JP2003286506A - Air-permeable metallic material and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing an air-permeable metallic material in a low temperature and low pressure condition, and to provide the metallic material having superior air permeability, which can be manufactured in the low temperature and low pressure condition. <P>SOLUTION: The method for obtaining the air-permeable metallic material 7 comprises preparing an SnO<SB>2</SB>powder 1 of an oxide of a low-melting metal, and an Fe powder or a nickel powder 2 which forms an intermetallic compound between itself and the SnO<SB>2</SB>powder 1, mixing the SnO<SB>2</SB>powder 1 with the Fe powder or the Ni powder 2, then molding a mixture of the metal powders to obtain a compact 3 of the metal powders, and further reducing the compact 3 of the metal powders in a reducing atmosphere at a low temperature. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a breathable metal material. The most important application of breathable metallic materials is in filters. For example, it is used in all industrial fields such as filtration of fuel and oil for automobiles, removal of uranium compounds in the field of nuclear power, and protection of valves, nozzles and instruments in high pressure fluid circuits. In addition, there are many applications that utilize the large specific surface area of breathable metal materials. For example, the porous nickel electrode of an alkaline battery or a fuel cell utilizes the effect that the reaction is extremely fast as compared with the bulk material because of its large specific surface area. The discharge cooling method using a gas permeable metal material used for gas turbine engine parts and nose tips of missiles utilizes the fact that heat exchange is easy because of its large specific surface area.

[0002]

2. Description of the Related Art At present, bronze, stainless steel, nickel alloys, titanium and aluminum are mainly used as breathable metal materials, and they are often manufactured by powder metallurgy. The manufacturing process of this powder metallurgy varies depending on the type of raw material powder and the purpose of use of the material to be made, but in general, (1) "milling process" for manufacturing powder, (2) component or particle size distribution is adjusted. , "Mixing process" to stabilize the operation in the next process by adding a lubricant, etc. (3) Fill the mold with powder and press it with the upper and lower punches, or pack the powder in a rubber bag and leave it quiet. "Compression molding process" in which compacts called green compacts or green compacts are created by applying water pressure. (4) Sintering that gives the desired properties by baking and compacting the compact at high temperature. After the sintering process, compression and sintering are repeated again depending on the application to densify and improve the strength, and for dimensional correction and corrosion resistance and wear resistance improvement to improve dimensional accuracy. Surface treatment may be applied.

In order to deepen the understanding of the present invention, the manufacturing process of the metal powder will be further described.

As a means for producing powder, for example, in the case of iron alloy powder, a "water atomizing method" is used in which a high-pressure water jet exceeding 20 MPa is sprayed on the flow of molten iron alloy to obtain fine powder.
Alternatively, a “gas atomizing method” using N ₂ or Ar gas in place of this high-pressure water, a “quench solidification method” in which a molten iron alloy is rapidly solidified to obtain fine powder, and the like, nickel alloy powder is used. The above-mentioned "water atomization method", "gas atomization method", "quenching solidification method", or vapor of carbonyl nickel Ni (CO) _{4 having} a boiling point of 103 ° C is 247 to 3
The "carbonyl method" for contacting the wall surface at 47 ° C to decompose into Ni fine powder and the "mechanical alloying method" for pulverizing alloy element powder with a high energy ball mill to obtain mechanical alloy powder in which oxides are finely dispersed are adopted. ing.

In addition, the powder mixing step is (1) "blending" for stabilizing the operating conditions in the powder processing process and adjusting the particle size distribution of the raw material powder in order to obtain a sintered part having the desired performance. It is suitable for fine powder because it has a mixing process such as "mixing" in which different kinds of powder such as carbon or lubricant is added, and (2) fine particles of several μm or less are easily aggregated and have poor fluidity. Granulation treatment to give agglomerated particles whose particle size and particle shape are adjusted by various methods, and (3) ceramic particles and organic particles mixed in the manufacturing process cause a decrease in strength, such as oxygen, nitrogen and water. Since the adsorbed gas weakens the crystal grain boundaries, the cleaning treatment performed to remove these mixed particles and adsorbed gas, and (4) the oxide film on the surface of the powder particles impairs compression moldability and reduces the green compact strength. Low Since thereby the reduction removal of the surface oxide film, includes a annealing process for the purpose of softening of the powder to improve the compressibility, each of these processes is performed as required.

