JPH08325661A - Porous aluminum sintered material - Google Patents

Abstract

PURPOSE: To assure mechanical strength and to improve bending workability by forming structures which are connected and bonded by bridging parts of hypereutectic structures and further forming projections on the inside wall surfaces of gaps. CONSTITUTION: The gaps 3 are formed among the particles of base powder 1 consisting of Al or Al alloy. These gaps 3 are communicated with each other to form curving open cells. The particles of the base powder 1 are bonded by interposing the bridging parts 2 therebetween. The bridging parts 2 are formed by adding an eutectic element making eutectic reaction with the Al or, an alloy contg. this element thereto. This eutectic element has a melting point higher than that of Al, for example, Cu. The structures of the bridging parts have the hypereutectic structures and the many projections or projecting parts 4 are formed on the inside wall surfaces of the gaps 3. As a result, the sound absorbing coefft. as a sound absorbing material and the filtration efficiency as a filter medium are enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a porous aluminum sintered material, and more specifically, to pores between powder particles of aluminum (hereinafter simply referred to as Al) or an alloy thereof (hereinafter simply referred to as Al alloy). It is a porous aluminum sintered material in which the pores are formed to communicate with each other to form communication holes that bend infinitely, and can effectively absorb noise from high-speed trains, automobiles, and industrial equipment. Filter material that has excellent physical properties, requires porosity and sufficient filtration area,
The present invention relates to a porous aluminum sintered material which is suitable as an adsorbent and the like, and which can greatly improve sound absorption characteristics and filtration efficiency.

[0002]

2. Description of the Related Art Conventionally, various porous metal materials have been proposed. Since the metal porous material has a structure having a large number of pores, by utilizing this structural characteristic, a sound absorbing material that absorbs noise and the like, a filtering material that filters dissolved matters dissolved in the solution, and the like. It is used as a deodorant for adsorbing malodorous substances on the inner wall surface of many pores.

Among these porous metal materials, a porous material in which a large number of straight through holes are formed in a metal plate of Al or Al alloy, so-called punching, is used because it is extremely easy to manufacture, inexpensive and excellent in economic efficiency. Metal is proposed.

[0004] The punching metal loses the energy of the sound while the sound passes through a large number of through holes, so that a certain sound absorbing effect can be achieved.

The punching metal is Al or Al.
Since it is made of an alloy plate material, it has a desired mechanical strength, and it can be easily processed into a desired shape, is lightweight, and is economically inexpensive. Therefore, it is widely used.

However, in the punching metal, the length of the through hole is short as the plate thickness is small, so that the sound absorption range is limited to the low frequency sound, for example, about 100 Hz.
Sounds at high frequencies, eg 500 Hz or higher, cannot be absorbed.

Due to the recent industrial development, various noise sources have been produced. By the way, a high-speed train or high-speed railway represented by the so-called Shinkansen runs at an extremely high speed. Therefore, as the vehicle travels at high speed, high frequencies (for example, 500
Sounds of up to 2000 Hz) are generated, which is a new noise source.

A new noise source has been created by the development and maintenance of the expressway network and the high-speed vehicles that drive there.
Further, due to the densely packed houses, there are problems such as noise from condominiums and noise from public halls and event halls.

The noise thus generated is a mixture of sounds with extremely high frequencies, and in order to remove this noise, the purpose cannot be achieved by the conventional punching metal or the like.

From this, a sound absorbing material made of a porous metal material, in particular, a porous aluminum sintered material obtained by sintering powder of aluminum or aluminum alloy has been proposed (Japanese Patent Publication No. 56-1).
(See Japanese Patent Publication No. 8646 and Japanese Patent Publication No. 56-11375).

This porous Al sintered material is formed by adding Al-Cu alloy powder to Al powder and molding it in a substantially non-pressurized state. Then, in a hydrogen atmosphere, the melting point of Al powder is 10 ° C. Below, it is formed by sintering at a low temperature, leaving pores between Al powders to form pores having a porosity of 30% or more in volume ratio.

In this porous Al sintered material, the pores existing between the powder particles communicate with each other to form an infinitely bent communicating hole, and the length or flow path of this communicating hole is infinitely long. It has excellent sound absorption and filtration characteristics.

As the Al-Cu alloy powder interposed between the Al powders forming the skeleton, an Al alloy powder having a eutectic composition (Cu 33%) is used because it has a melting point lower than that of the Al powder. When it is heated and melted during sintering, the Al powders forming the skeleton are directly bonded to each other, the Al—Cu alloy powder diffuses and disappears between these Al powders, and pores are formed in those portions.

