JPS6289831A - Manufacture of fiber preliminary compact - Google Patents

Abstract

PURPOSE:To obtain the titled compact capable of forming composite body with metal having required strength and rigidity, by adding and dispersing whisker into soln. of organic (metal) compd., further dipping reinforcing long fibers then taking out, compacting them using the soln. as binder, drying, hardening, then heating and calcining. CONSTITUTION:Hardener is added to solvent soln. of aceton, etc., with organic compd. (such as acrylic resin thermally decomposable at <=400 deg.C) or organic metal compd. (example; silicone resin) to prepare binder soln. Next, whiskers of SiC, etc., are added and dispersed in the soln., then reinforcing long fibers made of carbon fiber, etc., are dipped therein. The reinforcing long fibers are taken out from the soln., compacted while using the soln. as binder, then dried and hardened. Next, the hardened compact is heated, calcined to decompose most organic components in binder and preliminary fiber compact having <=10% fiber vol. ratio is obtd. By the method, reinforcing long fibers are not coagulated but uniformly dispersed, strength and rigidity reqiured at compositing with metal can be provided.

Description

[Detailed description of the invention] The present invention provides a long 4J&
This article relates to a method for manufacturing a fiber preform (briform) for obtaining fiber reinforced full bending (FRH) by a pressure casting method, a vacuum casting method, etc. using a fiber.

Fiber-reinforced steel (hereinafter referred to as FRH), which is made by reinforcing a J=L light alloy matrix with fibers, has been attracting attention recently because it has excellent properties such as light weight, high strength, high rigidity, and high heat resistance. This is the material that has been used. FRH is a production method that involves molding fibers into a desired shape using an organic or inorganic binder and placing the obtained fiber preform into a mold.
Pour molten metal and plunge I! - pressurize vi
The method of construction is known.

However, when the reinforcing materials are long fibers, it is difficult to give and maintain the desired shape to the fibers even if a binder is used, and it is difficult to give the fibers a desired shape and maintain it. It is not easy to bundle the fibers of a book. Therefore, great care must be taken when placing the formed fibers into the casting mold, and when pouring molten metal into the mold and pressurizing it, some of the miscellaneous material may be washed away. Due to deformation or even agglomeration of fibers, the fibers are dispersed non-uniformly, making it impossible to secure a microscopically predetermined fiber volume ratio (Vr), and causing unfilled matrix metal in the fiber aggregation area. Such problems may occur.

As a result, it is difficult to obtain a sound FRH, resulting in variations in strength, which impairs the reliability of the FRH.

However, the inorganic binder is effective for short fibers such as short m/i and whiskers, which have a lot of entanglement between fibers, but the binding force is insufficient for long fibers and it cannot be used. In addition, although the organic binder has sufficient binding strength, sag easily aggregates in chrysanthemums, and although it can be used to obtain a fiber preform with Vf≧60%, it has a low Vf
It is not possible to obtain a fiber preform with a fiber volume fraction as low as 30%, and if a large amount of organic components remain after compounding the matrix metal with mM, the properties of the FRH will not be adversely affected.

On the other hand, bundle I! A method of obtaining FRH by a sintering method such as entering metal powder between fibers, heating and press forming (for example, Japanese Patent Application Laid-open No. 5
6-119746) has been proposed, and by applying this method, 11 miscellaneous bundles containing powder and ensuring the necessary male volume fraction are used as fiber preforms in the pressurized tJ manufacturing method. Although it is conceivable that it could be used, it is impossible to apply it because the bonding strength of powder cannot be expected and the necessary rigidity cannot be obtained.

On the other hand, F reinforced with long fibers oriented in one direction
Although RH can significantly improve tensile strength in the direction of fiber orientation, there are problems in that the tensile strength in the direction crossing the fibers and the shear strength at the interface between tall and 71-Rix metal are low.

. It is an object of the present invention to have reinforcing long fibers that do not clump together, are uniformly dispersed, have the strength and rigidity necessary for composites with metals, and have the same properties as composites. The aim is to obtain a fiber preform that can eliminate the weak points in strength in the subsequent FRH.

