JP4233036B2 - Method and apparatus for producing aluminum matrix composite - Google Patents

Description

  The present invention relates to a method for manufacturing an aluminum matrix composite and an apparatus for manufacturing the same.

The aluminum-based composite material is made of aluminum and oxide ceramics, and alumina (Al ₂ O ₃ ) is used as the oxide ceramics, for example. The outline of the production method is as follows. First, a porous molded body made of an oxide ceramic is heated in a furnace, and the porous molded body is reduced with magnesium nitride. Subsequently, aluminum dissolved in the reduced porous molded body is infiltrated to obtain an aluminum-based composite material.

As such a manufacturing method, a manufacturing method of an aluminum-based composite material is known (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 2002-30361 (page 6, FIG. 3)

Patent document 1 is demonstrated based on the following figure.
12A and 12B are diagrams for explaining the basic principle of the conventional technique.
In (a), the aluminum-based composite material manufacturing apparatus 101 includes an atmosphere furnace 102, an argon gas supply unit 103, a nitrogen gas supply unit 104, and a vacuum pump 105.

The outline of the manufacturing process of the composite material manufactured by the manufacturing apparatus 101 will be described below.
First, a porous molded body 107, a porous partition body 108 made of alumina (Al ₂ O ₃ ) powder, and an aluminum alloy 109 are placed in a crucible 106. The porous molded body 107 is made by containing magnesium in porous alumina (alumina 111).

In (b), argon gas (Ar) is subsequently put into the atmosphere furnace 102 from the argon gas supply means 103 and replaced, and heating is started. After a predetermined time, nitrogen gas (N ₂ ) is supplied from the nitrogen gas supply means 104 to the atmosphere furnace 101, the atmosphere furnace 101 is set under reduced pressure, and the pressure is increased after a predetermined time has elapsed from the start of the pressure reduction.

  In the atmosphere furnace 102 that has undergone such a process, the magnesium 112 and the nitrogen gas 113 react with each other to produce magnesium nitride 114 by heating, and the magnesium nitride 114 reduces the alumina of the porous molded body 107 under reduced pressure. The dissolved aluminum alloy penetrates into the reduced porous molded body 107 under pressure. Therefore, the poor penetration portion can be eliminated.

However, in the method for producing an aluminum-based composite material of Patent Document 1, it takes time to fill the atmosphere furnace 102 with the nitrogen gas 113, and it takes time to generate a sufficient amount of magnesium nitride. In particular, when the crucible 106 is placed at the maximum density in the atmosphere furnace 102, the flow rate of nitrogen gas decreases depending on the location. As a result, the production of magnesium nitride was delayed, the manufacturing cycle time was prolonged, and the production efficiency was low.
Although it is possible to eliminate the delay in the formation of magnesium nitride by increasing the flow rate of nitrogen gas, it is necessary to supply an excessive amount of nitrogen gas, which increases the production cost.

  The present invention supplies nitrogen gas to all the crucibles almost uniformly and in a short time even if the crucible used for producing the aluminum matrix composite is placed at the maximum density in the heating furnace for producing the aluminum matrix composite. Thus, it is an object to shorten the production time of magnesium nitride in all the crucibles, shorten the production cycle time, and reduce the amount of nitrogen gas used.

The invention according to claim 1 includes a first step of placing a porous molded body or powder made of an oxide-based ceramic in a crucible and placing an aluminum alloy on the porous molded body or powder, and a plurality of crucibles together with magnesium or The second step of placing the magnesium generation source in the furnace, and heating the furnace in a nitrogen atmosphere and heating to produce magnesium nitride, the porous compact or powder is reduced by the action of magnesium nitride, reduced porous And a third step of obtaining an aluminum matrix composite by infiltrating a molten aluminum alloy into a green compact or powder, wherein the nitrogen atmosphere is from directly above a plurality of crucibles to the inside of the crucible. It forms by supplying nitrogen gas directly toward.

  The invention according to claim 2 is characterized in that the nitrogen gas is supplied by heating in advance.

The invention according to claim 3 is an aluminum-based composite material manufacturing apparatus comprising: a heating furnace for heating a workpiece; and a nitrogen supply means for supplying nitrogen to the heating furnace, wherein the nitrogen supply means is a heat source in the heating furnace. a gas preheating chamber provided in the vicinity of, in this gas preheating chamber, with a, a nozzle for supplying a gas to a plurality of crucibles central axis concentric with and attach each crucible that contained in the work It is characterized by that.

