JPH0672273B2 - Method for producing breathable metal material composed of iron, nickel, titanium, or alloys thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Field of Application> The present invention relates to a method for producing a breathable metal which has applications as oil-impregnated bearings, filters and many other highly functional materials.

<Prior art> A metal porous material having continuous pores is mainly a method of directly sintering raw material metal particles and a method in which a molten metal is pressed into a particle gap of a solvent-soluble particle compact and solidified, and then the particle component is dissolved by a solvent. It is manufactured by a method of elution (Japanese Patent Laid-Open No. 60-49703).

In particular, the metal porous by the latter method (hereinafter referred to as a gas permeable metal) has a very high porosity of 50-85%, which makes it possible to easily control the pore diameter and the pore shape, and to elute soluble particles before the elution. It has a feature that it is possible to perform machining with high dimensional accuracy by cutting without clogging the pores included in the stage. However, as an actual production example by this method, a permeable metal made of pure metal or alloy of lead-based, tin-based, zinc-based and aluminum-based using sodium chloride as soluble particles and copper-based using potassium phosphate. Of pure metals or alloys of the above, and from breathable metals of iron and its alloys and nickel and its alloys (hereinafter, iron-based and nickel-based are collectively referred to as iron group), titanium or its alloys. No breathable metal has been manufactured. The main reason for this is that solvent-soluble particles that withstand high melting temperatures of iron group metals and titanium have not been provided, and that the technology for pressing molten iron group metals into the interstices of the formed particles of the formed particles. Is not established.

<Problems to be Solved by the Present Invention> The present invention withstands the press-in temperature of the iron group-based or titanium-based molten metal and can be compounded with the iron group-based or titanium-based metal, and a solvent is used after the compounding. To provide a particulate material that can elute only the particle content, establish a method for molding the particle compact, and establish a method for press-fitting an iron group-based or titanium-based molten metal into the particle compact. It is an object of the present invention to provide a method for producing an iron group-based or titanium-based breathable metal.

<Means for Solving Problems> Means for achieving the above-mentioned object of the present invention are as follows. The solvent-soluble particles used for producing the air-permeable metal of the present invention are calcia (CaO) particles alone or composite particles in which calcium chloride (CaCl ₂ ) is applied to the surface of calcia particles. These particles are sintered to obtain a compact, which is placed in a case of porous heat insulating material that can withstand the melting temperature of iron group metal and titanium metal, preheated to an appropriate temperature for each case, and then quickly Air permeability that allows particles to be eluted from a particle-metal composite material obtained by charging a molten metal of iron group or titanium into the interstices of a particle compact and then pressing the molten metal into the mold. It is a manufacturing method of a metal material.

<Operation> The iron group or titanium-based air-permeable metal of the present invention includes a forming step of a solvent-soluble particle molded body, an iron group-based or titanium-based molten metal injecting step and a particle elution step into the particle gaps of the particle formed body. Is manufactured through.

The step of molding a solvent-soluble particle (hereinafter referred to as particle) molded body is a step of manufacturing a particle molded body by forming connecting portions at all contact points between particles loaded in a container.
The meaning of connecting particles is to elute the particles starting from the surface layer of the composite material through the connection part between particles when the particles are eluted from the composite material obtained by press-fitting molten metal into the particle gap. This is because it proceeds to the inside of the composite material. The presence of this connection between the particles allows for the complete elution and removal of the particles, thus producing a breathable metal with complete open pores.

The particles are usually connected by utilizing the sintering phenomenon due to the heat treatment, but pure calcia particles are difficult to sinter, and the difficulty is remarkable especially in the case of coarse particles. In the production of general calcia sintered bodies, the focus is on obtaining high-density sintered bodies, so it is possible to make the calcia particles of the raw material into fine particles or to have an appropriate particle size distribution. Since the sintering is performed after the particle filling degree is as high as possible, a sintered body having a particle filling rate of 90-95% is obtained despite the difficulty of sintering.

However, in a calcia particle molded body for producing a breathable metal, it is necessary to press the molten metal into the particle gap, so that the particle packing rate of the molded body cannot be increased indefinitely as in the above case. . When filling the container with spherical particles, the packing factor for the coarsest packing is 52.4% and for the densest packing is 74%. This 74
When the filling rate exceeds%, an isolated portion is formed in the space of the continuous particle gaps in the particle packed body, and the molten metal cannot be pressed into this isolated space. Therefore, in order to produce a completely breathable metal, it is essential that the particle filling rate of the calcia particle compact is always lower than the filling rate of 74% of the spherical particles which is the closest packing, and In the method for molding a particle-molded article, the connection of the particles in the molded body must occur only at the contact portions between the particles.

