CN108588461B - Polyimide-based graphite-metal composite material and preparation method thereof - Google Patents
Polyimide-based graphite-metal composite material and preparation method thereof Download PDFInfo
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- CN108588461B CN108588461B CN201810388089.1A CN201810388089A CN108588461B CN 108588461 B CN108588461 B CN 108588461B CN 201810388089 A CN201810388089 A CN 201810388089A CN 108588461 B CN108588461 B CN 108588461B
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/04—Making non-ferrous alloys by powder metallurgy
- C22C1/05—Mixtures of metal powder with non-metallic powder
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C21/00—Alloys based on aluminium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C28/00—Alloys based on a metal not provided for in groups C22C5/00 - C22C27/00
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C9/00—Alloys based on copper
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
- C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
- C23C18/31—Coating with metals
- C23C18/38—Coating with copper
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
- C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
- C23C18/52—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating using reducing agents for coating with metallic material not provided for in a single one of groups C23C18/32 - C23C18/50
Abstract
The invention discloses a polyimide-based graphite-metal composite material, which contains 20-95% by volume of polyimide-based graphite powder and 80-5% by volume of metal powder matrix, and the relative density of the composite material is more than 95%. The polyimide-based graphite-metal composite material can be prepared into sheets, plates and blocks with larger thickness, has higher strength and adjustable thermal expansion rate, and has higher thermal conductivity in the thickness direction. The technical defects that the thermal conductivity of a common graphite-metal composite material is lower than 600W/mK, the thickness of a polyimide-based graphite film with high thermal conductivity cannot be large, and the thermal conductivity in the thickness direction is too low are overcome.
Description
Technical Field
The invention belongs to the field of heat-conducting composite materials, and particularly relates to a polyimide-based graphite-metal composite material and a preparation method thereof.
Background
With the rapid development of the microelectronic industry, electronic devices and equipment are continuously developed toward high power, high density integration and miniaturization, and the resulting heat generation problem poses a serious challenge to the performance, reliability and lifetime of electronic products. Materials used for thermal management of electronic products are required to have not only ultra-high thermal conductivity but also a certain thermal capacity. The heat capacity is in direct proportion to the mass of the material, and when the area is fixed, the increase of the thickness has great significance for improving the heat capacity of the heat conduction material.
In recent years, polyimide-based graphite (PIG) films prepared by taking Polyimide (PI) films as raw materials are widely applied to electronic equipment such as smart phones and notebook computers, and the plane thermal conductivity of the PIG films is more than 1500W/mk. However, due to the limitation of the thickness of the PI film and the influence of the thicker PI film and the greater difficulty in graphitization, the thickness of the polyimide-based high thermal conductivity graphite film is below 100 μm, generally about 25 μm, and the urgent requirements of increasingly thinner electronic products on high heat capacity and high thermal conductivity graphite materials cannot be met.
Graphite-metal composite materials, especially graphite-metal composite materials prepared by powder metallurgy process, have been drawing attention in the application of heat pipe control materials due to their characteristics of high thermal conductivity, small thermal expansion coefficient, high strength, and being capable of being prepared into any shape and size. The flaky graphite powder is often used as a graphite material for a graphite-metal composite material, and its thermal conductivity is usually about 400W/mK. High-thermal conductivity, large-size and high-quality flaky graphite powder is difficult to obtain, the performance of the graphite-metal composite material depends on the characteristics of the graphite powder to a great extent, the heat conductivity of the flaky graphite-metal composite material is generally less than 600W/mK, and the heat conductivity needs to be further improved.
Disclosure of Invention
The present invention has been made to overcome the above-mentioned disadvantages and drawbacks of the background art, and an object of the present invention is to provide a polyimide-based graphite-metal composite material capable of satisfying both high thermal conductivity and high heat capacity, and a method for preparing the same. The problem that the thermal conductivity of a common graphite-metal composite material is lower than 600W/mK, and the thermal capacity of a polyimide-based high-thermal-conductivity graphite film is small due to thickness limitation is solved.
The polyimide-based high-thermal-conductivity graphite film can be broken to form large-length-diameter-ratio and large-size flake graphite powder, the plane thermal conductivity of the flake graphite powder can reach more than 1500W/mk, the polyimide-based graphite-metal composite material prepared by adopting the powder metallurgy process is not limited by the thickness, the flake graphite-metal composite material can inherit the high thermal conductivity of the polyimide-based graphite film, and the thermal capacity can be improved by increasing the thickness.
