CN100515615C - Carbon-coated magnetic superfine iron particle and its manufacturing method - Google Patents
Carbon-coated magnetic superfine iron particle and its manufacturing method Download PDFInfo
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- CN100515615C CN100515615C CNB2005100299688A CN200510029968A CN100515615C CN 100515615 C CN100515615 C CN 100515615C CN B2005100299688 A CNB2005100299688 A CN B2005100299688A CN 200510029968 A CN200510029968 A CN 200510029968A CN 100515615 C CN100515615 C CN 100515615C
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Abstract
The present invention discloses a kind of magnetic superfine iron granules covered by carbon. Its average grain size is 50-400 nm, and its composition includes (by wt% 65-85% of magnetic iron and 15-25% of carbon. Said magnetic superfine iron granules can be used as magnetic powder for making magnetic recording and can be used as carrier material for preparing magnetic target medicine.
Description
Technical field
The present invention relates to magnetic superfine iron particle of a kind of charcoal coating and preparation method thereof, particularly adopt chemical vapour deposition (CVD) to carry out superfine iron particle surface-treated method.
Technical background
Iron is a large amount of existence of nature and human widely used a kind of element.Usually, iron is to use as the block structure material, has ferromagnetism.Nano magnetic material then has special natures such as superparamagnetism.Ultra-fine iron particle as high density magnetic recording material, electromagnetic wave absorption material, magnetic fluid, magnetic target medicine carrier or with the compound preparation functional material of other material, become the focus of research.But nano iron particles is because its huge surface that has can make it very active, and pure nano iron particle can not stable existence in air, has limited the application of nano iron particles.Existing documents and materials show, the superfine iron particle surface is handled, and can make the existence stable in the air of its energy.
The surface treatment of existing superfine iron particle has several different methods.M.Pardavi-Horvath early proposes method (the Magnetic nanocomposites by reactionmilling of nanometer iron coated metal oxide, Scripta Metallurgica et Materialia, 1995,33 (10～11), 1731～1740), this method is to realize impurity content height in the product by ball milling.Zhao Xin waits the people to propose (structure and the magnetic of nanometer iron granules oxide on surface clearly; Acta Metallurgica Sinica; 2001; 37 (6); 633～636) nanometer iron is placed in inert gas for a long time; rely on the trace oxygen in the inert gas to make its surface metal iron oxidation generate the oxide film of iron, or iron particle is dispersed in the volatile solvent, form the oxide film of iron by the volatilization of solvent on its surface through eremacausis.
Zhong Peiwen etc. propose to adopt surfactant to coat nano iron particles (stability of nanometer iron powder and the bioavailability of superfine iron powder, Metallic Functional Materials, 2003,10 (2), 22～24); G.Kataby and R, Prozorow etc. propose to adopt macromolecule clad nano iron particle, (Characterization of self-assembled alcohols coatings on amorphous iron, Nanostructured Marerials, 1999, vol.12,421～424).The antioxygenic property of the nano iron particles that above-mentioned two kinds of method for coating obtain is poor, causes surface coating layer to lose efficacy because of oxidation or environment temperature height take place behind the placement certain hour in air, and the magnetic property of nano iron particles descends significantly with the prolongation of standing time.
People such as Wang Cuiying propose to adopt chemical plating method at magnetic coating (liquid phase production of nano metallic nickel powder, finishing and structural characterization, Chinese Journal of Chemical Physics, 1999,12 (6), 670～674) such as nano iron particles coating surface metallic nickels.Everett E.Carpenter then proposes with inert metal clad nano iron surfaces such as gold (Iron nanoparticles as potential magnetic carriers, Joural of Magnetism and Magnetic Materials, 225 (2001), 17～20).
(20～30nm) reacts nano iron particles (the Iron nanoparticlescoated with graphite nanolayers and carbon nanotubes that obtains the graphite coating with nanometer carbon black (30nm) to people such as Hisato Tokoro under 900～1200 ℃ high temperature with nanometer iron, Diamond and RelatedMaterials, 13 (2004), 1270～1273).Open existing equality people nano iron particles is coated charcoal at acetylene atmosphere ionic medium, (preparation carbon-encapsulated iron nanoparticles and sign thereof under the acetylene atmosphere, Qingdao University of Science and Technology's journal, 2004,25 (1), 30～32), this method ingredient requirement height, severe reaction conditions is difficult to a large amount of preparations.
Summary of the invention
The technical issues that need to address of the present invention are to disclose magnetic superfine iron particle and the manufacture method thereof that a kind of charcoal coats, overcome the defective of the application technology aspects such as the easy oxidation of the fine iron particle of high magnetic that exist on the conventional art, satisfy application demands such as magnetic target carrier and magnetic fluid.
