A carbon whisker-reinforced porous glassy carbon material and a method for producing the same

Abstract

The present application relates to the field of carbon material, specifically relates to a kind of carbon whisker reinforced porous glass carbon material and preparation method thereof, the carbon whisker reinforced porous glass carbon material, thermosetting phenolic resin is precursor, join alumina powder, carbon whisker reinforced porous glass carbon material is generated under high temperature condition heat treatment one step, the carbon whisker reinforced porous glass carbon material formed, glass carbon part graphite sheet layer is wound staggered, carbon whisker part graphite sheet layer is arranged neatly, respectively correspond to amorphous and crystalline structure;Two different forms of carbon materials are generated simultaneously in the present application by one-step method, the material is pure carbon quality crystalline whisker-amorphous glass carbon composite material.The raw material is simple and easy to obtain in the present application, and the process cost is low, and the final product carbon whisker reinforced porous glass carbon material is superior to dense carbon material in heat insulation performance, and is superior to porous carbon material in mechanical property, is a kind of porous material with excellent mechanical property.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of carbon materials, and particularly relates to a carbon whisker reinforced porous glassy carbon material and a preparation method thereof. BACKGROUND

[0002] Porous materials have important application value in the field of thermal insulation materials and the like. Due to the high melting point characteristics of carbon materials, porous carbon materials have a much wider temperature range of use than other porous materials as thermal insulation materials, and can normally serve at a high temperature of more than 2500℃. However, the mechanical properties of porous structures are usually poorer than those of dense structures, which in turn restricts the application of traditional porous carbon materials. The mechanical properties of porous carbon materials need to be enhanced. One-dimensional carbon materials such as carbon nanotubes, carbon whiskers and carbon fibers have good strength, and can be introduced to modify the porous carbon materials to improve the mechanical properties such as hardness and fracture toughness of the materials while maintaining the thermal insulation performance.

[0003] Document 1 "Wang Y, He Z, Zhan L, et al. Coal tar pitch based carbon foam for thermal insulating material [J]. Materials Letters, 2016, 169: 95-98." reports a method for preparing carbon foam material using coal tar pitch as a precursor. This carbon foam, as a kind of porous carbon material, has excellent thermal insulation performance, but the porous carbon materials such as carbon foam usually have the limitation of insufficient mechanical properties, low hardness and strength.

[0004] Document 2 "Wang Z, Ogata H, Morimoto S, et al. High-temperature-induced growth of graphite whiskers from fullerene waste soot [J]. Carbon, 2015, 90: 154-159." reports a method for preparing carbon whiskers by arc discharge on fullerene waste soot. Carbon whiskers, as a one-dimensional carbon material similar to carbon nanotubes, have excellent mechanical properties and their application needs to be further developed.

[0005] It can be seen that it has important research significance to introduce one-dimensional carbon materials to enhance porous carbon materials. SUMMARY

[0006] In order to solve the problems in the prior art, the present application provides a method for preparing a carbon whisker reinforced porous glassy carbon material by one-step method, which aims to solve the problem of insufficient mechanical properties of traditional porous carbon materials.

[0007] In order to achieve the above object, the technical scheme adopted by the present application is: a carbon whisker reinforced porous glass carbon material, taking thermosetting phenolic resin as a precursor, adding alumina powder, and heat treating under high temperature conditions of 1600-2100 DEG C to generate the carbon whisker reinforced porous glass carbon material in one step, the formed carbon whisker reinforced porous glass carbon material has glass carbon part with winding and interlaced graphite layers and carbon whisker part with neat arranged graphite layers, corresponding to amorphous and crystalline structures respectively.

[0008] Further, the thermal conductivity of the carbon whisker reinforced porous glass carbon material is 1.763 W·m -1 ·K -1 , the Vickers hardness reaches 65 MPa, and the fracture toughness reaches 0.329 MPa·m 1 / 2 .

