CN105272256B - A kind of high heat conduction graphite foam/carbon composite and preparation method thereof - Google Patents

Abstract

The invention relates to a high thermal conductivity graphite foam/carbon composite material and a preparation method thereof. Firstly, a graphite foam with high thermal conductivity is prepared as a reinforcing base by using mesophase pitch as a precursor; and then using mesophase pitch or coal tar pitch as a matrix carbon precursor The graphite foam reinforcing base is densified by medium and high pressure impregnation/carbonization technology; finally, the obtained material is subjected to a high-temperature graphitization treatment above 2500°C to obtain a density above 1.3g/cm ³ and a thermal conductivity greater than 300W/m K, the high thermal conductivity graphite foam/carbon composite material whose compressive strength can reach more than 9MPa, its thermal conductivity and compressive strength are more than 2 times and 3 times that of graphite foam material, compared with high thermal conductivity carbon/carbon composite material, the preparation cost And cycles are also greatly compressed.

Description

A kind of high thermal conductivity graphite foam/carbon composite material and preparation method thereof

technical field

The invention relates to a high thermal conductivity graphite foam/carbon composite material and a preparation method thereof, belonging to the technical field of high thermal conductivity carbon-based composite material manufacturing.

Background technique

With the rapid development of science and technology, thermal management and heat dissipation have become key technologies for the development of many fields. Various aerospace vehicles (aircraft, missiles, satellites and various spacecraft) require precise electronic equipment control systems to achieve automation and precise control and guidance of aerospace weapons. These electronic equipment need to operate under specific temperature conditions The next work can meet the requirements of use. Moreover, with the development of microelectronics technology and guidance technology, the integration of electronic equipment is getting higher and higher, the energy density is getting higher and higher, and the heat generated is increasing. In order to ensure the stable operation of the equipment, it is necessary to apply high-performance and high-thermal-conduction materials Effective thermal management of it. The local high-temperature components of aerospace vehicles are used in harsh environments, with high temperatures and prominent thermal stress. Lightweight, high-temperature-resistant, high-thermal-conductivity materials are required to perform the function of heat dissipation, thereby simplifying the heat-resistant design and improving the reliability of the aircraft. Traditional metal (aluminum, copper) heat-conducting materials are difficult to meet the development needs due to their own defects such as high density, high thermal expansion coefficient, and trace impurities that lead to a sharp drop in thermal conductivity. Therefore, the research and development of new high thermal conductivity materials is very important.

High thermal conductivity carbon-based composite materials have excellent properties such as low density, high thermal conductivity, low thermal expansion coefficient, certain structural strength, high temperature resistance, and corrosion resistance, making them the most promising candidate materials for high thermal conductivity. Thermal management, heat dissipation, high-energy electronics and other fields of space vehicles, such as electronic device cooling systems, heat exchange systems, space cryogenic systems, thermal energy storage systems, etc., to achieve miniaturization of corresponding thermal management components, lightweight devices, compact structures and Run more efficiently.

Due to the highly developed graphite lamellar structure of the existing high thermal conductivity graphite foam materials, as well as its porous structure and high porosity, the mechanical properties of graphite foam are not high, and its thermal conductivity is limited, so it is difficult to meet more requirements. Application requirements of thermal management devices with high energy density. As a new type of high thermal conductivity carbon-based composite material, high thermal conductivity carbon/carbon composite material has the characteristics of high temperature resistance and high strength, but its reinforcement base is a high thermal conductivity fiber braided prefabricated body, and the raw material of high thermal conductivity fiber can only be imported, and the price is expensive. The weaving cost of the upper fabric is high, the cycle is long, it is difficult to apply in batches, and the import of key raw materials with high thermal conductivity fibers is always limited. How to provide a composite material that meets the requirements of density and thermal conductivity and is suitable for mass production is an urgent problem to be solved in this field.

Contents of the invention

The purpose of the present invention is to overcome the above-mentioned deficiency of prior art, provide a kind of preparation method of high thermal conductivity graphite foam/carbon composite material, be applicable to bulk material, the density of this material is more ^than 1.3g/cm , thermal conductivity can reach 300W/m·K or more.