The magnetic superfine iron particle that charcoal of the present invention coats is that a kind of average grain diameter is the black powder of 50～400nm, and its component and weight content comprise: Armco magnetic iron is 65～85%, and carbon content is 15～25%.
Its important feature is that oxidizing temperature is not less than 400 ℃, is no less than 3 months saturation magnetizations under field conditions (factors) standing time and still is not less than 140emu/g.
The manufacture method of the magnetic superfine iron particle material that above-mentioned charcoal coats can comprise the steps:
(1) nano ferriferrous oxide magnetic and interleaving agent mixed grinding: with average grain diameter is that ferroferric oxide powder and the interleaving agent of 8～15nm becomes mixture in proportion, adding diameter is that 1～8mm (is preferably 2～6mm) steel ball ball milling, the part by weight of tri-iron tetroxide and interleaving agent is 1: 2～2: 1, the part by weight of mixture and steel ball is 1: 8～1: 10, the time is 12～36 hours during ball milling, preferred 20～24 hours;
Said nano ferriferrous oxide magnetic is to adopt the synthetic method preparation of general liquid phase, as ammonia precipitation process method (Zhang Daojiang, Wang Jianhua, ultramicro magnetic Fe
3O
4The preparation of particle, Sichuan Teachers University journal (natural science edition), 1997,20 (6)), the NaOH precipitation method (Zou Tao etc., ferromagnetism Fe
3O
4The preparation of nano particle and performance characterization thereof, fine chemistry industry, 2002,19 (2)) and pure water is total to hot method, and (hot altogether the sending out of alcohol-water prepares Fe for Ren Huanyu etc., chemical industry progress
3O
4Method such as magnetic fluid, 2003 (1)) is perhaps in preparation process and the material that adopts surfactant to handle after the preparation, as U.S. Pat P3764540 disclosed method;
Said interleaving agent is selected from the salt that the high temperature infusibility melts, and preferably is selected from one or more the mixture in sodium chloride, potassium chloride, the calcium chloride;
(2) ferroferric oxide magnetic powder reduction: the mixture after the grinding carries out high temperature reduction reaction 1～12 hour under 350～650 ℃ in hydrogen atmosphere, and making tri-iron tetroxide reduce becomes the fe particle;
According to preferred reducing process of the present invention, the oxygen content in the hydrogen is not more than 0.1%, preferably is not more than 0.05%, and the pressure of reduction reaction can be normal pressure or pressurization, is preferably normal pressure;
Normally, in order to guarantee that tri-iron tetroxide is reduced to fe fully, adopted the short reduction reaction time since under the higher reduction temperature, the reduction reaction time that the next employing of lower reduction temperature is long, the reduction reaction temperature height that adopts is then regulated according to the needs of end product particle size, the reduction temperature height, and the size of reduction back fe particle is big, otherwise reduction temperature is low, and the size of reduction back fe particle is little;
(3) charcoal coats the fe particle: the fe particle after will reducing carries out the surface and coats charcoal under 300～600 ℃ under mixed atmosphere, and according to the preferred cladding process of invention, preferred coating reaction temperature is 400～500 ℃;
Said mixed atmosphere is hydrogen, organic carbon hydrogen compound and inert gas, and in the mixed atmosphere, the percentage by volume content of hydrogen is 2～10%, is preferably 3～7%; The percentage by volume content of organic carbon hydrogen compound is 3～15%, is preferably 4～12%;
Inert gas is nitrogen or argon gas etc., and nitrogen is preferred;
A kind of or its mixture in said hydrocarbon optimal ethylene, acetylene, ethanol or the methyl alcohol;
The reaction time that the surface coats charcoal is 10～60 minutes, and preferred 20～40 minutes, the pressure of coating reaction can be normal pressure or pressurization, is preferably normal pressure;
In order to obtain the suitable thickness of charcoal clad and the uniformity, also promptly obtain the product of saturation magnetization height and high temperature oxidation resisting, do not wish to make hydrocarbon when the pyrolysis coating reaction, to generate such as accessory substances such as carbon nanotubes, normally, very high reduction temperature generates carbon nanotube easily, the product that obtains under the condition that generates carbon nanotube is owing to exist the non magnetic component of more organic carbon, and saturation magnetization is not high yet.And under the low excessively coating reaction temperature, the thermal decomposition of organic carbon hydrogen compound is insufficient, and the fe surface coats not exclusively, the antioxygenic property variation of product.
