JP4251518B2 - Method for producing aluminum matrix composite - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing an aluminum matrix composite.
[0002]
[Prior art]
As a method for producing an aluminum-based composite material, for example, there is one disclosed in Japanese Patent Application Laid-Open No. 10-183269 “Method for producing a metal / ceramic composite material”. According to paragraphs [0009] to [0019] of this publication, the method for producing this metal / ceramic composite material is as follows. However, the following explanation summarizes the original text.
[0003]
A porous molded body 6 is placed in a crucible 5, an aluminum alloy block 7 is placed thereon, and set in an atmosphere furnace 1 together with a magnesium generation source 9.
Heating is started in an argon gas atmosphere and at atmospheric pressure, and then magnesium is evaporated under reduced pressure. Next, as shown in FIG. 2 of the publication, argon (Ar) is replaced with nitrogen gas (N ₂ ), and magnesium nitride is generated at atmospheric pressure, and the porous molded body 6 is reduced.
On the other hand, the aluminum alloy block 7 is heated and melted, and the melted aluminum alloy is permeated in a reduced pressure state into the reduced porous molded body 6.
[0004]
[Problems to be solved by the invention]
In the manufacturing method described above, it is difficult for the molten aluminum alloy to flow into the central portion of the porous molded body 6 covered with the aluminum alloy block 7, and insufficient penetration may occur in the central portion. In particular, when the aluminum alloy block 7 has a large diameter, insufficient permeation becomes significant.
[0005]
Then, the objective of this invention is providing the manufacturing method of the aluminum matrix composite which can eliminate a penetration defect part and can reduce production cost.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, according to claim 1, an aluminum alloy and magnesium or a magnesium generation source are placed in a furnace together with a porous molded body made of oxide ceramics, and the temperature in the furnace is raised and nitrogen gas is supplied. Then, in a nitrogen gas atmosphere, magnesium nitride is produced , the oxide ceramic is reduced by the action of magnesium nitride, and the aluminum alloy melt is infiltrated into the porous oxide ceramic to produce an aluminum-based composite material In this method, a porous partition body and a crucible with fine pores that allow the molten aluminum alloy to pass through the molten metal with little pressure by gravity and pass through the molten metal are prepared, and the porous molded body is placed in the crucible. , placing a porous partition member in the porous shaped body, placing the aluminum alloy to the porous partition member, when pressure inside the furnace bets To, by heating, sump on a porous partition member by dissolving an aluminum alloy, then, be forced through the porous partition member pressurizes the upper surface of the dissolution of aluminum alloy by pressurizing the inside of the furnace Thus, the porous molded body in a reduced pressure state surrounded by a molten aluminum alloy that seals the upper surface of the crucible and the porous partition body and not communicating with the inside of the furnace is characterized by being penetrated.
[0007]
A porous partition is placed on the porous molded body, an aluminum alloy is placed on the porous partition, the temperature inside the furnace is raised, and after the reduction, the inside of the furnace is decompressed. At this time, by providing the porous partition, it is possible to reduce the pressure in the porous molded body located under the porous partition simultaneously with the pressure reduction in the furnace.
In the melting of the aluminum alloy, by providing a porous partition member, the penetration of the molten aluminum alloy is prevented, and the molten aluminum alloy is temporarily stored, and the porous molded body is sealed in a vacuum state. As a result, after securing a predetermined amount of molten metal, the entire amount can be uniformly permeated.
[0008]
Further, the upper surface of the molten aluminum alloy is pressurized and forced to pass through the porous partition body, and at the same time the porous molded body in a reduced pressure is sucked, so that the molten aluminum alloy actively flows into the porous molded body. Therefore, it can be made to penetrate even to the deep layer.
Furthermore, since the flow of the molten metal is controlled by the porous partition, it is not necessary to install a device for performing a new mechanical operation, and the production cost can be reduced.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings. The drawings are viewed in the direction of the reference numerals.
FIG. 1 is a flowchart of an aluminum-based composite material manufacturing method according to the present invention, and ST indicates a step.
ST01: A porous molded body, a porous partition body, and an aluminum alloy are prepared.