In the invention according to claim 1, since the nitrogen atmosphere is formed by supplying nitrogen gas directly from directly above the crucible into the crucible, even if a plurality of crucibles are placed at the maximum density in the heating furnace, Nitrogen gas can be supplied to the crucibles almost uniformly in a short time, and as a result, there is an advantage that the time for forming magnesium nitride in all the crucibles can be shortened.
Further, since the nitrogen atmosphere is formed by supplying nitrogen gas directly from directly above the crucible toward the inside of the crucible, the amount of nitrogen gas used can be reduced.

In the invention according to claim 2, since the nitrogen gas is heated and supplied in advance, the temperature of magnesium is prevented from lowering and the production of magnesium nitride (Mg ₃ N ₂ ) is promoted. As a result, even if crucibles are placed at the maximum density in the heating furnace, the magnesium nitride production time in all the crucibles can be further shortened, and the manufacturing cycle time can be shortened.

In the invention according to claim 3, the nitrogen supply means includes a gas preheating chamber provided in the vicinity of the heat source in the heating furnace, and each of the gas preheating chambers concentrically with the central axes of a plurality of crucibles included in the workpiece. a nozzle for supplying gas towards the inside crucible attach, because with a temperature of the gas preheating chamber by the heat source rises, elevated gas preheating chamber temperature and flowing a nitrogen gas, nitrogen heating in the process towards the gas to the nozzle. Therefore, nitrogen gas at a desired temperature can be supplied into the crucible in a short time.

  Further, since the nozzle of the gas preheating chamber is mounted in the crucible, even if the crucible is placed at the maximum density in the heating furnace, nitrogen gas can be reliably supplied to all the crucibles.

The best mode for carrying out 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 sectional view of an apparatus for producing an aluminum-based composite material according to the present invention.
The aluminum matrix composite manufacturing apparatus 11 includes a heating furnace 12, a gas supply apparatus 13 connected to the heating furnace 12 for supplying gas, a vacuum pump 14 for reducing the pressure in the heating furnace 12, and the heating furnace 12. And a control device 15 for controlling the gas supply device 13 and the vacuum pump 14. Reduced pressure means a pressure lower than atmospheric pressure.

  In the heating furnace 12, a heat insulating means 22 is attached in the pressure vessel 21, a heating means 23 is disposed inside the heat insulating means 22, a tight box 24 is provided inside the heating means 23, and a crucible is provided in the tight box 24. 25 is a furnace in which a mounting table 26 on which 25 is mounted is disposed.

  In the pressure vessel 21, first and second heads 31 and 32 are attached to both ends of the main body portion 28 through an opening / closing mechanism (not shown), and mounts 33 and 33 are attached to the lower portion of the main body portion 28. The first nozzle 34 (... indicates a plurality; the same applies hereinafter), the second nozzles 35, 35, and the third nozzle 36 are attached to the main body 28, and the workpiece is placed under a predetermined reduced pressure or pressure. To process.

  In addition, depending on what is processed, it is also possible to weld (overlay) stainless steel that prevents corrosion of the inner surface to the entire inner surface of the pressure vessel 21. Moreover, you may form a larger or smaller nozzle in the pressure vessel 21 as needed.

  The heat insulating means 22 has a cylindrical storage portion 37 attached to the pressure vessel 21, first and second door portions 41 and 42 are disposed at both ends of the storage portion 37, and the first and second door portions 41 and 42 are disposed. The first and second heads 31 and 32 are fixed, and the first and second door portions 41 and 42 are opened and closed simultaneously with the first and second heads 31 and 32.

  The heating means 23 is an electric heater, and includes an upper heat source 43 located above the crucible 25, a lower heat source 44 located below, a thermocouple 45 disposed above the crucible 25, and a thermocouple 46 disposed below. .

  The tight box 24 is made of graphite, partitions the components in the furnace such as the heater (heating means 23) and the heat insulating means 22 from the atmospheric gas and impurities generated during processing, prevents contamination in the furnace, and The purpose is to achieve soaking. It is also possible to omit the tight box 24 without attaching it.

The gas supply device 13 includes an inert gas supply means 47, a nitrogen supply means (nitrogen gas supply means) 48, a switching valve 49, and a pipe 51 connected to the second nozzles 35, 35. Then, an inert gas or nitrogen gas (N ₂ ) is supplied.