(4) post processing: the product after the carbon coating reaction cools to 10～40 ℃ in hydrogen or hydrogen and inert gas atmosphere, washing, and drying obtains inventing the magnetic superfine iron particle that said charcoal coats.
The magnetic superfine iron particle that the charcoal that adopts method of the present invention to obtain coats, its oxidizing temperature is not less than 400 ℃, is no less than 3 months saturation magnetizations under field conditions (factors) standing time and still is not less than 140emu/g.Method ingredient requirement of the present invention is not high, and the reaction condition gentleness is easy to industrialization and prepares in a large number.The superfine iron particle of soft magnetic characteristic of the present invention has that particle size is little, saturation magnetization is high and the magnetic property stable characteristics, is suitable for as the magnetic recording magnetic carrier material of magnetic target medicine etc.
Description of drawings
Fig. 1 is the electron micrograph of embodiment 1 product.
Fig. 2 is the X-ray spectrogram of embodiment 1 product.
Fig. 3 is the electron micrograph of embodiment 2 products.
Fig. 4 is the X-ray spectrogram of embodiment 2 products.
The specific embodiment
Do some change as change tubular react furnace into other type of furnace for those skilled in the art, fixed bed changes fluid bed into, the change of the charcoal source gas that uses, the adjustment of reaction temperature and reaction time, reaction gas flow, the change of the granularity of the change of the oxide of the former used iron of iron or iron primary oxide all belongs within the scope of the present invention.The embodiment of the invention does not limit scope of invention.
Embodiment 1
Taking by weighing 5g sodium chloride and 5g average grain diameter is the tri-iron tetroxide of 10nm, under 300 rev/mins rotating speed, dry grinded 24 hours behind the steel ball 80g of adding diameter 6mm, take by weighing the sodium chloride behind the 1g ball milling and the mixture tiling and Noah's ark bottom of tri-iron tetroxide, place the flat-temperature zone of tubular react furnace, the outlet of reacting furnace is a normal pressure, behind the hydrogen 30min of feeding 30ml/min flow, begin to heat up, 20 ℃/min of heating rate controls temperature at 600 ℃, reduction reaction 2hr.Hydrogen flowing quantity is adjusted into 5ml/min makes temperature reduce to 450 ℃; feed the nitrogen of 100ml/min and the acetylene gas of 10ml/min; coating reaction 30min; close nitrogen, acetylene; protection at hydrogen drops to room temperature; product spends deionised water (add silver nitrate do not have precipitation get final product) in washings, drying can obtain the magnetic superfine iron particle of carbon coating.
Product is graininess (seeing accompanying drawing 1) according to electron-microscopic analysis, and granularity is less than 500nm, and wherein 200～500nm accounts for 70～80%, less than 200nm particle about 20%; Vibrations sample magnetic strength instrumentation tries it than saturation magnetization intensity 147emu/g, and remanent magnetization 1.9emu/g, product place test saturation magnetization 141emu/g after three months; Its oxidation resistance temperature of thermobalance (TG) analytical test is 410 ℃; X-ray diffraction test (seeing accompanying drawing 2) shows that iron exists mutually with α-Fe in the product, contain micro-iron sulfide and iron oxide, α-Fe content 72% wherein, the obvious characteristics peak does not appear in the clad charcoal in X-ray spectrum, show that the clad charcoal exists with unformed charcoal, its content is 28%.
Embodiment 2
Ball milling and reduction are with embodiment 1, and different is that reduction reaction temperature is 500 ℃, and interleaving agent is a potassium chloride; Carbon coating reaction condition is with embodiment 1, and different is that carbon source acetylene changes ethanol and each 50% (volume ratio) of acetylene into.
Product is graininess (seeing accompanying drawing 3) according to electron-microscopic analysis, and the product granularity is based on 20～300nm; Vibrating specimen magnetometer is tested it than saturation magnetization intensity 143emu/g, and remanent magnetization 1.37emu/g, product place and test specific saturation magnetization after three months is 139emu/g; Its oxidation resistance temperature of thermobalance (TG) analytical test is 420 ℃; X-ray diffraction test (seeing accompanying drawing 4) shows that iron exists mutually with α-Fe in the product, contain micro-iron sulfide and iron oxide, α-Fe content 71% wherein, the obvious characteristics peak does not appear in the clad charcoal in X-ray spectrum, show that the clad charcoal exists with unformed charcoal, its content is 29%.
Claims (9)
1. the magnetic superfine iron particle that charcoal coats is characterized in that average grain diameter is 50～400nm, and its component and weight content comprise: Armco magnetic iron is 65～85%, and charcoal is 15～25%.