[0009] The present application also provides a preparation method of the above-mentioned carbon whisker reinforced porous glass carbon material, comprising the following steps:

[0010] adding alumina powder to the thermosetting phenolic resin and heating to realize curing;

[0011] carrying out high temperature heat treatment on the cured thermosetting phenolic resin under a protective atmosphere to generate the carbon whisker reinforced porous glass carbon material through pyrolysis and carbonization.

[0012] Further, the preparation method of the thermosetting phenolic resin comprises: dissolving hexamethylenetetramine powder in a formaldehyde solution, mixing with liquid phenol, and heating to generate the thermosetting phenolic resin.

[0013] Further, in the liquid phenol and the formaldehyde solution, the molar ratio of phenol molecules to formaldehyde molecules is 2:3-5:9.

[0014] Further, in the liquid phenol and the hexamethylenetetramine powder, the molar ratio of phenol molecules to hexamethylenetetramine molecules is 10:1-50:1.

[0015] Further, the mass ratio of the alumina powder to the liquid phenol is 1:160-1:40.

[0016] Further, the temperature for heating to generate the thermosetting phenolic resin is 90-110 DEG C.

[0017] Further, the temperature for heating and curing the thermosetting phenolic resin is 90-110 DEG C.

[0018] Further, the temperature for high temperature heat treatment is 1600-2100 DEG C, the heat treatment time is 2h, and the protective atmosphere comprises argon or nitrogen.

[0019] Compared with the prior art, the carbon whisker reinforced porous glassy carbon material has at least the following beneficial effects: the carbon whisker reinforced porous glassy carbon material is prepared by using a thermosetting phenolic resin as a precursor, heat treatment is carried out at a high temperature of 1600-2100 DEG C, and the porous glassy carbon is generated by carbonization of the resin, and the pyrolysis carbon hydrogen gas generated by carbonization is catalytically decomposed in the porous structure by alumina, and the carbon whisker is grown, two carbon materials with different structures and phases are grown at the same time by only one heat treatment, and the composite material is formed, that is, the carbon whisker reinforced porous glassy carbon material, which has excellent heat insulation performance and mechanical properties;

[0020] The thermosetting phenolic resin has a bulky molecular structure, is directly carbonized without a melting process in the temperature rising process of high temperature treatment, and the carbon residue rate is more than 50%. The random benzene ring orientation of the resin molecules is retained in the graphitic carbon material generated after carbonization, the graphite layers are intertwined and staggered, lack long-range ordered structure, and present a typical glassy carbon structure, which is an amorphous carbon material. The carbon hydrogen gas generated by pyrolysis of the phenolic resin in high temperature treatment is enclosed in the glassy carbon to form the porous glassy carbon. The carbon hydrogen gas in the hole is pyrolyzed to generate graphitic carbon under the catalysis of alumina to form a one-dimensional linear structure, that is, the carbon whisker, and the graphite layers are regular, which is a typical graphite crystal. The carbon whisker grown to the top of the hole supports the porous glassy carbon to form the carbon whisker reinforced porous glassy carbon material.

[0021] The carbon whisker reinforced porous glassy carbon material is a pure carbon crystal-amorphous composite material, the raw materials are simple compounds such as phenol, formaldehyde, hexamethylenetetramine and alumina, which are low in cost and easy to obtain, the synthesis process of the thermosetting resin is simple and convenient, the composite material of the two carbon materials is generated at the same time by only one high temperature treatment, the process is easy to implement, no special equipment is required, and the cost is lower than that of common glassy carbon materials. The carbon whisker reinforced porous glassy carbon material maintains the excellent heat insulation performance of the porous carbon material, the whisker reinforced porous structure improves the hardness and fracture toughness and other indexes, the mechanical properties are better than those of common porous carbon materials such as foam carbon, and the carbon whisker reinforced porous glassy carbon material has potential application value in the field of high temperature structural materials. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The morphology characterization result of the carbon whisker reinforced porous glassy carbon material prepared in the application.

[0023] Figure 2 The Figure 1 The phase characterization result of the product.

[0024] Figure 3 The Figure 1 The heat insulation performance test result of the product.

