CN101407322A - Method of preparing graphite heat conducting and heat radiating fin having anisotropy - Google Patents
Method of preparing graphite heat conducting and heat radiating fin having anisotropy Download PDFInfo
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Abstract
The invention relates to a preparation method of a graphite heat-conducting cooling fin with anisotropy. The preparation method comprises the following steps of: adopting natural graphite powder with particle size being 30 meshes to 80 meshes, placing the natural graphite powder into acid treatment fluid, with acid treatment at the temperature of 20-120 DEG C and treatment time for 1-2 hours; placing the graphite powder into a 2%-8% cyanogen fluoric acid solution for soaking for 30-50 minutes; washing process: after chemical treatment to the graphite, carrying out washing at the temperature of 0-20 DEG C; high-temperature expansion: placing the graphite after washing into a graphite expansion furnace for carrying out high-temperature expansion at the temperature of 800-950 DEG C; and forming process: through processing by flexible graphite coiled material production equipment preparing the graphite heat-conducting cooling fin with anisotropy. Compared the heat-conducting coefficient of the product prepared by the method with that of the product prepared by the common method, the heat-conducting performance is obviously improved.
Description
Technical field
The present invention relates to provide the manufacturing technology with anisotropic graphite heat conducting and heat radiating fin, specifically can provide new material for the electronic product heat conduction and heat radiation.
Background technology
Along with the acceleration of the continuous upgrading of electronic product and mini, high integrated and high-performance electronic equipment growing, the work package volume size is more and more littler, and the speed and the efficient of work are more and more higher, and thermal value is increasing.At present, known metal species heat conduction and heat radiation assembly has been subjected to its material and the restriction of self heat conduction and heat radiation ultimate, must adopt the advanced heat conduction and heat radiation technology and the heat conduction and heat radiation material of excellent performance to be defined as away heat, guarantee effective work of its electronic product, the graphite heat conducting heat sink material is because of distinctive low density (with respect to metal species) and high heat conduction and heat radiation coefficient and low thermal resistance become the preferred material that the hyundai electronics series products solves the heat conduction and heat radiation technology.
Graphite crystal belongs to the hexagonal crystal system, has typical layered structure.Carbon atom hexagonal ring shape in each layer is arranged, and each atom is centered on by three adjacent atoms, and its spacing is 1.42 * 10
-7Cm.And layer is 3.4 * 10 with layer this a distance
-7Cm.Have covalent linkage one metallic bond in the layer, and interlayer is a molecular linkage.The hexagonal array aspect of these carbon atoms is flat and directed or orderly, parallel to each other basically and equidistant basically.The plate of flat substantially, the parallel equidistant of carbon atom or layer are commonly referred to graphite linings or basal plane, its connection or be bonded together, and its many groups are with crystal arrangement.Very orderly graphite is made of the crystal of suitable size: crystal is highly arranged each other or is directed and have an intact carbon-coating of ordering.Therefore the graphite of high-sequential has the preferred crystal orientation of height, has determined graphite to have anisotropic structure, demonstrates or has anisotropic a lot of character, as thermal conductivity and electroconductibility and diffuse fluid.Graphite can be characterized by the rhythmo structure of carbon, that is, and the structure that constitutes by carbon atom overlapping layer that links together by weak van der waals forces or lamination.When considering graphite-structure, usually two axles or direction are carried out mark, i.e. " c " axle or direction and " a " axle or direction.Can regard " c " axle or direction as direction perpendicular to carbon-coating." a " axle or direction can be regarded as the direction that is parallel to carbon-coating or perpendicular to the direction of " c " direction, be suitable for making and have anisotropic soft graphite.
Now in the graphite chemical treatment, acid solution both economical and generally employing is that 8～98% the vitriol oil (contains pure H
2SO
4Be at least 90%) and 92～2% concentrated nitric acids (contain pure HNO
3Be at least 60%) mixed solution (weight ratio).Acid-treated temperature can be from room temperature to 120 ℃, and the treatment time should so that make fully oxidative attack graphite granule of acid, make graphite layers be subjected to sufficient erosion more than 1 minute at least.
Through the graphite after the oxidative attack, also will be through washing.The effect of washing at first is to remove harmful unnecessary acid, so that next step carries out the high temperature expansion process safely.In addition, through washing, a spot of water molecules infiltrates between the crystal aspect of graphite, combine with the oxygenant (being swelling agent) that originally invaded between the crystal aspect, when elevated temperature heat expansion process thereafter, it produces higher vapour pressure and impels graphite crystal on the c direction of principal axis high level expansion to take place, thereby this part moisture can play the effect of after-expansion agent.