In order to solve the technical problems, the technical scheme provided by the invention is as follows:
a polyimide-based graphite-metal composite material comprises 20-95% by volume of polyimide-based graphite powder and 80-5% by volume of metal powder matrix, and the relative density of the composite material is more than 95%.
The relative density in the present invention means a ratio of an actual density to an ideal density calculated from volume percentages and true densities of the polyimide-based graphite powder and the matrix, and is calculated by the following formula.
(relative density) ═ actual density)/(ideal density)
(ideal density) — (true density of polyimide-based graphite powder) × (% by volume of polyimide-based graphite powder)/100 + (true density of matrix) × (% by volume of matrix)/100
When the relative density is 95% or more, the composite material can be provided with almost no voids that inhibit heat conduction, and the properties such as mechanical strength can be improved.
In the composite material, the polyimide-based graphite powder preferably has an average aspect ratio of 5 to 100 and/or an average particle diameter of 20 to 2000 μm. Wherein the average aspect ratio is an average value of a representative length of the particles in the direction of the plane of the graphite sheets with respect to the thickness, and the average particle diameter is a representative average length of the powder in the direction of the plane of the graphite sheets. The average length-diameter ratio is too small (less than 5) or the average particle size is too small (less than 20), which is not favorable for the ordered arrangement of the powder, and the contact thermal resistance among the powder is increased, which is unfavorable for the heat-conducting property of the composite material; the average length-diameter ratio is too large (more than 100), and the processing difficulty of the powder is high; the average particle size is too large (greater than 2000 microns), and the composite material is difficult to press and sinter.
In the composite material, preferably, the metal powder matrix is one of copper, aluminum or an alloy thereof. Copper has a thermal conductivity second to that of silver, and gold and aluminum have slightly poor thermal conductivities.
In the composite material, the metal powder matrix preferably has an average particle diameter of 2 to 120 μm and an average thickness of 100 to 500 nm. From the viewpoint of improving the thermal conductivity and alleviating the segregation of metals, metal powder having a small particle size is preferable. The average thickness is less than 100 nanometers, and the metal powder is difficult to prepare; the average thickness is more than 500 nanometers, which is not beneficial to the dispersion of the metal powder in the graphite powder.
As a general inventive concept, the present invention also provides a method for preparing a polyimide-based graphite-metal composite material, comprising the steps of:
(1) the polyimide film is fired into polyimide-based graphite film, and then the polyimide-based graphite film is crushed into polyimide
A base graphite powder;
(2) mixing polyimide-based graphite powder and metal powder to obtain a powder mixture;
(3) preparing the powder mixture into a sintering precursor;
(4) and (3) performing pressure sintering on the sintering precursor.
In the step (1), the polyimide film is fired into the polyimide-based graphite film through two processes of carbonization and graphitization. The specific process of carbonization is that the polyimide film and the graphite paper are put into a carbonization furnace, vacuum pumping is carried out, the temperature is raised from room temperature to 500 ℃ at the heating rate of 5-15 ℃/min, then the temperature is raised to 600-650 ℃ at the heating rate of 1-5 ℃/min, heat preservation is carried out for 30-120min, then the temperature is raised to 700-800 ℃ at the heating rate of 1-5 ℃/min, heat preservation is carried out for 30-120min, finally the temperature is raised to 900-1500 ℃ at the heating rate of 5-15 ℃/min, and heat preservation is carried out for 0.5-4 h. The temperature rise rate (less than or equal to 5 ℃) needs to be slowed down at 800 ℃ (the rapid decoking stage) of 500-; the heating rate is too fast, and a large amount of waste gas such as tar and the like generated in the carbonization process of the PI film is difficult to rapidly remove from the PI film, so that the defects of unclean film decoking or tar spots and the like on the surface of the film are caused. At 900-.