When pure calcia particles are used, the particle compaction after sintering does not rise much more than that before sintering, and a particle compact having a strong connection at each particle contact part is calcined into calcia particles. This can be achieved by adding calcium chloride as a co-agent and sintering. In the present invention, calcium chloride is used as a simple binder between the calcia particles, not as a general sintering aid that promotes densification of the sintered body.

In the production of general high-density calcia sintered bodies, various oxides (for example, Fe ₂ O ₃ , Cr ₂ O ₃ , V ₂ O ₅ , MnO ₂ , CoO, Ti) are used as sintering aids.
_{O 2, NiO, Ca (PO} 4) 2, MgO, ZnO, ThO 2, ZnO 2, SnO 2) , but is used, high temperature reaction product of these oxides and calcia, various solvents to Since it is far more insoluble than calcia, iron group metals, or titanium metals, it is necessary to elute and remove only the particle component from the particle-metal composite material, and in the production of breathable metals, general sintering of them is required. Auxiliaries cannot be used.

In the sintered body of the system in which calcium chloride is added to calcia particles, calcium chloride is added to the calcia particles by the following operation in order to form a connecting part only in the contact part of the calcia particles. A saturated solution of calcium chloride in ethyl alcohol is added to the calcia particles and thoroughly kneaded to wet the surface of the calcia particles with the saturated solution evenly. Thereafter, the alcohol content is dried while continuing the kneading so that the particles do not adhere to each other to obtain calcia-calcium chloride composite particles whose surface is uniformly covered with calcium chloride. By filling the composite particles in a container and heating at an appropriate temperature,
It is possible to obtain a particle compact satisfying the above purpose.

Since the melting point of calcium chloride is 774 ℃, the sintering temperature is 7
The temperature is 74 ° C or higher, and 10% by weight of calcium chloride is sufficient.

When the above composite particles are sintered in the above temperature range, since the surface of the calcia particles is uniformly covered with a thin layer of calcium chloride, dissolution occurs in this surface layer, and the calcia particles are chlorinated with calcia. It is uniformly covered by a liquid layer of intermediate composition of calcium. This liquid layer flows and gathers in the contact portion between the calcia particles by the action of wetting and surface tension, and by cooling this, a strong bond can be formed only in the contact portion of the calcia particles.

In order to press-in the iron group-based or titanium-based molten metal into the particle gaps of the particle compact obtained by the above operation, it is necessary to preheat the particle compact to an appropriate temperature, and It is necessary to load in a mold that can withstand the pressure applied during press fitting. For example, when the breathable aluminum is produced by the conventional method (Japanese Patent Publication No. 60-49703), the particle preheating temperature is 500-600.
Since the temperature is at 0 ° C., a method has been adopted in which a particle molding is loaded into a steel mold, the mold is preheated, and molten aluminum is pressed into the mold after the preheating is completed.

On the other hand, in the case of producing an iron group-based or titanium-based breathable metal, the particle preheating temperature range for press-fitting the iron group-based or titanium-based molten metal exceeds 1000 ° C, and in this temperature range Even if the mold has sufficient oxidation resistance, mechanical strength, and thermal shock resistance, and it comes in contact with a molten iron-group metal of 1500-1700 ° C at this temperature under constant pressure, seizure does not occur. In order to avoid this, a special and expensive mold material is required. Therefore, in order to press-in the iron group molten metal, it is not realistic to preheat the mold loaded with the particle compact.

The method for preheating only the particle compact without preheating the die, and then press-fitting the iron group-based or titanium-based molten metal is as follows. Put the particle compact into a case of porous heat insulating material that can withstand the melting temperature of iron group metal or titanium metal, preheat it to a predetermined temperature, and immediately after preheating, load the case into a steel mold. Immediately, the iron group-based or titanium-based molten metal is pressed into the porous heat insulating material through the pores.
Since the porous heat insulating material case has sufficient heat insulating properties, the temperature of the particle compact in the case does not drop even when the case containing the particle compact is loaded into the mold. By this method, the mold for press-fitting the molten metal does not need to be preheated to a high temperature, therefore, a mold of a special material is not required, and the problem of seizure between the mold and the molten metal is released. Therefore, steel is sufficient as the mold for press-fitting the iron group-based or titanium-based molten metal.