Above-mentioned purpose of the present invention is mainly realized by following technical scheme:

A kind of preparation method of high thermal conductivity graphite foam/carbon composite material, concrete steps are as follows:

Step (1), using mesophase pitch as a precursor to prepare high thermal conductivity graphite foam as a reinforcement base, the density of the high thermal conductivity graphite foam reinforcement base is 0.5-0.9g/cm ³ , and the thermal conductivity is greater than 100W/m·K, The porosity is between 39% and 77%, and the open porosity is greater than 85%;

Step (2), impregnating the graphite foam reinforcing base prepared in step (1) with mesophase pitch or coal tar pitch; wherein the impregnation temperature of mesophase pitch is 280-370°C, the impregnation temperature of coal tar pitch is 160-240°C, and the impregnation pressure is 15-70MPa, the holding time is 1-5h;

Step (3), carbonizing the graphite foam after the step (2) is impregnated with mesophase pitch or coal tar pitch;

Step (4), putting the carbon-based composite material obtained after the carbonization treatment in step (3) into a high-temperature furnace for high-temperature treatment;

Step (5), judging whether the density of the composite material exceeds the set threshold value, and returning to step (2) if it does not exceed the set threshold value, and increasing the impregnation pressure when the mesophase pitch or coal tar pitch is impregnated; if the density of the composite material exceeds the set threshold value, execute the step (six);

Step (6), subjecting the carbon-based composite material to ultra-high temperature graphitization treatment to prepare a graphite foam/carbon composite material with high thermal conductivity.

In the preparation method of the above-mentioned high thermal conductivity graphite foam/carbon composite material, the carbonization treatment process curve in step (3) is: room temperature ~ 350 ° C, the heating rate is 5 ~ 15 ° C / min; 350 ~ 500 ° C, the heating rate is 1 ~ 5°C/min; 500°C, heat preservation 1-10h; 500-650°C, heating rate 1-5°C/min; 650°C, heat preservation 1-10h; 650-900°C, heating rate 3-5°C/min , 900 ℃, heat preservation 1 ~ 5h; free cooling.

In the preparation method of the above-mentioned high thermal conductivity graphite foam/carbon composite material, the high temperature treatment process curve in step (4) is: room temperature ~ 900 ° C, the heating rate is 10 ~ 20 ° C / min; 900 ~ 1200 ° C, the heating rate is 5 ~ 10°C/min; heat preservation at 1200°C for 1 to 5 hours; 1200°C to the target treatment temperature, with a heating rate of 3 to 5°C/min; heat preservation at the target treatment temperature for 1 to 5 hours; control the cooling rate to 5 to 15°C/min until The temperature is lowered to below 900°C; the temperature is lowered freely below 900°C; the target treatment temperature is 1800°C to 2500°C.

In the preparation method of the above-mentioned high thermal conductivity graphite foam/carbon composite material, the ultra-high temperature graphitization process curve in step (6) is as follows: the temperature is raised to above 2500° C. at a rate of 1-15° C./min and kept for 1-10 hours, and the temperature is freely lowered.

Preferably, the threshold is set at 1.3 g/cm ³ .

Preferably, the thermal conductivity of the high thermal conductivity graphite foam/carbon composite material is greater than 300W/m·K.

Preferably, in step (1), using mesophase pitch as a precursor to prepare high thermal conductivity graphite foam as a reinforcing base is specifically: adopting mesophase pitch with a softening point of 220-300°C for foam molding, and preparing high thermal conductivity foam after carbonization and graphitization. Thermally conductive graphite foam acts as a reinforcing base.

Preferably, if the density of the composite material in step (5) does not exceed the set threshold, return to step (2), increase the impregnation pressure during impregnation with mesophase pitch or coal tar pitch, and increase the temperature for high temperature treatment in the high temperature furnace.

