Material with directional thermal conduction and thermal insulation and preparation method thereof

Abstract

Disclosed is a material with directional thermal conduction and thermal insulation and a preparation method thereof. The method includes: (1) dispersing a viscose-based carbon fiber in water and adding a phenolic resin and polyacrylamide sequentially to obtain a dispersion I; dispersing a high-thermal conduction carbon fiber in water and adding a phenolic resin and polyacrylamide sequentially to obtain a dispersion II; (2) dividing equally the dispersion I and the dispersion II into several parts, respectively, pouring each part of the dispersion I and each part of the dispersion II into a mold alternately until all the dispersion I and the dispersion II are poured, draining after each pouring of a part of the dispersion I or a part of the dispersion II to obtain a porous carbon fiber skeleton, and solidifying the skeleton to obtain a preform; (3) subjecting the preform to a heat treatment to obtain the material.

Claims

1. A method for preparing a material with directional thermal conduction and thermal insulation, comprising: (1) dispersing a viscose-based carbon fiber in water and adding a phenolic resin and polyacrylamide in sequence to obtain a dispersion I; dispersing a high-thermal conduction carbon fiber in water and adding a phenolic resin and polyacrylamide in sequence to obtain a dispersion II, wherein a mass ratio of the high-thermal conduction carbon fiber, the phenolic resin and water range of 1.2:(50-70), and the high-thermal conduction carbon fiber has a length of 1 mm to 10 mm and a thermal conductivity of 600 W/(m.Math.k) to 1,000 W/(m.Math.k); (2) dividing equally the dispersion I and the dispersion II into several parts, respectively, pouring each part of the dispersion I and each part of the dispersion II into a mold alternately until all the dispersion I and the dispersion II are poured, draining after each pouring of a part of the dispersion I or a part of the dispersion II to obtain a porous carbon fiber skeleton, and then solidifying the porous carbon fiber skeleton to obtain a preform; and (3) subjecting the preform obtained in step (2) to a heat treatment to obtain the material with directional thermal conduction and thermal insulation.

2. The method according to claim 1, wherein in step (1), a mass ratio of the viscose-based carbon fiber, the phenolic resin and water is in a range of 1:(0.5-1):(50-70).

3. The method according to claim 1, wherein in step (1), the viscose-based has a length of less than 1 mm.

4. The method according to claim 1, wherein in step (1), in the dispersion I, a mass of polyacrylamide is 0.01% to 0.1% of a mass of the viscose-based carbon fiber; in step (1), in the dispersion II, a mass of polyacrylamide is 0.01% to 0.1% of a mass of the high-thermal conduction carbon fiber.

5. The method according to claim 1, wherein in step (1), the viscose-based carbon fiber, the phenolic resin and polyacrylamide are dispersed in water under stirring, and the stirring is conducted at a rotation speed within a range of 500 r/min to 800 r/min for 20 min to 40 min.

6. The method according to claim 1, wherein in step (2), the mold is a cylindrical mold.

7. The method according to claim 1, wherein in step (2), the dispersion I is poured into the mold to act as a substrate of the porous carbon fiber skeleton.

8. The method according to claim 1, wherein in step (2), the porous carbon fiber skeleton has a multi-layer structure.

9. The method according to claim 1, wherein in step (3), the heat treatment is conducted as follows: placing the preform in a heat treatment device, heating to 1,000° C. at a rate of 2° C/min to 5° C/min, and holding for 1 h to 2 h to obtain the material with directional thermal conduction and thermal insulation.

10. The method according to claim 1, wherein in step (1), the high-thermal conduction carbon fiber, the phenolic resin and polyacrylamide are dispersed in water under stirring, and the stirring is conducted at a rotation speed within a range of 500 r/min to 800 r/min for 20 min to 40 min.

11. The method according to claim 6, wherein the cylindrical mold has a diameter of 50 mm to 70 mm.

12. The method according to claim 1, wherein in step (2), the draining is conducted by suction filtration or press filtration.

13. The method according to claim 1, wherein in step (2), the porous carbon fiber skeleton is dried before the solidifying.

14. The method according to claim 1, wherein in step (2), the solidifying is conducted at a temperature within a range of 120° C. to 180° C.

15. The method according to claim 1, wherein in step (2), the solidifying is conducted for 3 h to 7 h.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a top view of the material with directional thermal conduction and thermal insulation prepared according to Example 3 of the present disclosure.