Further, compression molding means that by compressing metal powder, large voids are filled and densification is started, and further compression starts adhesion at the contact portion of the powder particles and plastic deformation of the entire powder particles. Finally, it is a molding method for making the powder compact as close as possible to the true density. As a compression molding means for obtaining a powder compact having a density ratio (apparent density / true density), which is an index of the ease of clogging of metal powder, closer to 1, cold isostatic pressing, hot pressing, etc. Often, pressure forming is performed. However, in cold isostatic pressing, generally 50
A high pressure of 00 kg / cm ² is applied to the metal powder, and in hot isostatic pressing, a high pressure of up to 2000 kg / cm ² is generally applied to the metal powder at a temperature below the melting point of the metal.

Finally, the sintering conditions such as the sintering temperature, the time, and the sintering atmosphere in the sintering process performed to give sufficient strength and desired properties are determined by the kind of powder, the properties, and the sintering material. Although it is set precisely according to various characteristics to be set, for example, 1100 to 1300 ° C for iron-based alloy steel, 1100 to 1350 ° C for stainless steel, and 1200 to 130 for Ti alloy.
It is sintered at an extremely high temperature such as 0 ° C.

[0008] For example, as a method for producing this type of porous cemented carbide, Japanese Patent Laid-Open No. 3-138304 discloses "WC.
Is used as the main component, and Ni or Co as the binding component and one or more of Cr, Ti, and Ta as the component for improving the characteristics are blended into a raw material powder, and the granulated powder is injected into a molding die. Pre-sintering for 30 minutes at 1160 ℃ in a vacuum atmosphere,
This temporary sintered body is cooled at 1370 ° C. in a vacuum atmosphere after furnace cooling.
A method of time main sintering "is disclosed. in this way,
In the method for producing a porous cemented carbide described in the publication, sintering is performed at an extremely high temperature.

[0009] Further, in the research result report of the New Energy Industrial Technology Development Organization in 1998, bubbles are generated in one direction in the metal due to precipitation of supersaturated gas atoms during unidirectional solidification from the molten state of the metal. A method for producing a lotus-type porous metal is described. However, in order to melt the metal according to this manufacturing method, for example, in the case of copper, it is necessary to raise the temperature to 1083 ° C. or higher.

[0010]

When the breathable metal material is manufactured by the powder metallurgy method, as described above, (1) "milling step", (2) "mixing step", (3) "compression molding step". "
And (4) a step corresponding to the "sintering step" is required, and the current compression molding method requires high temperature and high pressure, and sintering also requires high temperature. In order to realize and maintain the high temperature and high pressure state, equipment with a strong structure capable of withstanding it is required, which increases the equipment cost. In addition, maintaining high-temperature and high-pressure operation poses a safety problem.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to provide a method and a low temperature and low pressure which can produce a breathable metal material under low temperature and low pressure conditions. It is to provide a metal material having excellent breathability that can be manufactured under the conditions.

[0012]

In order to achieve the above object, the present invention provides a low melting point metal oxide and another metal forming an intermetallic compound between the low melting point metal at a low temperature. By placing in a reducing atmosphere, the oxide of the low melting point metal is reduced and the low melting point metal is melted to form an intermetallic compound having excellent air permeability between the melted low melting point metal and the other metal. .

For example, between iron and tin, FeSn having a melting point of 1130 ° C. can be obtained as shown in FIG. 11, and between nickel and tin as shown in FIG.
Ni ₃ Sn ₂ having a melting point of 1264 ° C. can be obtained.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION That is, the method for producing a gas permeable metallic material according to the present invention comprises a powder of an oxide of a low melting point metal and a powder of another metal forming an intermetallic compound between the powder of the low melting point metal and the powder. And mixing the powder of the low-melting metal oxide with the powder of the other metal, and then molding the mixture of the metal powder to obtain a metal powder compact, and further adding the low-melting metal powder compact to the metal powder compact. The feature is that the reduction treatment is performed in a reducing atmosphere at a temperature.

