JPS61130439A - Production of wire-shaped composite material - Google Patents

Abstract

PURPOSE:To obtain a composite material having the high tensile strength in the axial direction of carbon fibers having specified modulus of tension by coating Ti on said carbon fibers then impregnating the fibers with molten Al under specific conditions and solidifying the molten Al. CONSTITUTION:The multifilaments of the carbon fibers which have >=38ton/mm<2> modulus of elasticity in tension and is not subjected to a surface oxidation treatment are passed through a chemical vapor deposition stage by which boron is coated on the fibers and thereafter the Ti is coated thereto at about 100 Angstrom . The fibers are then dipped in the melt of Al or Al alloy. The dipping treatment is executed in the range satisfying 0.03T+0.6t<=22, t<3 when the temp. of the molten metal is designated as T deg.C and the dipping time as (t) minute. The carbon fibers are then pulled up and the molten Al sticking thereto is solidified. Aluminum carbide is formed at the boundary between the carbon fibers and Al to a smaller quantity and the wire-shaped composite material having the high tensile strength is obtd. by the above-mentioned method.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a method for producing a linear composite material, and more specifically, a method for producing a linear composite material in which carbon fiber is used as a reinforcing fiber and aluminum or an aluminum alloy is used as a matrix. Regarding how to.

In recent years, composite materials that use carbon fiber as a reinforcing fiber and metal as a matrix have attracted attention in various fields. Among these, those using aluminum or aluminum alloy as a matrix have relatively excellent specific strength and specific rigidity, and are therefore attracting particular interest in fields that require weight reduction.

There are various methods for manufacturing composite materials such as those mentioned above, but one of them is to cut a linear composite material of carbon fiber and aluminum or its alloy into desired lengths, collect them and hot press them. , there is a method of roll pressing. In that case, it is necessary to prepare the linear composite material prior to hot pressing or roll pressing. In this specification, unless otherwise specified, a linear composite material that is a so-called molding material is referred to as a linear composite material, and a composite material obtained by hot pressing or roll pressing the linear composite material. will simply be called a composite material to distinguish between the two for convenience.

Now, the method of manufacturing such a linear composite material is also
There are many kinds, but one of them is the special public service of 1973-1273.
After passing carbon fiber multifilaments through a chemical vapor phase illumination process and coating each filament with a substance that wets well with molten aluminum or aluminum alloy, as described in Publication No. 3 and others, the coated carbon fiber multifilament is There is a method in which a filament is immersed in the molten metal, the molten metal is impregnated between the filaments, and the molten metal is solidified by pulling it out. This method is very suitable for manufacturing linear composite materials because the process is continuous. However, when measuring the tensile strength in the fiber axis direction of a linear composite material obtained by such a method, it is sometimes found to be extremely low. The reason is that carbon fiber and aluminum react,
It is thought that this is due to the formation of a large amount of brittle aluminum carbide at the interface between the carbon fiber and the aluminum or aluminum alloy matrix. In other words, aluminum carbide is easily hydrolyzed even at room temperature, so if it is produced in large quantities, the linear composite material becomes extremely chemically unstable. Since the strength of the carbon fiber itself also decreases, it is estimated that these factors act synergistically to bring about a significant decrease in strength. However,
The formation of aluminum carbide can be prevented to some extent by increasing the coating thickness of the so-called wettable substance considerably. However, forming thick coatings by chemical vapor deposition significantly lengthens the manufacturing time and increases manufacturing costs.

While attempting to solve this problem, the inventor of the present invention discovered that in the conventional method described above, when specific carbon fibers are used and impregnation with molten metal is carried out under specific conditions, almost no aluminum carbide is produced. It has been discovered that it is possible to obtain a linear composite material with extremely high tensile strength in the fiber axis direction. That is,
An object of the present invention is to provide a method for producing a linear composite material having high tensile strength in the fiber axis direction, which uses carbon fiber as a reinforcing fiber and aluminum or an alloy thereof as a matrix.

In order to achieve the above object, the present invention is based on the method of chemical vapor deposition of carbon fiber multifilament having a tensile modulus of elasticity in the fiber axis direction of 38 tons/a+m2 or more and not subjected to surface oxidation treatment. Through the process, each filament is coated with titanium, and the multifilament of titanium-coated carbon fiber is immersed in molten aluminum or aluminum alloy, and the molten metal is impregnated between the filaments. When pulling up from the molten metal and solidifying the molten metal, the temperature of the molten metal is 1° C., and the immersion time of the titanium-coated carbon fiber 1 multifilament is t minutes, and the formula % is satisfied. The present invention is characterized by a method for manufacturing a linear composite material in a range.

