JP4883678B2 - Al impregnated three-dimensional C / C composite and method for producing the same - Google Patents

Description

  The present invention relates to an Al-impregnated three-dimensional C / C composite and a method for producing the same, more specifically, excellent in heat resistance, high strength and high rigidity, dimensional stability, wear resistance, chemical resistance, etc. The present invention relates to an Al-impregnated three-dimensional C / C composite suitably used for rocket nozzles, brake materials, high-temperature molds, gas turbine blades, re-entry capsules, heater materials, and the like, and a method for manufacturing the same.

C / C composite is an abbreviation for Carbon Carbon Composite (carbon / carbon composite material), which is a composite material using carbon fiber as a reinforcing material and carbon matrix material. Three-dimensional (multi-dimensional) materials are known (for example, see Patent Documents 1 to 3).
JP-A-8-109076 JP-A-6-143469 Japanese Patent Laid-Open No. 6-116032

In addition, C / C composites have excellent high temperature characteristics, light weight, high rigidity, corrosion resistance, combustion resistance, friction braking, biocompatibility and thermoelectric conductivity, and have been developed as heat resistant materials for space development such as rocket nozzles. (For example, refer to Patent Document 4).
Japanese Patent Laid-Open No. 5-124844

As a method for producing such a C / C composite, carbon fiber (CF) is carbonized at a high temperature with a material formed by impregnating phenol, furan resin, pitch, etc., and re-impregnated and carbonized repeatedly to increase the density, There is a method of directly depositing pyrolytic carbon by a CVD method (see, for example, Non-Patent Document 1).
Aerospace Engineering Handbook 3rd Edition, Japan Aerospace Society, published on November 30, 2005, page 199

As a substrate for electronic equipment, a carbon-based metal composite material in which a metal component is dispersed in a carbonaceous matrix has been proposed (see, for example, Patent Document 5).
JP 2001-58255 A

  However, the carbon-based metal composite material described in Patent Document 5 has a reduced elastic modulus in the plane direction, and the thermal expansion coefficient is not sufficient.

  The present invention has been made in view of such problems of the prior art, and an object of the present invention is to provide an Al-impregnated three-dimensional C / C composite that has excellent workability and exhibits a coefficient of thermal expansion close to zero. And a manufacturing method thereof.

  As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by impregnating aluminum in the voids of a three-dimensional C / C composite, and the present invention has been completed. It came to do.

That is, the Al-impregnated three-dimensional C / C composite of the present invention is an Al-impregnated three-dimensional C / C composite obtained by impregnating a C / C composite with aluminum,
The average density is 1.9 to 2.3 g / cm ³ , and the average thermal expansion coefficient is −0.41 × 10 ^{−6 to} 1.58 × 10 ⁻⁶ / ° C.

  Moreover, the suitable form of the Al-impregnated three-dimensional C / C composite of the present invention is characterized in that the ratio of the C / C composite and aluminum is 90:10 to 98: 2 in terms of volume.

Moreover, the production method of Al-impregnated 3-D C / C composites of the present invention where, upon manufacturing the Al-impregnated 3-D C / C composite, the following first to fifth step 1. The carbon fiber is woven into a three-dimensional network structure, as factories to preform
2 . High pressure carbonization process for pitch impregnation treatment and / or HIP treatment
3 . Graphitization process
4 . Forging process with molten aluminum
5 . It is characterized by performing a machining process .

Furthermore, a preferred embodiment of the method for producing an Al-impregnated three-dimensional C / C composite according to the present invention is characterized in that the second step and the third step are repeated 6 or 7 times for densification.

  According to the present invention, since the voids of the C / C composite formed in three dimensions are impregnated with aluminum, the Al-impregnated three-dimensional C / C composite exhibiting excellent workability and a coefficient of thermal expansion close to zero, and its A manufacturing method can be provided.

  Hereinafter, the Al-impregnated three-dimensional C / C composite of the present invention will be described in detail. In the present specification, “%” indicates a mass percentage unless otherwise specified.