For the breathable metal material of the present invention, a powder of an oxide of a low melting point metal and a powder of another metal forming an intermetallic compound between the low melting point metal are prepared. Mix the powder of the metal oxide and the powder of the other metal,
Then, the mixture of the metal powders is molded to obtain a metal powder compact, and the metal powder compact is subjected to a reducing treatment in a reducing atmosphere at a low temperature.

As the low melting point metal, mercury, cesium, gallium, rubidium, potassium, sodium, indium, lithium, selenium, tin, bismuth, thallium, zinc, tellurium, antimony, magnesium or aluminum can be used. Among the above metals, an element having a small free energy for oxide formation (which is easily oxidized) is not preferable. This is because an element having a small free energy for oxide formation is not easily reduced with hydrogen and the desired intermetallic compound is not formed.

The low melting point metal preferably has a low vapor pressure. This is because it is not preferable that the metal melt evaporates easily when the low melting point metal melts.

As a matter of course, a highly toxic metallic element is not preferable.

As the low melting point metal which does not have these disadvantages (large free energy of oxide formation, low vapor pressure, low toxicity or non-toxicity), gallium (melting point 30 ° C., boiling point 2400 ° C.), indium (melting point) 157 ° C, boiling point 20
80 ° C), tin (melting point 232 ° C, boiling point 2080 ° C), bismuth (melting point 271 ° C, boiling point 1560 ° C), thallium (melting point 304 ° C, boiling point 1457 ° C), tellurium (melting point 45).
0 ° C., boiling point 990 ° C.) and antimony (melting point 631 ° C., boiling point 1750 ° C.) are particularly preferable. The reduction temperature of these low melting point metal oxides is preferably 700 ° C. or lower.

As the other metal forming the intermetallic compound with the low melting point metal, iron, cobalt, nickel, palladium, platinum, copper, silver or gold can be used.

For example, selecting tin as the low melting point metal,
If iron or nickel is selected as the other metal forming an intermetallic compound with tin, and tin oxide powder and iron powder or nickel powder are mixed and reduced at low temperature, tin oxide is reduced and metal tin The molten metal penetrates into the gap between the iron powder or the nickel powder by melting, and an intermetallic compound is formed between the tin and the iron or nickel.

[0022]

EXAMPLES Examples of the present invention will be described below. (1) Preparation of raw materials and production of breathable metal material a. Manufacture of powder SnO as oxide of low melting point metal
₂ was selected, and iron or nickel was selected as the other metal. The iron powder powdered by the gas atomizing method was used, and the particle size of the iron powder obtained by sieving was in the range of 150 to 177 μm. The nickel powder used was powdered by the carbonyl method, and the average particle size was 150 μm. Also, SnO
The average particle size of the _two powders was 0.8 μm. Scanning electron microscope (SEM) photographs of iron powder are shown in FIGS. 1 (a) and 1 (b). 1 (a) has a magnification of 100 times, and FIG. 1 (b)
Has a magnification of 500 times. Scanning electron microscope (SEM) photographs of nickel powder are shown in FIGS. 2 (a) and 2 (b). 2 (a) has a magnification of 200 times, and FIG. 2 (b) has a magnification of 500 times. b. Mixing of powders SnO ₂ powder can be applied to the surface of iron powder or nickel powder when reduced to metallic tin.
The amount of SnO obtained by calculating so as to have a thickness of 0 μm
₂ powder (1 in FIG. 3 (a)) is mixed with iron powder or nickel powder (2 in FIG. 3 (a)), and this SnO ₂ powder and iron powder are mixed or SnO ₂ powder and nickel powder are mixed. The obtained mixture was uniformly mixed in a mortar.