It is the application for a patent for invention prospectus of CN1480394A that State Intellectual Property Office of the People's Republic of China disclosed publication number on March 10th, 2004, following technical scheme is disclosed in its background technology " usually; the expanded graphite sheet is that the mixing solutions of usefulness sulfuric acid, nitric acid etc. such as natural graphite, pyrolytic graphite, primary graphite is handled; after washing, the drying; with expansion furnace expansion processing under about 1000 ℃, make it in blocks by it is rolled.”
This content has only disclosed the method for traditional expanded graphite, but because the finished product impurity is more, can only be applicable to conventional heat radiation product or sealing prod.
Patent Office of the People's Republic of China (PRC) discloses the patent of invention that name is called expansible black lead and manufacture method thereof on October 29th, 1986, and this invention relates to the expansible black lead with stable high expansioning multiple.And the processing method of making this graphite.Belong to the chemical treatment of graphite.
The specification sheets of this patent has disclosed several background technologies, one, before the present invention makes, the method of manufacturing technology of expanded graphite meterial is as " electrical carbon " 1981 the 1st phases, with purity is more than 97%, and the above crystalline flake graphite of granularity 50 orders is put into nitric acid and the sulfuric acid mixture liquid for preparing by a certain percentage.Under the temperature of room temperature to 105 ℃, acidification is more than 1 minute.Be preferably 3-4 hour, filtering acid solution then is through washing back drying under 105 ± 5 ℃ of temperature. " and the graphite crossed through this acidification then is expansible black lead." it is again through 800-1000 ℃ high temperature instantaneously heating.
They are two years old, in addition disclosed just like No. 4146401, US Patent specification, " granular graphite is immersed in nitric acid and the vitriolic mixed solution; the granular graphite that acid soak is crossed cleans with the water of pH value gold 4-7, the granular graphite that soaks into is put into per kilogram again and is contained the phosphoric acid or the aqueous phosphatic of 0.05-1.0 molconcentration or preferably soaked 0.5 to 10 hour in the aluminium phosphate aqueous solution.Thereafter granular graphite is washed once more, through 800 ℃ of high temperature, just may expand to 60 times of former granular graphite size.
Through 105 ℃ temperature oven dry, its expansion multiple can obviously descend after the granular graphite washing after the acidifying, thereby the autohension of expanded graphite and compressibility are reduced.
The technical scheme of this patent, the method for manufacturing technology of expansible black lead of the present invention are " carbon content to be put into salpeter solution greater than 97% granularity earlier greater than 200 purpose crystalline flake graphites.The temperature of keeping room temperature to 100 ℃ is more than 1 minute, and better the weight ratio of granular graphite and nitric acid was (0.1-3) in 4-6 hour: 1, and better with 2: 1.The concentration of nitric acid is not less than 60%.Again it is taken out filtering acid solution and puts into sulphuric acid soln, keep the temperature one minute to 12 hours of room temperature to 100 ℃, with 2-8 hour for well.Graphite and vitriolic weight ratio are (0.1 ~ 3): 1.With 0,5: 1 better, vitriolic concentration is not less than 90%, the granular graphite that successively soaked through twice acid solution is taken out, the filtering acid solution, with the water of pH value 5 ~ 6 clean to pH value be 3.Empty then solid carbon dioxide part be not more than dry by the fire under 100 ℃ the temperature to water content less than 10%, add lime powder.Back placement 1-24 hour stirs.The weight of calcium oxide is with the 2-10% of granular graphite weight.Granularity is less than graphite particle size.The granular graphite that will add at last after calcium oxide is handled sieves, and removes the calcium oxide composition.Then the process for making of whole expansible black lead is finished.
