JPH0620639B2 - Carbon fiber reinforced magnesium alloy member - Google Patents

Description

Detailed Description of the Invention A. Object of the Invention (1) Field of Industrial Application The present invention relates to a carbon fiber reinforced magnesium alloy member in which carbon fiber is used as a reinforcing fiber and a matrix is made of a magnesium alloy.

(2) Conventional Technology Conventionally, this kind of member is manufactured by applying a high pressure solidification casting method, and therefore, an alloy for castings is used as the magnesium alloy.

(3) Problems to be Solved by the Invention However, the casting alloy contains aluminum in an amount of 5 to 1
Since it is contained in a large amount of 0% by weight, there is a problem that the aluminum easily reacts with the carbon fiber to form a large amount of embrittlement layer, and the tensile strength of the carbon fiber is remarkably reduced.

Further, as the content of aluminum increases, the amount of intermetallic compound phase such as Al ₁₂ Mg ₁₇ in the matrix increases, and this phase has a tensile strength of 8 to 12 kg / mm ² .
Since the elongation is very brittle at 0.3 to 0.5% and tends to segregate on the carbon fiber surface or in the vicinity thereof, the notch formation due to the initial fracture of this phase and the tensile strength of the member accompanying its progress There is also a problem that the quality is significantly reduced.

It is an object of the present invention to provide the member which can solve the above problems.

B. Structure of the invention (1) Means for solving the problems The present invention uses a carbon fiber as a reinforcing fiber, and a carbon fiber reinforced magnesium alloy member made of a magnesium alloy matrix, the aluminum content of the magnesium alloy 0.3 wt% or more and 5.0 wt%
It is characterized by the following settings.

(2) Operation When the aluminum content is set to 0.3% by weight or more and 5.0% by weight or less as described above, the amount of the embrittlement layer formed by the reaction between carbon fiber and aluminum decreases, and the Al content in the matrix is reduced. _{Since the} amount of brittle intermetallic compound phase such as ₁₂ Mg ₁₇ formed is small, it is possible to provide the member having practically sufficient tensile strength. However, when the aluminum content exceeds 5.0% by weight, the tensile strength of the member is drastically reduced and it cannot be put to practical use. On the other hand, if the content is less than 0.3% by weight, the castability is significantly impaired and the mass productivity is lowered.

(3) Example First, the production of a fiber molding made of carbon fiber will be described.

As shown in FIG. 1 (a), a carbon fiber having a diameter of 7 μm (Torayca T300 manufactured by Toray Industries, Inc.) was used with a hand-wound winder 1.
The long fibers of f are wound on an elongated loop, cut at one end A on the long diameter side and bundled at the other end B on the long diameter side to obtain a fiber bundle of 900,000 fibers. The reason for setting the number of fibers in this way is to set the volume content (Vf) of the fiber molded body to 30% in relation to the inner diameter of the molding glass tube described later.

Acrylic resin-based solution (Olivine (BP manufactured by Toyo Ink Co., Ltd.
S4668)) and acetone as a solvent are mixed at a ratio of 1: 1 and a curing agent (polyisocyanate) corresponding to 4% of the acrylic resin solution is added to this to prepare a binder solution. To the solution, Ti powder for preventing fiber adhesion having a particle size of 325 mesh or less is added at a rate of 100 g /.

As shown in FIG. 1 (b), the fiber bundle F is immersed in the binder solution L, the binder solution L is agitated while shaking the fiber bundle F, and the binder solution L containing Ti is added to the fiber bundle F. Allow it to fully penetrate between the fibers.

As shown in FIG. 1 (c), the fiber bundle F drawn from the binder solution L is passed through a glass tube T having an inner diameter of 12 mm to squeeze the excess binder solution L, and both ends are cut. Diameter 12
mm to obtain a preform having a length of 20 mm.

As shown in FIG. 1 (d), a dried and cured preform P
Is placed in an electric furnace E, and the preform P is fired at 400 ° C. for 1 hour in an argon gas atmosphere to obtain a rod-shaped fiber compact. The organic component is decomposed and removed by the firing treatment, and the residual organic component of the fiber molded body becomes 5% before the firing.

The table below shows the matrix magnesium alloy (I)
The chemical components of (VIII) are shown below.

After heating the fiber molded body at 400 ° C. for several minutes in an argon gas atmosphere, the fiber molded body is placed in the cavity of the mold, and immediately after the magnesium alloy (I) at 730 ° C.
The molten metal of (VIII) is poured into the cavity and 1000 kg / cm
Applying pressure of ² for 60 seconds, diameter 12mm, length 120m
Eight types of rod-shaped carbon fiber reinforced members of m are obtained.

FIG. 2 shows the relationship between the amount of aluminum alloy and the tensile strength of each member. In FIG. 2, (I) to (VIII) correspond to members having the magnesium alloys (I) to (VIII) as a matrix, respectively.

As is clear from FIG. 2, as the aluminum content of the matrix increases, the tensile strength decreases, but if the aluminum content is 5.0% by weight or less, ensure practically sufficient tensile strength. You can

If the content exceeds 5.0% by weight, the tensile strength is drastically reduced, and it cannot be put to practical use at all. The reason is that when the aluminum content exceeds 5.0% by weight, the amount of the embrittlement layer formed by the reaction between aluminum and the carbon fiber increases, and the amount of the brittle intermetallic compound phase such as Al ₁₂ Mg ₁₇ formed. Is to increase.

In addition, in a member in which the matrix is made of magnesium alone, the heat capacity of magnesium alone is small and the fluidity of the molten metal is poor, so that sufficient complexing cannot be performed.

As the member, for example, as shown in FIG.
Corresponds to the connecting rod 3 for an internal combustion engine reinforced by the rod-shaped carbon fiber molded body 2 arranged in the axial direction.

C. EFFECTS OF THE INVENTION According to the present invention, since the aluminum content of the magnesium alloy is set to 0.3% by weight or more and 5.0% by weight or less, the amount of the embrittlement layer formed by the reaction between the carbon fiber and aluminum and the matrix It is possible to provide the above-mentioned member having a practically sufficient tensile strength by reducing the formation amount of each brittle intermetallic compound phase such as Al ₁₂ Mg ₁₇ .

[Brief description of drawings]

FIG. 1 is an explanatory view of a manufacturing process of a fiber molded body, FIG. 2 is a graph showing a relationship between aluminum content and tensile strength of various members, and FIG. 3 is a vertical sectional front view of a connecting rod for an internal combustion engine.

Claims (2)

[Claims] 1. A carbon fiber reinforced magnesium alloy member comprising carbon fiber as a reinforcing fiber and a matrix made of a magnesium alloy, wherein the aluminum content of the magnesium alloy is 0.3% by weight or more and 5.0% by weight or less. A member made of a carbon fiber reinforced magnesium alloy characterized by being set to. 2. The carbon fiber reinforced according to claim 1, wherein the member is an internal combustion engine connecting rod, and a rod portion of the member is reinforced by the carbon fibers arranged in the axial direction. A member made of magnesium alloy.