At the same time, a high thermal conductivity graphite foam/carbon composite material, with high thermal conductivity graphite foam as the reinforcing base, mesophase pitch or coal tar pitch as the matrix carbon precursor, impregnated at 15-70MPa, carbonized, 1800 ℃ ~ 2500 ℃ high temperature heat treatment and 2500 It is prepared by ultra-high temperature graphitization above ℃.

Preferably, it is obtained by using the method for preparing the high thermal conductivity graphite foam/carbon composite material.

Compared with the prior art, the present invention has the following beneficial effects:

(1) The present invention uses mesophase pitch as a precursor, and prepares graphite foam with high thermal conductivity as a reinforcing base through foam molding-carbonization-graphitization; then uses mesophase pitch or coal tar pitch as a matrix carbon precursor, and passes High-pressure impregnation/carbonization technology densifies the graphite foam reinforcing base; finally, the obtained material is subjected to a high-temperature graphitization treatment above 2500°C, and the prepared density is above 1.3g/cm ³ , and the thermal conductivity is greater than 300W/m·K. The high thermal conductivity graphite foam/carbon composite material whose compressive strength can reach more than 9MPa, its thermal conductivity and compressive strength are more than 2 times and 3 times that of the graphite foam material, compared with the high thermal conductivity carbon/carbon composite material, the preparation cost and cycle are also shorter Greatly compressed, this process can also realize the preparation of large-scale and high-thermal-conductivity graphite foam/carbon composites.

(2) The present invention uses high thermal conductivity graphite foam with a density of 0.5-0.9g/cm ³ , a thermal conductivity greater than 100W/m·K, a porosity of 39-77%, and an open porosity greater than 85% as a reinforcing base. The graphite foam in the density range has good mechanical properties, which ensures that the reinforcing base can be combined with the matrix carbon under medium and high pressure conditions and is not easy to crack. The high porosity and open porosity of the reinforcing base can improve the impregnation efficiency, and the reinforcing base has high The thermal conductivity contributes to the improvement of the thermal conductivity of the final composite material.

(3) The present invention uses mesophase pitch as a high thermal conductivity precursor, and its excellent orientation and easy-to-graphitize structure can greatly improve the thermal conductivity of the final composite material; coal tar pitch is used as the matrix carbon precursor, and in terms of preparation cost It is lower than the mesophase pitch precursor, and it can also meet some actual needs; compared with resin precursors, using mesophase pitch or coal tar pitch as the matrix carbon precursor is easier to prepare carbon-based composite materials with high thermal conductivity.

(4) In the present invention, a slower carbonization heating rate and a specific high-temperature opening treatment temperature are adopted, which can avoid the cracking problem caused by the release of some light components during material carbonization and high-temperature treatment, and release stress at the same time; adopt ultra-high graphite Higher temperature and slower graphitization heating rate are conducive to the orientation ordering of graphite sheets and the growth of graphite grains, which improve the thermal conductivity of the final composite material.

(5) The present invention can select graphite foam reinforced base materials with different densities, pore structures and properties according to different application requirements, adjust the type of matrix carbon precursor and the impregnation/carbonization process, and can achieve different densities, thermal conductivity and structural strength. Preparation of High Thermal Conductivity Graphite Foam/Carbon Composites. Composite materials with different densities can be obtained by adjusting the impregnation pressure, high temperature treatment temperature, and the number of repetitions, and the number of repetitions can be determined according to the actual density requirements of the composite material. This method is flexible and effective, and can be applied to thermal management and heat dissipation systems for different environmental requirements. , strong practicability.

(6) The present invention can be applied to the preparation of large-scale high thermal conductivity graphite foam/carbon composite materials. Compared with the metal materials used in traditional thermal management systems, it has the characteristics of light weight, high thermal conductivity, and low linear expansion coefficient. Applied to thermal management and heat dissipation systems of aerospace vehicles, deep space exploration, satellites and high-energy laser weapons, etc., to promote the application of higher energy density electronic devices, and to achieve lightweight equipment and long-term efficient and reliable operation.

(7) Due to its low density, the high thermal conductivity graphite foam/carbon composite material prepared by the present invention can also be used as a reinforcing base to further compound with other materials, endowing it with new structure and function, and expanding its application field.

