JPS6341971B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a high modulus carbon fiber-reinforced aluminum composite fiber material that can be molded at low temperature and low pressure.
It has a layered structure, with the core as the first layer, a second layer of silicon (Si) or copper (Cu), and a third layer of aluminum-magnesium (Al-Mg) alloy, or conversely, the core is made of aluminum. -Relates to a novel high modulus carbon fiber reinforced Al composite fiber material having a second layer of Mg alloy and a third layer of Si or Cu. Recently, carbon fiber reinforced metal composite materials (hereinafter abbreviated as "CFRM"), especially carbon fiber reinforced aluminum composite materials (hereinafter abbreviated as "CFRAl"), have excellent specific strength, specific elasticity and heat resistance, and are particularly suitable for high heat resistance. It is seen as a promising structural material for aerospace because it can withstand high temperatures. Conventionally, the manufacturing method for CFRM, especially CFRAl, is
Methods of immersing carbon fibers in molten metal and methods of laminating carbon fibers and metal foil and heating and pressuring them are known, but recently prepreg sheets in which a metal layer is formed on the surface of carbon fibers using the ion plating method are known. (The prepreg sheet referred to here corresponds to carbon fiber reinforced plastic (CFRP) prepreg.
This is a preform material for obtaining CFRAl molded bodies. ), a method has been proposed in which they are laminated and heated and pressurized under vacuum (see Japanese Patent Laid-Open No. 53-66831). In the prepreg sheet for CFRAl, each single carbon fiber is coated with Al, so
It has good shapeability and moderate flexibility and is easy to handle, but it has the following problems when molding. In other words, in the case of prepreg sheets in which carbon fibers are directly coated with Al, the material deteriorates due to the reaction between carbon and Al when the temperature approaches 600℃, so to avoid this, the molding temperature is kept low at about 550 to 450℃. However, since this temperature is approximately 100-200°C lower than the melting point (660°C) of the base metal Al, it is necessary to increase the molding pressure to approximately 100-1000 kg/cm ² . Therefore, in this case, solid-phase diffusion bonding is required due to the low temperature, which makes it difficult to form into complex shapes other than flat plates, and the high pressure requires special large-scale equipment for this purpose. It has the disadvantage of requiring In addition, in the case of prepreg sheets in which carbon fibers are coated with Al through a protective film (also called a barrier layer, made of high-melting-point TiC, SiC, TiN, etc.), the deterioration prevention effect of the protective film can be used to form the prepreg sheet. Is the temperature the same as the melting point of Al?
Temperatures close to this can be maintained, and therefore the molding pressure can be as low as about 10 to 100 Kg/ ^cm2 . However, in this case, the protective film prevents the carbon fibers and Al Since it is a prerequisite to completely prevent the reaction, extremely strict process control is required when applying the protective film, which is an unavoidable industrial disadvantage. In view of these circumstances, the present inventors have conducted intensive research to develop a fiber material that does not have the above-mentioned drawbacks and can be molded at low temperature and low pressure.
We have discovered that by utilizing the solid-liquid coexistence properties of Mg--Si and Al--Mg--Cu, we can obtain something that meets our objectives, and have arrived at the present invention. That is, the present invention aims to provide a novel high-modulus carbon fiber-reinforced aluminum composite fiber material that can be molded at low temperature and low pressure, and has the following configuration. It has a three-layer structure with high modulus carbon fiber as the core component, the core component is the first layer, the second layer is made of silicon or copper, and the third layer is made of aluminum-magnesium alloy. - A fiber material for a high modulus carbon fiber reinforced aluminum composite material having a second layer made of a magnesium alloy and a third layer made of silicon or copper. When using the fiber material of the present invention, conventional
Compared to those coated with Al alone, it can be used at lower temperatures and pressures.
Can be formed into CFRAl and will be described later
CFRAl with a high fiber volume content (Vf) is obtained as a result of exuding unnecessary Al that has become viscous due to the solid-liquid coexistence state of Al-Mg-Si (or Cu). The reason why the fiber material of the present invention can be molded at low temperature and low pressure is as follows. In the case of the present invention, Si of the second layer (or third layer) is heated and pressurized during molding.
Alternatively, a solid-liquid coexistence state is formed at the interface between Cu and the Al-Mg alloy of the third layer (or second layer), and this state progresses internally and spreads throughout the entire Al-Mg alloy.
-Si alloy or Al-Mg-Cu alloy is formed. In these ternary alloys, the temperature range where the liquid phase appears and the temperature where the solid phase appears, that is, the temperature range of the solid-liquid coexistence state, is wide, and the temperature where the solid phase appears, that is, the lowest temperature of the solid-liquid coexistence state. Since this is relatively low, by utilizing this state of solid-liquid coexistence, it becomes possible to mold at low temperature and low pressure. Note that if a solid-liquid coexistence state is to be used, it would be sufficient to apply a coating layer of a ternary alloy in one step from the beginning, but if Al-Mg, Si, and Al-Mg
There is a difference in vapor pressure between Al-Mg-Si (or
It is practically impossible to apply a coating layer consisting of Cu) in one step. In addition, the solid-liquid coexistence state mentioned above is
It is also seen in ternary alloys such as Al-Cu-Si, Al-Mg-Mn, Al-Mg-Zn, etc., but when Al-Mg-Zn system is evaporated by ion plating method, Zn is significantly Impractical due to contamination. In addition, in the Al-Cu-Si and Al-Mg-Mn systems, Al-
The strength of CFRAl is slightly lower than that of Mg-Si system and Al-Mg-Cu system, and it is not suitable for obtaining the desired high-performance CFRAl. Hereinafter, the configuration of the present invention will be explained in detail. In the present invention, the high modulus carbon fiber refers to an elastic modulus of approximately
30T/mm2 or ^more , polyacrylonitrile,
Baking temperature from viscose rayon, pitucci, etc.
Refers to those obtained at temperatures of 1700 to 1800℃ or higher. The diameter is usually about 6 to 10μ, and the number of single fibers is about 1000.
It is a fiber bundle consisting of ~24,000 fibers. High-modulus carbon fibers have excellent thermal oxidation resistance compared to high-strength carbon fibers (modulus of elasticity of about 20 to 25 T/mm ² ), and are less likely to react with Al, so they do not cause material deterioration. Table 1 shows this.