However, even if the sintering is performed as described above, if the powder compact is formed by pressurizing before the sintering, a certain amount of porosity can be formed, but it is difficult to increase the porosity to about 30% or more. Without such a porosity, it cannot function as a sound absorbing material or a filtering material.

Therefore, in order to increase the porosity, the green compact is hardly formed before the sintering and the green compact is not formed, so that the sintering becomes insufficient and the mechanical strength as the sintered material is sufficient. The mechanical properties of can not be obtained.

Therefore, the porous Al sintered body of the conventional example is inferior in mechanical strength, etc. Further, since it is integrally sintered depending on the direct bonding between the Al powders forming the skeleton, it is sintered. Mechanical properties such as the mechanical strength of the binder depend on the sintering conditions, and it is not possible to obtain a uniform Al sintered body having excellent mechanical properties under a high yield.

Further, in the conventional porous Al sintered material, A
As described above, the communication hole formed by the continuous pores formed between the powder particles is infinitely bent, and the flow path is longer as it approaches infinity. Therefore, in comparison with so-called punching metal that is typical as a metal porous material, the porous Al sintered material of the conventional example can absorb sound with a high sound absorption coefficient even at high frequency sounds such as inside and outside of 1000 Hz. Since it has high filtration efficiency and the material is Al or Al alloy, it is extremely lightweight and versatile.

However, in spite of such advantages, the conventional porous Al sintered material depends on the direct bonding between the Al powders forming the skeleton, so that the tensile strength, toughness, and
Bending strength is inferior, and it has the drawback that it cannot be used for bending or other processing.

Furthermore, the sound absorbing characteristics as a sound absorbing material and the performance as a filtering material have their own limits, and it is difficult to further increase them.

As the sound absorbing material, in addition to the porous sintered material such as Al, glass fiber called glass wool,
It has been proposed to use slag wool by treating blast furnace slag, and also Al fibers obtained by subjecting Al or its alloy to treatment such as foaming.

Since these sound absorbing materials have a large number of voids and air is present in each void, the sound absorbing effect is good. However, it has almost no regularity, and fibers are likely to fly during construction work or due to secular change due to use, which is not preferable in terms of health and the like.

[0022]

SUMMARY OF THE INVENTION The present invention is directed to solving the above-mentioned drawbacks, and specifically, a large number of pores formed between powder particles of Al or an alloy thereof are continuously connected. In a porous Al sintered material having a communication hole, the mechanical strength of the joint between these powder particles is increased and the mechanical workability such as bending is also excellent. Furthermore, minute projections are formed on the inner wall surface of the communication hole. Alternatively, a porous Al sintered material having convex portions is proposed.

[0023]

Means for Solving the Problems Porous Al according to the present invention
In the sintered material, (a), the skeleton of this sintered material is Al powder particles or Al.
In addition to the alloy powder particles, it is composed of bridging portions connecting these powder particles. (B), the bridging portion is composed of an element that eutectic-reacts with Al (hereinafter referred to as eutectic element) in addition to Al, and is a hypereutectic element containing this eutectic element in excess of the eutectic composition. It is composed of crystal structure. (C), eutectic elements that undergo eutectic reaction with Al include Si, Ni,
One or more of Mn and Cu are used. (D), the bridging portion is mainly composed of a hard eutectic element and an Al intermetallic compound which solidify as a primary crystal, and around which a eutectic structure of an Al-rich solid solution, a eutectic element and an Al compound solidifies. It is a structure surrounded and surrounded by the eutectic structure of this structure. (E) A large number of minute projections or projections are formed on the inner wall surface of the pores or communication holes formed between the Al powder and the Al alloy powder, and these projections or projections are peritectic-reacted with Al and It is composed of peritectic elements having a peritectic temperature near the melting point. (F) The peritectic element is one or more of W, V, and Ti.

That is, the porous Al sintered material according to the present invention is a porous Al sintered material in which pores forming infinitely bent communication holes are formed between base powders made of aluminum or an alloy thereof. In the material, between the base powders, a eutectic element having a melting point higher than that of aluminum and performing a eutectic reaction with aluminum is contained at a eutectic point or more, and the balance is substantially composed of aluminum, and the structure is excessive. It is characterized in that they are connected and connected to each other by a bridging portion composed of a eutectic structure, and further, a large number of protrusions or projections are formed on the inner wall surface of the pores.

Now, the construction and operation of these means will be described more specifically with reference to the drawings.
It is as follows.

FIG. 1 is an enlarged view showing a part of the structure of the porous Al sintered material according to one embodiment of the present invention.

FIG. 2 is an explanatory view schematically showing the structure of the bridging portion of the porous Al sintered material shown in FIG.

