JPH06271957A - Porous metallic body and its production - Google Patents

Abstract

PURPOSE:To produce the porous metallic body having a porous metallic layer which is uniform and has high porosity on a metallic surface and the method for producing the same. CONSTITUTION:This porous metallic body has the porous layer which is uniform and has the high porosity on the surface of an alloy having a structure of >=2 phases consisting of >=1 kinds of intermetallic compound phases and >=1 kinds of solid soln. phases. The process for production of such porous metallic body consists of a first stage for of >=1 kinds of the intermetallic compound phases and >=1 kinds of the solid soln. phases, then heat-treating the casting and a second stage for eluting only the solid soln. phases from the casting produced in the first stage by an acid or alkaline soln. As a result, the porous metallic body having intricate shapes and pores of a relatively large surface area is obtd.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a porous metal body and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, for example, a method of directly adding a foaming agent to a molten metal and foaming it, or a metal powder as a method of manufacturing a porous metal body used for filtering fuel and oil of automobiles and artificial human bones. A powder metallurgical method (disclosed in Japanese Patent Application Laid-Open No. 4-32527) for sintering short fibers or the like is known.

Among these methods, the method of directly adding a foaming agent to the molten metal to foam it is to mix a foaming agent having a melting point of the molten metal or less with the molten metal and confine the gas generated during foaming in the molten metal. The method has a porosity of 0.8 to 0.
It is possible to obtain 9 foam materials. If Fe is considered when the porosity is 0.9, the density of Fe is 7.86K.
Since it is g / m ^3, it is even possible to create a steel material that floats in water.

On the other hand, the powder metallurgical method for sintering metal powder or short fibers is a method of producing Ti, Co-Cr-Mo, and stainless steel wire after molding and compression, and sintering, which is a method for producing bone of a human body. It is being researched as a biomaterial material for restoration. This material is characterized in that it can be directly bonded to bone, is lightweight and has excellent mechanical properties. on the other hand,
The intermetallic compound is generally known as a material having excellent heat resistance, wear resistance and corrosion resistance. For example, there is Ni ₃ Al which is under development as a turbine material for power generation. Then, it is possible to manufacture a porous body composed of an intermetallic compound by sintering the powder of the intermetallic compound as described above.

[0005]

However, in the method of foaming by directly adding a foaming agent to the molten metal, bubbles are united unless attention is paid to the viscosity of the molten metal when the foamed material becomes gas. Sometimes. There is a problem in obtaining uniform pores. Further, it has been attempted to apply this method to steel materials and cast iron, but there is a problem in that the melting point is high and the foam material is selected, and thus steel materials floating in water have not been completed.

Further, in the powder metallurgy method of sintering metal powder and short fibers, materials already made of stainless steel short fibers and Al short fibers are widely used as industrial materials, but in the conventional method, they are porous. There is a problem that a complicated shape cannot be formed because the metal body is formed into a required shape after being formed. Further, when the porous metal body is partially used, it has been relied on a method such as cast molding of the porous metal body, but this method has a drawback that the bonding strength is weak and the reliability is low.

Further, the porous metal body manufactured by using powder metallurgy as described above has a problem that the strength is low because the whole bulk is porous, so that the porosity and the strength can be balanced. is important. Further, it is very difficult to balance the porosity and strength of an intermetallic compound which is a brittle material. A first problem to be solved by the present invention is to provide a high-strength porous metal body.

A second problem to be solved by the present invention is
It is an object of the present invention to provide a method for producing a porous metal body which can easily produce the porous metal body having a complicated shape.

[0009]

In order to solve the first problem, in the porous body according to the present invention, the bulk portion of the main body is composed of one or more kinds of solid solution phase and one or more kinds of intermetallic compound phase. It is an alloy having a structure of at least a phase, and is characterized by having a porous layer composed of only the intermetallic compound phase on the bulk surface. That is, functionally, the bulk portion bears the strength, and the porous layer on the bulk surface bears the porosity.

A method of manufacturing a porous metal body according to the present invention for solving the second problem is characterized by comprising the following steps. (A) The first step of heat treating after casting an alloy having a structure of two or more phases consisting of one or more intermetallic compound phases and one or more solid solution phases. (B) A second step in which only the solid solution phase of the cast body obtained in the first step is eluted with an acid or alkali solution.

Specifically, Al having a structure of two or more phases of an Al-based intermetallic compound phase containing at least one element selected from the group of Ti, Zr and Cr and an Al solid solution phase.
The first step in which the alloy is melted in a smelting furnace, poured into a mold, cast, and heat-treated to produce a cast body. The cast body is in a state where the Al-based intermetallic compound phase and the solid solution phase are mixed, and is processed if necessary. Next, the casting process is soaked in a container containing an acid or alkali solution, and only the Al solid solution phase is eluted to obtain a porous metal body. The thickness of the porous layer is adjusted by the type of eluent, the concentration of the eluent, the elution time and the elution temperature. Table 1 shows examples of Al alloys.