The specific process of graphitization is to place the carbonized film after the PI film carbonization in a graphitization furnace, introduce argon gas to maintain the pressure in the furnace at a micro-positive pressure (the micro-positive pressure means that the pressure of the gas in the furnace is slightly higher than the atmospheric pressure of the environment outside the furnace body, namely, to ensure that the outside air cannot enter the furnace body), then raise the temperature to 2500 plus materials 3000 ℃ at the rate of 5-30 ℃/min, and preserve the temperature for 0.5-4h to complete the graphitization process. 2500 ℃ plus 3000 ℃ can ensure that the graphite film reaches the required graphitization temperature, and the higher temperature has high requirements on equipment and high energy consumption.
The thickness of the polyimide film is 5-150 mu m; the thermal conductivity of the polyimide-based graphite film reaches more than 1500W/mk. The PI film with the thickness less than 5 microns is difficult to prepare, the PI film with the thickness more than 150 microns is also difficult to prepare, the PI film is too thick, decoking is difficult in the carbonization process, the graphitization degree of the prepared graphite film is low, and the thermal conductivity is reduced.
In the above method, preferably, the raw material used for preparing the polyimide-based graphite powder in the step (1) is polyimide film scrap or polyimide-based graphite film scrap. The advantage of using these scrap is that the cost of the polyimide-based graphite powder can be reduced.
In the above method, preferably, the polyimide-based graphite film is crushed into polyimide-based graphite powder by a ball milling method. The ball milling and crushing method has high efficiency. The specific process of ball milling is that stainless steel grinding balls, ball milling media absolute ethyl alcohol and polyimide-based graphite films are added into a ball milling tank according to the mass ratio of (3-20)/(0.1-10)/1, ball milling is carried out on ball milling equipment at the rotating speed of 200-600r/min for 0.5-24h, then the grinding balls and the absolute ethyl alcohol are removed, drying and screening are carried out. The average length-diameter ratio of the crushed polyimide-based graphite powder is 5-100, and the average particle size is 20-2000 mu m.
The method of mixing the polyimide-based graphite powder and the metal powder in the step (2) may be performed by any method known in the art, and the polyimide-based graphite powder and the metal powder may be mixed with an inert liquid medium by using a planetary ball mill and then dried by using a dryer to obtain a mixed powder. The mixing ratio of the polyimide-based graphite powder and the metal powder is such that the final polyimide-based graphite powder accounts for 20-95 vol% of the composite material.
In the above method, preferably, in the step (3), the powder mixture filled in the mold is uniaxially pressed at a pressure of 5 to 150MPa, and the sintering precursor is prepared by multi-pass filling and pressing so that the polyimide-based graphite powder is oriented such that the plane direction of the graphite sheet layer is perpendicular to the pressing direction as much as possible. The obtained sintering precursor has high compact density and good formability.
In the above method, the sintering precursor obtained in the step (4) is preferably sintered while being uniaxially pressed to form a composite material. The obtained composite material has high sintering density, good orientation and high heat conductivity coefficient. The specific process is that the sintering precursor is firstly placed in a tungsten carbide mould and is placed in a hot-pressing sintering furnace, and then the furnace is vacuumized to keep 10 degrees in the furnace-3And (3) introducing nitrogen or argon serving as inert protective gas into the furnace at the vacuum degree of Pa, then preserving the heat for 0.5-2 h at the sintering temperature of 800-1000 ℃ under the hot-pressing pressure of 60-200 MPa, and finally cooling along with the furnace to obtain the polyimide-based graphite-metal composite material with the relative density of more than 95%.
In the above method, preferably, the polyimide-based graphite powder is subjected to surface copper plating or aluminum plating before being mixed with the metal powder. By plating copper or aluminum on the surface of the polyimide-based graphite powder, the specific gravity of the copper-plated or aluminum-plated polyimide-based graphite powder can be increased, segregation caused by an excessively large specific gravity difference between the graphite powder and a metal copper/aluminum matrix can be relieved, the affinity between the polyimide-based graphite powder and the metal copper/aluminum matrix can be increased, and the properties such as mechanical strength of the obtained composite material can be improved.
Preferably, the surface copper plating treatment mainly comprises a roughening process, a sensitizing process, an activating process, a glue dissolving process and a plating process. The specific process is as follows:
(a) soaking the polyimide-based graphite powder obtained in the step (1) in concentrated nitric acid with the temperature of 60-80 ℃ and the mass fraction of 60-65% for 1-3h, taking out and cleaning the polyimide-based graphite powder, and finishing roughening treatment; coarsening, namely oxidizing the surface of the graphite powder by using concentrated nitric acid to improve the surface activity of the graphite powder.