Description of drawings

Fig. 1 is a flow chart of the preparation method of the high thermal conductivity graphite foam/carbon composite material of the present invention.

detailed description

Below in conjunction with accompanying drawing and specific embodiment the present invention is described in further detail:

The present invention uses mesophase pitch as a precursor, and prepares graphite foam with high thermal conductivity as a reinforcing base through foam molding-carbonization-graphitization; Carbonization technology densifies the graphite foam reinforcement base; finally, the obtained material is subjected to a high-temperature graphitization treatment above 2500°C to prepare high thermal conductivity graphite with a density above 1.3g/cm ³ and a thermal conductivity greater than 300W/m·K Foam/Carbon Composite. Specific steps are as follows:

Step (1), using mesophase pitch as a precursor, prepare high thermal conductivity graphite foam as a reinforcing base through foam molding-carbonization-graphitization, its density is 0.5-0.9g/cm ³ , and its thermal conductivity is greater than 100W/m· K, the porosity is 39-77%, and the open porosity is greater than 85%.

Step (2), putting the graphite foam prepared in step (1) into a pitch impregnation tank for mesophase pitch or coal tar pitch impregnation; wherein the impregnation temperature of mesophase pitch is 280-370°C, and the impregnation temperature of coal tar pitch is 160-240°C , The impregnation pressure is 15-70MPa, and the holding time is 1-5h.

Step (3), putting the graphite foam impregnated with mesophase pitch or coal tar pitch in step (2) into a carbonization furnace for carbonization treatment.

The process curve of carbonization treatment is: from room temperature to 350°C, the heating rate is 5-15°C/min; from 350 to 500°C, the heating rate is 1-5°C/min; The heating rate is 1-5°C/min; 650°C, heat preservation 1-10h; 650-900°C, heating rate is 3-5°C/min, 900°C, heat preservation 1-5h; free cooling.

Step (4), putting the carbon-based composite material obtained after the carbonization treatment in step (3) into a high-temperature furnace for high-temperature opening treatment;

The high-temperature treatment process curve is: room temperature to 900°C, heating rate is 10-20°C/min; 900-1200°C, heating rate is 5-10°C/min; 1200°C heat preservation 1-5h; 1200°C to target treatment temperature, The heating rate is 3-5°C/min; keep warm at the target treatment temperature for 1-5 hours; control the cooling rate at 5-15°C/min until the temperature drops below 900°C; freely cool down below 900°C; the target treatment temperature is 1800℃～2500℃.

Step (5), according to the material application requirements, repeat steps (2) to (4), by adjusting the impregnation pressure during impregnation of mesophase pitch or coal tar pitch, carbon-based composite materials with different densities can be obtained.

Step (6), the carbon-based composite material is subjected to ultra-high temperature graphitization treatment above 2500°C to prepare a high thermal conductivity graphite foam/carbon composite material with a density above 1.3g/cm ³ and a thermal conductivity greater than 300W/m·K.

The process curve of ultra-high temperature graphitization treatment is as follows: the temperature is raised to above 2500°C at a rate of 1-15°C/min and kept for 1-10 hours, and the temperature is freely lowered.

Example 1

(1) Using mesophase pitch with a softening point of 275°C, foaming and molding at a pressure of 7.0 MPa and a temperature of 330°C, and preparing high thermal conductivity graphite foam as a reinforcing base through carbonization at 900°C and graphitization at 3000°C. The prepared graphite foam reinforced matrix has a density of 0.60g/cm ³ , a thermal conductivity of 138W/m·K, a porosity of 73%, and an open porosity of more than 90%.

(2) Put the graphite foam reinforcing base prepared in step (1) into a coal pitch dipping tank, embed the graphite foam with coal pitch, close the lid and heat up to 200°C and vacuumize to -0.1MPa, heat preservation and pressure After 1 hour, pressurize to 15MPa, heat and hold pressure for 4 hours, then cool down freely.

