JPH05209241A - Metallic porous material - Google Patents

Abstract

PURPOSE:To improve the adhesion of a layer of Al-based metal fibers and to provide a metallic porous material having excellent corrosion and weather resistance as well as enhanced rigidity. CONSTITUTION:A layer of Al-based metal fibers is compressed and immersed in or coated with a soln. of an auxiliary for improving the adhesion of the Al-based metal fibers to each other, preferably of water-soluble alkali silicate, cellulosic resin, acrylic resin, phenolic resin or fluororesin.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a porous metal material.
More specifically, the present invention relates to a porous metal material made of an aluminum-based metal fiber that improves the adhesion of the aluminum-based metal fiber layer to increase the rigidity and also has excellent corrosion resistance and weather resistance.

[0002]

2. Description of the Related Art Conventionally, the production of porous metal materials has been mainly a sintering method and a foaming method. However, since these porous materials are binders that are sintered in a container such as a mold, they are poor in workability such as bending. Also,
When the metal particles are sintered into a porous material, a low melting point substance is mixed with the metal particles to be sintered to form the porous material, and thus the atmosphere during sintering also requires a troublesome adjustment. However, the cost will increase. Furthermore, there are problems in terms of corrosion resistance and weather resistance.

To address these problems, the present inventor has found that aluminum (hereinafter referred to as Al) expanded metal and A
We have invented a metal porous material which is excellent in workability and environmental hygiene and can be manufactured at low cost by laminating an l-based metal fiber layer and pressing them together, and previously proposed this. (See JP-A-62-28922).

On the other hand, the inventor of the present invention, as a porous metal material having more excellent corrosion resistance and weather resistance, has a coating of a water-soluble alkali silicate-based substance on the surface of a metal porous material such as a metal sintered material or a metal fiber. Inventing a metal porous material having the above-mentioned structure and previously proposing it (see JP-A-62-202005).

[0005]

These metallic porous materials have properties such as workability, cost performance, corrosion resistance, and weather resistance that are different from conventional metallic porous materials such as sintered metal materials. It has extremely excellent performance and can be suitably applied to various applications such as sound absorbing materials, filter materials, and catalysts.

However, the demands on the porous metal material have become more and more diversified, and it is further desired to develop a porous metal material having various characteristics according to the use.

An object of the present invention is to solve the above-mentioned problems, and to improve the adhesion of the aluminum-based metal fiber layer to increase the rigidity, and also to improve the corrosion resistance and weather resistance of the metal porous metal. To provide quality materials.

[0008]

In order to solve the above-mentioned problems, the present invention comprises the steps of compressing an aluminum-based metal fiber layer and then dipping or applying it in an auxiliary agent for assisting adhesion between the aluminum fibers. A metal porous material is provided.

Further, it is preferable that the auxiliary agent is a water-soluble alkali silicate.

The alkali contained in the water-soluble alkali silicate-based substance is alkali metal, tertiary amine,
It is preferably one or more compounds selected from the group consisting of and quaternary amines.

Further, the auxiliary agent is one of cellulose-based, acrylic-based, phenol-based, or fluoride-based resins.
The above is preferable.

The metal porous material of the present invention will be described in detail below.

The metal porous material of the present invention basically comprises an auxiliary agent, preferably an aqueous solution of an alkali silicate material, which assists adhesion between compressed aluminum fibers after the aluminum metal fiber layer is compressed. Cellulosic resin solution, acrylic resin solution, phenolic resin solution,
Alkali silicate-based material, cellulose, preferably all over the surface (including the inside of the porous material) of the metal porous material in which the aluminum-based metal fibers are compressed by dipping in or coating the fluoride-based resin solution It is formed by forming a film of an auxiliary agent such as a resin, an acrylic resin, a phenol resin, or a fluoride resin.

The aluminum-based metal fiber layer (hereinafter referred to as Al fiber layer) applied to the porous metal material of the present invention is A
1 or a layer made of a metal fiber made of an Al-based alloy, and various Al or Al-based alloy fibers are applicable, but preferably Al or an Al-based metal fiber nonwoven fabric (hereinafter referred to as Al fiber nonwoven fabric) Is applied.

The Al fiber non-woven fabric is a cloth-like body in which Al fibers are formed into a layer. The Al fiber is a fiber made of Al or an Al-based alloy, and has a cross section of any shape such as a triangle or a circle, and has an effective diameter of about 50 to 250 μm and a generic name for an Al strip having a length of 1 cm or more. ..