(b) Soaking the coarsened polyimide-based graphite powder in a stannous chloride solution with the pH value of 1.5 for 5-10min to enable the surface of the polyimide-based graphite powder to adsorb a SnOHCl colloid membrane with viscosity and reducibility, taking out the polyimide-based graphite powder and then cleaning the polyimide-based graphite powder with deionized water to finish the sensitization process; the sensitization process is used for making the polyimide-based graphite powder surface adsorb a SnOHCl colloid membrane with viscosity and reducibility.
(c) Soaking the sensitized polyimide-based graphite powder in 0.5-3 g/L g/g palladium chloride solution or 0.5-3 g/L g/32 silver nitrate solution for 5-10min to enable the generated simple substance palladium or simple substance silver to be adsorbed on the surface of the polyimide-based graphite powder, then taking out and cleaning with deionized water to finish the activation process, wherein the activation process is that oxidant palladium ions or silver ions react with reducing agent SnOHCl generated in the sensitization process to generate simple substance palladium or simple substance silver, and the simple substance palladium or simple substance silver is adsorbed on the surface of the polyimide-based graphite powder;
(d) placing the activated polyimide-based graphite powder in 1-2 g/L of fluoboric acid aqueous solution, soaking for 3-5min, taking out, and cleaning with deionized water to finish the dispergation process, wherein the fluoboric acid has too low concentration, the solution composition changes rapidly, the process stability is poor, and the over-high concentration of the fluoboric acid can cause the over-dispergation;
(e) the method comprises the steps of preparing a copper plating solution, wherein the copper plating solution contains 10-15 g/L of copper sulfate pentahydrate, 10-15 ml/L of formaldehyde, 40-60 g/L of sodium potassium tartrate and 10-15 g/L of sodium hydroxide, copper particles are provided by the copper sulfate pentahydrate, the formaldehyde is used as a reducing agent, the sodium potassium tartrate is used as a complexing agent and can prevent copper ions from forming hydroxide precipitates and separating out, the sodium hydroxide is used as a pH regulator, the pH value of the plating solution is 9.0-13.0, the pH value is too low, copper plating reaction does not proceed or proceeds too slowly, polyimide-based graphite powder after peptization treatment is immersed in the plating solution, the plating temperature is increased to a plating temperature, the plating time is kept for a certain plating time, the plating process is completed, the plating temperature is 60-90 ℃, the plating time is 2-60min, after the plating is completed, the polyimide-based graphite powder is washed by deionized water, then is dried, the plating temperature is lower than 60 ℃, the copper plating rate is too low, the plating temperature is higher than 90 ℃, the copper plating rate is too high, the plating speed, the plating layer is uneven, the plating phenomenon and the plating layer stripping phenomenon is.
The weight of the polyimide-based graphite powder is increased by 2-40% after electroless copper plating. If the copper plating is less than 2%, the plating layer is too little and uneven; if the copper plating is higher than 40%, the plating layer is too thick, so that the plating layer and the graphite powder are not firmly combined easily, and the plating solution is wasted.
Compared with the prior art, the invention has the following advantages:
(1) the polyimide-based graphite-metal composite material can be prepared into sheets, plates and blocks with larger thickness, has higher strength and adjustable thermal expansion rate, and has higher thermal conductivity in the thickness direction.
(2) The invention can also adopt polyimide film leftover materials or polyimide-based graphite film leftover materials to prepare polyimide-based graphite powder, thereby realizing waste recycling.
Detailed Description
In order to facilitate an understanding of the present invention, the present invention will be described more fully and in detail with reference to the preferred embodiments, but the scope of the present invention is not limited to the specific embodiments below.
Unless otherwise defined, all terms of art used hereinafter have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present invention.
Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment and the like used in the present invention are commercially available or can be prepared by existing methods.
Example 1
The PI film with the thickness of 25 mu m and the graphite paper are stacked in a crossed manner and placed in a carbonization furnace; vacuumizing the carbonization furnace to be within 20Pa, starting a heating power supply, and heating the carbonization furnace to 500 ℃ from room temperature at the heating rate of 10 ℃/min; then raising the temperature to 600 ℃ at the heating rate of 2 ℃/min, and preserving the temperature for 30 min; raising the temperature to 750 ℃ at the heating rate of 2 ℃/min, and preserving the heat for 30 min; and finally, raising the temperature to 1200 ℃ at the heating rate of 10 ℃/min, and preserving the temperature for 1h to finish the carbonization of the polyimide film.