The amount of Sn obtained by calculation so that the thickness of the iron powder is 10 μm when reduced to metallic tin
A mixture and mixture of O ₂ powder is called FS10, and 10 μm when reduced to metallic tin on the surface of nickel powder.
A mixture of SnO ₂ powder in an amount obtained by calculating so as to have the above thickness is referred to as NS10. c. Molding of powders Mold molding is adopted as the molding means of powders, the molding method is uniaxial compression molding, and the molding pressure of FS10 is 100kg.
/ Cm ^2, and the molding pressure of NS10 is 60 kg / cm
By setting it to ² , a molded body 3 as shown in FIG. 3 (b) was obtained. As described above, according to the present invention, mold molding can be adopted as the powder molding means, and the molding pressure may be about 100 kg / cm ² (about 10 MPa) or less. d. The low temperature reduction molded body 3 of the molded body is inserted into an electric furnace as shown by 4 in FIG. 3 (c), hydrogen is introduced into the electric furnace 4 through an inlet 5, and the heater 6
The inside of the electric furnace 4 is heated to 600 ° C. by
After the time reduction treatment, a breathable metal material 7 having a shape as shown in FIG. 3 (d) was obtained.

FIG. 3E is an enlarged schematic view of a part of the metal material 7. The metal 8 in the shaded area represents Fe or Ni element, and the Fe element 8 or Ni element 8 is surrounded by Sn9. Is shown. (2) Test results a. FS10 FIG. 4 is a SEM photograph of the FS10 surface after reduction treatment at 600 ° C. for 1 hour, and FIG. 4 (a) shows the case of 50 times magnification.
FIG. 4B shows the case of 200 times.

In FIG. 4 (a), the portion indicated by the arrow indicates a void, and the iron powder and the tin powder form good intermetallic compounds as a whole, and the voids are present in an appropriate distribution state. I can ask.

FIG. 5 shows F after reduction treatment at 600 ° C. for 1 hour.
5 is a SEM photograph of S10 cross section, FIG.
FIG. 5B shows a kα X-ray photograph of Fe, and FIG. 5C shows a Lα X-ray photograph of Sn. Figure 5
From (a) to (c), Sn exists around Fe and Fe
It can be seen that an intermetallic compound is formed between Sn and Sn.

FIG. 6 shows F after reduction treatment at 600 ° C. for 1 hour.
It is a Cuk alpha X-ray diffraction pattern of the S10 surface. As is clear from FIG. 6, the intermetallic compound FeSn is generated. b. NS10 FIGS. 7A and 7B are SEM photographs of the surface of NS10 after reduction treatment at 600 ° C. for 1 hour. FIG. 7A shows a case of 50 times, and FIG. 7B shows a case of 200 times.

In FIG. 7 (a), the portion indicated by an arrow indicates a void, and the nickel powder and the tin powder as a whole form a good intermetallic compound, and the void is present in an appropriate distribution state. I can ask.

FIG. 8 shows N after reduction treatment at 600 ° C. for 1 hour.
8 is a SEM photograph of the S10 cross section, and FIG.
FIG. 8 (b) shows a kα X-ray photograph of Ni, and FIG. 8 (c) shows a Lα X-ray photograph of Sn. Figure 8
From (a) to (c), Sn exists around Ni and Ni
It can be seen that an intermetallic compound is formed between Sn and Sn.

FIG. 9 shows N after reduction treatment at 600 ° C. for 1 hour.
It is a Cuk alpha X-ray diffraction pattern of the S10 surface. As is clear from FIG. 9, the intermetallic compounds Ni ₃ Sn and Ni ₃ SN ₂
You can see that is generated. c. Air permeability test As shown in FIG. 10, a predetermined amount of water 11 is stored at the bottom of a bottomed cylindrical body 10 having an inner diameter substantially equal to the outer diameter of the metal material 7 shown in FIG. A metal material 7 having a shape shown in FIG. 3E is inserted therein, and a predetermined amount of water 12 is stored on the metal material 7, and an air inlet pipe 14 connected from the valve 13 to the bottom of the cylindrical body 10 is inserted. After passing high pressure air (1.5 kg / cm ² ) into the cylindrical body 10 and observing the cylindrical body 10 from above, it was observed that many bubbles 15 rise in the water 12. In this way, it was confirmed that the metal material 7 has sufficient air permeability.

[0031]

Since the method of the present invention is configured as described above, it is possible to manufacture a breathable metal material under low temperature and low pressure conditions. Further, according to the present invention, it is possible to provide a metal material having excellent air permeability.