The Al-impregnated three-dimensional C / C composite of the present invention is formed by impregnating a C / C composite with aluminum (Al).
The C / C composite is a three-dimensional array (3DC / C). This three-dimensional C / C composite is a homogeneous material that is formed by arranging carbon fibers in the longitudinal, lateral, and longitudinal directions, and has no anisotropy in thermal and mechanical properties.
By impregnating such a three-dimensional C / C composite with Al, the coefficient of thermal expansion is almost zero. FIG. 1 shows an example of the present Al-impregnated three-dimensional C / C composite.

The Al-impregnated three-dimensional C / C composite of the present invention has an average density of 1.9 to 2.3 g / cm ³ and an average coefficient of thermal expansion of −0.41 × 10 ^{−6 to} 1.58 × 10. ^-6 / ° C.
As a result, the density and workability are improved as compared with conventional materials, and the product can be enlarged.
For example, as shown in Table 1, with respect to Invar (registered trademark) and Super Invar (registered trademark), the density is particularly reduced to about 1/4 and becomes extremely lightweight. In addition, the specific elasticity and thermal expansion coefficient are particularly large for Zerodure (registered trademark).

Furthermore, from the viewpoint to approximate the thermal expansion coefficient more to zero, the average thermal expansion coefficient of -0.41 × ^{10 -} is suitably a ^{6 / ℃ - 6 ~0.37 × 10} .
In order to obtain such an Al-impregnated three-dimensional C / C composite, for example, it is possible to repeat the densification treatment of the manufacturing method described later 6 to 7 times.

With the configuration as described above, the Al-impregnated three-dimensional C / C composite of the present invention has a good balance of elastic modulus and thermal expansion coefficient, and typically has the following excellent characteristics.
1. It has heat resistance and does not decrease in strength up to about 2500 ° C. in an inert gas.
2. Compared to graphite materials, it has high strength and rigidity, and is excellent in impact resistance and heat resistance.
3. Since the coefficient of thermal expansion is small, there is dimensional stability. Isotropic properties.
4). Abrasion resistance.
5. Light weight.
6). Chemical resistance.
7). Good affinity with living body.

Furthermore, in the Al-impregnated three-dimensional C / C composite of the present invention, the ratio of the C / C composite and aluminum is preferably 90:10 to 98: 2 in terms of volume.
By making the impregnation amount of aluminum within this range, the coefficient of thermal expansion can be made closer to zero. FIG. 2 shows an example of the thermal expansion coefficient with respect to the Al content in the C / C composite.

Next, the method for producing the Al-impregnated three-dimensional C / C composite of the present invention will be described in detail.
In the production method of the present invention, the following first to fifth steps 1. 1. Weaving carbon fiber into a three-dimensional network structure to form a preform 2. High pressure carbonization step Graphitization step 4. 4. Forging with molten aluminum A machining process is performed to obtain the above-described Al-impregnated three-dimensional C / C composite.
By going through such a process, the coefficient of thermal expansion is almost zero.
The preform can be impregnated with carbon black (CB) or the like.

Here, each step will be specifically described.
First, in the first step, typically, carbon fibers having a diameter of 7 to 10 μm can be used, and a preform can be formed by weaving the carbon fibers in an orthogonal three-axis set.

  The high-pressure carbonization in the second step is typically preferably performed by one or both of pitch impregnation treatment and HIP treatment.

The pitch impregnation treatment can be performed under vacuum to pressurization conditions while maintaining the pitch furnace side temperature at 250 to 300 ° C. and the workpiece side temperature at 280 to 300 ° C. (under vacuum to about 0.5 MPa). .
Thereby, bubbling of the pitch at the time of carbonization can be suppressed and densification can be promoted.

The HIP treatment can be performed at a high pressure of about 50 to 100 MPa while maintaining the HIP furnace side temperature at 600 to 800 ° C. and the workpiece side temperature at 600 to 800 ° C.
In particular, it is preferable to perform the treatment 3 or 7 times under the condition of about 100 MPa after the treatment of 1 or 2 times under the condition of about 50 MPa.

