JPH05117780A - Fiber formed body for fiber-reinforced composite member - Google Patents

Abstract

PURPOSE:To obtain an isotropic fiber formed body for the fiber-reinforced composite member wherein short fibers are oriented at random by dispersing a tetrapod deformed fiber consisting of the core and acicular part in short fibers and forming the product. CONSTITUTION:This fiber formed body 1 is formed with short fibers 2 such as whiskers and the deformed fibers 3 consisting of plural acicular parts 5 extending from the core 4. The deformed fibers 3 are dispersed to randomly orient the short fibers 2. The content of the deformed fiber 3 is preferably controlled to 0.3-55vol.%. The formed body 1 is obtained by dispersing a mixture of the short fiber 2 and the deformed fiber 3 in a specified ratio in water to obtain a slurry, injecting the slurry into the cavity of a forming die and press- forming the slurry with a presser punch. An isotropic fiber formed body 1 which can be thickened and lowered in density is obtained in this way.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a fiber molding for a fiber-reinforced composite member.

[0002]

2. Description of the Related Art Heretofore, as this kind of fiber molded article, a short fiber, for example, one molded from whiskers has been known. This fiber molded body is generally molded by a method of injecting a slurry molding material in which short fibers are dispersed in a liquid into a molding die, and then removing the liquid and depositing the short fibers.

[0003]

However, in the conventional fiber molded body, since the short fibers have a regular orientation in which the length direction thereof is substantially orthogonal to the stacking direction, the fiber-reinforced composite member has the following characteristics. There is a problem that it is unsuitable to apply the composite member to a structural member to which polyaxial stress is applied, a functional member having a sliding portion in different directions, etc. due to anisotropy.

Further, since the conventional fiber molded body has a thin wall thickness and is easily densified due to the molding method, it is not possible to meet the demands for increasing the wall thickness and reducing the density. There is also a problem.

In view of the above, the present invention makes it possible to obtain a fiber-reinforced composite member in which anisotropy is alleviated in characteristics, and to meet the demands of increasing the wall thickness and reducing the density. It is an object of the present invention to provide the above-mentioned fiber molded body.

[0006]

A fiber molding for a fiber-reinforced composite member according to the present invention comprises a short fiber and a deformed fiber having a plurality of needle-shaped portions extending from a core portion. The short fibers are randomly oriented by being dispersed.

[0007]

1 and 2 show an embodiment of a fiber molded body 1 for a fiber-reinforced composite member, which fiber molded body 1 is composed of short fibers 2 and deformed fibers 3 in a substantially disc shape. ..

The short fibers 2 have a predetermined length having a relationship of L / D> 1, where L is the length and D is the diameter. In this embodiment, the silicon carbide whiskers (Si) are used.
C whiskers) are used. This silicon carbide whisker has a length L of 20 to 60 μm and a diameter D of 0.3 to 0.6.
μm. Further, as the deformed fiber 3, as shown in FIG. 3, a tetrapod-shaped fiber having a plurality of needle-shaped portions 5 extending from the core portion 4 as shown in FIG. 3, zinc oxide whiskers (ZnO in this embodiment). Whiskers are used. In this zinc oxide whisker, the length of the needle-shaped portion 5 from the core portion 4 is 10 to 100 μm.

In the fiber molded body 1, the deformed fibers 3 are uniformly dispersed throughout the fiber molded body 1, and the short fibers 2 are randomly oriented.

Next, a method for molding the fiber molded body 1 will be described.

FIG. 4 shows a molding die 6 used for molding the fiber molded body 1. The molding die 6 is provided with a mold body 8 having a cavity 7 opened upward, and slidably in the cavity 7. A plurality of drain holes 10 are formed on the bottom surface of the cavity of the mold body 8 and are configured by a press punch 9 to be fitted. The inlet of these drain holes 10 is covered with a filter 11, and the outlet side is connected to a suction pump 12.

First, a mixed fiber composed of the short fibers 2 and the irregularly shaped fibers 3 is dispersed in a liquid, in this molding example, water to prepare a slurry molding material.

Next, as shown in FIG. 4, a predetermined amount of the slurry-like molding material S is injected into the cavity 7.

Thereafter, as shown in FIG. 5, the suction pump 1
2 is operated and the pressure punch 9 is moved down to remove the liquid and deposit the mixed fibers to form the fiber molded body 1.

During the deposition of the mixed fibers, the irregularly shaped fibers 3 settle while embracing the short fibers 2, so that the regular orientation of the irregularly shaped fibers 2 is hindered, and the needle-shaped portions 5 of the irregularly shaped fibers 3 are prevented. As a result, the short fibers 2 are prevented from being densely packed, so that the deposit is kept at a low density.

Through the above steps, the fiber molded body 1 in which the random orientation of the short fibers 2, the uniform dispersion of the irregularly shaped fibers 3, the thickening and the low density are achieved can be obtained.

Specific examples of molding conditions for the fiber molded body 1 are as follows.

Dimensions of the fiber molding: diameter 86 mm, length 25
mm; Slurry molding material: 1000 cc of water, 97 mixed fibers
g, compounded amount of deformed fiber 5% by volume; pressure of pressure punch:
100 kg / cm ² ; suction pressure of suction pump: 10 Torr. When the volume of the mixed fibers (the sum of the volumes of the short fibers 2 and the irregular fibers 3) is V ₁ and the volume of the irregular fibers 3 is V ₂ , the compounding amount (volume%) of the irregular fibers 3 is (V ₂ / It is represented as V ₁ ) × 100.

