JP3133262B2 - Composite material molding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding method for producing a metal matrix composite material in a near net shape close to the final shape of a product.

[0002]

2. Description of the Related Art Conventionally, as a means for finishing a metal-based composite material by a near-net shape close to the final shape of a product by secondary processing, for example, forging or a composite material in which a reinforcing material is dispersed in a molten metal is used. Injection molding methods and the like are known.

[0003]

However, when the forging method is used as in the former case, defects such as cracks often occur due to low elongation of the composite material itself, and moreover, the volume content (Vf) of the reinforcing material is reduced. Molding over about 20% is often impossible. In addition, the shape is limited due to forging. In the latter case, the molten metal-dispersed composite material is melted in the same manner as ordinary metal and molded by casting, but air is involved during casting to cause gas defects, or the reinforcing material dispersed during melting. Sedimentation or agglomeration makes it difficult to maintain a uniform dispersion, which causes a problem in quality after casting.

[0004] Therefore, there is a demand for a molding method capable of molding a complicated shape and having good productivity without problems such as gas defects and uneven dispersion of the reinforcing material.

[0005]

According to the present invention, a billet of a metal-based composite material is heated to a temperature equal to or higher than a liquidus of a base metal, and the heated billet is placed in a mold cavity. In the method of forming a composite material, the metal-based composite material is composed of a reinforcing material of an oxide-based ceramic and a base material of an aluminum alloy, and is formed into a billet that is composited via a reducing agent such as magnesium. At the same time, the billet was heated to a temperature at which the billet shape could be maintained.

That is, a reducing agent such as magnesium is added to a reinforcing material of an oxide ceramic such as alumina (Al ₂ O ₃ ) and a matrix (base material) of an aluminum alloy and set in a furnace. Is sublimated under a rare gas atmosphere, and nitrogen gas is introduced into the furnace. The sublimated magnesium reacts with the nitrogen gas to produce magnesium nitride (Mg ₃ N ₂ ).
₃ N ₂₎ is to reduce the oxide of alumina (Al ₂ O ₃₎ surface portion to expose the Al metal.

The exposed Al metal improves the wettability of the interface between the alumina (Al ₂ O ₃ ) reinforcing material and the aluminum alloy base material, increases the bonding force, and maintains the contact state between the two even when the liquid phase is reached. It is held and quality deterioration hardly occurs. Incidentally, the reinforcing material may be a powder or a fiber.

If the heating temperature of such a billet is set to a temperature not lower than the liquidus line of the base metal and capable of maintaining the shape of the billet, the billet is formed by using the reinforcing material as a solid phase and converting the metal base material into a liquid phase. In other words, a state in which the metal is creating a semi-molten state in a pseudo manner, for example, in an aluminum alloy, the α phase is spheroidized as a solid phase to reduce heat acceptance and other eutectic parts Is a liquid phase, even in a semi-molten state, the aluminum alloy is in the same state as maintaining its shape. At this time, since the solid phase of the metal-based composite material is ceramics, it is not necessary to take thermal considerations into consideration, and it is needless to say that the shape thereof need not be spherical.

The quasi-semi-molten billet in which the reinforcing material is in the solid phase and the metal base material is in the liquid phase exhibits a thixotropic behavior of exhibiting fluidity when an external force is applied. Therefore, it is possible to set the billet in the mold cavity while maintaining the shape of the billet, and it is formed into a cavity shape by applying a molding pressure. Since the billet is in a pseudo semi-molten state, the dispersion of the reinforcing material does not become uneven, and gas defects due to entrainment of air and the like can be suppressed.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention has been developed for producing a product made of a metal-based composite material in order to produce a near net shape close to the final shape of the product and of high quality. the metal matrix composite material, an oxide-based ceramics such as alumina (Al ₂ O ₃₎ as a reinforcing material, an aluminum alloy as well as the matrix metal, at the stage of compounding, alumina (Al ₂ O with a reducing agent such as magnesium ₃ ) The surface layer is metallized to improve the wettability of the exposed metal and the matrix metal, and the interface is bonded in a so-called micro-clad state, which is a chemical contact state.