[0012]

[Table 1]

[0013]

EXAMPLES Examples of the present invention will be described below. Experimental Example 1 An alloy consisting of an Al alloy containing at least one selected from the group consisting of Ti, Zr, and Cr and an Al solid solution phase was
After casting into a cylinder of 40 × 10 mm, heat treatment is performed. Next, only the Al solid solution phase was eluted with an acid or alkali solution, and the elution depth, weight loss rate, and porosity were measured. Table 2 shows each condition of the alloy composition, the eluate and the elution time and the measurement result. The porosity was measured by the image analysis method only for the porous layer.

[0014]

[Table 2]

First, the composition will be described. Examples 1-8
Is within the composition range shown in Table 1 and is a two-phase alloy of an Al solid solution phase and an Al-based intermetallic compound phase. On the other hand, the alloys of Comparative Examples 1, 3, and 5 are out of the composition range shown in Table 1 and are single-phase alloys containing only the Al solid solution phase. It disintegrated and became a powder. Further, the alloys of Comparative Examples 2, 4, and 6 were also out of the composition range shown in Table 1, and there was no Al solid solution phase, and two types of Al were used.
Since it was a base intermetallic compound phase, no elution occurred even when immersed in an acid. Further, in the alloys of Examples 1 to 8, as the amount of Al increases, the proportion of the Al solid solution phase in the Al alloy increases, so that the porosity increases. In addition, Examples 9 to 11 are 3
It is a former alloy.

Next, the eluate will be described. In Experiment 1, 5% sodium hydroxide solution was used as the alkaline solution and 20% hydrochloric acid was used as the acid, but both could be eluted. It should be noted that even if the concentration is lower than these, elution is possible. Next, the elution temperature will be described. In Experiment 1, except for Example 8, elution was carried out at 20 ° C. room temperature, but when Elution was carried out with 80 ° C. hydrochloric acid in Example 8, the elution rate was improved by about 80 times.

After all, if it is within the composition range of Table 1, the manufacturing conditions are flexible, the alloy composition is optimized according to the porosity of the target porous layer, and the target porous layer thickness is obtained. The type of eluent, the concentration of the eluent, the elution temperature, and the elution time may be optimized according to the above. Experimental Example 2 In Experimental Example 2, a cast body was formed into a plate shape having a thickness of 2 mm, and
l The solid solution phase was eluted with an alkaline solution. Table 3 shows the measurement results of the alloy composition, elution conditions and porosity, weight loss rate, and porosity.

[0018]

[Table 3]

When the cast body has a plate shape, the entire sample is made porous by elution, and a porous metal body having an excellent porosity of 80% or more is obtained.

[0020]

According to the method for producing a porous metal body of the present invention, since the cast structure is utilized, it is possible to produce a porous metal body having a complicated pore shape and a large specific surface area.
Further, it is possible to easily form and manufacture a product having a complicated shape. Furthermore, the porous metal body obtained by the manufacturing method according to the present invention is used as a filter, a soundproofing or vibration isolating material, and is impregnated with an alloy or a lubricating oil to have strength and wear resistance of a composite material, a bearing material and the like. It can be applied to required products. For example, in a composite material, a piston is cast, only the head part is partially made into a porous layer, and the porosity part is impregnated with an alloy, so that only the piston head part can be composite-strengthened. It is possible to solve problems such as cracks at the boundary between the matrix alloy and the matrix alloy. On the other hand, as a bearing material, in addition to manufacturing a bearing that can be operated without lubrication by adding a lubricating oil to the inside of the bearing only, the bearing oil is made by adding lubricating oil to the bare metal of the porous metal body. Can be used as Further, it is possible to easily form and manufacture a product having a complicated shape.

Claims (4)

[Claims] 1. A porous metal body having a porous layer composed only of an intermetallic compound phase on a metal surface. 2. A method for producing a porous metal body, which comprises the following steps. (A) The first step of heat treating after casting an alloy having a structure of two or more phases consisting of one or more intermetallic compound phases and one or more solid solution phases. (B) A second step in which only the solid solution phase of the cast body obtained in the first step is eluted with an acid or alkali solution. 3. A method for producing a porous metal body, comprising the following steps. (A) consisting of Al-based intermetallic compound phase and Al solid solution phase 2
The first step of heat treating after casting an alloy having a phase or higher structure. (B) A second step in which only the solid solution phase of the cast body obtained in the first step is eluted with an acid or alkali solution. 4. The method for producing a porous metal body according to claim 3, wherein the Al alloy contains at least one element selected from the group consisting of Ti, Zr, and Cr.