The switching valve 49 guides the inert gas inlet 52 or the nitrogen inlet 53 to the outlet 54 based on the information of the control device 15 and closes the inert gas inlet 52 and the nitrogen inlet 53 as necessary.
The nitrogen gas supply means 48 includes a gas preheating chamber 56 provided near the heat source (heating means) 23 in the heating furnace 12, and a nozzle 57 that is attached to the gas preheating chamber 56 and supplies gas into the crucible 25. And so on.

  2 is a cross-sectional view taken along the line 2-2 of FIG. 1, and shows a heating furnace 12, a gas supply device 13, a vacuum pump 14, a control device 15, a heating means 23 disposed in the heating furnace 12, and a gas. A preheating chamber 56 is shown.

The heating means 23 includes the upper heat source 43 and the lower heat source 44 as already described.
The upper heat source 43 is obtained by attaching the first heaters 61, 61 to the first nozzles 34, 34, and the control device 15 controls the first heaters 61, 61 under the same conditions.

The lower heat source 44 is obtained by attaching the second heaters 62 and 62 to the first nozzles 34 and 34 in the lower part of the figure, and the control device 15 controls the second heaters 62 and 62 under the same conditions. That is, the heat source can control the upper and lower heat sources 43 and 44 separately.
Both the first and second heaters 61 and 62 have the same structure, and existing ones were used.

  The nitrogen gas supply means 48 is composed of the gas preheating chamber 56 and nozzles 57... Already described, and the gas preheating chamber 56 has a partition plate 66 on an arc portion 65 located above the tight box 24. It is a room formed in close contact with a shielding plate 67 in the center.

FIG. 3 is a perspective view of the gas preheating chamber and nozzle of the present invention.
Specifically, in the gas preheating chamber 56, a partition plate 66 closely contacting the arc portion 65 (see FIG. 2) of the tight box is formed in a width W, and sealing plates 71 and 71 are formed in arcs on both ends of the partition plate 66. It is configured to be attached so as to be in close contact with the portion 65 (see FIG. 2), with 16 outlets 72... Opened in the partition plate 66 at pitches P1, P2, and a shielding plate 67 disposed in the center. The central axis 73 of the outlet 72 and the central axis 74 of the crucible 25 are concentric, and the pitches P1, P2 are equal to the pitches Pm1, Pm2 when the crucibles 25 are arranged.
The number of outlets 72 is not limited to 16.

The nozzles 57 are conical tubes attached to the outlets 72.
In addition, when not attaching a tight box, the board equivalent to the circular arc part 65 (refer FIG. 2) is attached.

Next, the operation of the manufacturing apparatus of the present invention will be described.
When the controller 15 shown in FIG. 1 is turned “ON” and heating is started by the heating means 23, the temperature in the gas preheating chamber 56 starts to rise by the upper heat source 43. After a predetermined time has elapsed, when the switching valve 49 is operated and nitrogen gas is caused to flow into the heated gas preheating chamber 56, the nitrogen gas is warmed and the temperature of the nitrogen gas rises. Specifically, the nitrogen gas flowing in from the second nozzles 35, 35 in FIG. 3 is dispersed by the shielding plate 67 at 360 degrees as indicated by arrows a, b, c, d, and into the 16 outlets 72. Heat is transferred to reach the desired temperature. Therefore, nitrogen gas at a desired temperature can be supplied into the crucibles 25.

  Further, since the nozzles 57... Are attached to the gas preheating chamber 56 at predetermined positions, that is, into the crucibles 25..., The 16 crucibles 25. Even if it puts, nitrogen gas can be reliably supplied in 16 crucibles 25 ....

Next, another embodiment of the nitrogen supply means will be shown.
FIG. 4 is a diagram showing another embodiment. The same reference numerals are given to the same components as those in the embodiment shown in FIGS. 2 and 3 and the description thereof is omitted.

The nitrogen supply means (nitrogen gas supply means) 48B of another embodiment includes a gas preheating chamber 56B provided in the vicinity of the heat source (heating means) 23 (see FIG. 2) in the heating furnace 12, and a gas preheating chamber. 56B and nozzles 57 for supplying gas into the crucibles 25...
The gas preheating chamber 56 </ b> B is obtained by connecting the pipe members 76, 76 to the second nozzles 35, 35.