As an example of the method for producing Al fiber, there are a machining method by drawing, a method of spinning from molten Al, and the like.

In particular, when Al fibers spun from a molten Al-based metal mainly composed of metallic Al are used as the Al fibers,
The fibers are thin and flexible, and fine Al does not fall off during bending, etc., and is safe from the environmental hygiene standpoint.

The Al fiber non-woven fabric is formed into a cloth by molding such Al fibers in layers. There is no particular limitation on the method for molding the Al fiber nonwoven fabric, and any nonwoven fabric manufactured from metal fibers that have been cut or scraped off by a grinder or the like, or any other molded product known in the art can be provided. Among them, the melt spinning method which is generally used at present is preferably applied at the present point in view of price and the like.

The areal density of the Al fiber nonwoven fabric is not particularly limited and is usually about 1000 to 4000 g / m ² . The metallic porous material of the present invention can be adjusted in characteristics according to the application by adjusting the areal density of the Al fiber nonwoven fabric. For example, when applied as a sound absorbing material, the Al fiber nonwoven fabric is It is possible to improve the sound absorption characteristics in the low frequency range by increasing the surface density of the.

The thickness of the applied Al fiber nonwoven fabric is not particularly limited and may be appropriately determined according to the application and required characteristics.

The metal porous material of the present invention is made of such Al.
The Al fiber layer formed from the fibrous nonwoven fabric is compressed.

The method of compressing the Al fiber layer is not particularly limited, and may be continuously pressurized by a roller or the like, or may be compressed by a press machine or the like. Also, the compression pressure of the Al fiber layer is not particularly limited, but Al
In order to sufficiently exhibit the malleability and flexibility possessed by, and to appropriately adhere the Al fiber, it is preferably 300 to 20.
It is preferably about 00 kg / cm ² .

The Al fiber layer applied to the present invention may be treated with phosphate. KH ₂ PO ₄ .nH ₂ SiO ₄ obtained by phosphating
K ₃ PO ₄ and K ₃ PO ₄ are insoluble in water and act as a binder to increase the corrosion resistance of the surface. The phosphate treatment is a dipping or spraying treatment with manganese phosphate, zinc phosphate or the like which is usually performed as a rust preventive treatment for metals and the like.

The metal porous material of the present invention is made of such Al.
Auxiliary agent for assisting adhesion of the Al fiber to the compressed body of the fiber layer, preferably an aqueous solution of an alkali silicate material, a cellulose resin solution, an acrylic resin solution, a phenolic resin solution, a fluoride resin solution Dip or apply these. By having such a constitution, the adhesion strength of the Al fiber layer obtained by compression can be made stronger, the mechanical strength can be improved, and also excellent corrosion resistance and weather resistance can be imparted. You can

The alkali silicate material used in the present invention is represented by the general formula M ₂ 0.nSiO ₂ .mH ₂ O [in the above formula, M is an alkali metal such as Li, Na, K or Cs, The n: molar ratio of the primary amine and the quaternary amine (the number of moles of SiO ₂ with respect to 1 mole of M ₂ 0) is shown. ] Is the main constituent component, and is typically represented by the type of M and the value of n.
There is something like a table. In addition to these, a small amount of unavoidable impurities such as oxides of alkaline earth metals and metal oxides such as Fe ₂ O ₃ may be contained.

[0026]

After the Al fiber layer is compressed (hereinafter referred to as a compressed body), the compressed body is dipped in a concentrated aqueous solution of the alkali silicate-based substance or sprayed with a concentrated aqueous solution to obtain the surface of the compressed body. A film having an alkali silicate material is formed on the entire surface, preferably on the entire surface.

When the compressed body is dipped in a concentrated aqueous solution of an alkali silicate-based substance or is sprayed on the surface, a mixture of a plurality of alkali silicate-based substances may be used, or various kinds of alkali silicate-based substances may be used. It may be a multi-layer coating of a substance.
Since the alkali silicate-based substance has good wettability with a metal, the surface of the compressed body is covered by the surface tension at room temperature. Here, the porosity of the compressed body may be controlled by appropriately selecting the concentration of the concentrated aqueous solution of the alkali silicate-based substance and controlling the viscosity of the liquid.

Next, the compressed body, which has been dipped or sprayed with a concentrated aqueous solution of an alkali silicate-based substance, is naturally dried, or
Preferably, it is dried by heating at 100 ° C to 300 ° C. By heating at the time of drying, a concentrated hot solution having a high molar ratio is formed. The hot solution corrodes the surface of the metal, but forms a film of silicic acid and a metal oxide, and acts as a corrosion inhibitor.

