JPS6227338A - Production of whisker preform for fiber reinforcing material - Google Patents

Abstract

PURPOSE:To obtain a whisker preform having a uniform volumetric rate by specifying a dispersion medium liquid in the titled method for dispersing a whisker forming material into a dispersion medium liquid then subjecting the liquid to a solid-liquid sepn. by a screen and filter body and drying the whiskers. CONSTITUTION:The whisker forming material is introduced into the dispersion medium liquid which is polyhydric alcohol or the aq. soln. thereof and the liquid is stirred and mixed to uniformly disperse the whiskers. Such liquid mixture 10 is passed through the screen 20 and is poured into a vessel 26 to remove lumped whisker bodies 12 which are held intertwined without being loosened. The refined liquid mixture 14 in the vessel 26 is then poured into a vacuum suction vessel 30 which has the filter body 28 and is connected to a vacuum pump P. The liquid mixture is subjected to the solid-liquid sepn. by starting the pump P, by which whisker assemblages 40 are obtd. The assemblages 40 are compressed by a piston 32 for compression if necessary and oscillation is applied to the assemblages 40 in a free state to detach the assemblages from the filter body 28. Such assemblages are dried. The dispersion medium liquid has an adequate viscosity and the intended preform is obtd. according to such method.

Description

[Detailed Description of the Invention] L] Whisker preform (preform) for obtaining fiber reinforced material by infiltrating molten metal and molten resin into the inside of the yup.
This is about the BB method.

, -' and its IJ'' (1- Whiskers are less than a few cm in length and 1 to 10 μm in diameter, grown by reduction, coagulation of hot air, precipitation from solution, etc.)
It is a needle-like crystal with high strength and elastic modulus, and is effectively used as a composite reinforcing material for metals and resins. In order to composite the base metal or resin with the whiskers using the infiltration method, the preform, which is an aggregate of compression-molded whiskers, is held immovably, and the molten material is placed inside it. If sufficient penetration is required, four whiskers are required.In that case, if the whiskers are closely intertwined locally,
The base material penetrates and moves in that part, and even if it penetrates, the whisker agglomerated part will remain as an inclusion, making it impossible to obtain a product with the desired strength3.The whisker product formed by reduction method etc. They are tightly intertwined, and it is not possible to obtain a homogeneous preform by unraveling these tangles with -DN. As a method for obtaining the homogeneous preform, the whisker forming product is mixed with water, alcohol, etc. , acetone, ether, etc., stirred and dispersed, and then passed through a sieve to remove lump-like whisker products remaining undispersed from the dispersion medium, and then pass through a filter. Using (solid-liquid separation, the separated wet whisker aggregate is compressed,
There are known methods of drying.

However, in this method, if the viscosity of the dispersion medium is insufficient, when performing the solid-liquid separation 1'sIf, the sedimentation speed traces of the whiskers are too much and local flocculation ( The fiber volume (?, decreases to 11) occurs and C1 is uniform/<'
1 whisker aggregate with X rest rate! There's nothing I can do.

The object of the present invention is to provide a molded article with Wisno J-TZ whose fiber volume fraction (Vr) is uniform, thereby achieving a healthy LA. Y
'i high strength fiber reinforcement (at the point where Δ is ij?).

The purpose is to remove the bulky whisker products from the dispersion medium by dispersing them in a multi-hffi alcohol, or an aqueous solution thereof, and then passing them through a sieve, and then by using a filter. C. Grind the solid-liquid portion 1,
compressing the sorted wet whisker aggregate, or
This is achieved by avoiding drying without compaction.

Water, ethyl alcohol, acetone, or aqueous solutions thereof are known as the dispersion medium for dispersing whisker products. However, the viscosity of water is 1.0
The viscosity of ethyl alcohol is 1.19 cP, and the viscosity of acetic acid is 0.322 cP.
When P is 1 minute lower and P is used as a dispersion medium, it is not possible to form a whisker aggregate with a uniform fiber volume fraction (Vf). According to the results of tests conducted by the inventors of this f1 on S-C whiskers, the dispersion was 91. If the viscosity of the body fluid is d3 at 20°C and less than 2CP, the sedimentation rate of the whiskers will be high and local collection will occur.
When it exceeds 0 cP, the whiskers cannot be untangled by adding the whiskers into the dispersion medium and stirring, and it was found that a dispersion medium with a viscosity range of 2 to 20 cP (at 20°C) is appropriate. .

If this condition is not met, the dispersion medium liquid is a polyhedral alcohol or its aqueous solution. For example, the viscosity of a 50% aqueous solution of Eblen glycol is 3.14 cP (at 20'C).
, viscosity of propylene alcohol 40 medium temperature aqueous solution H1
0.0(:P (at 20℃), Lihiri:z50jfi1
% aqueous solution is 6.05 cP (at 20°C). In addition, the dispersion medium liquid should be selected based on the viscosity conditions (if the wetness with the whiskers is good), the wet whisker aggregate should be dried to form a whisker preform. It is difficult to avoid leaving residue during the preparation.In this sense, paraffinic hydrocarbon water cannot be used.

Further, the whiskers used in the present invention include the above-mentioned S, 1. C
Made of △Yu203, S3N4, graphite t'i, etc., diameter 01.~1μrn, width 50~200μ.
m no ra is suitable. The use of a dispersion medium liquid for whiskers is such that (whiskers/dispersion medium liquid) - approximately 1/1 is used to ensure uniform dispersion of whiskers during stirring and mixing.
0 (iEfil ratio) is preferable, and if the ratio is less than the iEfil ratio, the whiskers become entangled due to the stirring 11', and if it exceeds the Φ-inhibition, There is a tendency for agglomeration of small Wisno J- to occur.