[Table] Table 1 shows the results of an experiment to investigate how the strength of carbon fibers coated with Al using the ion plating method changed after being held at the indicated high temperatures in vacuum. According to this, in the case of high-modulus fibers, the strength does not change after being held at any high temperature, but in the case of high-strength fibers, the strength decreases significantly, especially when held at 700°C for 0.1 hour. It can be seen that the intensity has decreased by more than half. In the fiber material of the present invention, the surface of the high modulus carbon fiber forming the core component is coated with a second layer of Si or Cu and a third layer of Al-Mg alloy, or conversely, a second layer of Al-Mg alloy is coated with a second layer of Si or Cu and a third layer of Al-Mg alloy. It has a three-layer structure covered with one layer and a third layer of Si or Cu. The compositions of the three types of metals in the second and third layers of the present invention are, for example, as follows. For Al-Mg-Si system, Si1-20%, Mg1-10%, Al balance preferably Si3-10%, Mg2-5%, Al balance For Al-Mg-Cu system, Cu1-20%, Mg1-10 %, Al balance preferably Cu3-15%, Mg2-5%, Al balance The composition of the Al-Mg alloy in the present invention can be derived from the composition of the above ternary metals, for example
Mg1~12%, Al balance. In any case,
In Al-Mg-Si (or Cu) systems and Al-Mg alloys, Al occupies an overwhelmingly large proportion. The fiber material of the present invention usually has a core component as a first layer, and a second layer of Si or
Either a coating layer made of Cu is formed and then a coating layer made of Al--Mg alloy is formed as a third layer thereon, or conversely, a coating layer made of Al--Mg alloy is first formed, and then a coating layer made of Si or Mg alloy is formed. It is made by forming a coating layer made of Cu. At this time, the thickness of each layer is not constant in relation to the fiber volume content of CFRAl, but for example, for a highly elastic carbon fiber with a diameter of 7μ, the thickness of the Si or Cu layer is approximately 0.02 to 0.5μ, and the thickness of the Al-Mg alloy layer is approximately 0.02 to 0.5μ. is approximately 0.5-5.0μ. In the present invention, the volume content (Vf) of the high modulus carbon fiber of CFRAl is 10 to 80%, preferably 20 to 70%.
%. The fiber material of the present invention can be obtained by the ion plating method as follows. 10 ^-4 ~
After exhausting to below 10 ^-5 Torr (mmHg), introduce argon or nitrogen gas and maintain at 10 ^-2 to ^{10 -3} Torr.
Applying a potential and plasma-etching the surface of the highly elastic carbon fiber using plasma generated by glow discharge, forming a Si or Cu layer as the second layer, and then forming an Al--Mg alloy layer as the third layer. mosquito,
Alternatively, conversely, an Al--Mg alloy layer is formed as the second layer, and then a third Si or Cu layer is formed.
In this case, heating means such as resistance heating, high-frequency induction heating, or electron beam irradiation are used to heat and melt the metal, and the metal is ionized in the plasma region and coated on the fiber surface. The fiber material of the present invention thus obtained is
These are laminated and hot-pressed in vacuum, an inert atmosphere, or air to form CFRAl. EXAMPLES The present invention will be explained below with reference to Examples, but the present invention is not limited thereto. Example 1 After evacuating the system to 1×10 ^-5 Torr, N ₂ gas was introduced, the N ₂ partial pressure was maintained at 1×10 ^-2 Torr, a potential of 1.0 KV was applied, and a diameter of 6.6 mm was etched while performing plasma etching. μ high elasticity carbon fibers are placed, Si is melted and evaporated by high frequency induction heating to form a second layer, and then
Continuously supplies Al95wt%Mg5wt% alloy wire,
It was melted and evaporated by resistance heating to form a third layer. The obtained fiber material has a three-layer structure with high modulus carbon fiber as the core component, and the thickness of the second layer, Si, is
The thickness of the third layer, Al-Mg, was 1.8μ. This fiber material is laminated in a mold at 560℃ and 10Kg/
It was molded by hot pressing in ^cm2 . The alloy composition in the compact matrix is Si: 7.3wt%, Mg: 4.4wt%,
The remainder was Al. Similarly, fiber materials coated with Al-Mg alloy as the second layer and Si as the third layer were heated at 580℃ for 10 minutes.
Hot press molded at Kg/ ^cm2 . The thickness of the Al-Mg layer, which is the second layer of this fiber material, is
The thickness of the third Si layer is 0.1μ, and the alloy composition in the compact matrix is Si: 5.4wt%.
Mg: 4.7wt%, the balance was Al. When the obtained high modulus carbon fiber reinforced aluminum composite material was tested, its properties were as shown in Table 2.