For this purpose, solutions of organic or organometallic compounds,
Or in the solution diluted with an organic solvent, fiber 1 (whisker) volume fraction (Vf) 510% (preferably, Vf=
3 to 8%), whiskers are added and dispersed, reinforcing long fibers are immersed in the solution, then the reinforcing long fibers are taken out from the solution, and the reinforcing long fibers and This is achieved by forming the whiskers, drying and curing them, and then heating and baking to decompose most of the organic components in the organic compound or organometallic compound that is the binder.

As mentioned above, when an organic binder is used, the reinforcing long fibers tend to agglomerate, but the present inventors have found that by interposing powder between the reinforcing long fibers, the Focusing on the ability to maintain the spacing, by dispersing whiskers (instead of powder) in an organic binder, length 11
The inhibition of agglomeration and heterodispersion of 1 ff was measured. Also,
When the fiber preform is fired, if the organic component of the organic compound or organometallic compound completely disappears, the shape of the fiber preform cannot be maintained. The amount of decomposition and reduction is 90-99% (i.e., the amount remaining is 1-10%)
By selecting the heating and firing temperature and time such that the fiber preform is pressurized, it is possible to ensure the strength and rigidity required of the fiber preform during pressure casting. Whiskers are interposed between the long fibers of the fiber preform obtained by firing to maintain the fiber spacing, and residual organic matter components are strengthened by the whiskers incorporated therein. , a desired length mm volume fraction (Vf) can be ensured, and sufficient strength and rigidity can be obtained.

The fiber volume fraction (Vf) of the whisker is 10
% or less. The reason is that Vr is 10%
If the value exceeds 1, the whiskers will not be uniformly dispersed between the long liN fibers and will aggregate, resulting in unfilled matrix metal and F.
This is because it causes a decrease in RH strength.

When selecting the organic compound or organometallic compound used in the present invention, the tI when thermally decomposing them is
High-temperature deterioration of lff must be taken into consideration; for example, when high-strength carbon materials are used as long fibers for reinforcement, heating above 400°C in the atmosphere will cause the fibers to deteriorate. Therefore, it is necessary to use an organic compound or an organometallic compound that thermally decomposes at 400° C. or higher, and acrylic resins, styrene resins, cellulose resins, etc. are suitable.

In addition to the above-mentioned conditions, when using a specific metal compound, the remaining metal components after thermal decomposition must not have a negative effect on the fibers, and the silicone resin, which is a typical example of such compounds, must be In this case, the compatibility between the residual SL and the matrix metal must also be considered.

However, in a preform of long fibers bonded using an organic binder containing dispersed whiskers and heated and fired, whiskers are randomly oriented between the long fibers extending parallel to each other at intervals. 6. When composite reinforcement of metal is performed using the fiber preform, the whiskers effectively counter the tensile force acting in the direction crossing the long fibers.6. The cross-direction whiskers also counteract the shear force acting on the interface, preventing the peeling phenomenon between the long fibers and the matrix metal.

In addition, in order to more effectively maintain the distance between the long fibers, it is also effective to use a powder in combination with the whisker, and this powder may be a metal powder made of the same material as the matrix metal or its main element. Ceramic powders can also be used if dissolution into the matrix metal is undesirable.

A fiber preform was formed by the following procedure to obtain a carbon fiber reinforced magnesium alloy composite material.

■ Long carbon fiber with a diameter of 7 μm (Toshimagari T300) 600
A bundle of 900,000 fibers is obtained by putting together a unit fiber bundle consisting of 0 fibers.
0 was formed. The number of fibers in the fiber bundle 10 is determined in relation to the inner diameter of the glass tube 16 described later, and is aimed at a fiber volume ratio (Vr) of carbon fibers of −30%.

■Acrylic resin solution (manufactured by Toyo Ink ■, trade name: Olypain) and solvent acetone are mixed in a ratio of 1:1, and a binder solution is prepared by adding 2% hardening agent (polyisocyanate) to the solution. Prepared in a container 12 and added 3501? /j SλC whiskers (manufactured by Tokai Carbon ■) were added and mixed by stirring.

(2) The fiber bundle 10 is immersed in the binder solution 14, the binder solution is stirred, and the fiber bundle 10 is vibrated to spread the binder solution and S, -C whiskers between the fibers of the fiber bundle 10. (Please refer to Figure 1 for details on how to make sufficient inroads).

