JPH02277703A - Breakthrough type iron base porous body and manufacture thereof - Google Patents

Abstract

PURPOSE:To manufacture a breakthrough type iron base porous body having uniform quality at a low cost by allowing kneading liquid of the iron base powder of specific particle diameter and bonding liquid to flow into gap among plural stuck organic polymer spherical bodies, degreasing after drying and sintering. CONSTITUTION:The iron base powder having <=50mu average particle diameter obtd. with method of mechanically pulverizing pig iron and the bonding liquid of CMC water solution, etc., are kneaded. On the other hand, plural organic polymer spherical bodies 4 are charged and pressurized in a mold frame 5 to stick them and fill up. The above organic polymer spherical body 4 is preferable to be the one having <=0.30 apparent sp. gr. by executing foaming treatment. Successively, the above kneaded liquid is allowed to flow into the mold frame 5 to arrange this kneaded liquid into the mutual gap among the above spherical bodies 4. After that, this mold frame 5 is dried, and by executing heat treatment at about 100 - 400 deg.C, the organic polymer spherical bodies 4 are degreased, and the iron series powder is sintered at about 1,000 - 1,200 deg.C. Then, it is preferable to promote self-decarbonization by regulating content of C and O of the above iron series powder to satisfy the inequalities C>2.1wt.%, 4/3(C-2)<O<4/3(C+7). By this method, the porous body having the similar sizes of gas bubbles 1 and well-ordered skelton 2 of the iron base sintered bodies and communicated holes 3, is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a through-cell type iron-based porous body and a method for producing the same. The through-cell iron-based porous body of the present invention is preferable as a lightweight structural material, a heat insulating material, a soundproof material, and a shock-resistant material.

[Prior Art] JP-A-55-125202 relates to a through-cell type Ni-based porous body. In this method, metallic Ni powder is kneaded with an organic binder, applied to a polymer resin core skeleton, for example, a urethane foam skeleton, and subjected to degreasing and sintering steps to form a through-cell Ni-based porous body. However, in this porous body, the metallic Ni powder is expensive, the coating thickness of the crosstalk material tends to be uneven, the size and density of the through-hole bubbles are also uneven, and the uniformity of the material is insufficient.

[Problems to be Solved by the Invention] If a through-cell metal porous body can be manufactured at low cost, the field of use can be further expanded. Furthermore, if a through-cell metal porous body with uniform material can be manufactured, the strength and performance accuracy will be high, and design and use will be simplified.

The present invention provides a through-cell type metal porous body that is inexpensive and uniform in material, and a method for manufacturing the same.

[Means and effects for solving the problem Claim (1)
First, the invention will be explained. FIG. 1 is a diagram showing an example of the iron-based porous body of the present invention.

The present invention is an iron-based sintered body having a large number of cells, each cell having the same size and penetrating adjacent other cells. In FIG. 1, reference numeral 1 is a bubble, and an iron-based sintered skeleton 2 connects a large number of bubbles 1 to form a porous iron-based sintered body. For example, each bubble 1 has a uniform size with approximately the same diameter,
The other adjacent bubbles 1 are penetrated by through holes 3.

The iron-based porous body of the present invention is manufactured using iron-based powder, and as described later, iron-based powder is cheaper than metallic Ni powder, so the present invention is a metal porous body that can be manufactured at low cost. .

In the present invention, the bubbles 1 have uniform sizes, and the bubbles 1 and the iron-based sintered skeleton 2 are geometrically arranged in an orderly manner. Therefore, the porous body of the present invention has uniform properties such as strength and cell density.

In the present invention, the iron-based sintered body collectively refers to an iron sintered body that does not contain an alloying element and an iron sintered body that contains an alloying element that will be described later.

In addition, the size of each bubble is defined as 1. For example, when all the bubbles have the same diameter as shown in Figure 1, or when there are two or more types of bubbles with different diameters as shown in Figure 2, 1-1 and 1. -2 are arranged in a geometrically orderly combination.

Next, a method for producing an iron-based porous body according to the present invention will be explained.

In the present invention, iron-based powder having an average particle size of 50 μm or less is used. If the average particle size is 50 μm or more, it will not form a slurry when mixed with a coagulation liquid, and it will be difficult to pour it evenly into the gaps between the organic polymer spheres tightly packed in the mold. In addition, even if the mixed material is forced to pour in under pressure, the spacing between the iron particles is large, so unlike the normal high-pressure press type powder sintering method, the bonding force of the iron particles after sintering is weak, and the iron It is difficult to form a sintered body.

Figure 3 explains the influence of the carbon content (hereinafter abbreviated as [C]) and oxygen content (hereinafter abbreviated as [○]) of iron-based powder on the properties of the iron-based sintered skeleton. It is a diagram.

Pig iron containing 2.1% by weight or more of carbon, as well as Ni and C
r.

Pig iron contains alloying elements such as Cu, A Q , P, Mo, V, and Ti.

Ledeburite and cementite become the core during mechanical crushing,
Can be easily crushed. Especially when rapidly cooling hot metal, Cr,
Pig iron that has been made into white pig iron by increasing the content of V, S, etc. can be easily produced into fine powder up to several microns by mechanical grinding.