【table】

[Table] Core - First layer Example 2 After evacuating the system to 1 x 10 ^-5 Torr, Ar gas was introduced, the Ar partial pressure was kept at 1 x 10 ^-2 Torr, a potential of 1.0 KV was applied, and the plasma diameter while etching
Arranged with 6.6μ high elastic carbon fiber, Al95wt%,
Mg: 5wt% alloy wire is continuously supplied and melted and evaporated by resistance heating to form a second layer, followed by Cu.
was melted and evaporated by high-frequency induction heating to form a third layer. The obtained fiber material had a three-layer structure with high modulus carbon fiber as the core component.The thickness of the second layer, Al-Mg, was 2.0μ, and the thickness of the third layer, Cu, was 0.05μ. . This fiber material is laminated in a mold at 540℃10Kg/cm ²
Hot press molded. The alloy composition in the compact matrix was Cu: 9.5 wt%, Mg: 4.5 wt%, and the balance was Al. When the high elasticity carbon fiber reinforced aluminum composite material thus obtained was tested, its properties were as shown in Table 3.

[Table] Next, a comparative example is shown. Comparative Example 1 is an example using only Al--Mg alloy, and Comparative Example 2 is an example using high-strength carbon fiber. Comparing the results of these comparative examples with those of Examples 1 and 2 above, it can be seen that the CFRAl obtained from the ternary alloy fiber material of the present invention is superior in properties. Comparative Example 1 A fiber material having a core component of high elastic carbon fiber with an alloy composition of Mg: 2.5wt% and the balance Al was molded,
In order to obtain CFRAl having properties almost similar to those of Examples 1 and 2, high temperature and pressure of 600° C., 200 Kg/cm ² were required as molding conditions. In addition, in order to mold, the molding temperature was raised and molding was performed in a solid-liquid coexistence state, but the temperature range of the solid-liquid coexistence state was narrow, and a large amount of matrix (Al-Mg) flowed out, making it impossible to obtain a good molded product. Ta. Comparative Example 2 A matrix similar to that of Examples 1 and 2 was formed on high-strength carbon fibers, and then molding was performed under the molding conditions of Examples 1 and 2, respectively.
The high-strength carbon fiber deteriorated due to the reaction of Al, and CFRAl with good properties could not be obtained. Its characteristics were as shown in Table 4.

【table】

Claims (1)

[Claims] 1 Consisting of a three-layer structure with high modulus carbon fiber as the core component, the core component is the first layer, the second layer is made of silicon or copper, and the third layer is made of aluminum-magnesium alloy, or vice versa. A fiber material for a high modulus carbon fiber reinforced aluminum composite material having a second layer made of an aluminum-magnesium alloy and a third layer made of silicon or copper.