CN1395466A - Method for producing graphite base composite material for electromagnetic shield - Google Patents
Method for producing graphite base composite material for electromagnetic shield Download PDFInfo
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- CN1395466A CN1395466A CN 02124139 CN02124139A CN1395466A CN 1395466 A CN1395466 A CN 1395466A CN 02124139 CN02124139 CN 02124139 CN 02124139 A CN02124139 A CN 02124139A CN 1395466 A CN1395466 A CN 1395466A
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Abstract
The invention belongs to the technical area of the electromagnetic shielding material. First, the expandable graphite and the additive capable of generating the magnetic fine particles are mixed evenly by using the mechanical, physical method or the solution dissolving method. Then, in condition of temperature 700-1200 deg.C, making the graphite expand quickly so as to obtain the expanded graphitic worm with the magnetic fine particles. The expanded graphitic worm can be pressed in moulds to produce the products with needed shape. The invented technique is simple. The conductivity of the produced is better than the electric high molecular material. The magnetic performance is better than the plain flexible graphite. The electromagnetic shielding performance is improved markedly, especially, when the frequency is higher than 900 MHz.
Description
Technical field:
The invention belongs to technical field of electromagnetic shielding, particularly a kind of preparation method who is used for the graphite-base composite material of electromagnetic shielding.
Background technology:
Along with the high speed development of hyundai electronics industry and the rapid increase of various commercialization and domestic electronic appliances quantity, Electromagnetic Interference has become a kind of new public hazards.Particularly along with the miniaturization of electronic device, integrated, lightweight and digitized development, make various electronic equipments very easily be subjected to the external electromagnetic wave interference and malfunction, visual obstacle, audio distortions etc. occur; On the other hand, for reducing cost and being convenient to the consideration of large-scale industrial production, the case material metal of electronic product is replaced by a large amount of plastics and similar macromolecular material, and they itself are nonconducting mostly, and electromagnetic wave has been lost shielding properties.In order to address this problem, adopting functional composite material to carry out electromagnetic shielding is a kind of efficient ways.
At present, all mainly study and design about the article of electromagnetic shielding material and patent etc. from electromagnetic performance and two aspects of microwave absorbing property of material.The conductivity of material is good more, and its capability of electromagnetic shielding is also good more.In addition, also can improve the capability of electromagnetic shielding of material greatly by in basis material, adding metal powder, ferrite powder, carborundum powder or their absorbing materials such as fiber.Quite a few as research and patent aspect the electromagnetic shielding material, but substantially all is that raw material of wood-charcoal material with various forms joins in the macromolecule matrix as " conductive additive " about the raw material of wood-charcoal material, to prepare the high composite material that conducts electricity.But the conductivity of these macromolecular materials is than raw material of wood-charcoal material or much lower.
Can produce expansion through the synthetic compound between graphite layers of intercalation processing by natural flake graphite when being subjected to high temperature rapidly, the expanded graphite worm that obtains after the expansion has high conductance and specific area, thereby gives its capability of electromagnetic shielding preferably.This worm can link together in high-pressure process mutually, does not need to add any binding agent in the process of preparation section bar, will be an extraordinary selection so prepare high conducing composite material with expanded graphite as matrix.D.D.L.Chung finds that the flexible graphite that makes by this method has extraordinary shielding properties, have both extraordinary thermal stability, chemical stability and low thermal coefficient of expansion [D.D.L.Chung in addition, Electromagnetic interference shielding effectiveness ofcarbon materials, Carbon 39 (2001) 279-285].The electromagnetic shielding material of method manufacturing is diamagnetic thus, and specific insulation is 0.523 * 10
-4Ω cm, capability of electromagnetic shielding is general.