As described above, 1 to 3 are formed on the surface of the compressed body.
It is preferable to form a layer containing the alkali silicate-based material uniformly to approximately 0 μm, and to set the porosity to a desired value without crushing the pores as much as possible. If the layer containing the alkaline chlorine silicate substance is less than 1 μm, the rigidity, heat resistance, and
The desired effect cannot be obtained in terms of corrosion resistance, etc.
If it is more than m, cracks will occur in the coating after drying.

[0031] silicates, for example sodium silicate is ^{Na + O - - [Si (} OH) 2 O] has ^{_{n -Na + (n = 1,2,3 ...}} ) made structure, a silanol group by heating (Si- O
H) condenses and becomes three-dimensional. In addition, various metal surfaces react with silanol groups to crosslink the silicic acid tetrahedral skeleton of SiO ₄ ⁴ with metal ions, or react with alkali metal to fix alkali metal and promote the formation of silica gel. It is known that a cured product is produced by.

Further, as shown in Table 2, the alkali silicate film adhered to the surface of the compressed body (Al fiber) at various higher temperatures has various melting points, and depending on the purpose of use, the alkali silicate film may be It is considered that the corrosion resistance and heat resistance are increased, and the Al fibers on the surface are dissolved to form a silicate compound.

That is, these alkali silicates have a pH
12 strong alkalis. Therefore, it is considered that when these alkali silicates are made into a concentrated solution and applied to the compressed body, they generate a compound while dissolving the very surface of the Al fiber. If the alkali silicates have only the action of the binder, the alkali silicates will be redissolved and flow down when exposed to rainwater or the like. However, in reality, even if the compressed body having the coating of the alkali silicates is exposed to water, the alkali silicates do not redissolve and flow out, and this state is conjectured also because the compressed body is kept in a coated state. To be done.

[0034]

The coating having the alkali silicate-based substance on the surface of the compressed body functions as follows.

1. The concentrated hot solution of the alkali silicate-based material corrodes Al of the compressed body material, and as a result, it forms a coating film of silicic acid and metal oxide on the metal surface, so that the corrosion resistance is enhanced.

2. The surface of the porous metal exposed to high temperature is coated with an oxide film of SiO _{2 having} a low thermal conductivity, which can suppress the temperature rise of the metal and has a thickness of 10 μm.
In the presence of the m-heat coating layer, a temperature decrease of about 20 ° C. can be expected at a use temperature of 500 ° C.

3. Preferably, by heating and drying at 100 ° C. to 300 ° C., the melting point is improved by the surface reaction of the oxide of the alkali silicate-based substance and the Al fiber to form a ceramic of SiO ₂ .Al ₂ O ₃ . The surface of Al fiber is covered with an alkali silicate material at room temperature and has corrosion resistance. However, at a high temperature of 300 ° C or higher, the surface of the Al fiber cracks due to the difference in thermal expansion between Al and the dried alkali silicate material. Occurs and the corrosion resistance is impaired. However 54
Applying an alkali silicate material that dissolves at 0 ° C
The surface melts again at 0 ° C and maintains corrosion resistance. As described above, the corrosion resistance from room temperature to a high temperature is significantly improved.

In the metallic porous material of the present invention, not only such an alkali silicate substance but also an auxiliary agent is used as an auxiliary agent.
Cellulose resin, acrylic resin, phenol resin, fluoride resin and the like are also suitably applied.

Cellulose resins applicable to the present invention include cellulose represented by the general formula (C ₆ H ₁₀ O ₅ ) _n , various cellulose fibers, and cellulose derivatives such as cellulose ether and cellulose ester. Various known cellulosic resins such as the following resins are exemplified.

As the acrylic resin, various known ones can be applied, but it is preferable to use a two-component paint containing a silicone-crosslinked acrylic resin as a main component, and the side chain thereof is an alkoxyalkyl group or an alkoxyaryl group. An acrylic (organo) alkoxysilane having a is exemplified. Such an acrylic resin has a stable and strong cross-linking structure due to the siloxane bond in the resin, and by applying this, it exhibits high adhesion and increases the strength of the porous metal material, and also has high weather resistance. Can develop sex.

