JPH01239063A - Method for manufacturing carbon composite - 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] [Industrial Application Field] This invention relates to a method for producing a carbon composite, and in particular a method for producing a carbon composite useful as a brake material for aircraft, high-speed vehicles, automobiles, industrial machinery, etc. Regarding.

(Prior Art) A typical carbon composite is a mature wood pIa miscellaneous reinforced carbon composite (C/C2I composite) using carbon fiber as an aggregate. C/C composites are light seedlings, have high heat resistance, and have excellent friction properties at high temperatures.
It is especially important for aircraft control and high-speed vehicle brake control.

However, C/C composites have the disadvantage that the coefficient of friction decreases at low temperatures.

In response to this, attempts have been made to control the friction coefficient by adding a friction coefficient modifier to the C/C composite. For example, JP-A No. 62-70214 describes the use of graphite powder as a regulator, and the use of other inorganic compounds also allows for I'ii! It is known to be effective in controlling the coefficient of friction. Adding additives to carbon composites in this way is often effective in improving their properties.

[Problems to be Solved by the Invention] However, it is generally difficult to uniformly disperse such additives in the matrix.

A known method is to mix aggregates and additives with an omnimixer, but this method is inefficient because it is a batch method, and depending on the type of additive, the additive may be unevenly distributed even after mixing. There is.

In addition, Time DO60-54974 and Japanese Unexamined Patent Publication No. 6
Publication No. 1-21973 describes a method for producing a C/C11 composite after electrodepositing "-cus powder around carbon fibers, but the applicable additives are limited and the cost is high. There is a problem with this.

Furthermore, only carbon composites that can be manufactured using conventional manufacturing methods have a uniform composition.

However, for example, when a carbon composite is used as a brake material, its surface is required to have a high coefficient of friction, and its interior is required to have high strength. It is difficult to produce a carbon composite that satisfies this condition with a uniform composition. One possible solution to this is to manufacture multiple types of carbon composites in advance and bond them together later, but in this case, it is necessary to use a heat-resistant and high-strength adhesive.
Such adhesives are generally difficult to obtain.

In view of the above-mentioned circumstances, the present invention provides a method for producing a carbon composite in which additives can be efficiently and uniformly dispersed in 7 Trix, and its composition can be partially changed. The purpose is to

[Means for Solving the Problems] In the manufacturing method of the present invention, first, aggregate is placed in a porous mold and molded by compressing it to a predetermined degree, and the obtained molded body is compressed in the mold. Soak it in a mixture of pitch and additives. Next, the molded body impregnated with an appropriate amount of a mixed solution of pitch and additives is subjected to carbonization treatment of the impregnated pitch. Furthermore, in the manufacturing method of the present invention, when loading aggregate into a porous mold, structurally different types of aggregate can be stacked and loaded, respectively.

Hereinafter, the method for producing a carbon composite of the present invention will be explained in more detail.

The porous mold used in the manufacturing method of the present invention can be of any type as long as it allows pitch to pass through.
It is preferable that 1 to 4 pieces exist per 2 pieces.

Aggregate is placed in this mold and compressed to a predetermined size using a molding machine or the like. A specific example of this process will be explained with reference to the drawings. As shown in FIG. 1(a), first, a lower lid 1 is attached to the lower end of a mold side wall 2 having a large number of holes, and a filling guide 4 is attached to the upper end, and aggregate 5 is added to a predetermined amount. next,
The upper cover 3 is placed on top of the filled aggregate and covered under pressure via the shaft 6 and the pressurizing auxiliary plate 7. After compressing the aggregate to a predetermined size, the filling guide 4 is removed and the top lid 3 is fixed with a fastener 8, as shown in FIG. 1(b). The aggregates used here include those commonly used as aggregates for carbon composites, such as carbon fibers, metals, fibers, and classified compound fibers. Carbon fiber is a commonly used aggregate, and its shapes include short R fibers, long fibers, and woven fabrics.

Next, the aggregate compressed to a predetermined size is immersed in a mixed solution of pitch and additives while remaining in the mold.

This is preferably carried out by placing the entire mold in an impregnation tank, deaerating the tank to reduce the pressure in the tank, and then injecting and covering the mold with pitch mixed with additives. After pouring the mixed liquid into the tank, it is preferable to forcefully stir the mixture in order to uniformly disperse the additive. Furthermore, there are no particular limitations on the additives added to the pitch, but in the case of a solid, the particle size must be smaller than the diameter of the pores opening into the mold.