(3) Put the sample impregnated with coal tar pitch in step (2) into a carbonization furnace for normal pressure carbonization. The carbonization process curve is: room temperature ~ 350 ° C, heating rate 10 ° C / min; 350 ~ 500 ° C, heating rate 1°C/min; 500°C, heat preservation 3h; 500～650°C, heating rate 1°C/min; 650°C, heat preservation 5h; 650～900°C, heating rate 3°C/min, 900°C, heat preservation 3h; free cooling.

(4) Put the carbonized sample in step (3) into a high-temperature furnace for high-temperature treatment. The high-temperature treatment process curve is: room temperature to 900°C, heating rate 10°C/min; 900-1200°C, heating rate 5°C /min; heat preservation at 1200°C for 3 hours; 1200°C to 2000°C, heating rate 3°C/min; 2000°C, heat preservation 3h; control cooling rate 10°C/min until the temperature drops below 900°C; free cooling below 900°C.

(5) Steps (2) and (3) were repeated until the impregnation pressure reached 50 MPa, and the temperature was freely lowered after 3 hours of heat preservation and pressure holding.

(6) Step (4) was repeated, the maximum heat treatment temperature was adjusted to 2300° C., and the material density reached 1.38 g/cm ³ at this time.

(7) Put the material in step (6) into an ultra-high temperature graphitization furnace for ultra-high temperature graphitization treatment, raise the temperature to 3000 °C at a rate of 1-5 °C/min and keep it for 10 hours, then freely cool down to complete graphitization Processing, that is, the preparation of high thermal conductivity graphite foam/carbon composite materials.

The high thermal conductivity graphite foam/carbon composite has a final density of 1.35g/cm ³ , a thermal conductivity of 304W/m·K, and a compressive strength of 9.0MPa.

Example 2

(1) Using mesophase pitch with a softening point of 275°C, foaming and molding at a pressure of 7.5MPa and a temperature of 330°C, and preparing high thermal conductivity graphite foam as a reinforcing base through carbonization at 900°C and graphitization at 3000°C. The prepared graphite foam reinforced matrix has a density of 0.65g/cm ³ , a thermal conductivity of 152W/m·K, a porosity of 71%, and an open porosity of more than 90%.

(2), put the graphite foam reinforcing base prepared in step (1) into the mesophase pitch impregnation tank, wrap around the graphite foam with mesophase pitch, close the lid and heat up to 330°C and vacuumize to -0.1MPa, keep warm After holding the pressure for 1 hour, pressurize to 25MPa, keep the temperature and hold the pressure for 4 hours, and then cool down freely.

(3) Put the sample impregnated with mesophase pitch in step (2) into a carbonization furnace for normal pressure carbonization. The carbonization process curve is: room temperature ~ 350 °C, heating rate 10 °C/min; 350 ~ 500 ° C, heating Rate 3°C/min; 500°C, heat preservation 5h; 500～650°C, heating rate 1°C/min; 650°C, heat preservation 5h; 650～900°C, heating rate 3°C/min, 900°C, heat preservation 3h; free cooling .

(4) Put the sample carbonized in step (3) into a high-temperature furnace for high-temperature treatment. The high-temperature treatment process curve is: room temperature to 900 ° C, heating rate 10 ° C / min; 900 ~ 1200 ° C, heating rate 5 ℃/min; heat preservation at 1200℃ for 2 hours; 1200℃～2300℃, heating rate 3℃/min; 2300℃, heat preservation 4h; control cooling rate 10℃/min until the temperature drops below 900℃; free cooling below 900℃.

(5) Steps (2) and (3) were repeated until the impregnation pressure reached 50 MPa, and the temperature was freely lowered after 3 hours of heat preservation and pressure holding.

(6) Step (4) was repeated, the maximum heat treatment temperature was adjusted to 2500° C., and the material density reached 1.45 g/cm ³ at this time.

(7) Put the material into an ultra-high temperature graphitization furnace for ultra-high temperature graphitization treatment, raise the temperature to 3000 °C at a rate of 1-5 °C/min and keep it for 10 hours, and then cool down freely to complete the graphitization treatment, which is obtained High thermal conductivity graphite foam/carbon composite.

