JPS6215380A - Production of carbon fiber reinforced composite material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing a carbon fiber-reinforced carbon composite material, and particularly to a method for manufacturing a carbon fiber-reinforced carbon composite material with high toughness.

Prior Art and Problems to be Solved by the Invention Regarding a simple manufacturing method for high-performance carbon fiber reinforced carbon composite materials (hereinafter abbreviated as CFRC), the inventors have filed Japanese Patent Application No. 58-162433.
disclosed a new manufacturing method. These inventions involve mixing carbonaceous powder with a carrier resin, depositing this on a carbon fiber substrate using an electrodeposition method, and then molding and firing to form a CFR.
This relates to a method for obtaining C.

In the above invention, no treatment is applied to the carbon fibers before electrodeposition. Therefore apply a convergence agent and be carbon hot! When an i-base material is used, the presence of a sizing agent deteriorates the adhesion between the base material and the electrodeposited carbonaceous powder and carrier resin. Furthermore, since the carbon fibers are bundled by the binding agent, it becomes difficult for the carbonaceous powder and the carrier resin to penetrate into the carbon fiber bundle.

Means for Solving the Problems The present invention relates to a method for manufacturing CFRC, and is particularly aimed at solving the above-mentioned problems and improving toughness.

The reason why the CFRC obtained by the conventional method has low toughness is that the adhesion between the carbon fibers and the matrix material is poor, and the carbon fibers and the matrix material are separated to form a laminate structure.

In the present invention, we succeeded in increasing the adhesion between the carbon fibers and the matrix material by removing the sizing agent applied to the carbon fibers, and infiltrating the matrix material into the carbon fiber bundles to increase the toughness.

The present invention will be described below.

A carrier resin is attached to the finely divided carbonaceous powder as a charge carrier and dispersed in a liquid to create a dispersion. In this case, additives such as sintering aids, inorganic powders such as ceramics, etc. may be added to the carbonaceous powder.As the carrier resin,
Thermoplastics and thermosets that are ionizable in liquid can be used. Further, when mixing and dispersing the powder and resin, a dispersant and a surfactant can also be used. Although it is easy to use water as a dispersion medium, it is also possible to use a non-aqueous solvent depending on the purpose.

Next, heat treatment is performed to remove the binding agent applied to the carbon fibers.This method includes placing the carbon fibers in a high-temperature furnace and removing the binding agent by heating the atmosphere, or using a flame from a gas burner to remove the binding agent. A method such as directly heating the fibers to remove the binding agent is used.

The carbonaceous powder substrate from which the sizing agent has been removed in this manner is immersed in the above-mentioned dispersion liquid, and a direct current voltage is applied to deposit the carbonaceous powder and carrier on the substrate.

These operations can be performed by continuously supplying the base material or by batch processing.

Subsequently, the substrate is pulled up from the liquid, subjected to treatments such as washing if necessary, and dried to obtain a coated substrate.

When a thermosetting resin is used as a carrier, drying must be carried out to such an extent and within a time range that the curing reaction does not proceed too much. Thereafter, the coated base material may be used as it is or cut into an appropriate size and a predetermined amount thereof is placed in a mold and molded. Conditions such as temperature and pressure during molding are adjusted to appropriate conditions depending on the properties of the resin, powder, and base material. The molded body is subjected to treatments such as infusibility, hardening, annealing, and debanidering if necessary, and then carbonized and fired to form CFRC: The firing temperature is 700 to 3000°C depending on the purpose of use of the material.

The pressurization method is selected from uniaxial compression pressurization, isostatic hydrostatic pressurization, atmospheric pressurization, etc. depending on the purpose.

Examples and comparative examples will be explained below.

Examples and Comparative Examples (Comparative Example 1) (1) Carbonaceous powder with self-sintering properties and calcined coke powder were mixed at a weight ratio of 1:1 to give an average particle size of 5 μm.

(n) The above powder was thoroughly kneaded with a polyacrylonitrile-acrylic acid electrodeposition resin and a solvent, and then dispersed in water to form a so-called anionic coating dispersion. In this state, the ratio of carbon powder to resin was 1=1 by weight.

(III) Next, prepare a PAN-based carbon fiber woven fabric, use this as an anode, use a stainless steel plate as an opposing cathode, immerse it in the above dispersion, apply a voltage of about 50 V, and mix well with stirring. Electricity was applied for about 8 minutes.