(2) FIG. 2 shows a side view of the material with directional thermal conduction and thermal insulation prepared according to Example 3 of the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(3) In order to make the objects, technical solutions and advantages of the present disclosure more clear, the technical solutions of the examples in the present disclosure will be clearly and completely described below with reference to drawings of the examples in the present disclosure. It is evident that the examples described are merely a part, rather than all of the examples in the present disclosure. Based on the examples in the present disclosure, all other examples obtained by those ordinarily skilled in the art without creative work shall fall within the protection scope of the present disclosure.

(4) Example 1

(5) A multi-layer material with directional thermal conduction and thermal insulation was provided in the example. The material included a viscose-based carbon fiber, a high-thermal conduction carbon fiber and a binder.

(6) The viscose-based carbon fiber was used as a substrate with a fiber length of less than 1 mm. The high-thermal conduction carbon fiber was used as a thermal conduction enhancer. A cylindrical mold with a diameter of 60 mm was used, and 0.4 g of the high-thermal conduction carbon fibers was contained in each layer. The binder was phenolic resin powders.

(7) A preparation process was performed in the following steps: (1) 7 g of the viscose-based carbon fiber was added to 350 g of deionized water, stirred and dispersed evenly with a mechanical stirrer at a rotation speed of 700 r/min for 20 min, and poured into a beaker to obtain a dispersion I. 0.4 g of the high-thermal conduction carbon fiber was added to 20 g of deionized water, and stirred evenly with a mechanical stirrer at a rotation speed of 700 r/min for 20 min to obtain a dispersion II. 7 g of the phenolic resin powders were added to the dispersion I, and stirred evenly with a mechanical stirrer at a rotation speed of 700 r/min for 20 min. 0.4 g of the phenolic resin powders were added to the dispersion II, and stirred evenly with a mechanical stirrer at a rotation speed of 700 r/min for 20 min. 0.07 g of polyacrylamide was added to 20 g of deionized water for a full dissolution, and was then added to the dispersion I, followed by being stirred evenly with a mechanical stirrer at a rotation speed of 700 r/min for 5 min. 0.004 g of polyacrylamide was added to 10 g of deionized water for a full dissolution, and was then added to the dispersion II, followed by being stirred evenly with a mechanical stirrer at a rotation speed of 700 r/min for 5 min. (2) The dispersion I was divided into two equal parts and one part was poured into the mold which was a cylindrical sleeve with small holes at the bottom and a diameter of φ 60 mm. After conducting a press filtration, the dispersion II was poured into the mold and another press filtration was conducted. The remaining one part of the dispersion I was poured into the mold from the top and another press filtration was continued to obtain a porous carbon fiber skeleton with a thickness of 15 mm. The fiber skeleton was heated at 80° C. for 2 h and then solidified at 150° C. for 5 h to obtain a preform of porous carbon fiber-based thermal insulation material. (3) The preform obtained in step (2) was put into a tubular furnace for a heat treatment under protection of an argon atmosphere to obtain a material with directional thermal conduction and thermal insulation. The heat treatment was conducted at 1,000° C. for 1 h. The phenolic resin powders used as the binder were pyrolyzed and carbonized at high temperature and then attached to a surface of the fibers to bond the lapping joints of the fibers, so as to form sites at the lapping joints of the fibers, affording the porous carbon fiber-based thermal insulation material desirable mechanical properties.

(8) The thickness-direction thermal conductivity of the material at room temperature tested according to GB/T10295-2008 was 0.0577 W/(m.Math.K), and the in-plane thermal conductivity of the material at room temperature tested with a NETZSCH LFA457Micro Flash laser thermal conductivity meter was 0.507 W/(m.Math.K).

(9) Example 2

(10) A multi-layer material with directional thermal conduction and thermal insulation was provided in the example. The material included a viscose-based carbon fiber, a high-thermal conduction carbon fiber and a binder.

(11) The viscose-based carbon fiber was used as a substrate with a fiber length of less than 1 mm. The high-thermal conduction carbon fiber was used as a thermal conduction enhancer. A cylindrical mold with a diameter of 60 mm was used, and 0.4 g of the high-thermal conduction carbon fibers was contained in each layer. The binder was phenolic resin powders.

