JPH04234476A - Production of carbon-fiber-reinforced carbonaceous friction disc - 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]

0001

[Industrial Application Field] The present invention relates to a method for manufacturing a carbon fiber reinforced carbonaceous friction disk, which is particularly lightweight and has high mechanical strength and good braking characteristics at high speeds for use in aircraft, railway vehicles, automobiles, etc. The present invention relates to a method for producing a required carbonaceous friction material.

0002

BACKGROUND OF THE INVENTION A carbon fiber reinforced carbon material (hereinafter referred to as C/C composite) is a composite material in which a carbonaceous matrix such as a thermosetting or thermoplastic resin is reinforced with carbon fibers. C/C composites have superior heat resistance, mechanical strength properties, friction and braking properties, etc. compared to conventional carbon materials, so their practical application is particularly urgent as braking components for aircraft, railway vehicles, automobiles, etc. It is the material.

[0003] During production, carbon fiber tow,
After baking a molded body obtained by pressure molding, press molding, etc. in an inert atmosphere using a reinforced structure such as cloth or felt and a thermosetting resin such as phenol resin or furan resin or a binder such as pitch. , densification by repeating impregnation and firing using the resin or pitch, or by introducing hydrocarbons at high temperatures of 1000°C or higher and depositing decomposed carbon on the fiber surface (hereinafter referred to as CVD method). A method of obtaining a C/C composite through a process is known.

[0004] Among these, a method for strengthening the shear resistance of a sliding surface as a friction material is characterized by applying needle punching to a carbon fiber woven fabric, nonwoven fabric, or a laminate thereof to entangle the fiber layers. JP-A-61-2930 discloses a method in which carbon fiber woven fabric and non-woven fabric are alternately laminated so that the raised short fibers constituting the non-woven fabric entangle the fiber layers and contribute to strengthening the shear resistance. , disclosed in Japanese Patent Application Laid-Open No. 61-2929. Also, JP-A-6
1-27325, a C/C composite obtained by impregnating a laminate of small pieces cut from carbon fiber woven fabric with a phenol resin, molding and firing by a conventional method, or applying CVD treatment in advance. After impregnating a small piece of the woven fabric or a laminate thereof with a phenol resin, molding is performed by a conventional method.
A C/C composite is obtained by firing. That is, a method of improving shear resistance and oxidation resistance by using small pieces of woven fabric and combining it with a CVD method is disclosed.

[0005]

[Problems to be Solved by the Invention] By using structures such as bundles, woven fabrics, and non-woven fabrics as reinforcing materials for C/C composites, the friction material can be strengthened in one direction and two directions parallel to the sliding surface. The disadvantage is that it has anisotropy in strength properties, such as not being reinforced in the direction perpendicular to the sliding surface, and especially extremely low shear strength. However, the method described above,
In other words, in nonwoven fabrics such as felts and mats that are aggregates of short fibers, increasing the fiber length reduces the frequency of orientation in the vertical direction of the sliding surface of the fibers, and decreasing the fiber length decreases the orientation frequency in the vertical direction of the sliding surface. The shear strength is extremely low in both cases, such as not only weakening the entanglement between the fibers but also increasing breakage due to buckling and reducing the bonding strength between the fiber layers. The method of needle punching the aggregate is intended to improve these drawbacks by forcing the orientation of the fibers in the direction perpendicular to the sliding surface and increasing the frequency of intertwining between the fiber layers. Generally, since a higher needling density is required, the frequency of fiber orientation increases apparently, but the fiber density decreases significantly and the fiber length becomes uneven due to fiber pulverization, breakage, etc., and the desired reinforcing effect cannot be achieved. is not expressed. In the process of cutting, laminating, molding, etc., small pieces of carbon fiber woven fabric often fray or unravel the strands, and the shear strength does not improve significantly. In particular, the bonding force between fibers is weak in the longitudinal direction parallel to the sliding surface, and the bending strength is extremely low. In any case, it is possible to increase the density of C/C composites using the conventional method, which involves various processes such as shortening carbon fibers, cutting woven fabric into small pieces, felting, and needling, but it is not possible to achieve stable C/C composites. A friction material with sliding properties cannot be obtained. In addition, the CVD method has low productivity and requires a lot of time and advanced technology to achieve high density, so there are many problems in putting it into practical use. An object of the present invention is to provide a method for manufacturing a carbon fiber-reinforced carbonaceous friction disk, in which a friction material with excellent braking performance can be easily obtained by solving the above-mentioned problems in a simple manner.