[0010]
ST02: A porous molded body, a porous partition body and an aluminum alloy are placed in this order in the crucible, and the crucible is placed in the furnace.
ST03: While heating the inside of the furnace, the porous molded body is reduced in a magnesium nitride atmosphere, and then the inside of the furnace is decompressed.
[0011]
ST04: The aluminum alloy is melted under heating and reduced pressure, and collected on the porous partition.
ST05: Pressurize the upper surface of the molten aluminum alloy, forcibly pass through the porous partition, and permeate the porous molded body.
Next, ST01 to ST05 will be specifically described.
[0012]
FIGS. 2A to 2C are first explanatory views of the method for producing an aluminum-based composite material according to the present invention.
(A): First, a porous molded body 11, a porous partitioning body 12, and an aluminum alloy 13 as materials are prepared. Specifically, the porous molded body 11 is obtained by containing, for example, 3% by weight of magnesium (Mg) in porous alumina (Al ₂ O ₃ ).
[0013]
The porous partition 12 is formed by depositing alumina (Al ₂ O ₃ ) powder 14 to a thickness of 0.5 mm to 2.0 mm, and the average particle size of the powder 14 is 50 μm to 100 μm. desirable.
The aluminum alloy 13 is, for example, JIS-A6061 (hereinafter abbreviated as A6061) which is a kind of Al—Mg—Si based alloy.
[0014]
(B): Next, the porous molded body 11 is put into the crucible 15, and alumina (Al ₂ O ₃ ) powder 14 is formed on the porous molded body 11 to a thickness of 0.5 mm to 2.0 mm. A porous partition 12 is formed by placing it flat, and an aluminum alloy 13 is placed on the porous partition 12.
[0015]
In this case, the porous partition 12 forms a gap of 30 μm to 80 μm, which is a fine hole, by the powder 14. If the average particle diameter of the powder 14 is less than 50 μm, the gap becomes too small and it is difficult to penetrate. When the average particle diameter exceeds 100 μm, the gap becomes large, and the amount passing through the porous partitioning body 12 increases even by the gravitational action.
Moreover, when the thickness of the powder 14 is less than 0.5 mm, the amount passing through the porous partition 12 in the gravitational action increases, and when the thickness exceeds 2.0 mm, the penetration becomes difficult.
[0016]
(C): The crucible 15 containing the material is placed in the atmosphere furnace 21 of the aluminum-based composite material manufacturing apparatus 20. The aluminum-based composite material manufacturing apparatus 20 includes an atmosphere furnace 21, an argon gas supply means 22 and a nitrogen gas supply means 23 that supply gas to the atmosphere furnace 21, and a vacuum pump 24 that decompresses the atmosphere furnace 21. It is a thing. Here, the reduced pressure means a pressure lower than the atmospheric pressure.
[0017]
The air in the atmosphere furnace 21 in which the crucible 15 is placed is evacuated by a vacuum pump 24. When a certain degree of vacuum is reached, the vacuum pump 24 is stopped and argon gas (Ar) is supplied from the argon gas supply means 22 to the atmosphere furnace 21. 26 is supplied as shown by arrow (1). Then, the atmosphere furnace 21 is set to a pressure equal to or higher than a desired atmospheric pressure. In the drawing, the white arrow points downward in the drawing, indicating that the pressure in the atmospheric furnace 21 is higher than atmospheric pressure. Subsequently, the atmosphere furnace 21 is heated by the heating coil 27 as indicated by the arrow (2).
[0018]
FIGS. 3A and 3B are second explanatory views of the method for producing an aluminum-based composite material according to the present invention.
(A): The temperature in the atmosphere furnace 21 is raised, and the magnesium 28 contained in the porous molded body 11 is evaporated as shown by the arrow (3). Then, nitrogen gas (N ₂ ) 29 is flowed by the nitrogen gas supply means 23 while the argon gas 26 is being evacuated by the vacuum pump 24, and the nitrogen gas 29 is supplied to the atmospheric furnace 21 as indicated by the arrow (4), and the atmospheric pressure or higher is reached. Pressurize and replace with nitrogen gas 29.