■ The fiber optic 10 is pulled out from the binder solution 14 and passed through a glass tube 16 with an inner diameter of 12Mφ as shown in FIG.
m) was obtained.

(2) After drying and curing the molded body 18, it was heated for 400'c×1 hour in an argon gas atmosphere in an electric furnace 24 (see FIG. 3). By this heating and firing, the mineral components are decomposed, and the fiber volume fraction (Vf) of carbon fiber -30%,
A fiber preform with a fiber volume fraction (Vr) of −7% of SλC whiskers was prepared.

■ After preheating the general-purpose fiber preform for firing at 700°C for 15 minutes in an argon gas atmosphere, it was placed in a pressure & 2i mold, and immediately immediately ) is poured and the pressure is 1000K.
A carbon fiber-reinforced magnesium alloy composite material was obtained by pressurizing the composite material at g/cri.

A tensile test was conducted on this composite material, and the tensile strength was 76 to 9.
f/cri, modulus of elasticity 11, 000/(gf/cIIi
I got the result.

Further, as shown in FIG. 4, a part of the outer layer (matrix metal layer) 22 of the composite material is removed, and only the reinforcing layer 24 is applied to the frontage of the steel fixing plate 26. By grasping and applying a load in the direction of the arrow, the interface gfJ shear strength between the reinforcing layer 24 and the outer layer 22 is examined, and 5.8
/(917mm2) was obtained.

Also, as a comparative example, −r =
When the strength of a carbon fiber reinforced magnesium alloy composite material made in the same process as above except that powder (325 mesh or less) was used, the tensile strength was 73.
/mIn2. The modulus of elasticity was 10,5001 gf/cocoon 2. The shear strength was 2.3 Nyf/s+2.

From this test result, the interfacial shear strength of the composite material was 19% when using a fiber preform formed by interposing SLC whiskers between carbon fibers. It is understood that this is sufficiently large compared to that of the composite material obtained using this method.

Using an acrylic resin solution containing the same carbon II fibers and SLC whiskers as in Example 1, the carbon I miscellaneous material 31 unwound from the fiber supply bobbin 30 is passed through the binder solution 14 to form a rectangular cross section. After winding it up into a single layer at equal intervals on the winding tube 32, it was air-dried (see FIG. 5). Next, the wound carbon I1M is cut into a winding cylinder 32 along each ridge line 33, and a fiber preform 3 is obtained as shown in FIG. 6 (perspective view of main part).
4 (120X 120 shoes).

A plurality of these fiber preforms 34 are prepared, and a magnesium alloy (ASTHAZ31 material) shroud board 35 (120x1
20X O, 6 m) were alternately formed into four layers of W, and this was wrapped inside the stainless steel plate 36, and the periphery of the stainless steel plate 36 was welded leaving a vent hole. This was placed in a Matsufuru furnace and held at 400° C. for 4 hours while degassing the furnace to completely decompose the excess resin component.

Next, while keeping the inside of the furnace in a reduced pressure state, the temperature was increased to 120°C.
℃, and after 5 minutes have elapsed since the magnesium alloy has completely melted, the packaged body made of stainless steel plate 36 is taken out of the furnace, and immediately heated using a hydraulic press to form a composite of magnesium alloy and carbon fiber. .

The obtained plate-shaped FRH (120X 120X 5 trt
A plurality of test pieces 37 having different orientation angles (θ) (see FIG. 8) of carbon ll miscellaneous are cut out from ta ), and! When the relationship between the l-fiber orientation angle (θ) and the tensile strength was investigated, a curve (■) shown in FIG. 9 was obtained. In addition, P in Figure 8
indicates the tensile load direction in the tensile test.

Further, for comparison, a similar test was conducted on FRH composited with a fiber preform containing no SLC whiskers, and a curve (2) was obtained.

Based on JLJI The am volume fraction (Vr) of the hydrocarbon fibers (long fibers) was set at 30%, and each 1a cloth-equipped molded body with varying fiber volume fraction (Vr) of SLC whiskers was prepared using the same acrylic resin as in each of the above examples. The I! system resin solution is used to form the I! Magnesium alloy reinforced with fiber preforms (ASTM AZ3
The tensile strength of material 1) is determined by the orientation angle of carbon fiber (θ) = C”
, 45°, and 90@ (see Example 2), and the results are shown in FIG.