Therefore, iron-based powder is cheaper than metallic Ni powder.

Further, since iron containing 2.1% by weight or more of carbon is easy to crush, it is easier to produce iron-based powder than atomized iron powder or the like. Further, iron-based powders containing 2.1% or more of [C] have a large amount of low-melting ledebrite eutectic crystals and easily become liquid phase during sintering, so that an iron-based sintered skeleton with strong interparticle bonds can be obtained.

The iron-based powder with [C,] of 2.1% or more and [O] of 4/3 (CC coco-) to 4/3 ([Cco+7), shown in region 10 of FIG. During sintering, the carbon in the iron-based powder is self-decarburized, resulting in an iron-based sintered skeleton with good toughness.

Iron-based powders with [O] less than 4/3 ([C to 2), shown in area 20 in Figure 3, have insufficient self-decarburization and form a high-carbon iron-based sintered skeleton. , the toughness is insufficient and thermal strain cracking is likely to occur.

[○] shown in area 30 in Figure 3 is 4/3 ([C + +
7) Super iron-based powder forms an iron-based sintered skeleton containing unreduced oxides, but iron-based sintered bodies have low strength and are easily broken.

The adjustment of [C] and [O] can be carried out by wet-pulverizing pig iron or pig iron containing alloying elements and oxidizing the surface of the powder during crushing, or, for example, by dry-pulverizing it and then submerging it in water. This can also be done by boiling the powder to oxidize its surface.

[C] and [○] can also be adjusted by mixing l or more selected from iron powder whose surface is oxidized and ore powder, and carbon powder.

As iron-based powder, Si<1%, Mn(2%, Ni<10
%, Cr<25%, Mo(3%, Cu<3%, AQ<5
If iron-based powder containing one or more alloy components selected from As with steel, it improves the strength, toughness, heat resistance, corrosion resistance, etc. of iron-based porous bodies. As a method for incorporating alloy components, for example, pig iron containing alloy components may be produced and crushed, but for example, Ni, Ti, Cu, Si, etc. promote graphitization and are difficult to turn into white pig iron, so mechanical There are cases where crushing is difficult. In such a case, the alloy metal or alloy iron is separately ground to a particle size of 50 μm or less and mixed.

In the present invention, iron-based powder and a binding liquid are kneaded to form a kneading liquid. As the binding liquid, for example, an organic binder such as CMC or polyacrylic acid or an inorganic binder such as phosphoric acid bond or water glass is used by dissolving it in water.

In the present invention, a mold is prepared which is filled with a large number of organic polymer spheres in close contact with each other. In the present invention, organic polymer spheres are used to form bubbles in the iron-based sintered body, and during heat treatment described later, the organic polymer spheres are thermally decomposed and disappear, degreased, and form bubbles. Therefore, it is desirable that the organic polymer spheres generate a small amount of gas during heat treatment and are easily thermally decomposed and eliminated. If organic polymer spheres with high specific gravity are used, a large amount of gas will be generated during heat treatment.For example, if the iron-based sintered skeleton 2 is thin, the pressure of this gas may cause cracks or cracks in the iron-based sintered skeleton 2. This leads to deformation and falling off.

For example, styrene expanded foam (manufactured by Tsuki Kasei ■), Expancel plastic micro hollow spheres (manufactured by Japan Ferrite ■), and epoxy balloons (manufactured by Emerson Cuming)
etc. can be made into organic polymer spheres with an apparent specific gravity of 0.30 or less or with many fine pores by foaming treatment (heat treatment with steam, hot water, etc.) prior to use. Become. After these foaming treatments, the apparent specific gravity was reduced to 0.30.
When the following organic polymer spheres are used, the amount of gas generated during heat treatment is small, so that the iron-based sintered skeleton 2 does not crack, deform, or fall off.

As a method of filling organic polymer spheres in close contact with each other, as shown in No. 4, for example, a large number of organic polymer spheres 4 are placed in a mold 5 and pressure is applied, and the organic polymer spheres 4 are be in close contact with each other. Further, as shown in FIG. 5, for example, when the mutual contact points of the organic polymer spheres 4 are bonded with an adhesive 6, the organic polymer spheres 4 are brought into close contact with each other.

In the present invention, a slurry-like kneading liquid made by kneading iron-based powder and a binding liquid is poured into a mold filled with a large number of organic polymer spheres in close contact with each other, and is mixed into the gaps between the organic polymer spheres. Distribute the liquid.

The mold into which the kneading solution is poured is dried and heat treated.

During the heat treatment, the organic polymer spheres are thermally decomposed and disappear at 100 to 400°C in 15 to 30 minutes. Also 700-10
A self-reduction reaction occurs at 00°C, and sintering of the iron-based powder is completed at 1000-1200°C.

In the present invention, the voids where the organic polymer spheres disappear become air bubbles, and the mutual gaps between the organic polymer spheres in which the kneading liquid is placed when the mold is filled become the skeleton of iron-based sintering.