Next, in the third step, after the high-pressure carbonization treatment, graphitization treatment (high temperature treatment) can be performed stepwise at 1500 ° C. or more.
In this case, degassing is likely to be mild, which is effective. Note that dehydrogenation is performed in the temperature range of 700 to 1200 ° C.

The second and third steps described above are processes for densifying the three-dimensional C / C composite that is a preform. It is preferable that these processes are repeated 4 to 7 times.
This allows the preform to be densified leaving a void suitable for impregnating the desired amount of Al.
In particular, it is more preferable to repeat this densification treatment 6 or 7 times, and by impregnating the obtained three-dimensional C / C composite with Al, an Al-impregnated three-dimensional C / C exhibiting a coefficient of thermal expansion close to zero. A composite is obtained.
In order to increase the amount of impregnation of Al, the number of the densification treatments may be reduced to increase the voids.

  Next, in the fourth step, typically, a preform heated to about 700 to 750 ° C. can be placed in a molten aluminum of about 700 to 750 ° C. and impregnated under a pressure of 80 to 100 MPa.

Next, in the fifth step, typically, a desired shape can be machined using a band saw, a milling machine, a lathe or the like.
The size of the Al-impregnated three-dimensional C / C composite of the present invention can be manufactured up to about 450 mm × 450 mm × 400 mm at present.

Although the Al impregnated three-dimensional C / C composite of the present invention is obtained by the first to fifth steps described above, it is preferable to further perform nickel plating.
Thereby, abrasion resistance can be improved. Moreover, brittle fracture can be suppressed.
The thickness of such nickel plating can be typically about 5 to 10 μm. FIG. 3 shows a photograph of an Al-impregnated three-dimensional C / C composite in which nickel plating is performed at a film thickness of 5 μm and 10 μm.

  EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited to these Examples.

Example 1
Based on the flowchart shown in FIG. 4, an Al-impregnated three-dimensional C / C composite was produced.
Hereinafter, this flowchart will be described in the order of processes.

First, in Process 1 (hereinafter abbreviated as “P1”), pitch-based carbon fibers (XN20, manufactured by Nippon Graphite Fiber Co., Ltd.) were prepared as carbon fibers.
This carbon fiber has a tensile modulus of 200 GPa, a tensile strength of 2730 MPa, an electrical resistivity of 11 × 10 Ω · m, a thermal conductivity of 13 W / m · K, and a thermal expansion coefficient of −0.9 × 10 ⁻⁶ / K.

Next, a rod of φ0.97 mm was drawn using this carbon fiber (P2).
In addition, a preform was obtained by assembling the obtained rods with three orthogonal axes (P3).

Next, pitch impregnation treatment was performed on the obtained preform under vacuum to pressure conditions (P4).
In addition, the HIP treatment was performed at about 50 MPa for the first and second times and about 100 MPa for the third to seventh times (P5).
Further, graphitization was performed at 2400 ° C. (P6).
In addition, the densification process of P4-P6 was performed 4 times.

Next, the preform after the densification treatment was cut out to the size of the test piece and subjected to Al impregnation treatment (P7).
Specifically, Al molten metal forging was performed with a pressing force of about 100 MPa and a pressing time of 5 minutes.

  The obtained Al-impregnated three-dimensional C / C composite was machined with a band saw (P8) and subjected to electroless nickel plating to obtain a test piece (P9).

(Examples 2 to 4)
A test piece of Al-impregnated three-dimensional C / C composite was obtained by repeating the same operation as in Example 1 except that the densification treatment of P4 to P6 was changed to 5 to 7 times.

(Comparative Examples 1 and 2)
A test piece of 3D C / C composite was obtained by repeating the same operation as in Example 1 except that the densification treatment of P4 to P6 was 6 times and 7 times, and the Al impregnation treatment was not performed. It was.