The nitrogen gas supply means 48B of another embodiment exhibits the same effect as the nitrogen gas supply means 48 (see FIG. 3).
That is, the nitrogen gas flowing in from the second nozzles 35, 35 passes through the pipe members 76, 76, receives heat transfer in the process of reaching the 16 nozzles 57, and reaches a desired temperature. Therefore, nitrogen gas at a desired temperature can be supplied into the crucibles 25.

  Since the nozzles 57 are mounted in a predetermined position, that is, in the crucibles 25..., The 16 crucibles 25. Nitrogen gas can be reliably supplied into the crucibles 25 as indicated by arrows f and f.

Next, the manufacturing method of the aluminum matrix composite of this invention is demonstrated.
5A and 5B are explanatory diagrams of the first step of the manufacturing method of the present invention.
(A): First, a powder 81 made of an oxide ceramic is placed in the crucible 25, and an aluminum alloy 82 is placed on the powder 81.
The powder 81 is a mixed powder obtained by mixing alumina (Al ₂ O ₃ ) and magnesium (Mg). The aluminum alloy 82 is, for example, JIS-A6061 which is a kind of Al—Mg—Si alloy.
In addition, although the powder 81 which consists of oxide type ceramics was used, you may use the porous molded object which consists of oxide type ceramics.

(B): The crucible 25 containing the powder 81 and the aluminum alloy 82 is conveyed to the heating furnace 12 (see FIGS. 1 and 2).
In addition, since magnesium (Mg) is already dispersed in the powder 81, a container containing magnesium is not prepared. However, when magnesium is not put in the powder 81 or the crucible 25, separately from the crucible 25, Prepare a container containing magnesium.

FIG. 6 is an explanatory diagram of the second step of the manufacturing method of the present invention.
Magnesium is placed in the heating furnace 12 together with the crucibles 25. In the example shown here, since magnesium has already been included in the powder 81, the operation of storing magnesium in the heating furnace 12 is omitted. The first head 31 of the heating furnace 12 is opened, 16 crucibles 25... Are placed at predetermined positions on the mounting table 26, and the first head 31 is closed.

FIG. 7 is an explanatory view (No. 1) of the third step of the manufacturing method of the present invention, and is a cross-sectional view taken along the line 7-7 in FIG.
Sixteen crucibles 25 are placed at predetermined positions on the mounting table 26 of the heating furnace 12 to heat the heating furnace 12 under a nitrogen atmosphere. Specifically, in order to remove oxygen in the heating furnace 12, the inside of the heating furnace 12 is evacuated by the vacuum pump 14, and when a certain degree of vacuum is reached, the vacuum pump 14 is stopped and the switching valve 49 is not operated. An inert gas (for example, argon gas (Ar)) is supplied from the active gas supply means 47 to the gas preheating chamber 56 of the heating furnace 12 as indicated by an arrow g, and the heating means 23 contains powder 81 (magnesium (Mg)). And heating of the aluminum alloy 82 is started.

  The temperature inside the heating furnace 12 is raised (automatically) while being detected by thermocouples 45 and 46. In the process of reaching a predetermined temperature (for example, about 750 ° C. to about 900 ° C.), since the inside of the heating furnace 12 is in an inert gas atmosphere, the aluminum alloy 82 and magnesium are not oxidized.

FIG. 8 is explanatory drawing (the 2) of the 3rd process of the manufacturing method of this invention.
Next, nitrogen gas is introduced. Specifically, the operation of the switching valve 49 (see FIG. 7) supplies nitrogen gas from the nitrogen gas supply means 48 (see FIG. 7) to the gas preheating chamber 56 of the heating furnace 12 as indicated by the arrow h. 57... Supplies nitrogen gas into the crucible 25..., And simultaneously removes the inert gas with the vacuum pump 14 (see FIG. 7), and replaces the atmosphere in the heating furnace 12 with nitrogen gas (N ₂ ). To do. At the time of replacement, pressurization (for example, atmospheric pressure + about 0.5 kg / cm ² ) may be performed while supplying nitrogen gas.

  Thus, in the third step, the nitrogen atmosphere is formed by supplying nitrogen gas directly from directly above the crucibles 25... To the inside of the crucibles 25. Even if 16 crucibles 25 with a density of 1 are placed, nitrogen gas can be supplied to all the crucibles 25.

FIG. 9 is an explanatory view (No. 3) of the third step of the manufacturing method of the present invention, schematically showing.
When nitrogen gas is supplied to the gas preheating chamber 56 of the heating furnace 12 as indicated by the arrow h..., The nitrogen gas is heated in the gas preheating chamber 56. it can. When the inside of the heating furnace 12 is in an atmosphere of nitrogen gas, the nitrogen gas reacts with magnesium to generate magnesium nitride (Mg ₃ N ₂ ).