2. the manufacture method of the magnetic superfine iron particle that charcoal according to claim 1 coats is characterized in that, comprises the steps:
(1) ferroferric oxide powder is mixed with interleaving agent, adding diameter is the steel ball ball milling of 1～8mm;
Said interleaving agent is selected from more than one in sodium chloride, potassium chloride or the calcium chloride;
(2) mixture after grinding in hydrogen atmosphere in 350～650 ℃ of following reduction reactions 1～12 hour;
(3) the fe particle after will reducing carries out the surface and coats charcoal under 300～600 ℃ under mixed atmosphere;
Said mixed atmosphere is hydrogen, organic carbon hydrogen compound and inert gas, and in the mixed atmosphere, the percentage by volume content of hydrogen is 2～10%, and the percentage by volume content of organic carbon hydrogen compound is 3～15%;
(4) product after the carbon coating reaction cools to 10～40 ℃ in hydrogen or hydrogen and inert gas atmosphere, washing, and drying obtains the magnetic superfine iron particle that charcoal coats.
3. method according to claim 2 is characterized in that, the ferroferric oxide powder average grain diameter is 8～15nm.
4. method according to claim 2 is characterized in that, the part by weight of tri-iron tetroxide and interleaving agent is 1: 2～2: 1.
5. method according to claim 4 is characterized in that the part by weight of mixture and steel ball is 1: 8～1: 10, and the time is 12～36 hours during ball milling.
6. method according to claim 2 is characterized in that, in the mixed atmosphere, the percentage by volume content of hydrogen is 2～10%; In the mixed atmosphere, the percentage by volume content of organic carbon hydrogen compound is 3～15%.
7. method according to claim 2 is characterized in that, inert gas is nitrogen or argon gas.
8. method according to claim 2 is characterized in that, said hydrocarbon is selected from a kind of or its mixture in ethene, acetylene, ethanol or the methyl alcohol.
9. method according to claim 2 is characterized in that, the reaction time that the surface coats charcoal is 10～60 minutes.
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| Application Number | Priority Date | Filing Date | Title |
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| CNB2005100299688A CN100515615C (en) | 2005-09-23 | 2005-09-23 | Carbon-coated magnetic superfine iron particle and its manufacturing method |
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| CNB2005100299688A CN100515615C (en) | 2005-09-23 | 2005-09-23 | Carbon-coated magnetic superfine iron particle and its manufacturing method |
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| CN1935415A CN1935415A (en) | 2007-03-28 |
| CN100515615C true CN100515615C (en) | 2009-07-22 |
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Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102208641A (en) * | 2011-05-17 | 2011-10-05 | 广州市香港科大霍英东研究院 | Method for synthesizing Fe3O4/C lithium ion battery cathode material with hollow sphere structure by one-step process |
| CN103623824B (en) * | 2012-08-23 | 2015-10-28 | 华东师范大学 | A kind of Armco magnetic iron carbon composite and its preparation method and application |
| CN107523757A (en) * | 2017-08-25 | 2017-12-29 | 洛阳博林合金材料有限公司 | A kind of abrasion-resistant counterattack plate and preparation method thereof |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1334160A (en) * | 2001-08-09 | 2002-02-06 | 广东工业大学 | Graphite arc discharge method for synthesizing carbon-clad nm ferromagnetic metal particles |
| WO2004046257A3 (en) * | 2002-11-15 | 2004-07-29 | Timcal Sa | Metal coated carbon black, carbon black compositions and their applications |
| US20050181202A1 (en) * | 2004-02-18 | 2005-08-18 | Hitachi Metals, Ltd. | Fine composite metal particles and their production method, micro-bodies, and magnetic beads |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1334160A (en) * | 2001-08-09 | 2002-02-06 | 广东工业大学 | Graphite arc discharge method for synthesizing carbon-clad nm ferromagnetic metal particles |
| WO2004046257A3 (en) * | 2002-11-15 | 2004-07-29 | Timcal Sa | Metal coated carbon black, carbon black compositions and their applications |
| US20050181202A1 (en) * | 2004-02-18 | 2005-08-18 | Hitachi Metals, Ltd. | Fine composite metal particles and their production method, micro-bodies, and magnetic beads |
Non-Patent Citations (2)
| Title |
|---|
| Iron nanoparticles as potential magnetic carriers. Everett E.Carpenter.Journal of Magnetism and Magnetic Materials. 2001 * |
| Preparation of carbon-coated magnetic iron nanoparticlesfrom composite rods made from coal and iron powders. Jieshan Qiu et al.Fuel Processing Technology. 2004 * |
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