After the whiskers are added to the dispersion medium liquid, stirred and mixed to uniformly disperse the whiskers, as shown in Fig. ) Cloth first sieve 22 and 100-2
It is passed through a sieve 20 consisting of a second sieve 24 made of stainless steel fibers of 0.00 mesh and poured into a container 26, thereby removing untangled whisker lumps 12. Here, the reason why the mesh size of the sieve 20 is specified to be 100 to 200 meshes is that if the mesh size is less than 100 meshes, whisker aggregates will pass through, and if it exceeds 200 meshes, the dispersion medium liquid containing whiskers will pass through. ．． '1
This is because the processing efficiency decreases as the processing time increases by 1.1'.

Next, the purified mixed liquid 14 in the container 26 is placed on a steel plate with a large number of small holes formed thereon, and sequentially from the bottom, a stainless steel net, a polyamide film, and a filter paper are stacked. It is equipped with a filter body 28 (a glass filter may also be used) and is poured into a vacuum suction tank 30 connected to a vacuum pump P.
is operated to perform solid-liquid separation, and wet whisker aggregate 4
0 (see Figure 2). Then, if necessary, IL3
The wet whisker aggregate 40 is compressed using the compression screw 1-32 according to the fiber volume fraction (Vt) of the fiber-reinforced grain that is the final product, and the aggregate 40 is subjected to imaging in a free 4r state. , the assembly 40 is separated from the filter body 28'J.

The wet rice aggregate 40 separated from the filter body 28 is
This is dried in a drying oven to obtain a whisker preform, such as Ill, NILcJ alloy, A-Q.

Using the heat sink, it is composited with the corresponding Iscar molded body using the high-pressure solidification casting method to produce internal combustion engine parts such as rocker arms and valve spring retainers. 1! □? It is possible to do that.

1 of the Ia finished products! The veil volume ratio (Vf) is 5.30%.

Left side 1 (1) Example: diameter 0.2-0.5 μm, length 50-2
00mm S=C whisker 31gr with Ethylene.
The mixture was poured into a dispersion medium solution consisting of glycol 18Q gr and water 120 gr, and stirred for 30 seconds each time using a stirring device three times. Polyamide cloth first sieve 22.1
50 mesh stainless steel! It is passed through a sieve 20, which is a second sieve 24 made of II fiber, and poured into a container 26, and then the second sieve 7 as shown in FIG. 18x using '14' suction filtration device
forming a wet whisker mass of 18 x 180 mm;
Make this pressure 110-150! Compressed with j/cti (
Well, I got a whisker kitten molded object.

This whisker child 1iv molded body was composited with JIS AC4D material using the 1-V solid manufacturing method.1Vr=20
″)6 was used as the test material.

(2) Comparative example: The same SλC whiskers as in the example were dispersed in water according to the conventional method, and then compressed to remove water to form a wet whisker aggregate, and then under pressure of 110~ After compressing the aggregate at 1508 g/cm,
Dry the whisker preform in a drying oven for 17 hours.

This whisker kitten molded body was merged with JIS AC4D material by high pressure coagulation iJ Ju method, Vr = 20%.
What happened to the test material?

Next, for each of the example test material and comparative example test material, tensile strength Kg/rnIn2) and elastic modulus (Ky/m1n2
) and elongation (%) were investigated, and the results are shown in Table 1.

Table 1 Evaluation> The test month of the present invention example and the comparative example test material are the fiber volume fraction (Vf
) is 17%, and although the material is the same, the tensile strength and elastic modulus of the test shrine of the present invention are greatly improved, especially the elongation (%)
The increase in this is significant. The reason for such a large characteristic difference is that the dispersion of the SλC whiskers in the test shrine of the present invention example was sufficiently uniform, and the locally aggregated SλC whiskers were (This is because there is no [L.

As is clear from the above description, in the present invention, the whisker product is dispersed in a dispersion medium consisting of a polyhydric alcohol or an aqueous solution thereof, and then passed through a fl.i. The product is removed from the dispersion medium liquid, and the separated wet whisker aggregate is compressed or subjected to solid-liquid separation using a filter.
! By employing a method of forming a whisker preform by drying the whisker preform, it is possible to obtain a whisker preform with a uniform and fine volume without local agglomeration. By combining it with a resin, it is possible to obtain a fiber-reinforced structure that provides excellent mechanical properties.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of a state in which a dispersion medium liquid in which whiskers are dispersed is purified using a sieve, and Figure 2 shows a vacuum suction type filtration device for separating solid and liquid from the purified dispersion medium liquid. It is a schematic diagram. 1o...Mixed liquid, 12...Agglomerates, 14...Mixed liquid, 20...Sieve, 22...First sieve made of polyamide cloth,
24... Stainless steel fiber second sieve, 26... Container, 28... Filter body, 30... Pure air suction tank, 32...
-Ff compression piston 40...wet whisker aggregate, P...vacuum pump.

Claims (1)

[Claims] The whisker product is dispersed in a dispersion medium liquid, and then the lumpy whisker product is removed from the dispersion medium liquid by passing through a sieve, and the solid-liquid separation is further performed using a filter. , a method for producing a whisker preform for fiber reinforcing material in which a separated wet whisker aggregate is compressed or dried without being compressed, wherein the dispersion medium liquid is a polyhydric alcohol or an aqueous solution thereof. Characteristics: A method for producing a whisker preform for fiber reinforced material.