYSA-L 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 235000003891 ferrous sulphate Nutrition 0.000 description 1
- 239000011790 ferrous sulphate Substances 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- -1 methyl ethyl ketone Chemical compound 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 239000011591 potassium Substances 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000011946 reduction process Methods 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
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
- H01F1/061—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 with a protective layer
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
- B22F1/14—Treatment of metallic powder
- B22F1/142—Thermal or thermo-mechanical treatment
-
- 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
- H01F1/065—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 obtained by a reduction
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Hard Magnetic Materials (AREA)
- Manufacture Of Metal Powder And Suspensions Thereof (AREA)
- Powder Metallurgy (AREA)
Abstract
A method of producing ferromagnetic fine metal particles, which comprises drying wet ferromagnetic fine particles obtained by wet reduction at a temperature between room temperature and 240 DEG C in a non-oxidizing or reducing atmosphere to dry the metal particles; subjecting the dried metal particles to a heat treatment at a temperature between 200 DEG C and 600 DEG C in a non- oxidizing or reducing atmosphere; and immersing the treated metal particles in a protective solvent.
Description
SPECIFICATION
Method of producing fine metal particles
This invention relates to a method of producing fine ferromagnetic metal particles for a highdensity magnetic recording medium, and more specifically to heat treatments of fine ferromagnetic metal particles obtained by wet reduction.
The advancement in the art of magnetic recording equipment in recent years, as typified by the spread of home video tape recorders and commercial production of high performance audio cassettes, has called for a magnetic recording medium capable of high density recording than heretofore.
Among the materials known to meet the requirement for high density recording are fine ferromagnetic metal particles made by the wet reduction process with a compulsory reducing agent, such as sodium borohydride or potassium borohydride. The particles that result from wet reduction have good magnetic properties, ranging in coercive force (Hc) from 600 to 1850 Oe., in saturation magnetization (as) from 80 to 120 emu/g, and in squareness ratio from 0.4 to 0.6.
However, the magnetic properties the high-density magnetic recording medium is being required to possess are beyond these levels, and there is a great need for the development of fine metal particles which exhibit even higher coercive force, saturation magnetic flux density, and squareness ratio.
Fine metal particles with somewhat improved magnetic properties can be obtained when the particles formed by wet reduction are heat treated in a reducing atmosphere at 2000--4000C. In order to get more improved particles, a treatment at a higher temperature is necessary. However, the use of elevated heat-treatment temperature is questionable because it is likely to cause sintering or aggregation of the fine metal particles and it does not impart the particles with a high saturation magnetic flux density without some sacrifice or its coercive force or squareness ratio.
The present invention has for its object to provide a method or producing fine metal particles whereby the foregoing problems of the prior art can be obviated or mitigated and the fine metal particles obtained by wet reduction can be further improved in coercive force, saturation flux density, and squareness ratio.
The present invention is a method of producing ferromagnetic fine metal particles, which comprises: drying wet ferromagnetic fine particles obtained by wet reduction at a temperature between room temperature and 2400C in a non-oxidizing or reducing atmosphere to dry the metal particles; subjecting the dried metal particles to a heat treatment at a temperature between 2000C and 6000C in a non-oxidizing or reducing atmosphere; and immersing the treated metal particles in a protective solvent.
An embodiment of the invention will now be described, by way of example.
Fine metal particles of iron or iron-based alloys such as Fe-Co, Fe-Ni, Fe-Ni-Co alloys formed by wet reduction in a continuous reactor are recovered in water or one of alcohols, such as methyl alcohol, ketones, such as methyl ethyl ketone, or aromatic compounds, such as toluene, or a combination of those liquids. The mixture of the particles and the liquid or solution is squeezed down to a weight two to five times the dry weight of the fine metal particles.
The moistened mass of metal particles is placed in a rotary or stationary reducing furnace. In the furnace, wherein a non-oxidizing or reducing atmosphere is maintained at between ordinary temperature and 2400 C, the charge is subjected to a low-temperature treatment for 0.5 to 6 hours to dry the metal particles to a sufficient degree. A non-oxidizing atmosphere is formed by nitrogen, argon, or other inert gas, and a reducing atmosphere is formed by hydrogen or carbonic acid gas.