[0019]
When the atmosphere furnace 21 has an atmosphere of nitrogen gas 29, the nitrogen gas (N ₂ ) 29 reacts with the evaporated magnesium (Mg) 28 to generate magnesium nitride (Mg ₃ N ₂ ) 31. This magnesium nitride 31 to reduce the powder 14 of alumina porous compact _{11 (Al 2 O 3) 32} , and the alumina porous partition body 12 (Al ₂ O _3), alumina 32 and powder 14 wettability Will be better.
However, when the thickness of the powder 14 exceeds 2.0 mm, the wettability inside the porous partition 12 decreases.
[0020]
(B): After reducing the alumina 32, the supply of nitrogen gas is stopped, and the gas in the atmosphere furnace 21 is evacuated by the vacuum pump 24 to obtain a predetermined degree of vacuum. At that time, the gas in the pores of the porous molded body 11 and the gas in the gap of the porous partitioning body 12 are sucked as indicated by the arrow (5), and the degree of vacuum is the same as in the atmosphere furnace 21. In the drawing, the white arrow points upward in the drawing, indicating that the pressure in the atmosphere furnace 21 and the porous molded body 11 is lower than atmospheric pressure.
[0021]
4 (a) and 4 (b) are third explanatory views of the method for producing an aluminum-based composite material according to the present invention.
(A): After reaching a predetermined degree of vacuum, the temperature of the aluminum alloy 13 reaches a temperature at which melting starts, the molten aluminum alloy 13 begins to accumulate on the upper surface of the porous partition 12, and the molten metal seals the upper surface.
In this case, since the porous partition 12 uses the alumina powder 14, the gap through which the molten metal tries to pass is small, and the molten metal hardly passes by gravity.
[0022]
(B): All of the aluminum alloy is melted to obtain the melted aluminum alloy 33, and the melted aluminum alloy 33 accumulates on the porous partitioning body 12. When the melting is completed, the temperature of the molten aluminum alloy 33 starts to rise again, and is maintained at a predetermined upper limit temperature (for example, 900 ° C.).
[0023]
FIGS. 5A and 5B are fourth explanatory views of the method for producing an aluminum-based composite material according to the present invention.
(A): While maintaining the temperature, argon gas 26 is supplied to the atmosphere furnace 21 by the argon gas supply means 22 as indicated by the arrow (6). Then, the pressure in the atmosphere furnace 21 is raised to a desired pressure and held. In the drawing, it is shown that only the white arrow in the atmosphere furnace 21 is lower than the atmospheric pressure in the downward direction of the drawing, while the white arrow in the porous molded body 11 is lower than the atmospheric pressure in the upper direction of the drawing. Show.
[0024]
When the atmosphere furnace 21 is pressurized with the argon gas 26 in this way, the upper surface of the molten aluminum alloy 33 is pushed, and the molten aluminum alloy 33 starts to enter a large amount in each gap of the porous partitioning body 12. At this time, one of the porous molded bodies 11 is a vacuum, and the melted aluminum alloy 33 is drawn into the porous partition body 12 by this vacuum, so that the pushing resistance can be reduced.
[0025]
(B): Pressurizing the upper surface of the molten aluminum alloy 33 and forcibly passing the porous partition body 12, thereby allowing the molten aluminum alloy 33 to permeate the porous molded body 11 in a reduced pressure state.
[0026]
By providing the porous partition body 12 as shown in the figure, the penetration into the porous molded body 11 is temporarily stopped until the aluminum alloy 13 (FIG. 4A) is completely dissolved, and a predetermined amount of the molten aluminum alloy 33 is secured. To do. As a result, a predetermined amount of molten aluminum alloy 33 can be uniformly permeated into the porous molded body 11 by pressurization.
[0027]
Moreover, by providing the porous partitioning body 12, the penetration into the porous molded body 11 is temporarily stopped until all the aluminum alloy 13 (FIG. 4A) is dissolved, and the penetration is concentrated only from the pores that are easily penetrated. To prevent. Thereafter, the upper surface of the molten aluminum alloy 33 is pressurized and forced to pass through the porous partitioning body 12 so as to permeate the porous molded body 11 in a reduced pressure state. That is, the pouring of the molten metal is started almost simultaneously from the entire upper surface of the porous molded body 11, and the infiltration can be advanced while being flowed downward as it is without being affected by the ease of flow. Therefore, the poor penetration portion can be eliminated.