There is certain defective in the aforesaid method, one is not considered the influence of impurity, if graphite is impure, when containing impurity, lattice imperfection and dislocation will appear, the generation fringe region enlarges, active site increases, and impels edge response to accelerate, though this helps the generation of marginalisation compound, but have influence on the generation of intercalation compound, and the destruction layer lattice, make lattice become disorder and irregularity, and then make speed and the degree of depth of chemical substance to inter-level diffusion, the generation of intercalation compound is all hindered and is limited in the deep layer, thereby influences the raising of degrees of expansion.Therefore require the graphite impurities content must be within the limits prescribed.Especially particulate contamination allows to exist anything but, otherwise can cut off the graphite scale in pressing process, and the formed material quality is reduced; Its two at the order number of Graphite Powder 99 single; Its three, acid-treated effect is relatively poor, the expansible multiple is lower; Its four, whole select materials and acid-treated technological process conditional parameter comparatively wide in range; Its five, oxygenant commonly used even comprise in the oxygenants such as potassium permanganate, sodium dichromate 99 just has in six kinds of objectionable impuritiess (cadmium, lead, mercury, sexavalent chrome, Polybrominated biphenyl and Poly Brominated Diphenyl Ethers) that present international standard limits the use of one or more; Therefore, the foreign matter content of the graphite particle that usual method is handled is between 0.1～0.3%, and this expanded graphite powder is only applicable to make the common graphite product, is mainly used in sealing prod.
The continual renovation replacement requirement of modern society's development of science and technology and electronic product, the performance of graphite heat conducting heat sink material is more superior, therefore, how the better graphite heat conducting heat radiation product of manufacturing property becomes the problem that each producer and research institution face.
Summary of the invention
Problem to be solved by this invention is at the metal species heat conducting and heat radiating fin of the common employing of existing electronic product and the deficiency of graphite flake, a kind of preparation method with anisotropic graphite heat conducting and heat radiating fin is provided, this preparation method overcomes defective and the problem in original expanded graphite sheet chemical treatment method simultaneously, and the graphite heat conducting and heat radiating fin of a kind of heat conduction and good heat dispersion performance can be provided.
In order to achieve the above object, the present invention by the following technical solutions: a kind of preparation method with anisotropic graphite heat conducting and heat radiating fin, described preparation method may further comprise the steps:
(1) raw material is prepared: select carbon element content to be not less than 98% Graphite Powder 99, adopting the natural graphite size is 30 order to 80 purpose natural graphite powders;
The influence of graphite particle size, the size composition that also is embodied in batching can not be too wide, and promptly largest particle and smallest particles diameter difference can not be too big.Size composition is even, and processing effect is just relatively good, so in the above-mentioned steps, the grain difference of Graphite Powder 99 is 0 ~ 15%.
(2) chemical treatment: natural graphite powder is put into pickling agent, pickling agent is the mixed solution of sulphuric acid soln and Ammonium Persulfate 98.5 solution, weight ratio is a sulphuric acid soln: Ammonium Persulfate 98.5 solution=7～9: 1, and acid-treated temperature is 20 ℃～120 ℃, the time of processing is 1～2 hour;
Wherein, the concentration of sulphuric acid soln and Ammonium Persulfate 98.5 solution is 90% ~ 96%.
Because other oxygenant just carried out chemical treatment to Graphite Powder 99 in the past, make it have swellability; Select for use the benefit of this oxygenant mixed solution to be now, not only make Graphite Powder 99 in chemical treatment, have swellability, can make simultaneously the intercalation compound of graphite particle produce very big becoming flexible again more effectively, help the rejecting of impurity in the graphite particle, and purify favourable condition is provided for next step adds the cyanogen fluorspar acid solution in washing, ammonium persulphate can strengthen the loosening and space of interlayer of graphite particle, make down simultaneously the cyanogen fluorspar acid solution in the step be easy to insert, what is more important, select for use ammonium persulphate as oxygenant, the graphite particle that makes it after the chemical treatment does not contain various objectionable impuritiess.Such as oxygenant in the past commonly used: in the oxygenants such as potassium permanganate, sodium dichromate 99, six kinds of objectionable impuritiess that just have that present international standard limits the use of such as in cadmium, lead, mercury, sexavalent chrome, Polybrominated biphenyl and the Poly Brominated Diphenyl Ethers one or more; And the content of harmful of present oxygenant of the present invention, and can also effectively reject the various objectionable impuritiess of the original inherent of graphite particle with regard to well having avoided in chemical treatment, increasing because of the selective oxidation agent.
Graphite particle is through after the chemical treatment, had swellability, simultaneously, pass through the impurity of the various trace elements of the oxidized graphite particle interlayer of this strong oxidizer of ammonium persulphate again, produced new compound, make various trace elements peel away the graphite particle interlayer gradually, in water washing process, just these compounds can be washed substantially.
During the graphite chemical treatment, chemical reaction carries out simultaneously at the edge of graphite flake and the centre of layer, and chemically treated purpose is to generate intercalation compound, avoids or control generating the marginalisation compound.For reaching this purpose, to the selection of oxygenant, particularly important seems.Usually follow following two principles: (1) selected reagent will have stronger oxidisability; (2) reagent wants fast to the infiltration diffusion of graphite linings gap, and its speed of carrying out is greater than edge oxidizing reaction speed.