[Performance evaluation]
The following evaluation tests were conducted on the test pieces obtained in each example. The results are shown in Table 2.

(1) Density measurement The density was calculated from the size and weight of the test piece. A vernier caliper was used for dimension measurement. The weight was measured at 0.1 mg intervals.

(2) Thermal expansion measurement The thermal expansion coefficient was measured on condition of the following. Further, the temperature dependence of the thermal expansion coefficient is shown in FIGS.
a. Measurement sample: 10 mm (width) x 8 mm (thickness) x 15 mm (length)
b. Apparatus: Laser thermal dilatometer LIX-1 type manufactured by ULVAC-RIKO Co., Ltd. c. Data processing: TRC data processing system THADAP-TEX
d. Measurement mode: Constant temperature rise measurement e. Temperature increase rate: 2 ° C / min
f. Measurement temperature range: 25-100 ° C
g. Measurement atmosphere: in helium h. Load: about 17g
i. N number of measurements: 1
j. Measurement direction: longitudinal direction of measurement sample k. Temperature calibration: Wood alloy, indium and tin melting points

From Table 2 and FIGS. 5 and 6, it can be seen that the Al-impregnated three-dimensional C / C composites obtained in Examples 1 to 4 have a low coefficient of thermal expansion due to impregnation with Al.
Further, comparing Examples 3 and 4 with Comparative Examples 1 and 2, it can be seen from FIG. 6 that the coefficient of thermal expansion is very close to zero by impregnating with Al.
Therefore, the Al-impregnated three-dimensional C / C composite of the present invention has a low density, a small thermal expansion coefficient, and excellent workability.

It is a polarizing microscope photograph which shows an example of the Al impregnation three-dimensional C / C composite of this invention. It is a graph which shows the relationship between Al content and a thermal expansion coefficient. It is a photograph which shows an example of the Al impregnation three-dimensional C / C composite which gave nickel plating. It is a flowchart which shows an example of the manufacturing process of Al impregnation three-dimensional C / C composite of this invention. It is a graph which shows the temperature dependence of a thermal expansion coefficient. It is a graph which shows the temperature dependence of a thermal expansion coefficient.

Claims (8)

An Al-impregnated three-dimensional C / C composite obtained by impregnating a C / C composite with aluminum,
Three-dimensional Al impregnation having an average density of 1.9 to 2.3 g / cm ³ and an average coefficient of thermal expansion of −0.41 × 10 ^{−6 to} 1.58 × 10 ⁻⁶ / ° C. C / C composite. 2. The Al-impregnated three-dimensional C / C composite according to claim 1, wherein an average thermal expansion coefficient is −0.41 × 10 ^{−6 to} 0.37 × 10 ⁻⁶ / ° C. 3.   3. The Al-impregnated three-dimensional C / C composite according to claim 1, wherein the ratio of the C / C composite to aluminum is 90:10 to 98: 2 in terms of volume. The Al-impregnated three-dimensional C / C composite according to any one of claims 1 to 3, which is nickel-plated. Impinge on the production of Al-impregnated 3-D C / C composite according to any one of claims 1 to 4, the following first to fifth step 1. The carbon fiber is woven into a three-dimensional network structure, as factories to preform
2 . High pressure carbonization process for pitch impregnation treatment and / or HIP treatment
3 . Graphitization process
4 . Forging process with molten aluminum
5 . A method for producing an Al-impregnated three-dimensional C / C composite comprising performing a machining process. 6. The method for producing an Al-impregnated three-dimensional C / C composite according to claim 5 , wherein the second step and the third step are repeated 4 to 7 times for densification. 7. The method for producing an Al-impregnated three-dimensional C / C composite according to claim 6 , wherein the second step and the third step are repeated 6 or 7 times . The method for producing an Al-impregnated three-dimensional C / C composite according to any one of claims 4 to 7, wherein nickel plating is performed after the fifth step.

Images