CN1170019C - A manufacturing method and special device for high-strength carbon fiber - Google Patents

Abstract

The present invention relates to a preparation process of high-strength carbon fibers. CH4 and Ar are led into a plasma generator by a certain proportion; the plasma generator generates the high temperature of the local area of 2500 DEG C to 3500 DEG C under the condition of controlling the pressure and the current; carbon fibers pass through the plasma high temperature area; the retention time is from 10 to 20 seconds in a passing process; consequently, graphitized carbon fibers with high strength and high modulus are obtained. The present invention has the advantages of the simultaneous realization of graphitization and carburization on the fiber surfaces and in the fibers in one apparatus, simple technology and the acquirement of the graphitized carbon fibers with high strength and high modulus.

Description

A manufacturing method and special device for high-strength carbon fiber

Field:

The invention belongs to a high-strength carbon fiber manufacturing method and a special device, in particular to a method and a special device for preparing high-strength and high-modulus graphite fibers using thermal plasma technology.

Background technique:

As soon as carbon fiber came out, it was favored for its unique high strength, high modulus, ablation resistance, weavable, conductive and other excellent properties, and became a dazzling star in the material world. High modulus carbon (graphite) fiber is an important species in the carbon fiber family and is the most important reinforcing material for advanced composite materials. It has a wide range of uses in national defense construction and national economic construction, and can be used in aviation, aerospace, infrastructure, transportation and other fields. Therefore, the development speed is particularly alarming, and the economic scale of international carbon fiber is estimated to be 1000t/q. In addition to the substantial increase in output, the variety has also continued to increase and form a series of products. Taking Japan's Toray Corporation as an example, as far as PAN base is concerned, in terms of high modulus carbon (graphite) fibers, high modulus M series and high strength and high modulus MJ series products have been successively developed. In addition to Toray, some PAN-based high-modulus carbon fibers have also been produced by Hercules, Amoco, and SIGRI. In addition, the pitch-based high modulus carbon (graphite) fiber varieties of Japan's Osaka Gas Company, Kashima Petroleum and Mitsubishi Chemicals, as well as the American Amoco Company are also on the market. Foreign high-modulus carbon (graphite) fibers have reached the industrial production level of an economic scale of 100 tons, with continuous improvement in performance and complete product specifications. Its development characteristics have been used in non-load-bearing parts and secondary load-bearing parts since the early 1960s, and now it has entered the practical stage of main load-bearing parts; in addition, many new reinforcements for advanced composite materials have been developed, but in many Carbon (graphite) fiber reinforcements still dominate the reinforcements. Although my country has made great progress in the field of carbon fiber after decades of development, the development of high-performance carbon fiber is progressing slowly, which is far from meeting the needs of national defense high-tech and national economic development.

Graphite fiber is prepared by graphitization on the basis of carbon fiber. The carbon fiber is heated at 2000-3000°C under traction conditions, which increases the orientation degree of graphite crystallites in the carbon fiber along the axial direction, increases the size of graphite crystallites, and reduces the interlayer spacing, which greatly improves the degree of graphitization. The tensile modulus of the carbon fiber after graphitization is improved, and the carbon on the surface of the fiber evaporates in the graphitization high temperature zone, making the original surface defects more obvious, and the structural defects of the carbon fiber have a decisive impact on the strength of the carbon fiber. Strength has been reduced.

Invention content:

_The purpose of this invention is to provide a kind of manufacturing method and special device of high-strength carbon fiber. A high temperature of 2500°C to 3500°C is generated in a local area, and methane is cracked under the action of high-temperature arc plasma to generate ionic carbon vapor; the carbon fiber passes through the high-temperature plasma region, and the ionic carbon penetrates into the pores and surface of the graphitized carbon fiber and reaches the surface Densification treatment for the purpose of increasing strength and modulus.

The manufacture method of high-strength carbon fiber of the present invention comprises the steps:

(1), CH _and Ar are passed into the plasma generator with _CH accounting for 1-10% of the volume of Ar;

(2) When the control pressure is 0.3-0.5MPa and the current is 80-100A, the plasma generator generates a high temperature of 2500°C-3500°C in a local area, and the room temperature is outside this area, and methane is under the action of high-temperature arc plasma Cracking produces ionic carbon vapor;

(3) Pass the carbon fiber through the plasma high-temperature zone with a residence time of 10-20 seconds, thereby obtaining graphitized carbon fibers with high strength and high modulus.