The high thermal conductivity graphite foam/carbon composite has a final density of 1.42g/cm ³ , a thermal conductivity of 351W/m·K, and a compressive strength of 9.5MPa.

The above is only the best specific implementation mode of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of changes or modifications within the technical scope disclosed in the present invention. Replacement should be covered within the protection scope of the present invention.

The content that is not described in detail in the specification of the present invention belongs to the well-known technology of those skilled in the art.

Claims (4)

1. A kind of 1. preparation method of high heat conduction graphite foam/carbon composite, it is characterised in that：Comprise the following specific steps that：

   Step (1), using mesophase pitch as presoma prepare high heat conduction graphite foam as strengthen base, the high heat conduction graphite The density of foam enhancing base is 0.5~0.9g/cm³, thermal conductivity is more than 100W/mK, and for porosity 39~77%, percent opening is big In 85%；

   Step (2), the graphite foam enhancing base for preparing step (1) carries out mesophase pitch or coal tar pitch impregnates；In wherein Between asphalt phase dipping temperature be 280-370 DEG C, impregnation pressure 15-70MPa, dwell time 1-5h；Coal tar pitch dipping temperature For 160-240 DEG C, impregnation pressure 15-70MPa, dwell time 1-5h；

   Step (3), step (2) is impregnated to the graphite foam progress carbonization treatment after mesophase pitch or coal tar pitch；

   Step (4), the C-base composte material obtained after step (3) carbonization treatment is put into high temperature furnace carries out high-temperature process；

   Step (5), judge whether the composite density after high-temperature process exceedes given threshold, be not above given threshold then Return to step (two), increase impregnation pressure when mesophase pitch or coal tar pitch dipping；Composite density exceedes given threshold, Perform step (6)；

   Step (6), by C-base composte material carry out superhigh temperature graphitization processing, it is compound that high heat conduction graphite foam/carbon is prepared Material；

   Carbonization treatment technique curve is in the step (3)：Room temperature~350 DEG C, heating rate are 5~15 DEG C/min；350~ 500 DEG C, heating rate is 1~5 DEG C/min；500 DEG C, it is incubated 1~10h；500~650 DEG C, heating rate is 1~5 DEG C/min； 650 DEG C, it is incubated 1~10h；650~900 DEG C, heating rate is 3~5 DEG C/min, 900 DEG C, is incubated 1~5h；Freely cool；

   Superhigh temperature graphitization processing process curve is in the step (6)：3000 DEG C are warming up to 1~15 DEG C/min speed Above and 1~10h is incubated, freely cooled；

   Given threshold is 1.3g/cm³；

   The thermal conductivity of high heat conduction graphite foam/carbon composite is more than 300W/mK.
2. A kind of 2. preparation method of high heat conduction graphite foam/carbon composite according to claim 1, it is characterised in that： The step (4) high temperature handling process curve is：Room temperature~900 DEG C, heating rate are 10~20 DEG C/min；900~1200 DEG C, heating rate is 5~10 DEG C/min；1200 DEG C of 1~5h of insulation；1200 DEG C~target process temperature, heating rate is 3~5 ℃/min；1~5h is incubated under target process temperature；Control rate of temperature fall for 5~15 DEG C/min until temperature be down to 900 DEG C with Under；Less than 900 DEG C freely cool；The target process temperature is 1800 DEG C~2500 DEG C.
3. A kind of 3. preparation method of high heat conduction graphite foam/carbon composite according to claim 1, it is characterised in that： Prepare high heat conduction graphite foam as presoma using mesophase pitch in step (1) is specially as enhancing base：Use softening point for 220-300 DEG C of mesophase pitch foaming, high heat conduction graphite foam is prepared as enhancing by carbonization and graphitization processing Base.
4. A kind of 4. preparation method of high heat conduction graphite foam/carbon composite according to claim 1, it is characterised in that： Composite density is not above given threshold then return to step (two) in the step (5), increases mesophase pitch or coal drip Impregnation pressure during green grass or young crops dipping, and heighten the temperature that high-temperature process is carried out in high temperature furnace.