(3) processing of impurity: it is to soak into 30～50 minutes in 2%～8% the cyanogen fluorspar acid solution that Graphite Powder 99 is placed on concentration;
In this treating processes, the cyanogen fluorspar acid solution is impregnated into graphite layers fully, carries out chemical reaction with impurity, and the impurity of loosening graphite layers just can wash these impurity easily when washing, reach the purpose of purification.
After the processing of this process, the purity of Graphite Powder 99 has reached the requirement that preparation has the height anisotropic graphite sheet.
Usually, preparation has the height anisotropic graphite sheet impurity of trace element in the Graphite Powder 99 particle is required to less than 0.03%;
Through after the above-mentioned processing, foreign matter content is not more than 0.015%, and graphite raw material purity is high more, and the thermal resistivity of graphite flake is more little, and thermal resistivity is more little, and thermal conductivity is high more.
(4), water washing process: graphite is washed through after the chemical treatment, and the temperature of washing is 0～20 ℃;
Further requirement, the pH value of washing terminal point is 3～5.
The purpose of washing is to remove unnecessary acid.The temperature of water washing process is to the tangible influence of expansion multiple.The water temperature height, the reactive material between interposed layer can be overflowed from interlayer, and the interlayer thing is reduced.The also corresponding minimizing of vaporizer when next step heat, the vaporized expanding power of generation is just little, makes interlayer fully not expand, so expansion multiple reduces.
(5) high temperature expands; To put into the graphite expansion stove through the Graphite Powder 99 after the washing and carry out the high temperature expansion, the temperature of graphite expansion stove is 800～950 ℃, in each high temperature expansion process, the temperature difference of expansion temperature will be controlled within 50 ℃, the high temperature expansible time is 3 seconds～10 seconds, after high temperature expands and finishes, after leaving expansion furnace, not directly enter normal temperature environment, enter water cooler and make its slow cooling, as long as it is not too big that slowly the process of cooling can make the temperature of Graphite Powder 99 and the chiller temperature temperature difference, reality can make the temperature difference remain on 50 ~ 100 ℃ in lowering the temperature, and reaches the purpose of slow cooling; To guarantee that graphite is heated evenly.To note the time that graphite stops in the high-temperature zone simultaneously, can not be long or too short.
In above-mentioned expansion process, through forming crystalline flake graphite after the chemical treatment, generated new compound in graphite layers, again because of the generation of this compound, make distance between the graphite aspect by original 3.35 * 10
-10M becomes (6 ~ 11) * 10
-10M.This time expand to be called for the first time and expand.When this graphite that contains intercalation compound is carried out pyroprocessing, the graphite intercalation compound decomposition of gasifying rapidly, the power of pushing aspect open is bigger, and interfloor distance is enlarged again.This time expand to be called for the second time and expand.Graphite is through after this twice expansion, and the gap ratio between the layered planes is original to increase 300 ~ 500.This increase multiple is called expansion multiple.
(6) molding procedure: process soft graphite coiled material production unit is processed, and makes to have anisotropic graphite heat conducting and heat radiating fin.
Add man-hour, the thickness of described graphite heat conducting and heat radiating fin is 0.1 ~ 2.1mm.
Further scheme as technique scheme:
First kind of concrete improvement, adopting the natural graphite size during step (1) raw material is prepared is 30 purpose natural graphite powders;
In step (2) chemical treatment, natural graphite powder is put into pickling agent, and pickling agent is the mixed solution of sulphuric acid soln and Ammonium Persulfate 98.5 solution, and weight ratio is a sulphuric acid soln: Ammonium Persulfate 98.5 solution=9: 1, acid-treated temperature is 25 ℃, and the time of processing is 120 minutes;
In the processing of step (3) impurity, it is to soak into 30 minutes in 2% the cyanogen fluorspar acid solution that Graphite Powder 99 is placed on concentration;
In step (4) water washing process, the temperature of washing is 0 ℃;
During step (5) high temperature expanded, the temperature of graphite expansion stove was 950 ℃, and the high temperature expansible time is 3 seconds.