To explain this invention in more detail, in this invention, as the reinforcing fiber carbon fiber, preferably polyacrylonitrile fiber H (PANIIli) is used as the raw material fiber (precursor), A so-called graphitized carbon fiber having a tensile modulus (hereinafter referred to as tensile modulus) of 38 tons/g+s2 or more is used. When such carbon fibers are impregnated with molten aluminum or aluminum alloy under specific conditions, their reaction with aluminum is extremely low, and they hardly absorb aluminum carbide live.

That is, the carbon fiber has a structural unit consisting of an elongated ribbon-shaped polycyclic aromatic molecular fragment condensed with benzene rings and oriented in the fiber axis direction. These ribbon-like fragments have an extremely high degree of condensation of benzene rings, and can be seen as the ultimate aromatic compound. Several of these ribbon-like fragments stack up to form graphite crystal regions, and they also divide into fine fibrils. forming a structure. In other words, the surface is covered with carbon atoms in the network plane of the graphite crystal, but the tensile modulus is 3.
In the case of 8 tons/a+m2 or more, the degree of orientation of the ribbon-like fragments is extremely high, the carbon atoms in the surface network plane are arranged in an orderly manner, and the number of peripheral carbon atoms is small. In other words, it is considered to be more inert, and therefore the reaction with aluminum is suppressed.

When the above-mentioned carbon fiber is analyzed using laser Raman spectroscopy, it has a wave number of 1585 c, which is said to be 6, due to the EzQ symmetrical vibration of the graphite structure.
This may be because the band near m-' (hereinafter referred to as A band) and the AtQ symmetrical vibration (forbidden transition) of the graphite structure shift to an allowed transition due to the disorder of the structure at the crystal edge, or it may be due to The intensity ratio with the band near the wave number 1355 cm-1 (hereinafter referred to as B band), which is said to be due to the difference in chemical structure, is the peak height of B band/peak height of A band (hereinafter referred to as B band).
/A ratio) is 0.5 or less.

Here, laser Raman spectroscopy refers to the Raman effect of laser light, that is, when a laser beam is applied to a material and is scattered, light whose wavelength has changed by an amount specific to the folds of the material is mixed in the scattered light. It uses the phenomena that occur to obtain information about the molecular structure of the substance. Therefore, in this invention, such analysis is carried out using a laser Raman spectrophotometer JR8-400D manufactured by JEOL Ltd., with one to several carbon HH multifilaments attached to its holder, and placed in a nitrogen atmosphere. Light from an argon laser (wavelength: 25145) is applied, the Raman scattered light is focused, separated into spectra using a double grating, the spectrum is received by a photomultiplier tube and recorded on a chart, and B/A
This is done by reading the ratio.

Now, as mentioned above, the carbon arm has a tensile modulus of 38
ton/1I2J:X, but at the same time, it is necessary that the surface is not oxidized.

That is, regardless of whether it is linear or not, in general, in composite materials such as the one of the present invention, carbon-11 is subjected to surface oxidation treatment such as electrolytic oxidation treatment in order to improve adhesion at the interface with the matrix. , the surface is usually made to have an uneven surface. However, if the surface is uneven,
It is generally thought that a state called an anchor effect, in which the matrix is anchored to the irregularities, is created and the adhesion at the interface is improved. However,
The present invention uses carbon fibers that have not undergone such surface oxidation treatment and have relatively smooth surfaces.

In J5 of the present invention, carbon fibers as described above are used in the form of a multi-filament, that is, a continuous fiber bundle. Although it is possible to use it in the form of monofilaments, ie single fibers, this is hardly economically advantageous.

Next, regarding the so-called matrix, aluminum or an aluminum alloy is used in this invention. Examples of aluminum alloys include aluminum-silicon alloys,
Aluminum-copper alloy, aluminum-magnesium alloy, aluminum-silicon-magnesium alloy, aluminum-copper-zinc alloy, aluminum-manganese alloy, etc. can be used.