(IV) After electrodeposition, the electrodeposited body was dried at 110° C. for 20 minutes.

The weight ratio of the substrate to the coating after drying was 1:2.

(V) Seventy sheets of the above electrodeposited body were laminated and pressure-molded at a temperature of 200°C and a surface pressure of 20 kg/- for 10 minutes.

(Vl) Thereafter, while clamping under a surface pressure of 25 kg/cd, the mixture was heated in the atmosphere at 250° C. and 280° C. for 3 hours each to make it infusible.

(■ΣThis infusible material is 500Kg/- in an inert atmosphere.
The temperature was raised to 1000°C at a temperature increase rate of 30°C/hr under zero surface pressure, and then the temperature was raised to 2000°C at a temperature increase rate of 100°C/hr to obtain a CFRC.

(Example 1) A PAN-based carbon fiber woven fabric similar to that used in Comparative Example 1 was prepared and placed in a furnace heated to 300° C. for 20 minutes to remove the sizing agent. This woven fabric was immersed in the electrodeposition dispersion used in Comparative Example 1.

Using a carbon fiber base material as an anode and a stainless steel plate as an opposing cathode, a voltage of about 50 V was applied and the mixture was energized for about 8 minutes with thorough stirring and mixing. Thereafter, drying, molding, infusibility, and pressure firing were performed under the same conditions as in Comparative Example 1 to obtain a CFRC.

(Comparative Example 2) (1) Prepare a PAN-based carbon fiber filament yarn, continuously supply and immerse it in the electrodeposition dispersion used in Comparative Example 1, and apply a voltage of 150 V using it as an anode and a stainless steel plate as a cathode. Electrodeposition was carried out by applying electricity and stirring well. The yarn after electrodeposition was passed through a dryer and dried in an atmosphere of 80°C. After drying, the weight ratio of substrate to coating was 1:2.

(n) Cut the electrodeposited base material yarn into 10 to 50 mm pieces, fill it in a mold, and heat it for 10 minutes at a temperature of 200°C and a surface pressure of 20 kg/cj.
Pressure molded for minutes.

(III> The subsequent infusibility and pressure firing were performed under the same conditions as in Comparative Example 1 to obtain CFRC.

(Example 2) The PAN-based carbon fiber filament used in Example 2 was continuously added to the electrodepositing dispersion used in Comparative Example 1 while removing the sizing agent on the filament surface with the flame of a gas burner. Electrodeposition was performed under the same conditions as Comparative Example 2 by supplying and dipping.

After that, drying, shaping, infusibility, and pressure firing of the yarn were performed in Comparative Example 2.
CFRC was obtained under the same conditions as .

Charpy impact values were measured for the above Examples and Comparative Examples. The results are shown in Table 1.

(Span 60111I Visit 6X6@-2 Effects of the Invention As described above, according to the present invention, high toughness and high performance CFRC can be manufactured easily and inexpensively.

Claims (4)

[Claims] (1) After adsorbing the ionized carrier in a liquid to carbonaceous fine powder, it is dispersed in the liquid, a carbon fiber base material is immersed in this dispersion, and a DC voltage is applied between the base material and the counter electrode. In the production method, a carbon fiber-reinforced carbon composite material is obtained by depositing carbonaceous fine powder and a carrier on a carbon fiber base material to obtain a coating, and drying, heating, shaping, heat treating and carbonizing the coating. A method for producing a carbon fiber-reinforced carbon composite material, which comprises removing a sizing agent previously applied to a carbon fiber base material before applying a DC voltage. (2) A method for producing a carbon fiber-reinforced carbon composite material according to claim 1, characterized in that a heating atmosphere or a flame from a gas burner is used as a method for removing the sizing agent from the carbon fiber base material. . (3) Claim 1 or 2, characterized in that the carbon fiber base material used is a string-like material made by bundling single fibers, or a woven fabric, paper, or non-woven fabric. A method for producing carbon fiber-reinforced carbon composite materials. (4) Claim 1, characterized in that the carrier used is a resin that can be electrodeposited by modifying a polyacrylonitrile resin derivative or a thermosetting resin derivative.
A method for producing a carbon fiber-reinforced carbon composite material according to item 1, 2 or 3.