(12) A preparation process was performed in the following steps: (1) 7 g of the viscose-based carbon fiber was added to 350 g of deionized water, stirred and dispersed evenly with a mechanical stirrer at a rotation speed of 700 r/min for 20 min, and poured into a beaker to obtain a dispersion I. 0.8 g of the high-thermal conduction carbon fiber was added to 40 g of deionized water, and stirred evenly with a mechanical stirrer at a rotation speed of 700 r/min for 20 min to obtain a dispersion II. 7 g of the phenolic resin powders were added to the dispersion I, and stirred evenly with a mechanical stirrer at a rotation speed of 700 r/min for 20 min. 0.8 g of the phenolic resin powders were added to the dispersion II, and stirred evenly with a mechanical stirrer at a rotation speed of 700 r/min for 20 min. 0.07 g of polyacrylamide was added to 20 g of deionized water for a full dissolution, and was then added to the dispersion I, followed by being stirred evenly with a mechanical stirrer at a rotation speed of 700 r/min for 5 min. 0.008 g of polyacrylamide was added to 10 g of deionized water for a full dissolution, and was then added to the dispersion II, followed by being stirred evenly with a mechanical stirrer at a rotation speed of 700 r/min for 5 min. (2) The dispersion I was divided into three equal parts, and the dispersion II was divided into two equal parts. The parts of the dispersion I and the dispersion II were alternately poured into the mold which was a cylindrical sleeve with small holes at the bottom and a diameter of φ 60 mm. After one part was poured into the mold, a press filtration was conducted before the next part was poured, thereby obtaining a porous carbon fiber skeleton with a thickness of 15 mm. The fiber skeleton was heated at 80° C. for 2 h and then solidified at 150° C. for 5 h to obtain a preform of porous carbon fiber-based thermal insulation material. (3) The preform obtained in step (2) was put into a tubular furnace for a heat treatment under protection of an argon atmosphere to obtain a material with directional thermal conduction and thermal insulation. The heat treatment was conducted at 1,000° C. for 1 h. The phenolic resin powders used as the binder were pyrolyzed and carbonized at high temperature and then attached to a surface of the fibers to bond the lapping joints of the fibers, so as to form sites at the lapping joints of the fibers, affording the porous carbon fiber-based thermal insulation material desirable mechanical properties.

(13) The thickness-direction thermal conductivity of the material at room temperature tested according to GB/T10295-2008 was 0.0516 W/(m.Math.K), and the in-plane thermal conductivity of the material at room temperature tested with a NETZSCH LFA457Micro Flash laser thermal conductivity meter was 0.707 W/(m.Math.K).

(14) Example 3

(15) A multi-layer material with directional thermal conduction and thermal insulation was provided in the example. The material included a viscose-based carbon fiber, a high-thermal conduction carbon fiber and a binder.

(16) The viscose-based carbon fiber was used as a substrate with a fiber length of less than 1 mm. The high-thermal conduction carbon fiber was used as a thermal conduction enhancer. A cylindrical mold with a diameter of 60 mm was used, and 0.4 g of the high-thermal conduction carbon fibers was contained in each layer. The binder was phenolic resin powders.

(17) A preparation process was performed in the following steps: (1) 7 g of the viscose-based carbon fiber was added to 350 g of deionized water, stirred and dispersed evenly with a mechanical stirrer at a rotation speed of 700 r/min for 20 min, and poured into a beaker to obtain a dispersion I. 1.2 g of the high-thermal conduction carbon fiber was added to 60 g of deionized water, and stirred evenly with a mechanical stirrer at a rotation speed of 700 r/min for 20 min to obtain a dispersion II. 7 g of the phenolic resin powders were added to the dispersion I, and stirred evenly with a mechanical stirrer at a rotation speed of 700 r/min for 20 min. 1.2 g of the phenolic resin powders were added to the dispersion II, and stirred evenly with a mechanical stirrer at a rotation speed of 700 r/min for 20 min. 0.07 g of polyacrylamide was added to 20 g of deionized water for a full dissolution, and was then added to the dispersion I, followed by being stirred evenly with a mechanical stirrer at a rotation speed of 700 r/min for 5 min. 0.012 g of polyacrylamide was added to 15 g of deionized water for a full dissolution, and was then added to the dispersion II, followed by being stirred evenly with a mechanical stirrer at a rotation speed of 700 r/min for 5 min. (2) The dispersion I was divided into four equal parts, and the dispersion II was divided into three equal parts. The parts of the dispersion I and the dispersion II were alternately poured into the mold which was a cylindrical sleeve with small holes at the bottom and a diameter of φ 60 mm. After one part was poured into the mold, a press filtration was conducted before the next part was poured, thereby obtaining a porous carbon fiber skeleton with a thickness of 15 mm. The fiber skeleton was heated at 80° C. for 2 h and then solidified at 150° C. for 5 h to obtain a preform of porous carbon fiber-based thermal insulation material. (3) The preform obtained in step (2) was put into a tubular furnace for a heat treatment under protection of an argon atmosphere to obtain a material with directional thermal conduction and thermal insulation. The heat treatment was conducted at 1,000° C. for 1 h. The prepared materials with directional thermal conduction and thermal insulation were shown in FIG. 1 and FIG. 2. The phenolic resin powders used as the binder were pyrolyzed and carbonized at high temperature and then attached to a surface of the fibers to bond the lapping joints of the fibers, so as to form sites at the lapping joints of the fibers, affording the porous carbon fiber-based thermal insulation material desirable mechanical properties.