[0006]

[Means for Solving the Problems] In order to achieve the above object, according to the present invention, a laminated structure consisting of a carbon fiber woven or nonwoven fabric and a carbonaceous binder is molded and then fired in an inert atmosphere. In the method for producing a carbon fiber-reinforced carbonaceous friction disk which is carbonized or graphitized by carbonization, a woven or nonwoven fabric of the carbon fibers is arbitrarily provided with incisions, impregnated with the carbonaceous binder, and the tips of the fibers are rubbed. A method for producing a carbon fiber-reinforced carbonaceous friction disk is provided, which is characterized in that the bond between the fiber layers is strengthened and the shear strength is improved by orienting the fibers in the direction perpendicular to the dynamic surface.

The present invention will be explained in more detail below.

In the method of the present invention, arbitrary cuts are made in the plane of a sheet-like structure made of carbon fibers, the cut is impregnated with a carbonaceous binder, and then the structures are laminated to a predetermined thickness and molded. After this molded body is cured, it is fired in an inert atmosphere to carbonize or graphitize it. Its feature is that it eliminates the need for processes such as cutting single fibers, tows, strands, etc. into chops or cutting woven fabric into small pieces, and by making arbitrary cuts in the sheet-like structure, shear resistance can be easily improved. The goal is to improve.

[0009] The sheet-like structure may be a woven fabric, a felt made of an aggregate of various chops, a mat, etc., but the latter may reduce the reinforcing effect by making the fiber length too small. Preferably it is a woven fabric. X-axis (length direction) and Y-axis (width direction) of sheet-like structure plane
It is preferable that the interval between the cuts provided in parallel to the groove is 5 to 50 m/m. If it exceeds 50 m/m, the number of cuts per unit area of the plane of the sheet-like structure is small, and at the same time, the frequency of fiber orientation in the direction perpendicular to the sliding surface (hereinafter referred to as the Z-axis direction) is insufficient, resulting in small reinforcement hardening. Become. In addition, if it is less than 5 m/m, the number of cuts will increase, but the entanglement between the fiber layers will be small and the bonding force of the fiber layers (X-axis, Y-axis) parallel to the sliding surface will be weak, making it impossible to secure bending strength. It disappears. Therefore, it can be selected arbitrarily depending on the number of cuts, but preferably 10 to 20 m/
It is m. Although the length of the cut can be arbitrarily selected, it is preferable to provide the cut portion and the non-cut portion alternately in the same direction and with the same length, and uniformly on the X and Y axes, as shown in Fig. 1. be. If provided unevenly, there is a risk that variations in strength properties will increase, and in particular, a decrease in bending strength will increase. That is, the tips of the short fibers cut in the woven fabric become Z due to the interaction with the bundle, matrix, filler, etc. of the sheet-like structure during molding.
The axial orientation increases the interlacing frequency and strengthens the bond between adjacent fiber layers, which improves shear strength. After making cuts in the sheet-like structure, it is impregnated with a carbonaceous binder such as a resin or pitch, but a prepreg impregnated with the binder in advance may also be used. Further, a thermoplastic binder such as pitch is preferred because the carbon fibers move along with the binder in a plastic state during molding and effectively contribute to the entanglement of the fiber layers.

[0010] After laminating to a predetermined thickness, the molded product obtained by pressure molding or press molding is cured in an oxidizing or inert atmosphere, under pressure or normal pressure, and then in an inert atmosphere. It is fired at a temperature of 1000°C or above 1000°C to carbonize or graphitize. Further, by repeating impregnation with resin or pitch and firing as necessary to make the material denser, it is possible to easily obtain a carbon fiber-reinforced carbonaceous friction disk having excellent shear strength and bending strength.

[0011]

EXAMPLES The present invention will be specifically explained below based on examples.