Then, in a non-oxidizing or reducing atmosphere the temperature inside the furnace is increased to a range of 2000C to 6000C at a rate of 1 O to 50C per minute and the charge is heated for about 0 to 10 hours. The temperature for the low-temperature treatment is most desirably in the proximity of 1 500--2200C, and that for the high-temperature treatment is desirably in the proximity of 3700--5000C.
Finally, the heat-treated ferromagnetic metal particles are immersed in a solvent such as toluene, ketones or the like to protect the particles from oxidation.
The initial properties of the fine metal particles as the starting material being the same, it will be possible to obtain particles with properties suited for the intended use by properly setting the temperature or time for the high-temperature heating.
According to the manufacturing method of the invention above described, fine metal particles optimized for high-density magnetic recording, with the coercive force (Hc) in the range of 60012350 Oe., saturation flux density (as) of I 100--175 emu/g and squareness ratio of 0.5-0.6, can be obtained with ease.
The essence of the invention will now be illustrated by its Examples and a Reference Example.
EXAMPLE 1
(A) FeSO4. 7H20
(aq. soln. of ferrous sulfate) 0.7 mole/l COSO4. 7H2O (aq. soln. of cobalt sulfate) 0.3 mole/l
HC1
(aq. soln. of hydrochloric acid) 0.6 mole/l
(B)
NaBH4
(aq. soln. of sodium borohydride) 1.0 mole/l
The aqueous solutions (A) and (B) were allowed to undergo an equimolar reaction in a continuous reactor. Fine alloy particles thus obtained were recovered in ethanol. Upon drying in air, the product yielded fine alloy particles having a coercive force (Hc) of 1820 Oe., saturation magnetization (as) of 130 emu/g, and squareness ratio of 0.58. The powder so formed is called "P-i" " for the purposes of the invention.
The fine metal particles (P-l) recovered in ethanol in a moistened state were squeezed so that the combined weight of the solute and solvent was three to four times the weight of the solute alone, and the resultant was charged into a stationary reducing furnace. The furnace was then heated and the charge was subjected to a low-temperature heat treatment at 1 500C for three hours while passing hydrogen gas as a reducing gas through the furnace.
Following the low-temperature heat treatment, the temperature inside the reducing furnace was increased at a rate of 306 per minute, with the constant flow of hydrogen gas, up to 505 C.
Immediately after this, the furnace was cooled down to a room temperature, and improved fine metal particles were immersed in toluene.
The fine metal particles so obtained possessed a coercive force (Hc) of 1980 Oe., saturation magnetization (as) of 140 emu/g, and squareness ratio of 0.58, indicating considerable improvements in the coercive force (Hc) and saturation magnetization (as) over the fine metal particles (P-l) as the starting material.
EXAMPLE 2
The fine metal particles (P-1) obtained by the procedure of wet reduction described in Example 1 were placed in the reducing furnace referred to in the preceding example. The charge subjected to a low-temperature heat treatment at 1 500C for three hours while passing nitrogen gas as a non-oxidizing gas through the furnace.
Following the low-temperature heat treatment, the temperature was raised at a rate of 30C per minute up to 51000 and the charge was heat treated at the elevated temperature. It was then cooled down to a room temperature and the improved metal particles were recovered in toluene.
The fine metal particles thus obtained has a coercive force (Hc) of 1 950 Oe., saturation magnetization (as) of 1380 emu/g, and squareness ratio of 0.58. The product was considerably improved in the coercive force and saturation magnetization over the starting metal particles (P 1).
REFERENCE EXAMPLE1
The fine metal particles (P-l) obtained in Example 1 were dried at a room temperature and were thoroughly freed of water. The resultant was heated up to 5000C in a hydrogen stream and immediately thereafter it was cooled to a room temperature to obtain fine metal particles in toluene.
The metal particles exhibited a coercive force (Hc of 1 550 Oe., saturation magnetization (as) of 125 emu/g, and squareness ratio of 0.49, or proved rather inferior in the magnetic properties to the fine metal particles (P-l) as the starting material.