The method of eluting the particle component from the particle-metal composite material obtained by the above method is as follows. After cutting the particle-metal composite material into a product shape, an aqueous solution containing a chelating agent is contacted under alkaline conditions to elute only the particle component from the composite material, and an iron group-based or titanium-based breathable metal is removed. obtain.
In this elution operation, since the iron group metal and the titanium metal are insoluble in the above-mentioned solvent, only the magnesia particles can be eluted.

<Examples> The present invention will be described in more detail with reference to Examples.

Example 1 Saturated calcium chloride alcohol solution was added to calcia particles having a particle size of 250 μm and kneaded well, and the alcohol content was dried while continuing the kneading. By this operation, the added amount of calcium chloride coating the surface of calcia particles is 6% by weight.
The composite particles adjusted so that The composite particles were tamped and packed into a graphite container with an inner mold of 30 mm and a height of 80 mm,
Sintering was performed at 0 ° C. for 1 hour to obtain a particle compact. Put these particle compacts in the case of porous heat insulating material made of refractory fiber at 1100 ℃
Immediately after completion of preheating, it is loaded into a steel mold with an internal diameter of 50 mm and a height of 100 mm, and immediately eutectic cast iron melt at a temperature of 1400 ° C is pressed in at a pressure of 150 kg / cm ² to remove particles-metal. A composite material was obtained. After cooling and solidifying, the composite material was cut into a predetermined shape, and an aqueous solution containing a chelating agent (Lion Co., Ltd., trade name Dissolvin, the main ingredient is EDTA) was used.
The pH was adjusted to an alkaline region, and the composite material was dipped in this to elute only the particles, to obtain a breathable cast iron body having a porosity of 58.0%.

<Effects of the Invention> As described above, according to the present invention, as the solvent-soluble inorganic compound to be used, calcia plain which has sufficient heat resistance to withstand molten metal of iron group metal or titanium metal or alloys thereof Alternatively, a mixture of calcia and calcium chloride is used, and the preheating of these sintered bodies is performed for each heat insulating case, and since the die is not preheated, it can be used as a die material such as steel or other material having not so high high temperature strength.

And particularly in the method using a sintered body of a mixture of calcia and calcium chloride, it is easy to obtain a sintered body in which the contact portions of the respective particles are firmly connected, so that a breathable metal having continuous pores can be obtained. easy.

Therefore, there is an effect that a metal having a relatively high melting point such as iron, nickel or titanium, or an alloy thereof can be easily produced as a permeable metal having continuous porosity and a large porosity.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hidetoshi Ueno 807 Nonoshita, Tojuku-cho, Tosu City, Saga Prefecture 1 Kuju Industrial Research Institute (72) Sumio Nagata 807 Nonoshita, Tojyo-cho, Tosu City, Saga Prefecture 9 State Industrial Technology Laboratory (56) References JP 60-184651 (JP, A) JP 60-49703 (JP, B1)

Claims (3)

[Claims] 1. A calcia sintered body sintered and molded into a predetermined shape is placed in a heat insulating case, heated together with the case to a predetermined temperature, charged into a mold, and then iron or its alloy, nickel. Alternatively, its alloy, titanium or its alloy, or a molten alloy thereof is press-fit into the calcia sintered body, and after cooling and solidification, treated with a chelating agent-containing aqueous solution under alkaline conditions to obtain only the calcia sintered body. A method for producing a breathable metal material comprising iron, nickel, titanium, or an alloy thereof, which is characterized by elution. 2. A composite sintered body obtained by sintering particles of calcium chloride to which calcium chloride is added and mixed into a predetermined shape is placed in a heat insulating case, and each case is heated to a predetermined temperature,
It is loaded into a mold, and then molten metal of iron or its alloy, nickel or its alloy, titanium or its alloy, or their composite alloy is pressed into the above composite sintered body, and after cooling and solidification, chelate under alkaline conditions. A method for producing a breathable metal material comprising iron, nickel, titanium, or an alloy thereof, which comprises treating with an agent-containing aqueous solution to elute only the composite sintered body. 3. A breathable metal material comprising iron, nickel, titanium or alloys thereof according to claim 2, wherein calcium chloride is used in the form of an alcohol solution when calcium chloride is added to the calcia particles. Manufacturing method.