Second kind of improvement, in the step (1), adopting the natural graphite size is 32 purpose natural graphite powders;
In the step (2), natural graphite powder is put into pickling agent, pickling agent is the mixed solution of sulphuric acid soln and Ammonium Persulfate 98.5 solution, and weight ratio is a sulphuric acid soln: Ammonium Persulfate 98.5 solution=9: 1, acid-treated temperature are 25 ℃, and the time of processing is 60 minutes;
In the step (3), it is to soak into 40 minutes in 5% the cyanogen fluorspar acid solution that Graphite Powder 99 is placed on concentration;
In the step (4), the temperature of washing is 10 ℃;
In the step (5), the temperature of graphite expansion stove is 900 ℃, and the high temperature expansible time is 5 seconds.
The third improvement, in the step (1), adopting the natural graphite size is 40 purpose natural graphite powders;
In the step (2), sulphuric acid soln: the weight ratio of Ammonium Persulfate 98.5 solution is 9: 1, and acid-treated temperature is 20 ℃, and the time of processing is 110 minutes;
In the step (3), it is to soak into 50 minutes in 8% the cyanogen fluorspar acid solution that Graphite Powder 99 is placed on concentration;
In the step (4), the temperature of washing is 20 ℃;
In the step (5), the temperature of graphite expansion stove is 900 ℃, and the high temperature expansible time is 6 seconds.
The 4th kind of improvement, in the step (1), adopting the natural graphite size is 80 purpose natural graphite powders;
In the step (2), sulphuric acid soln: the weight ratio of Ammonium Persulfate 98.5 solution is 9: 1, and acid-treated temperature is 120 ℃, and the time of processing is 90 minutes;
In the step (3), it is to soak into 50 minutes in 8% the cyanogen fluorspar acid solution that Graphite Powder 99 is placed on concentration;
In the step (4), the temperature of washing is 20 ℃;
In the step (5), the temperature of graphite expansion stove is 800 ℃, and the high temperature expansible time is 10 seconds.
Below in conjunction with drawings and Examples technical scheme of the present invention is further described
Description of drawings
Accompanying drawing 1 is for using different grain size level graphite, the graphite heat conducting and heat radiating fin aerated density that makes and the graph of a relation of granularity;
Accompanying drawing 2 is graphite washing temperature and expansion multiple graph of relation.
Embodiment
Embodiment 1, a kind of preparation method with anisotropic graphite heat conducting and heat radiating fin, and described preparation method may further comprise the steps:
(1) raw material is prepared: select carbon element content to be not less than 98% Graphite Powder 99, adopting the natural graphite size is 30 purpose natural graphite powders, and the grain difference of Graphite Powder 99 is 0 ~ 15%; By accompanying drawing 1 as can be seen, the numerical range of its aerated density of Graphite Powder 99 of 30 ~ 80 order numbers is 30 ~ 95, all can be used for processing conducting strip;
(2) chemical treatment: natural graphite powder is put into pickling agent, pickling agent is the mixed solution of sulphuric acid soln and Ammonium Persulfate 98.5 solution, weight ratio is a sulphuric acid soln: Ammonium Persulfate 98.5 solution=9: 1, the concentration of sulphuric acid soln and Ammonium Persulfate 98.5 solution is 90%, acid-treated temperature is 25 ℃, and the time of processing is 120 minutes;
(3) processing of impurity: it is to soak into 30 minutes in 2% the cyanogen fluorspar acid solution that Graphite Powder 99 is placed on concentration, and foreign matter content is not more than 0.015%;
(4), water washing process: graphite is washed through after the chemical treatment, and the temperature of washing is 0 ℃, and the pH value of washing terminal point is 3～5;
(5) high temperature expands; To put into the graphite expansion stove through the Graphite Powder 99 after the washing and carry out the high temperature expansion, the temperature of graphite expansion stove is 950 ℃, and the high temperature expansible time is 3 seconds, and after high temperature expanded and finishes, Graphite Powder 99 entered water cooler and slowly lowers the temperature;
(6) molding procedure: through the processing of graphite coiled material production unit, making density is 0.7g/cm with Graphite Powder 99
3, thickness is respectively the graphite heat conducting and heat radiating fin of 0.1mm, 0.2mm, 0.3mm, 0.5mm, 0.8mm, 1.0mm, 1.2mm, 1.5mm, 2.0mm, 2.1mm.
According to above-mentioned steps, the condition and the parameter that change in the step are tested respectively, the result as shown in Table 1, by table one as can be seen, the ratio of sulphuric acid soln and Ammonium Persulfate 98.5 solution is that 7: 1 and 9: 1 o'clock expansion multiples are better.
Table one
According to the step of embodiment 1, the temperature that changes washing is tested respectively, the conclusion that draws as shown in Figure 2, therefrom as can be seen, 0 ~ 20 ℃ water temperature is to the expansible best results.