In order further to improve the shielding properties of graphite, wish in graphite matrix, to add some materials that help shielding.Because the apparent density and the intensity of expanded graphite are all very low, therefore very difficult method by routine is distributed in the graphite matrix additive equably and goes.Patent " EXPANDED GRAPHITE SHEET FOR ELECTROMAGNETIC WAVE SHIELDING AND PROCESSFOR PRODUCING THE SAME " (international publication number is WO9910598-A1) has been introduced with wet method and has been added materials such as fiber in the expanded graphite matrix method.This method at first is pressed into expanded graphite the low-density sample, and this sample put into to contain needs the suspension-turbid liquid of substance body, relies on absorption that substance is sucked in the sample, after the oven dry again compacting obtaining required sample.This manufacturing approach craft more complicated.
Summary of the invention:
The objective of the invention is by add magnetic medium in graphite, the shielding properties, particularly expanded graphite that further improves graphite-base composite material is the shielding properties of the composite material of base.
The present invention is a kind of method of making graphite-base composite material, it is characterized in that the method includes the steps of:
(1) be that 1～5: 1 expansible graphite and the additive that can produce magnetic particle mix by mechanical-physical and the method for solution dissolving mixes with mass ratio;
(2) mixture is put into 700～1200 ℃ atmosphere, expansible graphite will be expanded rapidly, obtain being attached with the expanded graphite worm of magnetic particle;
(3) expanded graphite worm that obtains is pressed into required form in mould.
In the above-mentioned step (1) for preparing the method for graphite-base composite material, any or several additives that are used as magnetic particle in ferrocene, hydronium(ion) oxidation nickel, the iron hydroxide add in the expansible graphite.
The pressure of described compacting section bar, the size of mould etc. is decided according to concrete condition, and the section bar that is pressed into such as also can shear as required at processing.
The graphite-base composite material of manufacturing of the present invention has following advantage:
1. material conductivity is better than general conducting polymer composite;
2. Zhi Bei material has better magnetic property than common flexible graphite material;
3. preparation technology is very simple, and has overcome magnetic particle and be difficult for being evenly distributed to difficulty in the graphite matrix;
4. the capability of electromagnetic shielding of the composite material by this method manufacturing improves significantly, and especially under high frequency (frequency surpasses 900MHz), the capability of electromagnetic shielding of composite material is significantly improved than pure flexible graphite.
Description of drawings:
Fig. 1 is the microscopic appearance that utilizes the expanded graphite worm of this method manufacturing.
Fig. 2 is the microscopic appearance that utilizes the sheet sample that the expanded graphite worm of this method manufacturing is pressed into.
Fig. 3 is to use the magnetic hysteresis loop of the wafer sample of vibration magnetometer (VSM, Lake Shore 7307) test.
Fig. 4 is the resolution chart of the capability of electromagnetic shielding of pure flexible graphite.
Fig. 5 is that expansible graphite and ferrocene crystal powder (mass ratio is 5: 4) mix and at the resolution chart of the capability of electromagnetic shielding of 1000 ℃ of expanded back manufacturing disks.
Fig. 6 is that expansible graphite and nickel hydroxide powder (mass ratio is 5: 2) mix and at the resolution chart of the capability of electromagnetic shielding of 1100 ℃ of expanded back manufacturing disks.
Fig. 7 is that expansible graphite and iron hydroxide powder (mass ratio is 5: 2) mix and at the resolution chart of the capability of electromagnetic shielding of 1100 ℃ of expanded back manufacturing disks.
Embodiment:
Embodiment 1:
(1) be that 1.25: 1 expansible graphite and ferrocene crystal powder mixes by mechanical-physical with mass ratio;
(2) mixture is put into 1000 ℃ atmosphere, expansible graphite will be expanded rapidly, obtain being attached with the expanded graphite worm of magnetic particle;
(3) expanded graphite worm that obtains being pressed into diameter in mould is that 16 millimeters, thickness are about 1 millimeter disk.
