Method for producing carbon fiber paper

Abstract

The invention discloses a method for producing carbon fiber paper, which comprises the following steps of: putting carbon paper raw paper into graphite plates, applying pressure to the upper and lower graphite plates to ensure that the carbon paper raw paper is in full contact with the graphite plates, then applying voltage to the graphite plates in a vacuum or inert gas environment to ensure that the temperature of the carbon fiber plates reaches 1000-1800 DEG C, and preserving heat to obtain the carbon fiber paper. Compared with a traditional method for preparing the carbon fiber paper through a heating mode of a heating furnace, the method for preparing the carbon fiber paper through the Joule hot pressing mode needs at least half an hour or above of heating time, the Joule hot pressing heating time is within 10 min, and the heating time can be effectively shortened by at least 50% or above; and the harsh requirement of the whole device on the thermal insulation material is reduced, so that the cost of the whole device can be reduced by more than 30%.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon paper production, and particularly relates to a method for producing carbon fiber paper. Background Art

[0002] Carbon fiber paper (carbon paper, CF) is a planar sheet-like carbon material, which has the advantages of high electrical conductivity, high thermal conductivity, low thermal expansion coefficient and density, fatigue resistance and high temperature resistance of carbon materials. At present, it has been widely used in many fields, such as aerospace, automobile manufacturing, fuel cells, catalytic materials, and high-performance electronic products, etc. However, the current preparation cost of carbon paper is high, mainly because the production of carbon paper not only requires the use of expensive carbon fiber as raw material, but also the carbonization after impregnating resin makes the preparation process of carbon paper involve two high-energy-consuming carbonization processes (i.e., the carbonization of raw material carbon fiber and the carbonization of impregnated resin), which makes the cost of carbon paper remain high. Among them, the carbonization of carbon fiber paper is the most energy-consuming and high-cost stage. Taking an electric heating carbonization furnace as an example, first, the resistance wire is used to convert electrical energy into heat energy to heat the graphite muffle, and then the carbon material precursor is carbonized. The most fundamental heat source is the resistance wire. When an electric current passes through the resistance wire, the resistance wire heats up. The resistance wire is in direct contact with the graphite muffle, and the graphite muffle is heated by heat conduction. Then the carbon paper precursor enters the interior of the graphite muffle and is heated by the inert gas (thermal convection) in the graphite muffle and the thermal radiation heating of the graphite muffle, and then carbonized. It can be seen that electrical energy needs to go through three steps of heat transfer to carbonize the precursor, and it also takes a long time for the resistance wire to heat the graphite muffle to the specified temperature. Joule heating is an instant heating technology. By directly passing an electric current through a highly conductive sample and heating the sample by the Joule heat law, the energy conversion efficiency can be improved and the heating-up time can be greatly shortened. However, the Joule heating technology limits that the heated sample must have strong electrical conductivity, which limits the application of the Joule heating technology in the preparation of carbon materials. Therefore, new methods are needed to improve the Joule heating technology to make its application range wider. Summary of the Invention

[0003] The purpose of the present invention is to solve the problems in the prior art and provide a method for producing carbon fiber paper.

[0004] In order to achieve the above purpose, the technical solution of the present invention is as follows:

[0005] A method for producing carbon fiber paper includes the following steps,

[0006] The first step: Place the carbon paper base paper in the graphite plate, apply pressure to the upper and lower graphite plates so that the contact between the carbon paper base paper and the graphite plate is sufficient;

[0007] The second step: Place both the carbon paper base paper and the graphite plate in a vacuum or inert gas environment (such as argon, nitrogen), connect the graphite plate to the circuit, and apply voltage;

[0008] Step 3: Heat the carbon fiber board to 1000 - 1800 °C and keep it warm. After removing the voltage, carbon fiber paper can be obtained.

[0009] Preferably, the pressure applied to the upper and lower graphite plates in the first step is 500 - 1000 Pa.

[0010] Preferably, the voltage applied in the second step is 20 - 40 V.

[0011] Preferably, the heat preservation time in the third step is 0.1 - 10 min.