In the present invention, titanium is first deposited on each filament, that is, each carbon fiber, constituting the multifilament, using a chemical vapor deposition method. Titanium improves the wettability of carbon fibers, and allows molten aluminum or aluminum alloy to be easily and uniformly impregnated between the filaments in the impregnation step described below. The thickness of the titanium coating is about 1oO~1000~i0 However, titanium itself does not wet carbon fiber very much. Therefore, prior to coating with titanium, a layer with a thickness of 100 to 100 mm is coated as a base layer using the →beam chemical vapor deposition method.
It is preferable to apply a boron coating of about 0.

The boron or titanium coating by chemical vapor deposition is preferably applied as follows.

, (V, namely, boron trichloride, boron tribromide, or boron heptadide, zinc, and argon combined vapor) is passed through the reaction tube, and a multifilament of carbon fibers is passed through the reaction tube. , and exposed to the above mixed vapor for 0.5 to 5 minutes.

Then, the boron compound is reduced by zinc to zinc chloride, zinc boride, or zinc fluoride, and each filament making up the multifilament is coated with boron. The reaction temperature is about 650 to 750"C. Alternatively, a mixed vapor of boron trichloride or boron tribromide and hydrogen may be used to reduce the boron compound with hydrogen. In this case. The reaction temperature is 900-1
300''C. On the other hand, the ≠tan coating is also applied in the same manner as the boron coating.

That is, a mixed vapor of titanium tetrachloride, zinc, and argon is used to reduce titanium tetrachloride with zinc. It may be reduced with hydrogen.

In this invention, next, a titanium-coated carbon fiber multifilament is passed through a molten metal of aluminum or its alloy, and the molten metal is impregnated between the filaments.

The temperature of the melt 11jl at this time is kept at or above the solidification start point temperature of aluminum or aluminum alloy, but is preferably as low as possible so as not to significantly deteriorate the carbon fibers. However, from the viewpoint of easy temperature control, it is preferable to set the wet corrosion temperature at least 5° C. higher than the solidification starting point temperature. Therefore, this impregnation step needs to be carried out within a range that satisfies the following formula, where the temperature of the molten metal is T''C1 and the immersion time of the titanium-coated carbon fiber multifilament is t minutes. As shown in the Examples, if these formulas (1) and (2) are not satisfied at the same time, a linear composite material with high tensile strength in the fiber axis direction (hereinafter referred to as tensile strength) cannot be obtained.

Next, the present invention will be explained in more detail based on examples.

A carbon fiber multifilament without surface oxidation treatment (23,000 filaments) with a tensile modulus of about 40 tons/l12, a tensile strength of about 280 kmM mi2, and a B/A ratio of about 0°4. ), 6.3% by weight of boron trichloride, 6.611% by weight of zinc, 87% by weight of argon.
．． Each filament was coated with boron by applying a 1% by weight steam mixture at about 680° C. for about 1 minute. The thickness of the boron coating was 100 mm.

Next, the boron-coated carbon fiber multifilament was treated with a steam mixture at about 680°C consisting of 3.2% by weight of titanium tetrachloride, 2.611% by weight of zinc, and 94.3% by weight of argon for about 1 minute to remove the boron. A titanium coating approximately 100 mm thick was applied over the coating.

Next, the titanium-coated carbon IIH multifilament is passed through a molten aluminum alloy (JIS A6061) whose solidification starting point temperature is about 658°C, and pulled up to solidify the molten metal, so that the carbon fiber volume content is about 50°C. % linear composite material was obtained.

At this time, the temperature of the molten metal and the immersion time of the titanium-coated carbon fiber multifilament were varied to obtain a total of eight types of linear composite materials.

Next, for the eight types of linear composite materials mentioned above, the tensile strength and the weight of carbon consumed in the production of aluminum carbide relative to the weight of carbon fiber were determined. The measurement results are shown in the table. The tensile strength was measured using a universal testing machine IM500 manufactured by Shimadzu Corporation. Further, the carbon consumption was calculated by utilizing the fact that aluminum and aluminum carbide are hydrolyzed to generate hydrogen and methane as described below, and by quantifying the amount of methane using a gas chromatograph.

AQ+C3+12H20 1→3CH+ +4Aff (OH)3Jul+3H2
0 1→3/2・H2+Aa(OH)3 From the table above, the linear composite materials with N, 1 to 5, which satisfy all the conditions stipulated by this invention, satisfy the above formula 0 but have 0 It can be seen that the tensile strength is significantly higher than that of -6 to -8, which do not satisfy the formula. That is, -6
In the case of samples No. 8 to 8, the amount of carbon consumed, that is, the amount of aluminum carbide produced was very large, and this is thought to be the reason for the decrease in tensile strength.