For example, when alumina (Al ₂ O ₃ ) powder and magnesium powder are mixed and heated together with an aluminum alloy in a nitrogen atmosphere, magnesium is nitrided to produce magnesium nitride (Mg ₃ N ₂ ). When magnesium nitride (Mg ₃ N ₂ ) is brought into contact with the surface of alumina (Al ₂ O ₃ ), aluminum metal is exposed by a reducing action.

The composite is formed into a billet in a state where the metal is exposed as described above. By reducing the composite, the wettability is improved and the composite is rapidly formed, and at the same time, the bond is firmly bonded. Incidentally, the reinforcing material such as alumina (Al ₂ O ₃ ) may be a fiber or the like in addition to the powder.
Any method such as a molten metal dispersion method, a high pressure casting method, and a powder metallurgy method may be used.

Next, the composite billet is heated to a temperature range which can maintain the billet shape and is higher than the liquidus line of the aluminum alloy base material. That is, the billet heated as described above has a state similar to a semi-molten state in which a reinforcing material such as alumina (Al ₂ O ₃ ) is used as a solid phase and an aluminum alloy base material is used as a liquid phase. When an external force is applied to the composite, the composite exhibits thixotropic behavior due to shear stress and exhibits fluidity.

The temperature range which can maintain the billet shape and is equal to or higher than the liquidus line of the aluminum alloy base material varies depending on the volume content (Vf) of the reinforcing material such as alumina (Al ₂ O ₃ ). In the case of a composite material using alumina (Al ₂ O ₃ ) particles as a reinforcing material, the range of the hatching in FIG. 1A is shown. In the case of a composite material using alumina (Al ₂ O ₃ ) fibers as a reinforcing material, FIG. (B) is the range of hatching.

The billet heated to a temperature range not lower than the liquidus line of the aluminum alloy base material while maintaining the billet shape is put into a high-pressure die-casting machine and injection-molded by a plunger. Then, as described above, the composite billet is filled into the mold by the thixotropic behavior, and a complex shape can be manufactured.

At this time, since the casting is performed by utilizing the thixotropic property while maintaining the shape of the billet of the composite material, the dispersibility of the reinforcing material is not impaired, and a general high pressure die is used. Unlike a cast, the molten metal is not filled in the mold while being scattered, but is a thixotropic material flow. Therefore, a higher quality product can be manufactured without entrainment of air.

Hereinafter, specific examples and comparative examples will be described. (Example 1) Alumina (Al ₂ O ₃ ) particles were used as a reinforcing material,
A composite material using an aluminum alloy as a matrix metal is composited under reduction with magnesium, and an aluminum (Al ₂ O ₃ ) particle-dispersed aluminum-based composite billet having a diameter of 75 mm and a height of 155 mm (volume content (Vf) of about 20%, The liquid phase of the base material was 620 ° C).

The composite billet is heated in an electric furnace, and
The temperature was raised to 30 ° C. This composite billet is 630 ° C
But he kept that shape. Next, this billet was set in the injection sleeve of a high pressure die casting machine, the plunger speed was 0.2 m / sec for the first speed, 2.0 m / sec for the second speed, the gate speed was about 20 m / sec, and the casting pressure was 8
It was injected into a mold for air conditioner compressor molding under the condition of 00 kgf / cm ² .

After curing for about 8 seconds, the near-net molded composite compressor parts were taken out and inspected. The dispersibility of the particles was good, and the gas amount was measured to be 1.2 cc / 100 g Al. And was very good.

(Example 2) A composite material comprising alumina (Al ₂ O ₃ ) short fiber (trade name: Safir) as a reinforcing material and an aluminum alloy as a matrix metal was composited under reduction with magnesium to have a diameter of 75 mm and a height of 75 mm. 155 mm alumina (Al ₂ O ₃ ) short fiber-dispersed aluminum-based composite billet (volume content (Vf) about 12%, liquid phase of base material 620)
° C).