Embodiment 2, a kind of preparation method with anisotropic graphite heat conducting and heat radiating fin, described preparation method may further comprise the steps:
(1) raw material is prepared: select carbon element content to be not less than 98% Graphite Powder 99, adopting the natural graphite size is 32 purpose natural graphite powders, and the grain difference of Graphite Powder 99 is 0 ~ 15%;
(2) chemical treatment: natural graphite powder is put into pickling agent, pickling agent is the mixed solution of sulphuric acid soln and Ammonium Persulfate 98.5 solution, weight ratio is a sulphuric acid soln: Ammonium Persulfate 98.5 solution=9: 1, acid-treated temperature is 25 ℃, the time of handling is 60 minutes, and the concentration of sulphuric acid soln and Ammonium Persulfate 98.5 solution is 92%;
(3) processing of impurity: it is to soak into 40 minutes in 5% the cyanogen fluorspar acid solution that Graphite Powder 99 is placed on concentration, and foreign matter content is not more than 0.015%;
(4), water washing process: graphite is washed through after the chemical treatment, and the temperature of washing is 10 ℃; In the step (4), the pH value of washing terminal point is 3～5;
(5) high temperature expands; To put into the graphite expansion stove through the Graphite Powder 99 after the washing and carry out the high temperature expansion, the temperature of graphite expansion stove is 900 ℃, in each high temperature expansion process, the temperature difference of expansion temperature will be controlled within 50 ℃, the high temperature expansible time is 5 seconds, after high temperature expanded and finishes, Graphite Powder 99 entered water cooler and slowly lowers the temperature;
(6) molding procedure: through the processing of soft graphite coiled material production unit, making density is 1.0g/cm
3And 2.0g/cm
3, thickness is respectively the graphite heat conducting and heat radiating fin of 0.1mm, 0.2mm, 0.3mm, 0.5mm, 0.8mm, 1.0mm, 1.2mm, 1.5mm, 2.0mm, 2.1mm.
According to above-mentioned steps, the condition and the parameter that change in the step are tested respectively, the result as shown in Table 2, by table two as can be seen, the ratio of sulphuric acid soln and Ammonium Persulfate 98.5 solution is that 8: 1 and 9: 1 o'clock expansion multiples are better.
Table two
Embodiment 3, a kind of preparation method with anisotropic graphite heat conducting and heat radiating fin, described preparation method may further comprise the steps:
(1) raw material is prepared: select carbon element content to be not less than 98% Graphite Powder 99, adopting the natural graphite size is 40 purpose natural graphite powders, and the grain difference of Graphite Powder 99 is 0 ~ 15%;
(2) chemical treatment: natural graphite powder is put into pickling agent, pickling agent is the mixed solution of sulphuric acid soln and Ammonium Persulfate 98.5 solution, the concentration of sulphuric acid soln and Ammonium Persulfate 98.5 solution is 95%, sulphuric acid soln: the weight ratio of Ammonium Persulfate 98.5 solution is 9: 1, acid-treated temperature is 20 ℃, and the time of processing is 110 minutes;
(3) processing of impurity: it is to soak into 50 minutes in 8% the cyanogen fluorspar acid solution that Graphite Powder 99 is placed on concentration, and foreign matter content is not more than 0.015%;
(4), water washing process: graphite is washed through after the chemical treatment, and the temperature of washing is 20 ℃, and the pH value of washing terminal point is 3～5;
(5) high temperature expands; To put into the graphite expansion stove through the Graphite Powder 99 after the washing and carry out the high temperature expansion, the temperature of graphite expansion stove is 900 ℃, in each high temperature expansion process, the temperature difference of expansion temperature will be controlled within 50 ℃, the high temperature expansible time is 6 seconds, after high temperature expanded and finishes, Graphite Powder 99 entered water cooler and slowly lowers the temperature;
(6) molding procedure: through the processing of soft graphite coiled material production unit, making density is 1.5g/cm
3, thickness is respectively the graphite heat conducting and heat radiating fin of 0.1mm, 0.2mm, 0.3mm, 0.5mm, 0.8mm, 1.0mm, 1.2mm, 1.5mm, 2.0mm, 2.1mm.
According to above-mentioned steps, the parameter that changes in the step is tested respectively, the result as shown in Table 3, by table three as can be seen, the ratio of sulphuric acid soln and Ammonium Persulfate 98.5 solution is that 7: 1 and 9: 1 o'clock expansion multiples are better.
