JPH0196340A - Aluminum alloy composite material and its manufacture - Google Patents

Abstract

PURPOSE:To easily and economically manufacture the title composite material having no deterioration by pressurizing and impregnating an aluminum alloy as the matrix into a spare molded body having carbon fiber in which an alumina covered layer is formed thereon as the fibrous skeleton. CONSTITUTION:The carbon fiber having about 10mum average diameter and about 3,000mum average length is immersed in an alumina sol, is thereafter dispersed and dried in the air. By this method, the alumina covered layer having several mum thickness is applied to the surface of the carbon fiber. The carbon fiber having said alumina covered layer is regulated to the fibrous skelton to produce the spare molded body having about 30vol.% ratio. Said spare molded body 1 is set into a mold 2. The whole is then heated to about 500-700 deg.C and the molten aluminum alloy matrix 4 is poured into the mold 2. The matrix 4 is directly pressurized by a piston 5 and is impregnated into the spare molded body 1 to form a composite part 6. The piston 5 is furthermore pushed down to spread the composite body 6 into the whole of the spare molded body 1. By this method, the title composite material is formed without destroying the spare molded body 1.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention provides a preformed body (
The present invention relates to a metal matrix composite material manufactured by pressure-impregnating a molten metal matrix into a preform (preform), and particularly to an aluminum alloy composite material using an aluminum alloy as a matrix and a method for manufacturing the same.

(Prior art) In recent years, carbon mtttt, alumina mlL, silicon carbide 1
Metal matrix composite materials reinforced with ceramic fibers such as M navy blue are attracting attention as one of the new materials. Carbon fiber-reinforced aluminum alloy composite materials, which have carbon IN as a reinforcing fiber and aluminum alloy as a matrix metal, are used for space equipment, robot parts, automobile parts, etc. It is expected to be applied in a wide range of fields.

A molten metal impregnation pressure casting method (hereinafter referred to as an infiltration method) is known as a method for manufacturing the carbon 4M miscellaneous reinforced aluminum alloy composite material. The infiltration method is said to be a manufacturing method suitable for ceiling-hanging production because it can cast at a rate close to that of the normal high-pressure casting method and can produce a large number of complex-shaped parts at one time.

The manufacturing process of a carbon fiber reinforced aluminum alloy composite material by the infiltration method will be explained using FIGS. 2 (Δ) to (D).

First, a predetermined shape and fiber volume fraction (Vf'
) to create a carbon mW1 preform 1. This preformed body 1 was set in a mold 2, and heated to 500
Heat to ~700°C (Figure 2(A)).

After that, the molten aluminum alloy matrix 4 is poured into the mold 2, and the molten aluminum alloy matrix 4 is poured into the piston 5.
The preform 1 is impregnated by direct pressurization to obtain a composite part 6 (FIG. 6(B)). The pressure of the piston 5 required to impregnate the molten aluminum alloy matrix 4 into the carbon fiber preform 1 depends on the fiber volume ratio of the preform 1, the mold 2, and the molten aluminum alloy matrix 4. Although it varies depending on the temperature conditions and the composition of the molten aluminum alloy matrix 4, it is generally 300 to 1000 atmospheres.

Roughly push down the piston 5 to completely fill the preform 1 with the molten aluminum alloy matrix 4 (FIG.
)) After solidification, the aluminum alloy composite material 7 is removed from the mold 2 ((D) in the same figure).

By the way, in general, in fiber-reinforced composite materials, the magnitude of the bonding force between the fibers and the matrix metal, so-called good wettability, is a medium-sized factor. It is also known that the formation of a layer of harmful reaction products between the fibers and the matrix metal is undesirable.

Carbon till reinforced aluminum alloy composite II 7 to J
3. Carbon! ! Depending on the manufacturing method and conditions, Aj! can easily form between the fiber and the aluminum alloy matrix. 4c3 is formed and this Aj! 111ft of carbon is degraded by 4C3. Furthermore, it is known that when A(4C3) is formed, the wettability between carbon fiber and aluminum alloy is poor.