And (3) placing the carbonized film obtained after the PI film carbonization in a graphitization furnace, introducing argon to maintain the pressure in the furnace at a micro-positive pressure, starting a heating power supply to heat to 2850 ℃ at a heating rate of 15 ℃/min, and preserving heat for 0.5h to complete the preparation of the polyimide-based graphite film.
Adding stainless steel grinding balls, absolute ethyl alcohol and a polyimide-based graphite film into a ball milling tank according to a mass ratio of 9/5/1, wherein the addition volume accounts for 2/3 of the volume of the ball milling tank, carrying out ball milling on a planetary ball mill for 4 hours at a rotating speed of 350r/min, filtering out the grinding balls and the absolute ethyl alcohol, drying in a hot air drying box at 70 ℃ for 3 hours, and sieving to obtain the polyimide-based graphite powder with the average thickness of 6 microns and the average particle size of 150 microns.
Soaking polyimide-based graphite powder in concentrated nitric acid with the temperature of 80 ℃ and the mass fraction of 65% for 2h, taking out and cleaning to finish roughening treatment, soaking the roughened polyimide-based graphite powder in stannous chloride solution with the pH of 1.5 for 8min to enable the surface of the polyimide-based graphite powder to adsorb a SnOHCl colloidal membrane with viscosity and reducibility, taking out and cleaning with deionized water to finish the sensitizing process, soaking the sensitized polyimide-based graphite powder in palladium chloride solution with the pH of 1 g/L for 5min to enable generated simple substance palladium to be adsorbed on the surface of the polyimide-based graphite powder, taking out and cleaning with deionized water to finish the activating process, placing the activated polyimide-based graphite powder in fluoboric acid aqueous solution with the concentration of 1 g/L, soaking for 5min, taking out and cleaning with deionized water to finish the degumming process, preparing plating solution with copper sulfate of 10 g/L, formaldehyde of 10 ml/L, sodium potassium tartrate of 40 g/L and sodium hydroxide of 10 g/L, taking out and drying the polyimide-coated graphite powder at the temperature of 70 min after weight gaining, applying deionized water, and drying the polyimide-plated graphite powder;
adding copper-plated polyimide-based graphite powder, metal copper powder, ethanol and stainless steel balls into a ball milling tank of a planetary ball mill according to the mass ratio of 5/3/3/24, wherein the average particle size of the metal copper powder is 20 mu m, the average thickness of the metal copper powder is 200nm, mixing the planetary ball mill for 30min at the rotating speed of 150r/min, taking out the obtained powder mixture from the planetary ball mill, and then drying the powder mixture in a hot air drying box at the temperature of 70 ℃ for 3 hours;
spreading the obtained powder into a die, wherein the spreading thickness of the powder is about 1-3mm, performing uniaxial pressing by adopting the pressure of 30MPa, and continuously filling the powder and pressing until a powder pressed blank with the required thickness is obtained;
placing the pressed green body in a tungsten carbide mould and a hot-pressing sintering furnace, vacuumizing to make the vacuum degree in the furnace reach 10-3Pa, introducing argon to increase the pressure in the furnace to atmospheric pressure, continuously maintaining the argon flow of 5L/min and opening an air outlet valve of a sintering furnace, then heating to 900 ℃ under the pressure of 200MPa, preserving the heat for 1h, and finally cooling along with the furnace to obtain the polyimide-based graphite-copper composite material with the thickness of more than 500 mu m, wherein the density of the composite material is 3.16g/cm3The relative density was 97%, the in-plane thermal conductivity measured at 25 ℃ was 830W/mK, the thickness-direction thermal conductivity was 25.2W/mK, and the flexural strength was 33.5 MPa.
Example 2
The procedure of example 1 was repeated to manufacture a composite material, except that copper-plated polyimide-based graphite powder, metallic copper powder, ethanol, and stainless steel balls were added to the ball mill pot of the planetary ball mill at a mass ratio of 2/3/3/24 in the preparation of the powder mixture. The density of the resulting composite was 4.118g/cm3The relative density was 97.5%, the in-plane thermal conductivity measured at 25 ℃ was 720W/mK, the thickness-direction thermal conductivity was 35.2W/mK, and the flexural strength was 40.5 MPa.