[0028]
Further, the molten aluminum alloy 33 is accumulated on the porous partitioning body 12, and then the upper surface of the molten aluminum alloy 33 is pressurized to force the porous partitioning body 12 to pass therethrough, so that the porous molded body in a reduced pressure state is obtained. 11 to penetrate. As a result, the porous compact 11 in a reduced pressure sucks the molten aluminum alloy 33, so that no air pool is generated. Therefore, the poor penetration portion can be eliminated.
In addition, since the porous molded body 11 in a reduced pressure sucks the molten aluminum alloy 33, it can be efficiently infiltrated by a synergistic effect with pressurization, and the production efficiency can be improved.
[0029]
6 (a) and 6 (b) are fifth explanatory views of the method for producing an aluminum-based composite material according to the present invention.
(A): The molten aluminum alloy 33 penetrates the entire porous molded body 11. In particular, in the method for producing an aluminum-based composite material of the present invention, it is possible to penetrate into the central portion 36 located in the deep layer of the porous molded body 11.
(B): The molten aluminum alloy is solidified to complete the aluminum-based composite material 34.
[0030]
As shown in FIG. 6A, the use of alumina powder 14 for the porous partition 12 controls the flow of gas suction, accumulation of molten aluminum alloy 33, and passage through the porous molded body 11. be able to. As a result, it is not necessary to install a device for performing a new mechanical operation in the furnace, and the production cost can be reduced.
Further, the alumina powder 14 is inexpensive, and the production cost can be further reduced.
Further, when alumina powder 14 is used, the porous partition 12 becomes an equivalent component to the porous molded body 11 and does not adversely affect the porous molded body 11.
[0031]
Next, the method for producing an aluminum matrix composite according to the present invention will be supplementarily described with a diagram.
FIG. 7 is a diagram showing the outline of the method for producing an aluminum matrix composite according to the present invention, wherein the upper diagram shows the pressure diagram, the lower diagram shows the relationship between time and temperature, The molded body 11 (see FIG. 2) and the thick broken line indicate the aluminum alloy 13.
[0032]
First, temperature increase is started in an argon atmosphere, magnesium is evaporated at time Sm and temperature Tm from the start of temperature increase, and pressure is applied at pressure Pn while supplying nitrogen gas at time Sn.
The porous molded body 11 (see FIG. 3) is reduced between time Sc (temperature Tc) and time Sb (required time Hc), and the activation of the porous molded body 11 is completed at time Sb. At this time, the heating rate of the porous molded body 11 (see FIG. 3) is increased by activation.
[0033]
Suction is performed from time Sb, and a predetermined degree of vacuum Pb is obtained at the required time Hb.
The melting of the aluminum alloy 13 (see FIG. 2) starts at the time Ss and the temperature Ts, and all the aluminum alloy 13 is melted at the time Sf and the temperature Tf to complete the melting. Thereafter, the temperature is further increased to Tx, for example, 900 ° C. and held.
[0034]
Argon gas 26 (see FIG. 5) is supplied at time Sp, the pressure in the atmospheric furnace 21 is increased to a desired pressure, and infiltration is started.
Infiltration is completed at time Sy, and solidification is completed at time Sz.
[0035]
Note that the relationship between the time and temperature and the pressure in FIG. 7 shown in the embodiment of the present invention is a representative example, and the present invention is not limited to this.
The porous partition 12 in FIG. 2 is not limited to alumina (Al ₂ O ₃ ), and is not limited to powder.
The porous partition body 12 uses alumina powder, but the powder may be formed into a plate shape and placed on the formed body.
[0036]
The aluminum-based composite material manufacturing apparatus 20 in FIG. 2 is not limited to this. For example, heating, pressurization, and decompression may be performed in a dedicated pressure vessel, and the argon gas supply unit 22 and the nitrogen gas supply unit 23 may be configured to obtain a desired pressure and purity. .