The microscopic appearance of the prepared expanded graphite worm that is attached with magnetic particle can see that magnetic particle has been mixed in the worm of expanded graphite equably as shown in Figure 1; The microscopic appearance that utilizes the wafer sample that this method makes as shown in Figure 2; The magnetic hysteresis loop of wafer sample is with vibration magnetometer (VSM, Lake Shore 7307) test, the result as shown in Figure 3, as seen from the figure, this sample is a ferrimagnetism; The conductivity that adopts the vanderburg method in the four-point probe method to test sample, its specific insulation is 1.66 * 10
-3Ω cm, capability of electromagnetic shielding is seen Fig. 5.
Embodiment 2:
(1) be that 5: 1 expansible graphite and ferrocene crystal powder mixes by mechanical-physical with mass ratio;
(2) mixture is put into 700 ℃ atmosphere, expansible graphite will be expanded rapidly, obtain being attached with the expanded graphite worm of magnetic particle;
(3) expanded graphite worm that obtains being pressed into diameter in mould is that 16 millimeters, thickness are about 1 millimeter disk.
The conductivity that adopts the vanderburg method in the four-point probe method to test sample, its specific insulation is 1.39 * 10
-3Ω cm.
Embodiment 3:
(1) be that 2.5: 1 expansible graphite and nickel hydroxide powder mixes by mechanical-physical with mass ratio;
(2) mixture is put into 1100 ℃ atmosphere, expansible graphite will be expanded rapidly, obtain being attached with the expanded graphite worm of magnetic particle;
(3) expanded graphite worm that obtains being pressed into diameter in mould is that 16 millimeters, thickness are about 1 millimeter disk.
The conductivity that adopts the vanderburg method in the four-point probe method to test sample, its specific insulation is 0.962 * 10
-3Ω cm, capability of electromagnetic shielding is seen Fig. 6.
Embodiment 4:
(1) be that 2.5: 1 expansible graphite and iron hydroxide mixes by mechanical-physical with mass ratio;
(2) mixture is put into 1100 ℃ atmosphere, expansible graphite will be expanded rapidly, obtain being attached with the expanded graphite worm of magnetic particle;
(3) expanded graphite worm that obtains being pressed into diameter in mould is that 16 millimeters, thickness are about 1 millimeter disk.
The conductivity that adopts the vanderburg method in the four-point probe method to test sample, its specific insulation is 1.10 * 10
-3Ω cm, capability of electromagnetic shielding is seen Fig. 7.
Embodiment 5:
(4) be that 5: 1 expansible graphite and iron hydroxide mixes by mechanical-physical with mass ratio;
(5) mixture is put into 1200 ℃ atmosphere, expansible graphite will be expanded rapidly, obtain being attached with the expanded graphite worm of magnetic particle;
(6) expanded graphite worm that obtains being pressed into diameter in mould is that 16 millimeters, thickness are about 1 millimeter disk.
The conductivity that adopts the vanderburg method in the four-point probe method to test sample, its specific insulation is 1.02 * 10
-3Ω cm.
Embodiment 6:
(1) getting mass ratio is 1: 1 expansible graphite and ferrocene, earlier ferrocene is dissolved in the acetone, then expansible graphite is immersed in the solution;
(2) along with the volatilization of acetone, solution becomes pasty state, and this mixture is put into 1000 ℃ atmosphere, and expansible graphite will be expanded rapidly, obtains being attached with the expanded graphite worm of magnetic particle;
(3) expanded graphite worm that obtains being pressed into diameter in mould is that 16 millimeters, thickness are about 1 millimeter disk.
The conductivity that adopts the vanderburg method in the four-point probe method to test sample, its specific insulation is 1.22 * 10
-3Ω cm.
Claims (2)
1, a kind of method of making graphite-base composite material is characterized in that the method includes the steps of:
(1) mass ratio is that 1～5: 1 expansible graphite and the additive that can produce magnetic particle mix by mechanical-physical or the method by the solution dissolving mixes;
(2) mixture is put into 700～1200 ℃ atmosphere, expansible graphite will be expanded rapidly, obtain being attached with the expanded graphite worm of magnetic particle;
(3) expanded graphite worm that obtains is pressed into required form in mould.