Table three
Embodiment 4, a kind of preparation method with anisotropic graphite heat conducting and heat radiating fin, described preparation method may further comprise the steps:
(1) raw material is prepared: select carbon element content to be not less than 98% Graphite Powder 99, adopting the natural graphite size is 80 purpose natural graphite powders, and the grain difference of Graphite Powder 99 is 0 ~ 15%;
(2) chemical treatment: natural graphite powder is put into pickling agent, pickling agent is the mixed solution of sulphuric acid soln and Ammonium Persulfate 98.5 solution, the concentration of sulphuric acid soln and Ammonium Persulfate 98.5 solution is 96%, the weight ratio of sulphuric acid soln and Ammonium Persulfate 98.5 solution is 9: 1, acid-treated temperature is 120 ℃, and the time of processing is 90 minutes;
(3) processing of impurity: it is to soak into 50 minutes in 8% the cyanogen fluorspar acid solution that Graphite Powder 99 is placed on concentration, and foreign matter content is not more than 0.015%;
(4), water washing process: graphite is washed through after the chemical treatment, and the temperature of washing is 20 ℃, and the pH value of washing terminal point is 3～5;
(5) high temperature expands; To put into the graphite expansion stove through the Graphite Powder 99 after the washing and carry out the high temperature expansion, the temperature of graphite expansion stove is 800 ℃, and the high temperature expansible time is 10 seconds, and after high temperature expanded and finishes, Graphite Powder 99 entered water cooler and slowly lowers the temperature;
(6) molding procedure: through the processing of soft graphite coiled material production unit, making density is 1.8g/cm3, and thickness is respectively the graphite heat conducting and heat radiating fin of 0.1mm, 0.2mm, 0.3mm, 0.5mm, 0.8mm, 1.0mm, 1.2mm, 1.5mm, 2.0mm, 2.1mm.
According to above-mentioned steps, the condition and the parameter that change in the step are tested respectively, the result as shown in Table 4, by table four as can be seen, the ratio of sulphuric acid soln and Ammonium Persulfate 98.5 solution is that 8: 1 and 9: 1 o'clock expansion multiples are better.
Table four
The chemical treatment method of acid treatment step is with now usual method is basic identical as can be seen to table four by table one, and key point is that pickling agent is on the ratio difference of the difference of oxygenant and concentration and consumption proportion.
Embodiment 5, present graphite chemical treatment method, the acid solution of employing are 90% the vitriol oil and the mixed solution of 90% concentrated nitric acid, and its weight ratio is 9: 1.120 ℃ of acid-treated temperature, in 1 hour treatment time, then through washing, expanding through high temperature then makes the graphite flake of different densities and thickness shown in table five, table six.
The contrast table of the product that itself and the method applied in the present invention make is as follows:
The graphite flake thermal conductivity synopsis that table five is handled for graphite flake and the inventive method of general chemistry processing
The graphite flake thermal conductivity synopsis that table six is handled for graphite flake and the inventive method of general chemistry processing
By table five and table six as can be seen, prepared its thermal conductivity of product of method of the present invention is compared with usual way, and heat conductivility obviously improves.
Claims (10)
1, a kind of preparation method with anisotropic graphite heat conducting and heat radiating fin, it is characterized in that: described preparation method may further comprise the steps:
(1) raw material is prepared: select carbon element content to be not less than 98% Graphite Powder 99, adopting the natural graphite size is 30 order to 80 purpose natural graphite powders;
(2) chemical treatment: natural graphite powder is put into pickling agent, pickling agent is the mixed solution of sulphuric acid soln and Ammonium Persulfate 98.5 solution, weight ratio is a sulphuric acid soln: Ammonium Persulfate 98.5 solution=7～9: 1, and acid-treated temperature is 20 ℃～120 ℃, the time of processing is 1～2 hour;
(3) processing of impurity: it is to soak into 30～50 minutes in 2%～8% the cyanogen fluorspar acid solution that Graphite Powder 99 is placed on concentration;
(4), water washing process: graphite is washed through after the chemical treatment, and the temperature of washing is 0～20 ℃;
(5) high temperature expands; To put into the graphite expansion stove through the Graphite Powder 99 after the washing and carry out the high temperature expansion, the temperature of graphite expansion stove is 800～950 ℃, and the high temperature expansible time is 3 seconds～10 seconds, and after high temperature expanded and finishes, Graphite Powder 99 entered water cooler and slowly lowers the temperature;
(6) molding procedure: process soft graphite coiled material production unit is processed, and makes to have anisotropic graphite heat conducting and heat radiating fin.