Therefore, in order to suppress such deterioration of carbon fibers, a layer of carbide such as titanium carbide, zirconium carbide, silicon carbide, etc. Conventionally, a method has been adopted in which the carbide layer is formed to suppress the reaction between the carbon fiber and the aluminum alloy matrix.

(Problems to be Solved by the Invention) In the above method of forming a carbide layer on the surface of the charcoal 1111M, the surface of the IA fiber 1 is G V D (Chcmi-cat v
Special coating methods such as apor deposition methods are required.

Therefore, the manufacturing cost of the carbon fiber reinforced aluminum alloy composite material becomes extremely high. In addition, depending on the conditions, the strength of the carbon-Nil fiber itself may decrease during the coating process, so
There is a problem in that the strength of the carbon llff thus obtained is weaker than that of the original carbon fiber.

Furthermore, although the carbide layer acts as a barrier to diffusion between the solid phase aluminum alloy and the IA fibers, it is not a very effective barrier when it comes into contact with the liquid phase aluminum alloy. When compounding by immersion method, carbon m due to interfacial reaction
fibers deteriorate. Therefore, there is a problem that the strength of the composite material cannot be sufficiently improved.

Furthermore, when producing the carbon fiber preform 1 with a carbide layer formed on the surface by a coating method such as the CVD method, since the bonding force between the carbon fibers is weak, the surface of the press-formed preform 1 Crank is likely to occur. Moreover, since the strength of the preform lA1 is low, the preform 1 may be destroyed during impregnation and pressure casting, making it difficult to obtain a completely reinforced composite material.

The present invention has been made in consideration of the above circumstances, and
It is an aluminum alloy composite that does not require expensive high-temperature/high-vacuum equipment such as methane, and can be manufactured in the atmosphere with extremely simple equipment, has good workability, and is economical. The purpose is to provide materials and methods for producing the same.

Another object of the present invention is to create an aluminum alloy composite material in which the preform is not destroyed during co-immersion pressurization, and the carbon fibers do not deteriorate due to the reaction between the carbon fibers and the aluminum alloy matrix. and a manufacturing method thereof.

[Structure of the invention]

(Means for solving the problem) The method for manufacturing an aluminum alloy composite material according to the second invention of the present invention includes manufacturing a preformed body having a fiber skeleton of carbon fiber,
In the method for manufacturing an aluminum alloy-based material in which the preform is pressure-impregnated with an aluminum alloy as a matrix to form a composite, before the preform is impregnated with the aluminum alloy, a fiber skeleton of the preform is constructed. An alumina coating layer is formed on the surface of carbon fiber.

The aluminum alloy composite material 1 according to the second invention includes a preformed body made of carbon fibers having an alumina coating layer on its surface, and an aluminum alloy and gold impregnated as a matrix in this preformed body. It is something that we have.

(Function) Before the preform is impregnated with aluminum alloy, an alumina coating layer is formed on the surface of the carbon fibers constituting the fiber skeleton of the preform.
The elementary fibers are strongly bonded, and the strong electric current of the preform is oriented smoothly.

Therefore, the preform is not destroyed during impregnation and pressurization to vI, and the carbon fibers are not deteriorated due to the reaction between the carbon dioxide and the aluminum alloy matrix. Therefore, an aluminum alloy composite material having sufficient strength can be provided.

In addition, the culm, which avoids forming an alumina coating layer on the surface of the carbon fibers that make up the fiber skeleton of the preform, can be used for expensive high-temperature treatment.
Manufactured using popular and extremely efficient equipment that does not require high vacuum equipment or reaction gas! ! ! It is easy to work with and easy to perform.

(Example) An example of the aluminum alloy composite material and the manufacturing method thereof according to the present invention will be described with reference to the drawings.