2,, it is characterized in that in described step (1) in any or several additive adding expansible graphites in ferrocene, hydronium(ion) oxidation nickel, the iron hydroxide as magnetic particle according to the described method for preparing graphite-base composite material of claim 1.
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| CN 02124139 CN1240263C (en) | 2002-07-12 | 2002-07-12 | Method for producing graphite base composite material for electromagnetic shield |
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| CN 02124139 CN1240263C (en) | 2002-07-12 | 2002-07-12 | Method for producing graphite base composite material for electromagnetic shield |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101179921B (en) * | 2006-11-09 | 2010-05-12 | 南京大学 | Method for preparing electromagnetic shielding light graphite based nanometer magnetic metal composite material |
| CN101275036B (en) * | 2007-03-28 | 2011-04-20 | 南京理工大学 | Preparation for polymer conductive nanometer compound material |
| CN102050443A (en) * | 2010-11-22 | 2011-05-11 | 中科恒达石墨股份有限公司 | Method for manufacturing doped flexible graphite products |
| CN101031508B (en) * | 2004-06-16 | 2011-06-08 | 圣卡洛斯联邦大学 | Method for manufacturing magnetic graphite material and materials made therefrom |
| CN107799752A (en) * | 2017-10-31 | 2018-03-13 | 湖南国盛石墨科技有限公司 | A kind of preparation method of nano oxidized iron particle/expansion micro crystal graphite composite for lithium ion battery |
| CN109734448A (en) * | 2019-03-19 | 2019-05-10 | 电子科技大学 | A kind of preparation method of carbon aerogels base electromagnetic screen material |
| CN114725361A (en) * | 2022-05-11 | 2022-07-08 | 滨州裕能化工有限公司 | Iron-containing oxide coated sulfur-doped expanded graphite/silicon electrode material and preparation method thereof |
-
2002
- 2002-07-12 CN CN 02124139 patent/CN1240263C/en not_active Expired - Fee Related
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101031508B (en) * | 2004-06-16 | 2011-06-08 | 圣卡洛斯联邦大学 | Method for manufacturing magnetic graphite material and materials made therefrom |
| CN101179921B (en) * | 2006-11-09 | 2010-05-12 | 南京大学 | Method for preparing electromagnetic shielding light graphite based nanometer magnetic metal composite material |
| CN101275036B (en) * | 2007-03-28 | 2011-04-20 | 南京理工大学 | Preparation for polymer conductive nanometer compound material |
| CN102050443A (en) * | 2010-11-22 | 2011-05-11 | 中科恒达石墨股份有限公司 | Method for manufacturing doped flexible graphite products |
| CN102050443B (en) * | 2010-11-22 | 2013-12-11 | 中科恒达石墨股份有限公司 | Method for manufacturing doped flexible graphite products |
| CN107799752A (en) * | 2017-10-31 | 2018-03-13 | 湖南国盛石墨科技有限公司 | A kind of preparation method of nano oxidized iron particle/expansion micro crystal graphite composite for lithium ion battery |
| CN109734448A (en) * | 2019-03-19 | 2019-05-10 | 电子科技大学 | A kind of preparation method of carbon aerogels base electromagnetic screen material |
| CN114725361A (en) * | 2022-05-11 | 2022-07-08 | 滨州裕能化工有限公司 | Iron-containing oxide coated sulfur-doped expanded graphite/silicon electrode material and preparation method thereof |
| CN114725361B (en) * | 2022-05-11 | 2024-04-05 | 滨州裕能电子材料股份有限公司 | Iron-containing oxide coated sulfur doped expanded graphite/silicon electrode material and preparation method thereof |
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|---|---|
| CN1240263C (en) | 2006-02-01 |
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Granted publication date: 20060201 Termination date: 20130712 |