[0037]
【The invention's effect】
The present invention exhibits the following effects by the above configuration.
In claim 1, a porous molded body made of an oxide-based ceramic is placed in a crucible, a porous partition body having fine pores is placed on the porous molded body, an aluminum alloy is placed on the porous partition body, The aluminum alloy is melted and accumulated on the porous partition by heating, and then the upper surface of the melted aluminum alloy is pressurized by pressurizing the inside of the furnace to force the porous partition. By passing, the porous molded body in a reduced pressure state surrounded by the molten aluminum alloy sealing the upper surface of the crucible and the porous partition body and not communicating with the inside of the furnace is infiltrated.
By using a porous partition, all the aluminum alloy is melted and temporarily stored. As a result, a predetermined amount of molten aluminum alloy can be evenly supplied to the porous compact by pressurization, and insufficient supply can be prevented. Therefore, the poor penetration portion can be eliminated.
[0038]
In addition, by placing the porous partition body, it is possible to form a vacuum by simultaneously sucking the gas in the pores of the porous molded body at the time of decompression. The molten aluminum alloy accumulated at the time can be poured. That is, by pressurizing the inside of the furnace to pressurize the upper surface of the molten aluminum alloy and forcibly pass the porous partition, the furnace is surrounded by the molten aluminum alloy that seals the upper surface of the crucible and the porous partition. Penetration starts almost simultaneously from the entire upper surface of the porous molded body under reduced pressure that is not in communication, and the molten aluminum alloy can be forced to flow into pores that are difficult to penetrate due to the synergistic effect of suction of the porous molded body. As a whole, the penetration can be continued down to the bottom. Therefore, the poor penetration portion can be eliminated.
[0039]
Further, since the porous partition member is configured with fine holes that pass through the molten metal by applying pressure to the molten aluminum alloy while hardly passing the molten aluminum alloy by gravity, the flow of gas and molten metal can be controlled. As a result, it is not necessary to install a device for performing a new mechanical operation in the furnace, and the production cost can be reduced.
[Brief description of the drawings]
FIG. 1 is a flowchart of an aluminum matrix composite manufacturing method according to the present invention. FIG. 2 is a first explanatory diagram of an aluminum matrix composite manufacturing method according to the present invention. FIG. 4 is a third explanatory diagram of the manufacturing method of the aluminum matrix composite according to the present invention. FIG. 5 is a fourth explanatory diagram of the manufacturing method of the aluminum matrix composite according to the present invention. FIG. 7 is a fifth explanatory view of the method for producing an aluminum matrix composite according to the present invention. FIG. 7 is a diagram showing the outline of the method for producing an aluminum matrix composite according to the present invention.
DESCRIPTION OF SYMBOLS 11 ... Porous molded object, 12 ... Porous partition, 13 ... Aluminum alloy, 28 ... Magnesium, 31 ... Magnesium nitride, 33 ... Molten aluminum alloy, 34 ... Aluminum group composite material.

Claims (1)

Along with a porous molded body made of oxide ceramics, an aluminum alloy and magnesium or a magnesium generation source are placed in a furnace, the inside of the furnace is heated and nitrogen gas is supplied to bring it into an atmosphere of nitrogen gas. a method of generating, reducing the oxide-based ceramics by the action of magnesium the nitride, the aluminum alloy melt is infiltrated into the porous oxide ceramics for producing an aluminum-based composite material, and
A porous partition body and a crucible with fine holes that allow the molten aluminum alloy to pass through the molten metal with little pressure by gravitational action and put the porous molded body into the crucible are prepared. A porous partition body is placed on the porous molded body, the aluminum alloy is placed on the porous partition body, and the inside of the furnace is decompressed and heated to melt the aluminum alloy and collect it on the porous partition body, Next, by pressurizing the inside of the furnace to pressurize the upper surface of the molten aluminum alloy and forcibly pass the porous partition, the furnace surrounded by the molten aluminum alloy sealing the upper surface of the crucible and the porous partition A method for producing an aluminum-based composite material, which comprises infiltrating a porous molded body in a reduced pressure state not communicating with the inside .

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