2, a kind of preparation method with anisotropic graphite heat conducting and heat radiating fin as claimed in claim 1 is characterized in that: in the step (1), the grain difference of Graphite Powder 99 is 0 ~ 15%.
3, a kind of preparation method with anisotropic graphite heat conducting and heat radiating fin as claimed in claim 1 is characterized in that: in the step (2), the concentration of sulphuric acid soln and Ammonium Persulfate 98.5 solution is 90% ~ 96%.
4, a kind of preparation method with anisotropic graphite heat conducting and heat radiating fin as claimed in claim 1, it is characterized in that: in the step (3), foreign matter content is not more than 0.015%.
5, a kind of preparation method with anisotropic graphite heat conducting and heat radiating fin as claimed in claim 1 is characterized in that: in the step (6), the thickness of described graphite heat conducting and heat radiating fin is 0.1 ~ 2.1mm.
6, a kind of preparation method with anisotropic graphite heat conducting and heat radiating fin as claimed in claim 1 is characterized in that: in the step (4), the pH value of washing terminal point is 3～5.
7, as one of them described a kind of preparation method with anisotropic graphite heat conducting and heat radiating fin in the claim 1 ~ 6, it is characterized in that: adopting the natural graphite size during step (1) raw material is prepared is 30 purpose natural graphite powders;
In step (2) chemical treatment, natural graphite powder is put into pickling agent, and pickling agent is the mixed solution of sulphuric acid soln and Ammonium Persulfate 98.5 solution, and weight ratio is a sulphuric acid soln: Ammonium Persulfate 98.5 solution=9: 1, acid-treated temperature is 25 ℃, and the time of processing is 120 minutes;
In the processing of step (3) impurity, it is to soak into 30 minutes in 2% the cyanogen fluorspar acid solution that Graphite Powder 99 is placed on concentration;
In step (4) water washing process, the temperature of washing is 0 ℃;
During step (5) high temperature expanded, the temperature of graphite expansion stove was 950 ℃, and the high temperature expansible time is 3 seconds.
8, as one of them described a kind of preparation method with anisotropic graphite heat conducting and heat radiating fin in the claim 1 ~ 6, it is characterized in that: in the step (1), adopting the natural graphite size is 32 purpose natural graphite powders;
In the step (2), natural graphite powder is put into pickling agent, pickling agent is the mixed solution of sulphuric acid soln and Ammonium Persulfate 98.5 solution, and weight ratio is a sulphuric acid soln: Ammonium Persulfate 98.5 solution=9: 1, acid-treated temperature are 25 ℃, and the time of processing is 60 minutes;
In the step (3), it is to soak into 40 minutes in 5% the cyanogen fluorspar acid solution that Graphite Powder 99 is placed on concentration;
In the step (4), the temperature of washing is 10 ℃;
In the step (5), the temperature of graphite expansion stove is 900 ℃, and the high temperature expansible time is 5 seconds.
9, as one of them described a kind of preparation method with anisotropic graphite heat conducting and heat radiating fin in the claim 1 ~ 6, it is characterized in that: in the step (1), adopting the natural graphite size is 40 purpose natural graphite powders;
In the step (2), sulphuric acid soln: the weight ratio of Ammonium Persulfate 98.5 solution is 9: 1, and acid-treated temperature is 20 ℃, and the time of processing is 110 minutes;
In the step (3), it is to soak into 50 minutes in 8% the cyanogen fluorspar acid solution that Graphite Powder 99 is placed on concentration;
In the step (4), the temperature of washing is 20 ℃;
In the step (5), the temperature of graphite expansion stove is 900 ℃, and the high temperature expansible time is 6 seconds.
10, as one of them described a kind of preparation method with anisotropic graphite heat conducting and heat radiating fin in the claim 1 ~ 6, it is characterized in that: in the step (1), adopting the natural graphite size is 80 purpose natural graphite powders;
In the step (2), sulphuric acid soln: the weight ratio of Ammonium Persulfate 98.5 solution is 9: 1, and acid-treated temperature is 120 ℃, and the time of processing is 90 minutes;
In the step (3), it is to soak into 50 minutes in 8% the cyanogen fluorspar acid solution that Graphite Powder 99 is placed on concentration;
In the step (4), the temperature of washing is 20 ℃;
In the step (5), the temperature of graphite expansion stove is 800 ℃, and the high temperature expansible time is 10 seconds.
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