The base material immersed in the mixture of pitch and additives is appropriately impregnated with the pitch mixture, and then fired and carbonized while being held in the mold. The conditions for impregnating aggregate with pitch mixture vary depending on the aggregate and mold used.
Although it also depends on the compression conditions of the aggregate, it is usually 1
Calcination of the aggregate impregnated with the pinch mixture can be carried out at 80-350"C for 0.5-1 hour.
It is carried out for 8 to 40 hours at 0°C.

If necessary, the fired body after carbonization can be taken out of the mold, impregnated with pitch, and fired. Here, only pitch is impregnated into the fired body. Firing after pitch impregnation 6 It can also be carried out by a method commonly used in this field, and usually 150
It is carried out for 0.5 to 1 hour at ~300°C. This pitch impregnation and carbonization firing can be repeated multiple times.

Incidentally, the aggregate loaded into the porous mold may be loaded so that the composition is almost homogeneous throughout the molded body, or aggregates with different structures may be loaded in layers so that the composition is partially different. Te Shiyoi. For example, by first layering plain weave carbon fibers and binder pitch alternately in a plurality of layers V1 in a mold, and then filling the laminate with a predetermined amount of short fibrous carbon fibers, as shown in FIG. 2(a), Thus, it is possible to obtain a carbon composite in which the upper surface portion and the lower surface portion have different properties. Here, the upper surface part is a C/C composite part 9 that uses short fibrous carbon fiber as an aggregate, and efficiently incorporates additives contained in the impregnated pitch, and contains a friction coefficient modifier as an additive. When used, the upper surface portion is superior in terms of coefficient of friction. The lower surface part is a C/C composite part 10 made of plain-woven carbon MA strip as an aggregate, and has excellent strength. Therefore, a carbon composite having such a structure has both a high coefficient of friction on the surface and high strength inside, and is suitable for use as a brake pad. Furthermore, by changing the loading procedure,
Carbon composites shown in FIG. 2(b) and FIG. 2(C) can also be obtained.

(Examples) Example 1 First, a pitch mixture was prepared by adding 8% by volume of iron powder and 2% by volume of talc as friction coefficient modifiers to pitch having a softening point of 150° C. and a carbonization yield of 68%. Next, short fibrous carbon fibers (manufactured by Kureha) 2 and 3 were sufficiently opened, placed in a porous mold (diameter 300 mm), compression molded to a thickness of G (J mm), held with a perforated lid, and then molded. After degassing and reducing the pressure inside the impregnation tank, the pinch mixture described above was introduced into the impregnation tank, and the pinch mixture was impregnated into the carbon fibers through a porous mold.Inside the impregnation tank The temperature is 250
It was kept at ℃.

After the carbon fiber molded product was impregnated with the pitch mixture, the entire mold was transferred to a furnace, and the temperature was raised to 1000° C. at a heating rate of 2° C./min for carbonization.

After the fired product was taken out of the mold, it was placed in an impregnation tank different from the above-mentioned impregnation tank, and pitch with a softening point of 120° C. was introduced therein to impregnate it with pitch. After impregnating the pitch, 8
It was fired at 00°C. This pitch impregnation d3 and carbonization firing were repeated one more time to obtain a C/C composite.

The properties of the 1q C/C composite were measured and the results are shown in Table 1. Measurements were uniform throughout the composite.

Example 2 Instead of 2 kg of carbon fiber, a mixture of short fibrous carbon fiber (manufactured by Kureha) 1.71 (ff) and yellow 8 pi A fiber 1.3/(y) was thoroughly mixed and opened, and a pitch mixture was added. The same operation as in Example 1 was performed except that coke powder and molybdenum disulfide MO32 were used as agents instead of iron powder and talc.

The properties of the obtained C/C composite were measured, and the results are also listed in Table 1. Measurements were uniform throughout the composite.

Comparative Example 1 Short fibrous carbon fiber (Kureha Soso) 2Ky for omni mixer
, iron powder i, eK! 7. Add 0.6 Ky of talc and mix for 5 minutes. The blued mixture was molded into a porous mold (300 m in diameter).
The entire mold was placed in an impregnating tank and immersed in pitch having a softening point of 150''C at 250°C. Pitch impregnation and carbonization firing were performed roughly three times.

The properties of the obtained C, /CJ embodi l- were measured, and the results are also listed in Table 1. Measured values vary depending on the sampling location, and the table shows values for the periphery and center of the disk.

As is clear from Table 1, the carbon composite produced by the production method of the present invention is homogeneous throughout and has sufficiently satisfactory performance, whereas the carbon composite of the comparative example has a constant composition. Rather, performance varies depending on location.