In order to realize the above invention, a special device for the plasma generator is designed, which is connected by an insulating flange between the cathode and the anode; the cooling water pipe and the methane introduction pipe are connected with the anode. The anode and the reaction tube are connected by a flange, and the argon gas inlet tube is connected to the cathode

Compared with the prior art, the present invention has the following advantages: due to the adoption of the above scheme, graphitization and carburization of the fiber surface and interior can be realized simultaneously in a set of equipment, which solves the problem of strength reduction caused by surface defects after carbon fiber graphitization A major problem, the process is simple, and graphitized carbon fibers with high strength and high modulus are obtained.

Detailed ways:

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Fig. 1 is a longitudinal sectional structural diagram of a plasma reactor.

Example 1

As shown in the figure, the cathode 4 and the anode 3 are connected by an insulating flange 7; the cooling water pipe 2 and the hydrocarbon feed pipe 1 are connected to the anode 3 by welding; the molybdenum lining 6 and the anode 3 are inlaid connection; the anode 3 and The reaction tubes 9 are connected by flanges 8 . The argon gas introduction pipe 5 is connected to the cathode 4 . Cooling water is introduced from the inlet 2 of the cooling water pipe, argon gas is introduced through the argon gas inlet pipe 5, and methane is fed through the methane inlet pipe 1 in an amount of 1% of the argon volume at the same time, and the pressure is 0.3MPa to the cathode 4 and the anode 3 apply a direct current of 80A to make the gas continuously discharge and form an arc. Pass through carbon fiber from reaction tube 9, control the residence time of carbon fiber in furnace to be 20 seconds. After the reaction, the tensile modulus and tensile strength were tested, and the results are listed in Table 1.

Example 2

Methane was continuously introduced together with argon at a ratio of 5% by volume of argon, the current was adjusted to 90A, and the pressure in the reaction tube was 0.4MPa. Control the residence time of carbon fiber in the furnace to be 15 seconds. Others are carried out by the same method and conditions as in Example 1, and the tensile modulus and tensile strength are tested after the reaction, and these results are listed in Table 1.

Example 3

Methane was fed continuously together with argon in a ratio of 10% of the argon volume, the current was adjusted to 100A, and the pressure in the reaction tube was 0.5MPa. Control the residence time of carbon fiber in the furnace to be 10 seconds. Others are carried out by the same method and conditions as in Example 1, and the tensile modulus and tensile strength are tested after the reaction, and these results are listed in Table 1.

Table 1 condition, result/case number Example 1 Example 2 Example 3 Methane/Argon (%) 1 5 10 Pressure (MPa) 0.3 0.4 0.5 Residence time (s) 20 15 10 Current (A) 80 90 100 Tensile modulus (GPa) 375 382 390 Tensile strength (MPa) 4528 4531 4550

It can be seen from the above table that the tensile modulus and tensile strength of the manufactured graphite fiber have reached the level of M60J (377GPa, 4410MPa) by adopting the above-mentioned embodiment.

Claims (2)

1. A manufacturing method of high-strength carbon fibers, characterized in that it may further comprise the steps: (1), CH4 and Ar are passed into the plasma generator with CH4 accounting for 1-10% proportioning of Ar volume; (2) When the control pressure is 0.3-0.5MPa and the current is 80-100A, the plasma generator generates a high temperature of 2500°C-3500°C in a local area, and the room temperature is outside this area, and methane is under the action of high-temperature arc plasma Cracking produces ionic carbon vapor; (3) Pass the carbon fiber through the plasma high-temperature zone with a residence time of 10-20 seconds, thereby obtaining graphitized carbon fibers with high strength and high modulus. 2. the used device of a kind of manufacturing method of high-strength carbon fiber as claimed in claim 1 is characterized in that it is connected by insulating flange (7) between cathode (4) and anode (3); Cooling water pipe (2 ) and the methane inlet pipe (1) are connected to the anode (3), the anode (3) and the reaction tube (9) are connected by a flange (8), and the argon inlet pipe (5) is connected to the cathode (4).

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