The deformed fibers 3 may be broken at the needle-shaped portions 5 during handling thereof. If there are at least two needle-shaped portions 5, the staple fibers 2 can be prevented from being regularly oriented. Those effects are improved as the number of the needle-shaped portions 5 is increased.

FIG. 6 compares the tensile strengths of the fiber-reinforced composite members obtained by using the fiber moldings of the present invention and comparative examples. In the figure, the A direction indicates a direction parallel to the deposition direction as shown in FIG. 1, and the B direction indicates a deposition direction as shown in FIG. 1, and thus a direction orthogonal to the A direction.

The fiber molding 1 of the present invention is a mixture of silicon carbide whiskers as the short fibers 2 with 5% by volume of the zinc oxide whiskers, which are the modified fibers 3, and the silicon carbide whiskers are randomly oriented. The volume fraction Vf of the fiber compact 1 in the fiber-reinforced composite member is 20%.

COMPARATIVE EXAMPLE A fiber molded product was formed from only silicon carbide whiskers and had a volume fraction Vf of 20%. Silicon carbide whiskers had an orientation in which the length direction was made substantially orthogonal to the A direction. Have.

As the matrix forming material, Al--S
An i-Cu-Mg-based alloy was used, and a molten metal forging method was applied in manufacturing the composite member.

As is apparent from FIG. 6, in the fiber-reinforced composite member using the fiber molded body 1 of the present invention, the difference in strength between the A and B directions is smaller than that in the comparative example, and the characteristics are different. The directionality of the silicon carbide whiskers is relaxed because the silicon carbide whiskers are randomly oriented.

FIG. 7 shows the relationship between the blending amount of the irregularly shaped fibers 3 and the strength difference between the directions A and B in the fiber-reinforced composite member, and FIG. 8 is an enlarged view of the main part of FIG. Figure 7,
From FIG. 8, it can be seen that the strength difference between the A and B directions is reduced by setting the blending amount of the deformed fiber 3 to 0.3% by volume or more. The preferable compounding amount of the deformed fiber 3 for obtaining such an effect is 3% by volume or more.

FIG. 9 shows the relationship between the amount of the modified fibers 3 and the amount of wear in the fiber-reinforced composite member. From FIG. 9, it is understood that the abrasion resistance of the composite member is improved by blending the modified fibers 3, but the upper limit thereof is 55% by volume.

FIG. 10 shows the relationship between the compounding amount of the irregularly shaped fibers 3 and the minimum moldable volume fraction Vf in the fiber molded body 1. The short fibers 2, aluminum borate whisker _{(9Al 2 O 3 · 2B 2} O 3 whisker) is used, the length L is 10 to 20 [mu] m, the diameter D is 0.5 to 3 [mu] m. As the deformed fiber 3, the zinc oxide whisker was used. As is clear from FIG. 10, the minimum volume fraction Vf decreases when the content of the deformed fibers 3 is 0.3% by volume or more, so that the fiber molded body 1 having a large wall thickness and a low density can be obtained. Becomes

FIG. 11 shows the relationship between the length of the needle-like portion 5 of the irregularly shaped fiber 3 and the minimum volume fraction Vf that can be molded in the fiber molded body 1. The short fibers 2 and the irregularly shaped fibers 3 are the same as those in the example of FIG. It can be seen from FIG. 11 that the minimum volume fraction Vf decreases as the length of the needle portion 5 increases.

[0029]

EFFECTS OF THE INVENTION According to the present invention, it is possible to provide a fiber molded product in which short fibers are randomly oriented by using short fibers and specific deformed fibers as constituent materials. It is possible to obtain a fiber-reinforced composite member that is relaxed. It is also possible to provide a fiber molded product having a large wall thickness and a low density.

[Brief description of drawings]

FIG. 1 is a perspective view of a fiber molded body.

2 is a sectional view taken along line 2-2 of FIG.

FIG. 3 is a perspective view of a deformed fiber.

FIG. 4 is an explanatory view showing a state where a slurry-like molding material is injected into a molding die.

FIG. 5 is an explanatory diagram during molding of the fiber molded body.

FIG. 6 is a graph showing the tensile strengths of a fiber-reinforced composite member using the fiber molding of the present invention and a fiber-reinforced composite member using the comparative fiber molding.

FIG. 7 is a graph showing the relationship between the blending amount of irregularly shaped fibers and the strength difference between A and B directions in the fiber-reinforced composite member.

FIG. 8 is an enlarged view of a main part of FIG.

FIG. 9 is a graph showing the relationship between the amount of modified fibers and the amount of wear in a fiber-reinforced composite member.

FIG. 10 is a graph showing the relationship between the blending amount of irregularly shaped fibers and the minimum moldable volume fraction of a fiber molded body.

FIG. 11 is a graph showing the relationship between the length of the needle-shaped portion of the irregularly shaped fiber and the minimum volume fraction of the fiber molded body that can be molded.

[Explanation of symbols]

 1 Fiber molding 2 Short fiber 3 Deformed fiber 4 Core part 5 Needle part

Claims (2)

[Claims] 1. A short fiber (2) and a modified fiber (3) having a plurality of needle-shaped parts (5) extending from a core part (4), wherein the modified fiber (3) is dispersed. The short fiber (2) is randomly oriented according to the above to provide a fiber molding for a fiber-reinforced composite member. 2. The fiber molding for a fiber-reinforced composite member according to claim 1, wherein the compounded amount of the irregularly shaped fibers (3) is set to 0.3 volume% or more and 55 volume% or less.