The phenolic resin is a resin composition obtained by a condensation reaction of phenols such as phenol and cresol with aldehydes such as formaldehyde and acetaldehyde, and various known resins are used in the present invention. Both are applicable.

Further, various known resins such as polytetrafluoroethylene (PTFE) can be applied as the fluoride resin, but polyvinylidene fluoride is preferably exemplified. What is polyvinylidene fluoride?
A resin obtained by radical polymerization of vinylidene fluoride (CH ₂ ═CF ₂ ), which has excellent weather resistance and chemical resistance. By applying this resin, a metal porous material having excellent weather resistance can be obtained. You can

There is no particular limitation on the method of applying or dipping these resins to the compressed body, and these various resins are dissolved in an appropriate solvent depending on the resin type, and then immersed in this resin solution, or It may be applied by various known methods such as spraying. Then, it may be dried at a temperature depending on the applied resin, solvent and the like.

Such a porous metal material of the present invention is made of Al
It is not limited to one composed only of a fiber layer, and Al as disclosed in JP-A-62-289222 is used.
It is also suitably applicable to a metal porous material obtained by laminating a fiber layer and an Al expanded metal and press-bonding the laminated layers.
In this case, after the laminated body of the Al fiber layer and the Al expanded metal is pressure-bonded, as described above, the pressure-bonded body is dipped in a concentrated aqueous solution of an alkali silicate-based substance or sprayed with a concentrated aqueous solution. A film having an alkali silicate-based substance may be formed on the surface of the pressure-bonded body.

Although the metal porous material of the present invention has been described in detail above, the present invention is not limited to this, and various modifications and improvements may be made without departing from the scope of the present invention. Of course.

[0047]

EXAMPLES The present invention will be described in more detail with reference to specific examples of the present invention.

<Example> Area density 2000 g / m ² , thickness 5 mm
The Al fiber non-woven fabric of is compressed at 1000 kg / cm ² to 0.5
A compressed body of mm was obtained. Various kinds of coatings were formed on the compressed body (Comparative Example) as described below to prepare the metal porous material of the present invention.

A. Alkali silicate The compressed body was treated with Na ₂ O.4SiO ₂ (specific gravity 1.2 g / c
c, molar ratio 2.5, viscosity 8 cP at 20 ° C.), and then heated to 200 ° C. while removing water in a furnace to form a coating of SiO ₂ · Al ₂ O _{3 on} the Al fiber surface. did.

B. Phenol-based resin The compressed body is composed of 70 wt% of phenol, 10 wt% of sodium hydroxide, 10 wt% of formalin, and 10 w of water.
A phenol resin film was formed on the surface of the Al fiber by immersing in a resin solution obtained from t% and then drying in a furnace at 80 ° C.

C. Fluoride-based resin The compressed body was coated with polyvinylidene fluoride paint (Nippon Yushi Co., Ltd. product name Bellflon 1000), enamel 5/1,
A polyvinylidene fluoride coating film was formed on the Al fiber surface by immersing in a resin solution mixed in a clear ratio of 4/1 and then drying in a furnace at 80 ° C.

D. Acrylic resin: The compressed body is dipped in an acrylic silicone resin solution containing an acrylic resin (trade name: Berthite 1000 manufactured by NOF CORPORATION) as a main component, and then dried in a furnace at 70 ° C to obtain an acrylic resin on the Al fiber surface. A resin coating was formed.

Tensile strength was measured for the porous metal material (invention product) thus formed with various coatings and the compressed body (comparative example) having no coating. The results are shown in the table below.

[0054]

From the above results, the effect of the present invention is clear.

[0056]

As described in detail above, the porous metal material of the present invention has excellent rigidity by improving the adhesion of the aluminum-based metal fiber layer, and also has excellent corrosion resistance and weather resistance. Therefore, it can be suitably applied to various uses such as a sound absorbing material and a filter material.

Claims (4)

[Claims] 1. A porous metal material obtained by compressing an aluminum-based metal fiber layer and then immersing or coating it in an auxiliary agent for assisting adhesion between the aluminum fibers. 2. The porous metal material according to claim 1, wherein the auxiliary agent is a water-soluble alkali silicate. 3. The alkali contained in the water-soluble alkali silicate-based substance is one or more compounds selected from the group consisting of alkali metals, tertiary amines, and quaternary amines. Item 3. A metal porous material according to item 2. 4. The porous metal material according to claim 1, wherein the auxiliary agent is one or more of a cellulose-based, acrylic-based, phenol-based, or fluoride-based resin.