[0012] The beneficial effects of the present invention are as follows:

[0013] A method for producing carbon fiber paper according to the present invention is a method for preparing carbon fiber paper by using the Joule hot pressing method. First, the carbon paper base paper is heated by pressing with a carbon plate. Since the carbon paper base paper becomes conductive after being heated and carbonized, it starts to receive the electron flow from the carbon plate. At this time, heating by the carbon plate and self-heating can be carried out simultaneously. Compared with the method of preparing carbon fiber paper by the heating method of a traditional heating furnace, which requires at least half an hour or more of heating time, the heating time of the Joule hot pressing is within 10 min, which can effectively reduce the heating time by at least more than 50%, and reduce the harsh requirements of the entire device for heat insulation materials, so that the cost of the entire device can be reduced by more than 30%. Description of the Drawings

[0014] Figure 1 It is an electron scanning (SEM) image of the carbon fiber paper prepared from the carbon plate at 1000 °C;

[0015] Figure 2 It is an SEM image of the carbon fiber paper prepared from the carbon plate at 1400 °C;

[0016] Figure 3 It is an SEM image of the carbon fiber paper prepared from the carbon plate at 1800 °C;

[0017] Figure 4 It is an XRD pattern of the carbon fiber paper prepared at different temperatures. Detailed Embodiments

[0018] In order to enable those skilled in the art to better understand the solution of the present invention, the present invention will be further described in detail below in conjunction with the embodiments.

[0019] Embodiment 1

[0020] Place the carbon paper base paper in a graphite plate, apply a pressure of 500 Pa to the upper and lower graphite plates to ensure sufficient contact between the carbon paper base paper and the graphite plates. Both the carbon paper base paper and the graphite plates are in a vacuum environment. Connect the graphite plate to the circuit and apply a voltage of 20 V. Raise the temperature of the carbon fiber plate to 1000 °C and keep it warm for 0.1 min. Then remove the voltage to obtain the carbon fiber paper. The carbon fiber paper obtained in this example is as shown in Figure 1 shown.

[0021] Example 2

[0022] Place the carbon paper base paper in a graphite plate, apply a pressure of 800 Pa to the upper and lower graphite plates to ensure sufficient contact between the carbon paper base paper and the graphite plates. Both the carbon paper base paper and the graphite plates are in an inert gas (nitrogen) environment. Connect the graphite plate to the circuit and apply a voltage of 30 V. Raise the temperature of the carbon fiber plate to 1400 °C and keep it warm for 5 min. Then remove the voltage to obtain the carbon fiber paper. The carbon fiber paper obtained in this example is as shown in Figure 2 shown.

[0023] Example 3

[0024] Place the carbon paper base paper in a graphite plate, apply a pressure of 1000 Pa to the upper and lower graphite plates to ensure sufficient contact between the carbon paper base paper and the graphite plates. Both the carbon paper base paper and the graphite plates are in an inert gas (nitrogen) environment. Connect the graphite plate to the circuit and apply a voltage of 40 V. Raise the temperature of the carbon fiber plate to 1800 °C and keep it warm for 10 min. Then remove the voltage to obtain the carbon fiber paper. The carbon fiber paper obtained in this example is as shown in Figure 3 shown.

[0025] From Figures 1-3 the SEM images, it can be seen that after Joule hot pressing, the morphology of the fiber paper is still a three-dimensional network structure cross-linked by multiple nanofibers, and the morphology of the fiber paper after heating for 0.1 - 10 min is the same, indicating that the carbonization time within 10 min has no effect on the morphology of the finished carbon paper. In addition, Figure 4 from the XRD patterns, it can be seen that the samples obtained by Joule hot pressing within 0.1 - 10 min all show characteristic peaks of carbon at about 26° and 44°, indicating that the fiber papers are all carbonized to obtain carbon papers.

[0026] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A method for producing carbon fiber paper, characterized in that: The following steps are included: Step 1: Place the carbon paper base on the graphite plate and apply pressure to the upper and lower graphite plates to ensure full contact between the carbon paper base and the graphite plate; Step 2: Place the carbon paper and graphite plate in a vacuum or inert gas environment, connect the graphite plate to the circuit, and apply voltage; Step 3: Make the temperature of the carbon fiber plate reach 1000-1800℃ and keep it warm. After removing the voltage, the carbon fiber paper can be obtained.

2. The method for producing carbon fiber paper according to claim 1, characterized in that: In the first step, the pressure applied to the upper and lower graphite plates is 500-1000 Pa.

3. The method for producing carbon fiber paper according to claim 1, characterized in that: The voltage applied in the second step is 20-40V.

4. The method for producing carbon fiber paper according to claim 1, characterized in that: The heat preservation time in the third step is 0.1-10min.

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