(Example 1) Commercially available carbon fiber woven fabric (PAN
type, satin weave), length 100m/m, X axis (length direction)
, the spacing parallel to the Y axis (width direction) was fixed at 10 m/m, and cuts were made at the positions shown in FIG. That is, the number of cuts is 500/m2, and the area ratio of the cut portion to the non-cut portion is 1:1. This woven fabric was impregnated with phenolic resin and the prepreg was adjusted to have a basis weight of approximately 35% (wt).
After laminating the sheets and molding them at 150°C under a pressure of 1.0 kg/cm2, they were then heated at 200°C in an oxidizing atmosphere for 5 hours.
The molded product was cured by R treatment, and was then subjected to after-curing for 40 hours at the same temperature to obtain a molded product having a diameter of 250 mm and a thickness of 16 m/m. This molded body is fixed with a jig and set in a graphite container,
After packing with coke breeze, it was heated in an inert atmosphere at a heating rate of 5°C/hr from 200 to 600°C, 60°C/hr from 600 to 1000°C, and then heated at the same temperature for 2 hours.
R was retained and carbonized.

Next, this fired body was impregnated with coal tar pitch, and after repeating infusibility and carbonization to give an apparent density of 1.6 or more, it was fired at 2000° C. in an inert atmosphere to graphitize it. The strength characteristics of the obtained C/C composite were as follows. Apparent density Shear strength Bending strength (g/cm3) (MPa/mm2
) (MPa/mm2)1.62
21 240

00
14] (Example 2) A commercially available carbon fiber woven fabric (PAN type, satin weave) was fixed at a length of 100 m/m and at intervals of 25 m/m parallel to the X axis (length direction) and Y axis (width direction). Then, cuts were made at the positions shown in FIG. Number of cuts is 250/
m2, and the area ratio of the cut portion to the non-cut portion is 1:1. The strength characteristics of the C/C composite obtained by the same treatment as in Example 1 were as follows. Apparent density Shear strength Bending strength (g/cm3) (MPa/mm2
) (MPa/mm2)1.64
19 210

00
15] (Comparative Example 1) C/C obtained by processing in the same manner as in Example 1 except that the carbon fiber woven fabric was used without the above-mentioned incisions.
The strength properties of the composite were as follows. Apparent density Shear strength Bending strength (g/cm3) (MPa/mm2
) (MPa/mm2)1.61
6 170

0
(Comparative Example 2) The strength characteristics of a C/C composite obtained by processing in the same manner as in Example 1 except that small pieces of carbon fiber woven fabric cut into 20 m/m squares were used were as follows. . Apparent density Shear strength Bending strength (g/cm3) (MPa/mm2
) (MPa/mm2)1.63
15 135

00
17]

Effects of the Invention Since the present invention is constructed as described above, by strengthening the sliding surface of the carbonaceous friction material in the vertical direction, the shear strength is 3 to 3 times higher than that of conventional two-way reinforced friction materials. The anisotropy in mechanical strength was significantly reduced. However, it is suitable for friction materials that require high mechanical strength and stable braking characteristics at high speeds.

[0018] Further, it has the advantage that it can be produced easily and at low cost without requiring complicated processes such as chopping single fibers, strands, tows, etc., making felts or mats, and cutting woven fabric into small pieces.

[Brief explanation of the drawing]

[Fig. 1] Cutting depth of 100m/m in the X and Y axes.
FIG. 2 is a schematic diagram of carbon fiber woven fabrics provided at regular intervals of m/m.

[Figure 2] Cutting depth of 100m/m on the X and Y axes is 25mm.
FIG. 2 is a schematic diagram of carbon fiber woven fabrics provided at regular intervals of m/m.

[Explanation of symbols]

W Cutting width S Cutting interval L Cutting length

Claims (1)

[Claims] [Claim 1] A method for manufacturing a carbon fiber-reinforced carbonaceous friction disk, which comprises forming a laminated structure consisting of a woven or nonwoven carbon fiber fabric and a carbonaceous binder, and then firing it in an inert atmosphere to carbonize or graphitize it. In this method, cuts are arbitrarily made in the carbon fiber woven fabric or nonwoven fabric, and the carbon fiber binder is impregnated into the cut, and the fiber tips are oriented in a direction perpendicular to the sliding surface to strengthen the bond between the fiber layers. , a method for producing a carbon fiber-reinforced carbonaceous friction disk characterized by improved shear strength.