The composite billet is heated in an electric furnace, and
The temperature was raised to 80 ° C. This composite billet is 780 ° C
But he kept that shape. Next, this billet was set in the injection sleeve of a high pressure die casting machine, the plunger speed was 0.2 m / sec for the first speed, 2.0 m / sec for the second speed, the gate speed was about 20 m / sec, and the casting pressure was 8
It was injected into a mold for air conditioner compressor molding under the condition of 00 kgf / cm ² .

After curing for about 8 seconds, the near-net molded composite compressor parts were removed and inspected. The dispersibility of the short fibers was in a good state. 100gAl was very good.

COMPARATIVE EXAMPLE 1 A composite material (volume content (Vf) of about 20%) using alumina (Al ₂ O ₃ ) particles as a reinforcing material and an aluminum alloy as a matrix metal was heated to 720 ° C. and completely melted. I let it. And this billet
Set in the injection sleeve of a pressure die casting machine, plunger speed is 0.2m / sec for 1st speed, 2nd speed for 2.
0m / sec, gate speed about 20m / sec, casting pressure 800
It was injected into a mold for air conditioner compressor molding under the condition of kgf / cm ² .

After curing for about 8 seconds, the compressor component of the near net-formed composite material was taken out and inspected. As a result, many agglomerations and deviations were observed in the dispersibility of the particles. In the gas amount measurement, the gas contained a large amount of 61 cc / 100 g Al.

Comparative Example 2 An aluminum alloy for die casting was heated to 720 ° C. and completely melted. Using this molten aluminum, it is set in the injection sleeve of a high-pressure die-casting machine, and the plunger speed is set to 0.
2m / sec, 2nd speed 2.0m / sec, gate speed about 20m / se
(c) Injection was made into a mold for air conditioner compressor molding under the conditions of a casting pressure of 800 kgf / cm ² . After curing for about 8 seconds, the compressor parts were taken out and the gas amount was measured.
It contained cc / 100g Al gas.

The above Examples and Comparative Examples are summarized in Table 1, confirming the effectiveness of the production method of the present invention.

[0027]

[Table 1]

[0028]

As described above, the method for forming a composite material according to the present invention is suitable for producing a metal-based composite material formed from a reinforcing material of an oxide ceramic and a base material of an aluminum alloy.
While being compounded via a reducing agent such as magnesium,
This was heated to a temperature above the liquidus line of the base metal and capable of maintaining the billet shape, so that the dispersibility of the reinforcing material could be maintained in a good state, and the entrainment of air and the like was small. High quality products can be molded in near net shape.

[Brief description of the drawings]

FIG. 1 is a graph showing a temperature range in which a billet shape can be maintained, wherein (A) is an aluminum-based alumina particle-dispersed composite material, and (B) is an aluminum-based alumina fiber-dispersed composite material.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yutaka Sugaya 1-10-1 Shinsayama, Sayama-shi, Saitama Honda Engineering Co., Ltd. (56) References JP-A-63-224857 (JP, A) 1-222029 (JP, A) JP-A-10-180344 (JP, A) JP-A-10-180396 (JP, A) JP-A 8-117964 (JP, A) JP-A-6-240383 (JP, A) A) JP-A-6-172890 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B22D 19/14 B22D 17/00 B22D 18/02 C22C 49/00

Claims (1)

(57) [Claims] 1. A method of molding a composite material, comprising heating a billet of a metal-based composite material to a temperature equal to or higher than a liquidus of a base metal, and molding the heated billet in a mold cavity. A method of forming the metal-based composite material from a reinforcing material of an oxide ceramic and a base material of an aluminum alloy, and forming a composite billet of the reinforcing material and the base material using a reducing agent such as magnesium; The method of molding a composite material, wherein the heating temperature of (1) is a temperature at which a billet shape can be maintained.