In the present invention, when manufacturing iron-based porous products with complex shapes such as tubular or uneven shapes, the formwork also has a complicated shape that matches the shape of the product. Filling of the polymer spheres and pouring of the kneading liquid can be carried out in the following manner. For example, granular organic polymer spheres are charged into the mold through a charging port provided in the mold. Next, the granular organic polymer spheres in the mold are compressed and pressurized. By applying this pressure, the organic polymer spheres are packed in close contact with each other as described in FIG. After that, the kneading liquid is poured into the mold.

In the present invention, organic polymer spheres of uniform size are filled into the mold in a geometrically orderly manner. Both of them have the same dimensions and are arranged in an orderly geometric manner. Therefore, the iron-based porous body of the present invention has highly accurate and uniform properties such as strength and cell density. In the present invention, the mutually close contact portions of the organic polymer spheres serve as through holes, and the dimensions of each through hole are highly accurate and uniform. Furthermore, in the present invention, by changing the size of the organic polymer spheres used, it is possible to easily produce various iron-based porous bodies having different properties such as strength and cell density.

[Example] After quenching hot metal, it was pulverized in a wet ball mill to produce pig iron powder with an average particle size of 5 μm, the composition of which was C: 3.5.
%, Si: o, 01%, Mn: 10%, Cr:
0.5%.

P: 0.02%, S: 0.01%, and oxygen: 6%.

This pig iron powder was kneaded into a slurry with water glass and water to obtain a kneading liquid. 2 styrene foam spheres with a diameter of 10 mm
It was filled into a mold of 00+++m x 50mm x 50+n11+, and the contact points of each sphere were adhered. Pour the kneading solution into the evacuation of the styrene foam spheres in the formwork, dry,
The material was degreased at 0° C. and reduced and sintered in a nitrogen atmosphere furnace at 1200° C., resulting in the through-cell type iron-based porous body shown in FIG. This iron-based porous material has a bending strength of approximately 100 kg/
cm” and was made of strong material.

[Effects of the Invention] The porous body of the present invention can be manufactured at low cost, and has uniform strength, cell density, etc. with high accuracy.

[Brief explanation of drawings]

Fig. 1 is a diagram showing an example of the iron-based porous body of the present invention, Fig. 2 is a diagram showing another example of the iron-based porous body of the present invention, and Fig. 3 is a diagram showing [C] and [O ] is an explanatory diagram of the influence of iron-based sintering on the properties of the skeleton. Figure 4 is an explanatory diagram of a method for making organic polymer spheres adhere to each other. Figure 5 is an explanatory diagram of a method for making organic polymer spheres adhere to each other. This is an explanatory diagram of the method. 1.1-1.1-2: Bubbles, 2: Iron-based sintered skeleton, 3
: Communication hole, 4: Organic polymer sphere, 5: Formwork, 6: Adhesive. Figure 1 Figure 2 Patent license applicant Nippon Steel Corporation

Claims (8)

[Claims] (1) An iron-based sintered body having a large number of bubbles, each of which is of the same size and has a through-cell type iron-based porous body characterized by mutually penetrating other adjacent bubbles. body. (2) A kneading solution of iron-based powder with an average particle size of 50μ or less and a binding solution is poured into a mold filled with a large number of organic polymer spheres in close contact with each other, dried, and heat-treated. A method for producing a through-cell iron-based porous body by degreasing polymer spheres and sintering iron-based powder. (3) Producing the through-cell iron-based porous body according to claim (2), wherein the iron-based powder is an iron-based powder containing oxygen and carbon in an amount satisfying the following formula [1]. Method. [C]>2.1%, 4/3 ([C]-2)<[O]<4
/3([C]+7)...[1] However, [O]: Oxygen content of iron-based powder (wt%) [C]: Carbon content of iron-based powder (wt%) (4) The iron-based powder is iron containing oxygen and carbon, which is produced by wet-pulverizing pig iron or pig iron containing an alloying element, oxidizing the surface of the powder during crushing, or oxidizing the surface of the powder after crushing. The method for producing a through-cell type iron-based porous body according to claim (3), which is a powder based on the iron-based material. (5) The iron-based powder is a mixture of one or more selected from iron powder, surface-oxidized iron powder, ore powder, and carbon powder.
Claim (3) It is an iron-based powder containing oxygen and carbon.
A method for producing a through-cell iron-based porous body described in . (6) The iron-based sintered body contains Si<1%, Mn<2%, Ni
<10%, Cr<25%, Mo<3%, Cu<3%, A
An iron-based sintered body formed of an iron-based sintered skeleton containing one or more alloy components selected from l < 5%,
A through-cell iron-based porous body according to claim (1). (7) Iron-based powder contains Si<1%, Mn<2%, Ni<1
0%, Cr<25%, Mo<3%, Cu<3%, Al<
Claim (2) or (3) or (4) is an iron-based powder containing one or more alloy components selected from 5%.
) or (5), the method for producing a through-cell iron-based porous body. (8) Organic polymer spheres are foamed to reduce their apparent specific gravity to 0.
The method for producing a through-cell type iron-based porous body according to claim 2, which is an organic polymer sphere having a particle diameter of 30 or less.