[0025] Figure 4 The Figure 1The micron indentation test results of the product. Detailed Implementation

[0026] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] This invention provides a carbon whisker-reinforced porous glassy carbon material. Using thermosetting phenolic resin as a precursor, alumina powder is added, and the material is heat-treated at 1600-2100℃ in a single step to produce the carbon whisker-reinforced porous glassy carbon material. In this material, the graphite sheets in the glassy carbon portion are intertwined and interwoven, while the graphite sheets in the carbon whisker portion are neatly arranged, corresponding to amorphous and crystalline structures respectively. Simultaneously with the carbonization of the resin to produce porous glassy carbon, the pyrolytic hydrocarbon gas generated during carbonization is catalytically decomposed by alumina within the porous structure, and carbon whiskers are grown. Only one heat treatment is needed to simultaneously grow two carbon materials with different structures and phases, forming a composite material, which is a carbon whisker-reinforced porous glassy carbon material.

[0028] The present invention will now be further described in conjunction with the embodiments and accompanying drawings:

[0029] Example 1:

[0030] 1) Dissolve 0.25g of hexamethylenetetramine powder in 10mL of 37% formaldehyde solution, then mix with 8g of liquid phenol and react at 100℃ for 1h to generate thermosetting phenolic resin.

[0031] 2) Add 0.05g of alumina powder to the generated thermosetting phenolic resin and keep it at 100℃ for 24h to complete the curing of the thermosetting phenolic resin.

[0032] 3) The cured thermosetting phenolic resin was heated to 1900℃ at a rate of 5℃ / min for 2 hours in an argon atmosphere, and then naturally cooled to room temperature to produce a carbon whisker-reinforced porous glassy carbon material. The morphology characterization results of the product are as follows: Figure 1 As shown, Figure 1 (a) and Figure 1 (b) shows the microstructure of the cross-section of the carbon whisker-reinforced porous glassy carbon material. SEM images at different resolutions reveal the morphological characteristics of the one-dimensional whisker-reinforced porous structure. The phase characterization results of the product are as follows: Figure 2 As shown, Figure 2 (a) is the XRD pattern of carbon whisker-reinforced porous glassy carbon material, showing typical graphite carbon characteristic peaks. Figure 2 (b) and Figure 2(c) are TEM micrographs of glassy carbon matrix and carbon whisker reinforcement respectively at higher resolution, where the glassy carbon part has interwoven and interlaced graphite layers, and the carbon whisker part has well-aligned graphite layers, corresponding to amorphous and crystalline structure respectively. The thermal insulation performance test results of the product are shown in Figure 3 , Figure 3 (a) and Figure 3 (b) are the plots of thermal conductivity and thermal diffusivity versus temperature of the carbon whisker reinforced porous glassy carbon material at room temperature 25℃ to 500℃ respectively. The thermal conductivity of common graphite carbon material at room temperature is 1.91·10 3 W·m -1 ·K -1 , and the thermal conductivity of glassy carbon at room temperature is usually 6 W·m -1 ·K -1 . The thermal conductivity of the carbon whisker reinforced porous glassy carbon material at room temperature in the present application is only 1.763 W·m -1 ·K -1 , which embodies good thermal insulation performance. The microindentation test results of the product are shown in Figure 4 , Figure 4 (a), Figure 4 (b) and Figure 4 (c) are the optical micrographs of the left side crack, the indentation and the right side crack on the surface of the carbon whisker reinforced porous glassy carbon material produced by a 10kg diamond cone indenter. The Vickers hardness of the carbon whisker reinforced porous glassy carbon material reaches 65MPa and the fracture toughness reaches 0.329MPa·m 1 / 2 , which can be calculated from the diagonal of the indentation and the length of the crack. The fracture toughness of carbon foam as a common typical porous carbon material is only 0.137MPa·m 1 / 2 . The carbon whisker reinforced porous glassy carbon material as a kind of porous carbon material maintains mechanical strength while maintaining thermal insulation performance.

[0033] Example 2:

[0034] 1) Dissolve 0.5g of hexamethylenetetramine powder in 12mL of formaldehyde solution with a concentration of 37%, and then mix with 8g of liquid phenol to generate thermosetting phenolic resin at 110℃ for 1h.