(18) The thickness-direction thermal conductivity of the material at room temperature tested according to GB/T10295-2008 was 0.0491 W/(m.Math.K), and the in-plane thermal conductivity of the material at room temperature tested with a NETZSCH LFA457Micro Flash laser thermal conductivity meter was 1.136 W/(m.Math.K).

(19) Example 4

(20) Example 4 differs from Example 1 in that in step (2), the dispersion II was divided into two equal parts and the dispersion I was one part. The dispersion II, dispersion I and dispersion II were poured into the mold in sequence to form a porous carbon fiber skeleton, from which a material with directional thermal conduction and thermal insulation was finally prepared.

(21) The material with directional thermal conduction and thermal insulation prepared in the example had a deteriorated thermal insulation performance in thickness direction, and the high-thermal conduction carbon fiber tended to shrink during heating and carbonization, which was not conducive to maintaining the shape of the material.

(22) Comparative Example 1

(23) Comparative Example 1 differs from Example 1 in that the dispersion I was not divided into equal parts, but was directly mixed with the dispersion II and then poured into the mold. The other steps were the same as those in Example 1. A material with directional thermal conduction and thermal insulation was prepared.

(24) The material with directional thermal conduction and thermal insulation provided in the example had poor in-plane heat conduction and a reduced thermal conductivity.

(25) The fibers are anisotropic, and the thermal conductivity along a fiber direction is higher. When the high-thermal conduction fibers are located in the same layer, these fibers are basically distributed in x and y directions, and thus a thermal conduction path may be formed in the plane. If the two fibers are simply mixed, the heat transfer in the plane may be affected due to the poor thermal conduction of the viscose-based carbon fiber. Meanwhile, in the case of the multi-layer structure, the heat may be partially dissipated at the first layer of high-thermal conduction fibers before transferring downward, bringing a better protection for the parts under the layer of high-thermal conduction fibers.

(26) Comparative Example 2

(27) Comparative Example 2 differs from Example 1 in that no high-thermal conduction carbon fiber was used, that is, no dispersion II was contained. The other steps were the same as those in Example 1. A material with directional thermal conduction and thermal insulation was prepared.

(28) In the absence of high-thermal conduction carbon fibers, the in-plane thermal conduction of the material is significantly reduced, failing to achieve the effect of heat dissipation. A test on a laser thermal conductivity meter shows that a pure viscose-based carbon fiber has an in-plane thermal conductivity of only 0.113 W/(m.Math.K), while a high-thermal conduction carbon fiber has a thermal conductivity of 800 W/(m.Math.K) along a fiber direction. In a background temperature test, under the same heating temperature, a temperature increase of the high-thermal conduction fiber along the fiber direction is at least 250° C. higher than that of the viscose-based carbon fiber.

(29) Finally, it should be noted that the embodiments above are only used for illustrating the technical solutions of the present disclosure, rather than limiting the present disclosure. Although the present disclosure is described in detail with reference to the above embodiments, it should be understood that for those ordinary skilled in the art, several modifications could be made to the technical solutions described in the above embodiments, or several equivalent substitutions could be made to some of the technical features therein. These modifications or substitutions do not make the essence of the corresponding technical solutions depart from the spirit and scope of the technical solutions in the embodiments of the present disclosure.