First, aluminum alloy composite material! The EJ manufacturing method will be explained. In the method for manufacturing an aluminum alloy composite material, first, carbon fibers (SiC whiskers) of PAN type, PITCH type, etc. are prepared. The size of carbon fiber is, for example, an average diameter of 10μ
The milk has an average thickness of 3000 μm.

An example of the characteristics of this charcoal M machine navy blue is not shown in Table 1.

Next, the above carbon Al11 [was immersed in alumina sol (containing alumina hydrate approximately 20% by weight) using a solution such as water as a dispersion medium for about 10 minutes, stirred, dehydrated, and further heated from room temperature to 150°C. Disperse and dry, for example, in the air, for about 2 hours at 4 degrees Celsius.

In this way, by immersing mmM of carbon in alumina sol, stirring, dehydrating and drying the alumina sol, the alumina sol gels and becomes a three-dimensional network structure, and carbon! ! A uniform alumina coating layer is formed on the surface of the material. The thickness of this alumina coating layer is determined by the concentration of alumina sol in the molecule &'ll=
It is determined by the number of the above surface treatment steps. Generally, the appropriate thickness of the alumina coating layer is several micrometers.

Next, apply the above alumina coating layer to the right carbon fiber by 10 times
After approximately 1% water is added and mixed uniformly, a preform is produced by compression molding. The size of the preform is, for example, 80# in diameter, 80# in height, and the volume ratio is 30#.
It is about %.

Thereafter, the preform is heated at 4 degrees, for example 500° C., for 4 hours. By heating the preform, carbon IA
The gelled alumina sol on the IM surface crystallizes to become δ alumina, forming a uniform δ alumina coating layer on the surface of the IA cable [ff, and a strong bonding force is generated by the δ alumina crystallized at carbon m intervals. The δ-alumina coating layer formed on the surface of the carbon fiber can be confirmed by the diffraction pattern of the transmission electron group rllII restricted light.

Next, the heat-welded preform is placed in a mold, and a matrix molten metal made of, for example, 6061 aluminum alloy is poured into it under the conditions shown in the examples of the present invention in Table 2, and the composite is formed by impregnation and pressure casting. .

Table 2 Numbers le Next, regarding the aluminum alloy composite material according to the present invention. explain.

A preformed body made of carbon fiber and matrine Δ The aluminum stand impregnated into the preform as a It consists of gold.

Attb according to the present invention manufactured by the above-mentioned manufacturing method =
aft'fi@44Fl□. 1. A7. ．． Ka.

Using carbon mm without coating, a preform was prepared under the same conditions as the present invention example as shown in Comparative Example Light in Table 2,
By combining it with 6061 aluminum alloy, an aluminum FT composite material was produced.

As a result of observing the new surface of the vertical center plate of these aluminum alloy composite materials using a mirror, it was found that many cracks occurred in the aluminum alloy composite materials using wooden preforms without alumina coating. On the other hand, no cracks were observed in the aluminum alloy composite material (Example of the present invention) using an alumina-coated kitten molded body.

Next, aluminum alloy material without alumina coating (
Comparative example) and aluminum alloy composite material coated with alumina (
Sample v1 was taken out from each sample (Example of the present invention) and subjected to X-ray diffraction. The results are shown in No. N. In the X-ray diffraction pattern of the aluminum-gold composite material (comparative example) that was not coated with alumina, a diffraction pattern due to 4th C3 was clearly observed. On the other hand, the X-ray diffraction pattern of the aluminum alloy composite coated with alumina (example of the present invention) has Aj! No diffraction lines due to No. 43 were observed.

Further, the aluminum alloy of the aluminum alloy composite material of the comparative example and the aluminum alloy of the aluminum alloy composite material of the example were dissolved using a OH aqueous solution, and carbon 4i & navy blue were extracted. Al4C3 was identified in the aluminum-gold composite material of the comparative example from the transmission electron microscopy selected area diffraction pattern of the surface of the hl+ carbon fiber. On the other hand, the aluminum alloy composite material of the invention example has Al4C.
3 were not identified.