For comparison, when producing the -1 linear composite material that showed the highest tensile strength, the immersion time in the molten metal was set to 3 minutes, and the tensile strength of the obtained linear composite material was approximately 9.
5 ka/tel;! , which has decreased significantly.

In order to manufacture the best linear composite material, we used amine fibers with tensile modulus and tensile strength of approximately 40 tons/■.
2. The tensile strength of the linear composite material is about 280 kMsm2, which is the same, but when I changed it to one that had been subjected to surface oxidation treatment (B/A ratio: about 0.6), the tensile strength of the obtained linear composite material was about 78 kMsm2. It was only kcl/mm2. Carbon consumption increased to approximately 0.3% by weight.

Roughly, for comparison, when manufacturing a linear composite material of N,1, carbon fiber was used with a tensile modulus of about 32 tons/■2
When the tensile strength of the linear composite material was changed to one with a tensile strength of about 360 ka/mm2 and no surface oxidation treatment (B/A ratio: about 0.8), the tensile strength of the obtained linear composite material was about 80 ka/mm2.
ka/+ei2, carbon consumption is approximately 0.3% by weight
Met. Also, although no surface treatment has been applied, the tensile modulus is approximately 24 tons/l12 and the tensile strength is approximately 360k.
When Mav2 was changed, the tensile strength of the obtained linear composite material was only about 30 ka/vs2, and the carbon consumption was also significantly increased to about 211%.

In Example 1 above, the molten metal has a solidification starting point temperature of about 6
Aluminum-silicon alloy (JIS A
2 according to the method of the invention of [04C) 1 (temperature: about 630°C) with different kidneys and soaking times of 1 minute and 2.5 minutes.
Obtained seven kinds of linear composite materials.

When these two types of linear composite materials were subjected to the same test as in Example 1, the tensile strength of the one immersed for 1 minute was approximately 152 kg/11112 (carbon consumption 0°002% by weight), and 2 , for 5 minutes it is about 140k
In a/- garden 2 (carbon consumption ff 10.0061%), all values were high.

I11 In Example 2 above, when manufacturing a product with a dipping time of 2.5 minutes, the tensile modulus was about 46 tons/I-2, the tensile strength was about 240 ka/ls2, and the surface oxidation treatment was performed. Untreated carbon fiber (number of filaments:
When 6000 wires and B/A ratio of about 0°3) were used, a linear composite material with a high tensile strength of about 1301 to/mm2 was obtained. The carbon consumption in this linear composite material was approximately 0.001% by weight.

For comparison, we used carbon fibers with the same tensile modulus and tensile strength, but with surface oxidation treatment (8
/A ratio: about 0°6), the tensile strength was about 60
It decreased significantly to 12 kg/l.

Also, carbon consumption increased to about 0.3% by weight.

Effects of the Invention The method of the present invention uses carbon fibers which have a tensile modulus of elasticity in the fiber axis direction of 38 tons/ms2 or more and which have not been subjected to surface oxidation treatment, and which are coated with titanium as a wetting substance. Since the multifilament is impregnated with the molten metal under conditions that satisfy the formula 0.03T+0.6t≦22t<3, where the temperature of the molten metal is T''C1[i and the immersion time is t minutes, It is possible to obtain a linear composite material with extremely high tensile strength.
It is presumed that this is because the amount of aluminum carbide produced at the interface between the miscellaneous material and the matrix aluminum or aluminum alloy becomes extremely small.

Claims (1)

[Claims] Multifilaments of carbon fibers with a tensile modulus of elasticity in the fiber axis direction of 38 tons/mm^2 or more and without surface oxidation treatment are subjected to a chemical vapor deposition process to coat each filament with titanium. The titanium-coated carbon fiber multifilament is immersed in molten aluminum or aluminum alloy to impregnate the molten metal between the filaments, and the molten metal-impregnated carbon fiber multifilament is pulled up from the molten metal to solidify the molten metal. When the molten metal is impregnated, the temperature of the molten metal is T° C., and the immersion time of the multifilament of titanium-coated carbon fiber is t minutes, within a range that satisfies the following formula: 0.03T+0.6t≦22 t<3. A method for producing a linear composite material, characterized in that: