JPH0841563A - Production of metal-ceramic composite material - Google Patents

Abstract

PURPOSE:To produce a composite material in which metal and ceramic are integrated without executing pressurizing or the like. CONSTITUTION:A pure Al block 7 and a ceramic porous formed body 8 are set in a crucible 3, and a prescribed amt. of Mg9 is set in a crucible 4. Thereafter, the inside of a furnace 1 is substituted by gaseous Ar, and the pressure in the furnace is reduced to 0.5atm to perfectly sublimate the Mg9 while heating the furnace up to >=900 deg.C. The same state is continued, and Mg vapor is uniformly dispersed into the porous formed body 8. Next, gaseous nitrogen is introduced into the furnace 1, is brought into reaction with the same sublimated Mg to form Mg3N2, and this Mg3N2 is brought into contact with Al2O3 formed on the surface of the porous formed body 8 and is reduced to expose Al. Since this Al is extremely active, it is high in wettability with the molten metal of Al (7a), thus, the molten metal Al (7a) of infiltrates into the porous formed body 8 in a short time and the porous formed body 8 sinks into the molten metal of Al (7a).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a composite material in which metal and ceramics are integrated.

[0002]

2. Description of the Related Art By integrating dissimilar materials, it is possible to obtain a composite material having the advantages of each material. Recently, a metal / ceramics composite material has been attracting attention as such a composite material, and a method for producing the metal / ceramics composite material has not been conventionally used because the metal as a base material has poor wettability with respect to ceramics (reinforcement material). After setting the reinforcing material in the mold, pressure casting is performed to pressurize the molten metal and forcibly form a composite.

[0003]

In the above-mentioned conventional method, a mold and a pressurizing device are required, which is a large scale as a whole. In addition, the volume ratio (V
f) changes, and it is difficult to produce a composite material having a larger size.

[0004]

In order to solve the above-mentioned problems, the present invention sets a porous compact made of oxide ceramics such as Al ₂ O ₃ and magnesium in a furnace, and sets Ar in the furnace. Magnesium is sublimed in a rare gas atmosphere such as, and magnesium vapor is dispersed in the porous compact, and nitrogen gas is further introduced into the furnace to react with the sublimed magnesium and magnesium nitride (Mg ₃ N ₂ ) To produce A on the surface of the porous molded body.
The metal atom was exposed by bringing it into contact with an oxide such as l ₂ O ₃ to reduce the metal atom, and then the metal melt was permeated into the porous molded body by a capillary phenomenon or the like.

Here, the sublimation of magnesium is preferably carried out not only in a rare gas atmosphere but also under reduced pressure, and the oxygen concentration in the furnace for sublimation of magnesium is 1
% Or less is preferable.

[0006]

When Mg ₃ N ₂ comes into contact with the oxide film such as Al ₂ O ₃ covering the surface of the porous molded body, oxygen constituting the oxide film is bonded to Mg and the metal atom is exposed on the surface of the molded body. To do. By exposing the pure metal in this way, the surface is activated and enters a state of extended wetting with a wetting angle of approximately 0 °, and the molten metal instantly penetrates into the porous molded body.

[0007]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Here, FIG. 1 illustrates the method of the present invention in the order of steps, in which (a) is a diagram showing a state in the furnace before the start of compounding, and (b) is a state in the furnace in which Mg is sublimated. FIG. ₂ (c) is a view showing a state in the furnace where N ₂ gas is introduced, (d) is a view showing a state where the porous compact is submerged in the molten metal, and FIG. 2 is an atomic arrangement. Shown among these (a)
Is a schematic diagram of the atomic arrangement of Al powder particles in the state where Mg is sublimated, (b) is a schematic diagram showing the state in which sublimated Mg and N are bonded, and (c) is a state in which Mg and O are bonded and Al is exposed. It is a schematic diagram which shows the state which was done.

In the drawing, reference numeral 1 denotes a furnace, a heater 2 is arranged outside the furnace 1, graphite crucibles 3 and 4 are provided in the furnace 1, and a gas introducing pipe 5 and a gas are further provided in the furnace 1. The discharge pipe 6 is connected via valves 5a and 6a.

In order to manufacture a composite material using the above apparatus, first, as shown in FIG. 1 (a), a pure Al block 7 and a porous molded body 8 are set in the crucible 3, and A predetermined amount of magnesium 9 is set in the crucible 4. Here, as the porous molded body 8, Al ₂ O ₃ fiber or Al ₂ O _{3 is used.}
For example, the volume ratio (Vf) of particles is about 20%.

After that, as shown in FIG. 1B, the inside of the furnace 1 was replaced with Ar gas, the temperature was raised to 900 ° C., and the inside of the furnace was 0.5 atm.
Magnesium 9 is completely sublimated by reducing the pressure to. The state of the atoms at this time is shown in FIG.
By raising the temperature to 900 ° C, block 7 of pure Al
Becomes molten metal 7a, but since the porous molded body 8 contains gas, the porous molded body 8 floats on the molten metal 7a.

This state is continued for about 30 seconds to uniformly disperse the magnesium vapor in the porous compact 8 and then
As shown in FIG. 1 (c), nitrogen gas is introduced into the furnace 1 at an internal pressure of 1 at
It is introduced until it reaches m and reacted with the sublimed magnesium to form magnesium nitride (Mg ₃ N ₂ ).
The state of the atoms at this time is shown in FIG.

Then, by holding at 900 ° C. to 950 ° C. for about 10 minutes, the generated magnesium nitride (Mg ₃ N
_The metal atom (Al) is exposed by bringing ₂ ) into contact with the fibers or the particles of Al ₂ O ₃ formed on the surface of the particles forming the porous molded body 8 to reduce it.

The reaction formula in the furnace is shown below. As can be seen from ΔG (Gibbs standard energy of formation) in these equations, O atoms are released from Al ₂ O _{3 in} the presence of Mg ₃ N ₂ . _{3Mg (gas) = + N 2} = Mg 3 N 2 ΔG = -202KJ (950 ℃) 2Mg 3 N 2 + 2Al 2 O 3 2AlN + 6MgO + 2Al +
_{N 2 ΔG = -191KJ (950 ℃} ) Mg 3 N 2 + 2Al 2 O 3 + 3Mg = 2AlN + 6MgO + 2
Al ΔG = -396KJ (950 ° C)

As described above, the O atom is desorbed from Al ₂ O ₃ and the remaining Al is extremely active.
The wettability with is in a state of extended wetting with a wetting angle of approximately 0 °,
In a short time, the Al melt 7a penetrates into the porous compact 8 and the porous compact 8 sinks into the Al melt 7a as shown in FIG. 1 (c).

Then, when the product was taken out after being rapidly cooled to 200 ° C., an extremely dense metal / ceramic composite material having the interior filled with pure Al was obtained.

The following (Table 1) and FIG. 3 show the relationship between the oxygen concentration in the furnace and the composite rate. As is clear from these (Table 1) and FIG. 3, the oxygen concentration in the furnace is The lower the better. However, if the oxygen concentration is 1% or less, the composite rate is 90% or more, so a sufficient value can be obtained.

[0017]

[Table 1]

The following (Table 2) shows the degree of compounding when Mg and other elements are added to pure Al and utilized as an Al alloy. From this (Table 2), Mg
1 to 14 wt% is suitable for the porous molded body, and preferably 4 to 14 wt%, and Ca, Si, or Cu does not cause complexation.

[0019]

[Table 2]

In the embodiment, the porous compact was set on the pure Al before melting, and the molten pure Al was automatically permeated into the porous compact. It is also possible to prepare a molten solution of pure Al at a position and pour the molten solution of pure Al into the porous compact whose surface is activated by reduction.

[0021]

According to the present invention as described above,
Magnesium nitride (Mg ₃ N ₂ ) is brought into contact with the oxide on the surface of the porous compact made of oxide-based ceramics as a reinforcing material, oxygen is removed by reduction and metal atoms such as Al are exposed, resulting in an extremely active state. Then, since the molten metal was made to penetrate into this porous molded body, the wettability between the metal and the oxide-based ceramics is improved,
A metal / ceramic composite material with extremely high adhesion can be obtained.

Further, according to the method of the present invention, it is not necessary to pressurize the molten metal so that it penetrates into the reinforcing material as in the conventional method.
The device does not become large, and the metal / ceramic composite material can be obtained at low cost.

[Brief description of drawings]

FIG. 1 (a) is a diagram showing a state in a furnace before the start of compounding,
(B) is a figure which shows the state in the furnace which sublimated Mg, (c)
Is a diagram showing a state in the furnace where N ₂ gas is introduced, and (d) is a diagram showing a state in which the porous compact is submerged in the molten metal.

FIG. 2 (a) is a schematic diagram of an atomic arrangement of Al powder particles in a state where Mg is sublimated, (b) is a schematic diagram showing a state in which sublimated Mg and N are bonded, and (c) is Mg and O. Schematic diagram showing a state in which and are combined and Al is exposed

FIG. 3 is a graph showing the relationship between oxygen concentration and composite rate.

[Explanation of symbols]

1 ... Furnace, 3, 4 ... Crucible, 7 ... Pure Al, 7a ... Melt of pure Al, 8 ... Porous compact, 9 ... Magnesium.

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[Procedure amendment]

[Submission date] August 4, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction content]

The reaction formula in the sintering furnace is shown below. 3Mg (gas) + N ₂ = Mg ₃ N ₂ 2Mg ₃ N ₂ + 2Al ₂ O ₃ = 2AlN + 6Mg O + 2Al +
_{N 2 Mg 3 N 2 + 2Al} 2 O 3 + 3Mg = 2AlN + 6MgO + 2
Al these formulas .DELTA.G (standard formation Gibbs energy) is negative, since the reaction proceeds to the right, Al ₂ in the presence of Mg ₃ N ₂
O atom is released from O ₃ .

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 2

[Correction method] Change

[Correction content]

[Fig. 2]

Claims (4)

[Claims] 1. A porous compact made of oxide-based ceramics and magnesium are set in a furnace, magnesium is sublimated in the furnace in a rare gas atmosphere, and the magnesium vapor is dispersed in the porous compact. Further, by introducing nitrogen gas into the furnace and reacting it with the sublimed magnesium to generate magnesium nitride (Mg ₃ N ₂ ), the magnesium nitride is brought into contact with the oxide on the surface of the porous compact to reduce it. A method for producing a metal / ceramic composite material, which comprises exposing metal atoms and then infiltrating a molten metal into the porous molded body. 2. The method for producing a metal / ceramic composite material according to claim 1, wherein the sublimation of magnesium is performed in a rare gas atmosphere and under reduced pressure. 3. The metal according to claim 1 or 2.
In the method for producing a ceramic composite material, a method for producing a metal-ceramic composite material, characterized in that a molten metal is permeated into the porous molded body by a capillary phenomenon. 4. The method of manufacturing a metal / ceramic composite material according to claim 1, wherein the oxygen concentration in the furnace for sublimating magnesium is 1% or less. Composite material manufacturing method.