[0035] 2) Add 0.1g of aluminum oxide powder to the generated thermosetting phenolic resin and heat at 110℃ for 24h to complete the curing of the thermosetting phenolic resin.

[0036] 3) Heat the cured thermosetting phenolic resin to a high temperature of 1600℃ at a rate of 5℃ / min in an argon atmosphere for 2h, and naturally cool to room temperature to produce the carbon whisker reinforced porous glassy carbon material product.

[0037] Example 3:

[0038] 1) Dissolve 1 g of hexamethylenetetramine powder in 11 mL of formaldehyde solution with a concentration of 37%, and then mix with 8 g of liquid phenol to generate a thermosetting phenolic resin by reacting at 90°C for 1 h.

[0039] 2) Add 0.2 g of aluminum oxide powder to the generated thermosetting phenolic resin and keep at 90°C for 24 h to complete the curing of the thermosetting phenolic resin.

[0040] 3) Heat the cured thermosetting phenolic resin to a high temperature of 2100°C at a rate of 5°C / min in an argon atmosphere for 2 h, and then naturally cool to room temperature to generate a carbon whisker reinforced porous glassy carbon material product.

Claims

1. A carbon whisker-reinforced porous glassy carbon material, characterized by, The carbon whisker reinforced porous glassy carbon material is produced by adding alumina powder as catalyst to thermosetting phenolic resin as precursor and heat treating at high temperature of 1600-2100 ℃ in one step. The carbon whisker reinforced porous glassy carbon material has glassy carbon part with interwoven and staggered graphite layers and carbon whisker part with neat graphite layers, corresponding to amorphous and crystalline structures respectively.

2. The carbon whisker-reinforced porous glassy carbon material according to claim 1, wherein Thermal conductivity is 1.763 W m -1 K -1 , Vickers hardness reaches 65 MPa, and fracture toughness reaches 0.329 MPa m 1 / 2 .

3. The method for preparing carbon whisker-reinforced porous glassy carbon material as described in claim 1 or 2, characterized in that, The method comprises the following steps: adding alumina powder to thermosetting phenolic resin and heating to solidify; heat treating the solidified thermosetting phenolic resin at high temperature in a protective atmosphere to produce carbon whisker reinforced porous glassy carbon material by pyrolysis and carbonization.

4. The method of claim 3, wherein the carbon whisker-reinforced porous glassy carbon material is prepared by the steps of: The method for preparing thermosetting phenolic resin comprises: dissolving hexamethylene tetramine powder in formaldehyde solution, mixing with liquid phenol, and heating to react to generate thermosetting phenolic resin.

5. The method of claim 4, wherein the carbon whisker-reinforced porous glassy carbon material is prepared by the steps of: The molar ratio of phenol molecules to formaldehyde molecules in the liquid phenol and formaldehyde solution is 2:3-5:

9.

6. The method of claim 4, wherein the carbon whisker-reinforced porous glassy carbon material is prepared by the steps of: The molar ratio of phenol molecules to hexamethylene tetramine molecules in the liquid phenol and hexamethylene tetramine powder is 10:1-50:

1.

7. The method of claim 4, wherein the carbon whisker-reinforced porous glassy carbon material is prepared by the steps of: The mass ratio of alumina powder to liquid phenol is 1:160-1:

40.

8. The method of claim 4, wherein the carbon whisker-reinforced porous glassy carbon material is prepared by the steps of: The temperature for heating to react to generate thermosetting phenolic resin is 90-110 ℃.

9. The method of claim 3, wherein the carbon whisker-reinforced porous glassy carbon material is prepared by the steps of: The temperature for heating to solidify thermosetting phenolic resin is 90-110 ℃.

10. The method of claim 3, wherein the carbon whisker-reinforced porous glassy carbon material is prepared by the steps of: The temperature for high temperature heat treatment is 1600-2100 ℃, the heat treatment time is 2 h, and the protective atmosphere comprises argon or nitrogen.

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