Example 3
The procedure of example 1 was repeated to manufacture a composite material, except that the following aspects were used.
A PI film with the thickness of 50 mu m is adopted to replace a PI film with the thickness of 25 mu m; ball-milling polyimide-based graphite powder on a planetary ball mill at a rotating speed of 350r/min for 8 hours when the polyimide-based graphite powder is prepared by ball-milling a polyimide-based graphite film, and sieving to obtain the polyimide-based graphite powder with the average thickness of 10 microns and the average particle size of 50 microns; the plating time of the polyimide-based graphite powder is changed to 40min, and the weight of the plated polyimide-based graphite powder is increased by 30%; when the powder mixture is prepared, copper-plated polyimide-based graphite powder, metal copper powder, ethanol and stainless steel balls are added into a ball milling tank of a planetary ball mill in a mass ratio of 1/3/3/18.
The density of the obtained composite material was 5.85g/cm3The relative density was 96%, the thermal conductivity in the plane direction measured at 25 ℃ was 630W/mK, the thermal conductivity in the thickness direction was 45.2W/mK, and the bending strength was 52.5 MPa.
Comparative example 1
The procedure of example 1 was repeated except that crystalline flake graphite powder was used instead of polyimide-based graphite powder to produce a composite material having a planar thermal conductivity of 450W/mK and a thickness-direction thermal conductivity of 37W/mK as measured at 25 ℃.
The above embodiments illustrate that the technology provided by the present invention can prepare a high thermal conductivity composite material with a thickness of more than 500 μm, a thermal conductivity in a planar direction of more than 600W/mK, and a thermal conductivity in a thickness direction of more than 25W/mK. Compared with the graphite-metal composite material which adopts the crystalline flake graphite as the raw material, the composite material has higher plane heat conductivity coefficient.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (3)
1. A method for preparing polyimide-based graphite-metal composite material,
the composite material contains polyimide-based graphite powder with the volume of 20-95% and metal powder matrix with the volume of 80-5%, and the relative density of the composite material is more than 95%;
(relative density) — (actual density)/(ideal density);
(ideal density) — (true density of polyimide-based graphite powder) × (% by volume of polyimide-based graphite powder)/100 + (true density of matrix) × (% by volume of matrix)/100;
the average length-diameter ratio of the polyimide-based graphite powder is 5-100, and/or the average particle size is 20-2000 mu m; the average particle size of the metal powder matrix is 2-120 mu m, and the average thickness is 100-500 nm;
the preparation method comprises the following steps:
(1) firing the polyimide film into a polyimide-based graphite film, and crushing the polyimide-based graphite film into polyimide-based graphite powder;
(2) mixing the polyimide-based graphite powder and metal powder to obtain a powder mixture;
(3) preparing the powder mixture into a sintering precursor;
(4) pressure sintering the sintering precursor;
in the step (3), the powder mixture filled in the die is subjected to uniaxial pressurization by adopting the pressure of 5-150 MPa; the preparation of the sintering precursor is completed by adopting a multi-pass filling and pressing mode;
in the step (4), the obtained sintering precursor is sintered while being uniaxially pressurized; hold 10 during sintering-3Pa, vacuum degree, 60-200 MPa of hot pressing pressure, 800-1000 ℃ of sintering temperature and sintering heat preservation time of 0.5-2 h;
the thickness of the composite material is more than 500 μm;
in the step (1), the polyimide film is sintered into the polyimide-based graphite film through two processes of carbonization and graphitization, wherein the specific process of carbonization is to put the polyimide film and the graphite paper into a carbonization furnace, vacuumize, raise the temperature from room temperature to 500 ℃ at the heating rate of 5-15 ℃/min, then raise the temperature to 600-plus-one 650 ℃ at the heating rate of 1-5 ℃/min, preserve the heat for 30-120min, then raise the temperature to 800 ℃ at the heating rate of 1-5 ℃/min, preserve the heat for 30-120min, finally raise the temperature to 1500-plus-one at the heating rate of 5-15 ℃/min, preserve the heat for 0.5-4 h; the specific process of graphitization is that the carbonized film after the polyimide film is carbonized is placed in a graphitization furnace, argon gas is introduced to maintain the pressure in the furnace at a micro-positive pressure, then the temperature is raised to 2500-;