In addition, test pieces were taken from the aluminum alloy composite material of the above comparative example and the aluminum alloy composite material of the invention example, and T6
After the heat treatment, a tensile test was conducted. The results are shown in Table 3.

Table 3 As shown in Table 3, the aluminum alloy composite material without alumino coating (comparative example) has a tensile strength of 0.2% yield strength compared to that of 6061 aluminum alloy. A remarkable strengthening effect was observed. However, the aluminum alloy composite material coated with alumina (example of the present invention) had significantly improved tensile strength, 0.2% yield strength, and elongation compared to the comparative example.

The alumina coating layer in the above embodiment is used as a binder that improves the formability when solidifying the carbon fibers into a preform and the strength of the preform. Further, the alumina coating layer acts as an effective barrier against diffusion between the liquid phase aluminum alloy and the carbon fibers when composited by the infiltration method.

Therefore, when impregnating and press-casting an aluminum alloy composite material using preforming with an alumina coating layer, the interfacial reaction between the carbon afM and the liquid phase aluminum alloy can be qualitatively eliminated. Furthermore, cracks occur in the preliminary shape and the composite 4
1FI! Factors that cause l1tIi to become defective can be excluded.

As described above, according to the above embodiment, the preform is not destroyed during impregnating ff casting (and the aluminum alloy does not cause deterioration due to the reaction between the carbon fiber and the aluminum alloy matrix). A composite material and a method for manufacturing the same can be provided.

Further, in the above-mentioned embodiment, expensive high-temperature/high-vacuum equipment and reaction gas are not required, and production can be performed in the atmosphere with extremely simple equipment, so that workability is good and it is also economical.

In the above examples, specific numerical values were given and explained for the size of carbon fiber, the concentration of alumina sol, the shape of the preform, heating temperature and time, etc., but these numerical values are merely examples. However, the present invention is not limited to this, and various other embodiments are possible.

(Effects of the Invention) In the aluminum alloy composite material and the manufacturing method thereof according to the present invention, before the preform is impregnated with aluminum alloy, an alumina coating layer is applied to the surface of the carbon fibers constituting the fiber M skeleton of the preform. By forming an aluminum alloy composite material comprising a preformed body made of carbon ta@ having an alumina-coated N layer on the surface, and an aluminum alloy impregnated into the preformed body as an i-mix. Since the preform is manufactured, the preform is not destroyed during impregnation and pressure casting, and the reaction between the carbon fiber and the aluminum alloy matrix allows the carbon t
No deterioration of lAM occurs.

Further, the present invention does not require expensive high-temperature/high-vacuum equipment or reaction gas, and can be manufactured in the atmosphere with extremely simple equipment, so it is easy to work with and is economical.

[Brief explanation of the drawing]

Fig. 1 is a characteristic diagram showing the X-ray diffraction results of the aluminum alloy composite material 11 according to the present invention in comparison with a comparative example, and Fig. 2 (A) to (
D) is a process diagram showing the manufacturing process of aluminum alloy material by infiltration method. 1... Preformed body, 4... Molten aluminum alloy matrix, 7... Aluminum alloy composite material. Applicant's agent Hisashi Hatano G (1) - Comparative example (2) - Akii Ipponbon J (A) (B) Figure 2

Claims (1)

[Scope of Claims] 1. A method for producing an aluminum alloy composite material, in which a preformed body having carbon fiber as a fiber skeleton is manufactured, and the preformed body is impregnated with an aluminum alloy as a matrix under pressure to form a composite. Before impregnating the preform with aluminum alloy, the surface of the carbon fibers that make up the fiber skeleton of the preform is coated with
A method for producing an aluminum alloy composite material, comprising forming an alumina coating layer. 2. An aluminum alloy composite material comprising a preformed body made of carbon fiber having an alumina coating layer on its surface, and an aluminum alloy impregnated as a matrix in this preformed body.