In this way, in the third step, the nitrogen atmosphere is formed by supplying nitrogen gas directly from directly above the crucibles 25... To the inside of the crucibles 25. Even if 16 crucibles 25 of the density are placed, nitrogen gas can be supplied to all of the crucibles 25 almost uniformly in a short time. As a result, all the crucibles 25. .. There is an advantage that the magnesium nitride formation time in the inside can be shortened.
Further, since the nitrogen atmosphere is formed by supplying nitrogen gas directly from directly above the crucibles 25 to the inside of the crucibles 25, the amount of nitrogen gas used can be reduced.

FIG. 10 is an explanatory view (No. 4) of the third step of the manufacturing method of the present invention, schematically showing.
Nitrogen gas is heated and supplied in advance to prevent the temperature of magnesium from decreasing and promote the production of magnesium nitride (Mg ₃ N ₂ ).

Thus, in the third step, even if 16 crucibles 25... Having the maximum density are placed in the heating furnace 12, the time for producing magnesium nitride in all the crucibles 25. Manufacturing cycle time can be shortened.
Magnesium nitride reduces alumina (Al ₂ O ₃ ), so that alumina has better wettability.
In parallel with the reduction with magnesium nitride, the aluminum alloy 82 is dissolved.

FIG. 11 is an explanatory view (No. 5) of the third step of the manufacturing method of the present invention, which is schematically shown.
The molten aluminum alloy 82 penetrates into the gaps between the powders 81 made of alumina that has been reduced and has improved wettability. The aluminum alloy 82 is solidified to complete the aluminum-based composite material.

  The method for producing an aluminum-based composite material according to the present invention is suitable for producing a composite material whose base material is an aluminum alloy (including aluminum).

Sectional view of the aluminum matrix composite manufacturing apparatus of the present invention 2-2 sectional view of FIG. The perspective view of the gas preheating chamber and nozzle of the present invention Another embodiment diagram Explanatory drawing of the 1st process of the manufacturing method of this invention Explanatory drawing of the 2nd process of the manufacturing method of this invention Explanatory drawing of the 3rd process of the manufacturing method of this invention (the 1) Explanatory drawing of the 3rd process of the manufacturing method of this invention (the 2) Explanatory drawing of the 3rd process of the manufacturing method of this invention (the 3) Explanatory drawing of the 3rd process of the manufacturing method of this invention (the 4) Explanatory drawing of the 3rd process of the manufacturing method of this invention (the 5) Diagram explaining the basic principle of conventional technology

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Manufacturing apparatus of aluminum matrix composite material, 12 ... Furnace (heating furnace), 23 ... Heat source (heating means), 25 ... Crucible, 34 ... Nozzle, 48 ... Nitrogen supply means (nitrogen gas supply means), 56 ... Gas reserve Heating chamber, 81 ... powder, 82 ... aluminum alloy.

Claims (3)

A first step of placing a porous molded body or powder made of an oxide-based ceramic in a crucible, and placing an aluminum alloy on the porous molded body or powder;
A second step of accommodating a plurality of the crucibles together with magnesium or a magnesium source in a furnace;
The furnace is placed in a nitrogen atmosphere and heated to produce magnesium nitride, the porous molded body or powder is reduced by the action of magnesium nitride, and the molten aluminum alloy is infiltrated into the reduced porous molded body or powder. A third step of obtaining an aluminum matrix composite, and a method for producing an aluminum matrix composite comprising:
The method for producing an aluminum-based composite material, wherein the nitrogen atmosphere is formed by supplying nitrogen gas directly from directly above a plurality of crucibles into the crucible.   2. The method for producing an aluminum-based composite material according to claim 1, wherein the nitrogen gas is supplied by heating in advance. In an aluminum-based composite material manufacturing apparatus comprising a heating furnace for heating a workpiece, and a nitrogen supply means for supplying nitrogen to the heating furnace,
The nitrogen supply means includes a gas preheating chamber provided in the vicinity of the heat source in the heating furnace, to the gas preheating chamber, the crucible attach respectively to the central axis concentric with the plurality of crucibles contained in the work An apparatus for producing an aluminum-based composite material, comprising: a nozzle for supplying gas toward the inside.

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