<Evaluation> According to FIG. 9, both materials 1. While the difference in tensile strength of II is small, for tensile force in the direction crossing the carbon fiber,
It can be seen that the FRH according to this example containing SLC whiskers has excellent strength.

Also, in the vicinity of θ=45°, both materials 1. The difference in II is large, and it can be seen that the shear strength is significantly improved by using SLC whiskers.

According to Fig. 10, at θ=06, when the mtN1 volume fraction (Vr) of S=C whiskers exceeds 7%, the tensile strength is low, and this is due to the aggregation of S=C whiskers. be. Also, θ=45°.

At 90°, the fiber volume fraction (Vr
) is 3 to 8%, it can be seen that the strength improving effect is large.

As is clear from the above explanation, in the method for producing a fiber preform for fiber-reinforced metal according to the present invention, in a solution of an organic compound or an organometallic compound, or in the solution diluted with an organic solvent, Adding and dispersing whiskers, immersing reinforcing long fibers in the solution, then taking out the reinforcing long fibers from the solution, molding the reinforcing long fibers using the solution as a binder, drying, and curing; Moreover, most of the organic components in the organic compound or organometallic compound serving as the binder are decomposed by heating and firing, thereby obtaining a fiber preform with an appropriate volume ratio of 41811 in which no agglomeration of the reinforcing long fibers occurs. and the FRH obtained using the m-line preform has a tensile force acting in a direction crossing the long fibers due to the randomly existing whiskers, and a tensile force between the long fibers and the 71-lix gold bending force. It is also strengthened against shear forces acting on the interface, eliminating the weaknesses of ``1 (H'') using long fibers.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a state in which the fiber preform is immersed in a binder solution to which SLC whiskers are added in a method for manufacturing a fiber preform according to an embodiment of the present invention, and FIG. 2 is a diagram showing a state in which carbon fibers are pulled out from the binder solution. Figure 3 shows how a bundle of fibers is passed through a glass tube to remove excess resin, and the carbon! [Diagram 4 showing a state in which the bundle is heated in a heating furnace and the resin components are decomposed.]
The figure shows a test mode for examining the shear strength of FItH obtained using the carbon fiber bundle, and FIG. Figure 1 shows the state in which fibers are passed through a binder solution, Figure 6 shows a membrane-like body of carbon fibers bonded with a binder, and Figure 7 shows a state in which the fibers are passed through a binder solution.
The figure shows a state in which the film-like body is alternately laminated with magnesium plates and wrapped in a stainless steel plate, and Figure 8 is a diagram showing a test piece cut from FltH obtained by this manufacturing method. FIG. 9 shows an FRH using a carbon fiber preform containing SLC whiskers obtained by the method of the present invention and an FRH using a carbon fiber preform containing no SλC whiskers.
Graph showing the relationship between fiber orientation angle and tensile strength, No. 10
The figure is a graph showing the influence of SLC whisker fiber volume fraction on the tensile strength of FRH. DESCRIPTION OF SYMBOLS 10... Fiber bundle, 12... Container, 14... Binder solution, 16... Glass tube, 18... Binder solution, 2
2... Outer layer, 24... Reinforcement layer, 26... Steel fixing plate, 30... Fiber supply bobbin, 31... Carbon fiber, 32... Winding cylinder, 33... Ridge line, 34... Fiber preform, 36... Stainless steel plate, 31...
Test pieces. Agent Patent Attorney Nozomi Ehara 2 people No. 12 Figure 2 Figure 3 Figure 4 Figure 3, Figure 5 Figure 6

Claims (1)

[Scope of Claims] A method for producing a fiber preform for fiber-reinforced metals, wherein a fiber (whisker) volume fraction (Vf) ≦10 is added to a solution of an organic compound or an organometallic compound, or a solution thereof diluted with an organic solvent. %, whiskers are added and dispersed, reinforcing long fibers are immersed in the solution, then the reinforcing long fibers are taken out from the solution, and the reinforcing long fibers are molded using the solution as a binder. A method for producing a fiber preform, which comprises drying, curing, and heating and baking to decompose most of the organic components in the organic compound or organometallic compound that is the binder.