As has been described hereinbefore, the manufacturing method of the invention is characterized in that it comprises a step of heating at a low temperature the fine metal particles in a moistened state obtained by wet reduction and thereby removing water from the particles, and an immediately following step of heat treating said fine metal particles at a higher temperature than in the preceding step. In this way fine metal particles improved in all of the coercive force, saturation magnetization, and squareness ratio can be made without difficulty. Thus, according to the invention, fine metal particles quite suitable for the high-density magnetic recording medium can be easily manufactured.
Claims (6)
1. A method of producing ferromagnetic fine metal particles, which comprises:
drying wet ferromagnetic fine particles obtained by wet reduction at a temperature between room temperature and 2400C in a non-oxidizing or reducing atmosphere to dry the metal particles;
subjecting the dried metal particles to a heat treatment at a temperature between 2000C and 6000C in a non-oxidizing or reducing atmosphere;
and immersing the treated metal particles in a protective solvent.
2. A method as claimed in claim 1 , wherein the ferromagnetic metal particles are iron or iron based alloys.
3. A method as claimed in claim 1 or claim 2, wherein said non-oxidizing or reducing atmospheres are selected from nitrogen, rare gases, nitrogen and carbon dioxide.
4. A method as claimed in any preceding claim, wherein the drying step is effected at a temperature between 1500C and 2000C and the heat treatment step is effected at a temperature between 3700C and 5000C.
5. A method as claimed in claim 4, wherein the drying step is effected for a period of from 0.5 to 6 hours and the heat treatment step is effected for such an initial period to give a temperature increase rate between 1 00/mien. and 500/mien. and then for a period of up to 10 hours.
6. A method of producing ferromagnetic fine metal particles substantially as hereinbefore described.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP54107572A JPS5855201B2 (en) | 1979-08-23 | 1979-08-23 | Method for producing metal fine particles |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2058845A true GB2058845A (en) | 1981-04-15 |
| GB2058845B GB2058845B (en) | 1983-09-21 |
Family
ID=14462565
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8026454A Expired GB2058845B (en) | 1979-08-23 | 1980-08-13 | Method of producing fine metal particles |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS5855201B2 (en) |
| DE (1) | DE3031768A1 (en) |
| GB (1) | GB2058845B (en) |
| NL (1) | NL8004746A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4486225A (en) * | 1982-06-07 | 1984-12-04 | Mpd Technology Corporation | Production of highly reflective metal flake |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| IT1172540B (en) * | 1983-09-07 | 1987-06-18 | Finike Italiana Marposs | FORK COMPARATOR FOR THE CONTROL OF LINEAR DIMENSIONS OF MECHANICAL PIECES |
| JPS6140303A (en) * | 1984-07-31 | 1986-02-26 | Fuji Boseki Kk | Production of low-molecular-weight chitosan |
| JPS6279201A (en) * | 1985-10-01 | 1987-04-11 | Fuji Boseki Kk | Method for producing porous granular N-acylated chitosan |
| JPH089641B2 (en) * | 1988-05-13 | 1996-01-31 | 大日精化工業株式会社 | Method for producing low molecular weight chitosan |
| JP3884611B2 (en) | 2000-09-13 | 2007-02-21 | 和夫 酒井 | Improving agent for impulsive disease |
| KR20190061828A (en) | 2017-11-27 | 2019-06-05 | 이보균 | Method for producing chitosan for forage use |
-
1979
- 1979-08-23 JP JP54107572A patent/JPS5855201B2/en not_active Expired
-
1980
- 1980-08-13 GB GB8026454A patent/GB2058845B/en not_active Expired
- 1980-08-21 NL NL8004746A patent/NL8004746A/en not_active Application Discontinuation
- 1980-08-22 DE DE19803031768 patent/DE3031768A1/en not_active Withdrawn
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4486225A (en) * | 1982-06-07 | 1984-12-04 | Mpd Technology Corporation | Production of highly reflective metal flake |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5633401A (en) | 1981-04-03 |
| DE3031768A1 (en) | 1981-03-26 |
| JPS5855201B2 (en) | 1983-12-08 |
| NL8004746A (en) | 1981-02-25 |
| GB2058845B (en) | 1983-09-21 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |