JP2998828B2 - Manufacturing method of metal / ceramic composite material - Google Patents

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 a metal and a ceramic are integrated.

[0002]

2. Description of the Related Art By integrating dissimilar materials, a composite material having the advantages of each material can be obtained. Recently, a metal / ceramic composite material has attracted attention as such a composite material. This method of producing a metal / ceramic composite material has not been conventionally used because the base metal has poor wettability to ceramics (reinforcement). After setting the reinforcing material in the mold, pressure casting is performed to forcibly composite the molten metal by pressurizing it.

[0003]

In the above-mentioned conventional method, a mold and a pressurizing device are required, and the whole becomes large. In addition, the volume ratio (V
f) changes, making it difficult to produce composites of larger dimensions.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention sets a porous compact made of an oxide ceramic such as Al ₂ O ₃ and magnesium in a furnace, and sets the inside of the furnace to Ar. Sublimate magnesium in a rare gas atmosphere such as above, disperse the magnesium vapor in the porous molded body, further introduce nitrogen gas into the furnace, react with the sublimated magnesium, and react with magnesium nitride (Mg ₃ N ₂ ). Is formed, and this magnesium nitride is converted to A on the surface of the porous molded body.
The metal atoms were exposed by being brought into contact with an oxide such as l ₂ O ₃ to reduce the metal atoms, and then the molten metal was allowed to penetrate into the porous molded body by capillary action or the like.

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

[0006]

[Function] When Mg ₃ N ₂ comes into contact with an oxide film such as Al ₂ O ₃ covering the surface of the porous formed body, oxygen constituting the oxide film is combined with Mg, and metal atoms are exposed on the surface of the formed body surface. I do. By exposing the pure metal in this way, the surface is activated to be in an extended wetting state with a wetting angle of approximately 0 °, and the molten metal instantaneously 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) shows a state in a furnace before the start of compounding, and (b) shows a state in a furnace where Mg is sublimated. FIG. 2C is a diagram showing a state in a furnace into which N ₂ gas has been introduced, FIG. 2D is a diagram showing a state in which a porous molded body is submerged in a molten metal, and FIG. (A)
Is a schematic view of the atomic arrangement of Al powder particles in a state where Mg is sublimated, (b) is a schematic view showing a 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 carried out.

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

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

Thereafter, as shown in FIG. 1B, the inside of the furnace 1 is replaced with Ar gas, the temperature is raised to 900 ° C., and the inside of the furnace is 0.5 atm.
The pressure is reduced to completely sublimate the magnesium 9. The state of the atoms at this time is shown in FIG.
By raising the temperature to 900 ° C., the pure Al block 7
Is the molten metal 7a, but since the gas is contained in the porous molded body 8, the porous molded body 8 is floating on the molten metal 7a.

This state is continued for about 30 seconds to uniformly disperse the magnesium vapor in the porous molded body 8.
As shown in FIG. 1 (c), nitrogen gas is introduced into the furnace 1 at an internal pressure of 1 at.
m, and reacted with the sublimated magnesium to produce 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 produced magnesium nitride (Mg ₃ N
₂ ) is brought into contact with Al ₂ O ₃ formed on the surface of the fibers or particles constituting the porous molded body 8 to reduce the metal atoms (Al).

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 + 6MgO + 2Al + N 2 Mg 3 N 2 + 2Al 2 O 3 + 3Mg = 2AlN + 6MgO + 2Al ( standard formation energy of Gibbs) .DELTA.G of these equations is negative, since the reaction proceeds to the right, Al ₂ in the presence of Mg ₃ N ₂
O atoms are eliminated from O ₃ .

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

Thereafter, the product was rapidly cooled to 200 ° C. and the product was taken out. As a result, an extremely dense metal / ceramic composite material in which the inside was 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 compounding ratio. As is clear from Table 1 and FIG. It is better to be as low as possible. However, if the oxygen concentration is 1% or less, the composite ratio becomes 90% or more, so that 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 used as an Al alloy. From this (Table 2), Mg
1 to 14% by weight, preferably 4 to 14% by weight, is added to the porous molded body, and no complexation occurs with Ca, Si or Cu.

[0019]

[Table 2]

In the embodiment, the porous molded body is set on the pure Al before melting, so that the molten pure Al automatically penetrates into the porous molded body. A pure Al melt may be prepared at a location, and the pure Al melt may be poured into a porous compact whose surface has been activated by reduction.

[0021]

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

Further, according to the method of the present invention, there is no need to pressurize the molten metal to permeate the reinforcing material as in the prior art.
The apparatus does not need to be large and a metal / ceramic composite material can be obtained at low cost.

[Brief description of the drawings]

FIG. 1A is a diagram showing a state in a furnace before the start of compounding,
(B) is a diagram showing a state in the furnace where Mg has been sublimated, (c).
Is a view showing a state in a furnace into which N ₂ gas is introduced, and (d) is a view showing a state in which a porous formed body is submerged in a molten metal.

FIG. 2 (a) is a schematic view of the atomic arrangement of Al powder particles in a state where Mg is sublimated, FIG. 2 (b) is a schematic view showing a state in which sublimated Mg and N are bonded, and FIG. Schematic diagram showing a state in which Al is exposed by bonding with

FIG. 3 is a graph showing a relationship between an oxygen concentration and a composite ratio.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Furnace, 3, 4 ... Crucible, 7 ... Pure Al, 7a ... Melt of pure Al, 8 ... Porous molded body, 9 ... Magnesium.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C22C 1/09 C22C 1/10 B22D 19/14

Claims (4)

(57) [Claims] 1. A porous molded body made of an oxide-based ceramic and magnesium are set in a furnace, and magnesium is sublimated in a rare gas atmosphere in the furnace to disperse the magnesium vapor in the porous molded body. Further, nitrogen gas is introduced into the furnace, and reacted with the sublimated magnesium to generate magnesium nitride (Mg ₃ N ₂ ). The magnesium nitride is brought into contact with an oxide on the surface of the porous formed body to reduce it. A method for producing a metal / ceramic composite material, comprising 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,
A method for producing a ceramic composite material, wherein a molten metal is permeated into the porous molded body by capillary action. 4. The method of claim 1, in the method for manufacturing a metal-ceramic composite material according to claim 2 or claim 3, the oxygen concentration in the furnace for performing the sublimation of the magnesium and characterized in that a 1% or less Of manufacturing metal-ceramic composite materials.