in the step (1), a ball milling method is adopted to crush the polyimide-based graphite film into polyimide-based graphite powder, the specific process of ball milling is that stainless steel grinding balls, ball milling media absolute ethyl alcohol and the polyimide-based graphite film are added into a ball milling tank according to the mass ratio of (3-20)/(0.1-10)/1, ball milling is carried out on ball milling equipment for 0.5-24h at the rotating speed of 200-600r/min, then the grinding balls and the absolute ethyl alcohol are removed, and drying and sieving are carried out;
before polyimide-based graphite powder and metal powder are mixed, performing surface copper plating or aluminum plating treatment on the polyimide-based graphite powder, wherein the surface copper plating treatment mainly comprises a roughening process, a sensitizing process, an activating process, a glue dissolving process and a plating applying process, and the specific process comprises the following steps:
(a) soaking polyimide-based graphite powder in concentrated nitric acid with the temperature of 60-80 ℃ and the mass fraction of 60% -65% for 1-3h, taking out and cleaning, and finishing roughening treatment;
(b) soaking the coarsened polyimide-based graphite powder in a stannous chloride solution with the pH value of 1.5 for 5-10min to enable the surface of the polyimide-based graphite powder to adsorb a SnOHCl colloid membrane with viscosity and reducibility, taking out the polyimide-based graphite powder and then cleaning the polyimide-based graphite powder with deionized water to finish the sensitization process;
(c) soaking the sensitized polyimide-based graphite powder in 0.5-3 g/L g/g palladium chloride solution or 0.5-3 g/L g/g silver nitrate solution for 5-10min to enable the generated simple substance palladium or simple substance silver to be adsorbed on the surface of the polyimide-based graphite powder, then taking out and cleaning with deionized water to complete the activation process;
(d) placing the activated polyimide-based graphite powder in a fluoroboric acid aqueous solution of 1-2 g/L, soaking for 3-5min, taking out, and then washing with deionized water to finish the dispergation process;
(e) preparing a copper plating solution, wherein the copper plating solution contains 10-15 g/L of copper sulfate pentahydrate, 10-15 ml/L of formaldehyde, 40-60 g/L of sodium potassium tartrate and 10-15 g/L of sodium hydroxide, copper particles are provided by the copper sulfate pentahydrate, the formaldehyde is used as a reducing agent, the sodium potassium tartrate is used as a complexing agent and can prevent copper ions from forming hydroxide precipitates and separating out, the sodium hydroxide is used as a pH regulator, the pH value of the copper plating solution is 9.0-13.0, polyimide-based graphite powder after peptization treatment is immersed in the copper plating solution, the polyimide-based graphite powder is heated to a plating temperature and kept for a certain plating time, and the plating process is completed, wherein the plating temperature is 60-90 ℃, the plating time is 2-60min, the copper-plated polyimide-based graphite powder is cleaned by deionized water after plating is completed and then dried for standby, and the weight of the polyimide-based graphite powder after chemical plating is increased by 2-40%.
2. The method of preparing a polyimide-based graphite-metal composite of claim 1, wherein the metal powder matrix is one of copper, aluminum or alloys thereof.
3. The method of preparing a polyimide-based graphite-metal composite material according to claim 1, wherein in the step (1), the raw material for preparing the polyimide-based graphite powder is polyimide film scrap or polyimide-based graphite film scrap.
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| CN103924119A (en) * | 2014-04-23 | 2014-07-16 | 北京科技大学 | Ultrahigh heat conduction graphite flake/copper composite material and preparation method thereof |
| CN106521230A (en) * | 2016-12-06 | 2017-03-22 | 湖南科技大学 | Graphite flake/copper composite material used for vertical directional heat dissipation, and preparation method thereof |
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| CN106521230A (en) * | 2016-12-06 | 2017-03-22 | 湖南科技大学 | Graphite flake/copper composite material used for vertical directional heat dissipation, and preparation method thereof |
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| 高导热石墨膜的制备及表征;袁观明等;《功能材料》;20151231;第46卷(第17期);17097-17106 * |
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