Example 3 Plain weave carbon 1 fiber (Toshi T-300) in a porous mold (diameter 300 mm), softening point 315°C, carbonization yield 90%
40 layers of binder pitch were alternately laminated, and 2.5 Ky of chopped carbon R1A fibers were further placed thereon. This is molded using ■ 90/(g weight/cm 2 = 60 II
The mold was compressed to a thickness of 1.1 mm, fixed with porous material, and placed in an impregnation tank together with the mold, and then the inside of the impregnation tank was evacuated to reduce the pressure. On the other hand, a pitch mixture was prepared by mixing pitch with a softening point of 210° C. and 8% by volume of iron powder, and the pitch mixture was fed into an impregnating tank which was depressurized and degassed. Impregnation of pitch mixture is 285.3
The experiments were carried out at temperatures of 0.5,330°C and 345°C. The molded body impregnated with pitch mixture liquid is 1000 pieces per mold.
Calcined at ℃. Thereafter, the fired body was taken out of the mold and impregnated with pitch having a softening point of 120°C at 220°C.
A composite carbon fiber-reinforced carbon composite (composite C/C composite) was obtained by roughly repeating the step of firing at ooo°C twice.

The structure of the obtained composite C/C composite is shown in Figure 2 (a>
It was as shown in

The properties of the obtained composite C/C composite were measured, and the results are shown in Table 2 and FIG. The friction coefficient in the table is the value for cast iron FC25, and the measurement is for short fibrous carbon 41.
This was done only for the part where the beginning was the previous month.

Example 4 The same operation as in Example 3 was performed except that copper powder was used instead of iron powder added to the pitch mixture and the impregnation temperature was only 305°C.

The properties of the obtained lζ composite C/C composite were measured, and the results are also listed in Table 2.

Comparative Example 2 A binder pitch prepared by mixing 10 parts of pitch with 3.6 parts of iron powder and felt carbon fibers were laminated in a mold at a ratio of 4.1 parts of pitch to 1 carbon fiber.

This is heated to 90% using a high-temperature molding machine.
Compression molding was performed at a pressure of cm 2 and back-warmed to 800°C.

After that, pitch impregnation and carbonization firing were carried out in the same manner as in Example 3.

The properties of the obtained C/Cl composite were measured, and the results are also listed in Table 2.

As is clear from Table 2, the composite C/C composite produced by the IB method of the present invention has much greater bending strength than the C/C composite of Comparative Example 2. In addition, Figure 3 shows the relationship between the temperature difference between the impregnation temperature of pitch containing iron powder and the softening point of binder pitch, and the iron content of the part where the plain weave carbon 1 fibers of composite C/C composite 1~ are splintered. However, it has been shown that the greater the difference between the binder pitch softening point and the impregnation temperature, the greater the iron content.

(Effects) As described above, according to the 143m method of the present invention, the additive can be efficiently and uniformly dispersed in the matrix of the carbon composite, and the composition of the carbon composite can be partially changed. It is possible.

[Brief explanation of the drawing]

Figure 1(a); J3 and (Ll) are the V of this invention.
FIG. 2 is a cross-sectional view showing an embodiment of a porous mold according to the W method, and FIG. Figure 3 shows the relationship between the temperature difference between the binder pitch softening point and the impregnation temperature and the iron content W in the part using plain-woven carbon fiber as aggregate in the composite C/C composite crushed by the manufacturing method of the present invention. It is a graph diagram. 1... Lower cover, 2... Side wall, 3... Upper cover, 4...
Filling guide, 5... aggregate, 6... shirt 1-17
... Pressure auxiliary plate, 8 ... Fastener, 9 ... Short fibrous carbon 1 fiber C/C composite 1 part 10 ... Plain weave carbon fiber C/C-J composite part I ~ part 11ji ”；j personj′
(°, Liu Danshijima Etakehiko)
1(a)
(b) Figure 1 (a) (b)) 2nd mouth Figure 3

Claims (6)

[Claims] (1) Aggregate is loaded into a porous mold and compression molded, and the resulting molded body is compressed in the mold and immersed in pitch containing additives to impregnate the pitch and additives into the molded body. 1. A method for producing a carbon composite, comprising: thereafter subjecting the molded body to carbonization treatment of impregnated pitch. (2) The manufacturing method according to claim 1, wherein the aggregate is carbon fiber, metal fiber, or a mixture thereof. (3) The manufacturing method according to claim 1, characterized in that structurally different types of aggregates are stacked and loaded into the mold. (4) The manufacturing method according to claim 3, wherein the different types of aggregates are plain weave carbon fibers and short fibrous carbon fibers. (5) The manufacturing method according to claim 1 or 3, wherein the additive is a friction coefficient modifier. (6) The manufacturing method according to claim 1 or 3, wherein the process of carbonizing and firing the entire mold, taking out the fired body from the mold, impregnating it with pitch, and carbonizing and firing is repeated a plurality of times.