[Brief description of drawings]

FIG. 1 is a scanning electron microscope (SEM) photograph of iron powder, and FIG. 1 (a) shows a magnification of 100 times.
(B) has a magnification of 500 times.

FIG. 2 is a scanning electron microscope (SE) of nickel powder.
M) is a photograph, and FIG. 2 (a) is a magnification of 200 times,
In FIG. 2B, the magnification is 500 times.

FIG. 3 is a diagram showing a schematic manufacturing process of the breathable metal material of the present invention.

FIG. 4 shows FS1 after reduction treatment at 600 ° C. for 1 hour.
It is a SEM photograph of 0 surface, FIG.4 (a) shows the case of 50 times, FIG.4 (b) shows the case of 200 times.

FIG. 5 shows FS1 after reduction treatment at 600 ° C. for 1 hour.
It is a SEM photograph of 0 cross section, FIG.5 (a) shows the case of 1000 time, FIG.5 (b) shows the k (alpha) X-ray photograph of Fe,
FIG. 5C shows an Lα X-ray photograph of Sn.

FIG. 6 is a Cukα X-ray diffraction pattern of the FS10 surface after reduction treatment at 600 ° C. for 1 hour.

FIG. 7 shows NS1 after reduction treatment at 600 ° C. for 1 hour.
It is a SEM photograph of 0 surface, FIG.7 (a) shows the case of 50 times, FIG.7 (b) shows the case of 200 times.

FIG. 8 shows NS1 after reduction treatment at 600 ° C. for 1 hour.
It is a SEM photograph of 0 cross section, FIG.8 (a) shows the case of 1000 times, FIG.8 (b) shows the k (alpha) X-ray photograph of Ni,
FIG. 8C shows a Lα X-ray photograph of Sn.

FIG. 9 is a Cukα X-ray diffraction pattern of the NS10 surface after reduction treatment at 600 ° C. for 1 hour.

FIG. 10 is a diagram illustrating a method for testing air permeability of a metal material.

FIG. 11 is an Fe—Sn system binary state diagram.

FIG. 12 is a Ni-Sn system binary state diagram.

[Explanation of symbols]

1 ... SnO ₂ powder 2 ... Iron powder or nickel powder 4 ... Electric furnace 6 ... Heater 7 ... Breathable metal material 8 ... Iron or nickel 9 ... Tin

Claims (6)

[Claims] 1. A low melting point metal oxide powder and a powder of the other metal forming an intermetallic compound between the low melting point metal are prepared, and the powder of the low melting point metal oxide and the other metal are prepared. And a mixture of the metal powders, and then the mixture of the metal powders is molded to obtain a metal powder compact, and the metal powder compact is subjected to a reduction treatment in a reducing atmosphere at a low temperature. Of manufacturing a conductive metal material. 2. The reduction temperature is 700 ° C. or lower.
A method for producing the breathable metal material as described above. 3. The low melting point metal is mercury, cesium, gallium, rubidium, potassium, sodium, indium,
Lithium, selenium, tin, bismuth, thallium, zinc,
The method for producing a breathable metal material according to claim 1 or 2, which is tellurium, antimony, magnesium or aluminum, and the other metal is iron, cobalt, nickel, palladium, platinum, copper, silver or gold. 4. A low melting metal oxide powder and another metal powder forming an intermetallic compound between the low melting metal oxide powder are prepared, and the low melting metal oxide powder and the other metal powder are prepared. And the air permeability obtained by subjecting the mixture of the metal powder to a metal powder compact to obtain a metal powder compact, and further subjecting the metal powder compact to a reduction treatment in a reducing atmosphere at a low temperature. Metal material. 5. The reduction temperature is 700 ° C. or lower.
The breathable metal material described. 6. The low melting point metal is mercury, cesium, gallium, rubidium, potassium, sodium, indium,
Lithium, selenium, tin, bismuth, thallium, zinc,
The breathable metal material according to claim 4 or 5, which is tellurium, antimony, magnesium or aluminum, and the other metal is iron, cobalt, nickel, palladium, platinum, copper, silver or gold.