FIG. 3 is an explanatory view showing in cross section the precipitation mode of the primary crystal structure or the eutectic structure in one structure of the bridging portion shown in FIG.

FIG. 4 is an explanatory view showing in cross section the precipitation mode of the primary crystal structure and the eutectic structure shown in FIG. 3 in one structure of the bridging portion of the comparative example.

FIG. 5 is a graph showing the concentration distribution of the eutectic element in the length direction of the bridging portion shown in FIG. 2 together with the bridging portion of the comparative example shown in FIG.

FIG. 6 is a state diagram of Al and a eutectic element which causes a eutectic reaction with Al.

First, in FIG. 1, reference numeral 1 is powder particles of Al or Al alloy (hereinafter referred to as base powder) 2, a bridging portion connecting these base powders 1 and 3 is base powder. The pores formed between 2 and 4 are communicating holes or pores 3.
3 shows a projection or a protrusion formed on the inner wall surface of the.

As shown in FIG. 1, pores 3 are formed between the base powders 1, and the pores 3 communicate with each other to form a communication hole which bends infinitely. The base powders 1 are positively connected by the bridging portion 2 to be integrated. As described above, the bridging portion 2 can be formed without directly connecting the base powders 1 to each other to bond them together.
When the bridge portion 2 is bonded by interposing, the mechanical strength is increased and the toughness is also improved by further improving the structure as follows.

That is, the bridging portion 2 is formed by utilizing liquid phase sintering. The bridging portion 2 is thinner than the base powder 1 of Al or Al alloy to be connected as shown in FIG.
Compared with the powder 1, the mechanical strength is insufficient, and further, stress is likely to be concentrated on the joint portion at the end. For this reason, if the bridging portion 2 is fragile, no improvement can be expected in the mechanical properties of the sintered material as a whole, no matter how the other portion, that is, the base powder 1, is reinforced.

Therefore, in the Al sintered material according to the present invention, in order to improve the mechanical properties, the bridging portion 2 is formed in order to bond the base powders of Al or Al alloy to each other. It also improves the mechanical properties of the junction 2.

In other words, the bridging portion 2 is formed by adding a eutectic element which reacts eutectic with Al or an alloy containing the element,
Paying attention to the fact that the solidified structure of the sintered body has a great influence on the characteristics of the sintered body, particularly the characteristics of the bridging portion 2 connecting the base powders 1 to each other, the porous Al sintered body according to the present invention. The binding is established.

More specifically, the eutectic elements to be solute are the same, and the combination of Al and Al is different in the combination of the primary crystal and the eutectic in the hypoeutectic and hypereutectic. That is, FIG. 6 is a state diagram of Al and a eutectic element (generally indicated as M), and the eutectic element M is Cu. In this Al-Cu alloy system, a hypoeutectic composition (probably, c in FIG.
The composition. ), As shown in FIG. 4, the Al-rich and soft crystal 21 is first solidified and precipitated as the primary crystal. Then, around this crystal 21, a eutectic composed of an Al-rich solid solution 22 and an intermetallic compound 23 such as CuAl ₂ is solidified and precipitated. That is, the Al-rich and soft crystal 21 is crystallized as a primary crystal, and the periphery thereof is covered with such eutectic crystals 22 and 23.

On the other hand, assuming a hypereutectic composition (probably the composition d in FIG. 6), first, CuAl is used as the primary crystal.
_The intermetallic compound 23 such as ₂ solidifies, and then the eutectic composed of the intermetallic compound 23 such as CuAl ₂ and the Al-rich solid solution 22 solidifies and precipitates around it (FIG. 3).
reference).

In this case, the eutectic element involved in the solidification precipitation as described above is an element having a higher melting point than Al and causing a eutectic reaction with Al. Therefore, it is harder and has higher strength than Al even at a high temperature where Al softens during sintering.

That is, in the case of a bridging portion having a hypoeutectic structure as shown in FIG. 4, the surrounding structure becomes harder than the solidification center structure, whereas the hypereutectic structure as shown in FIG. In the bridging portion 2, the tissue around the coagulation center becomes softer than the tissue around the coagulation center.

Further, comparing the eutectic portions of both, the eutectic in the hypereutectic composition as in the present invention is harder than the eutectic of the hypoeutectic composition in the phase of the intermetallic compound such as CuAl _2. Occupies a large proportion in the eutectic portion, and the bridging portion 2 is hard and has high strength.

Therefore, when the bridging portion 2 is formed as a hypereutectic structure as in the present invention, the porous Al sintered material has a sufficient strength and a large deformation is continuous to the periphery and has a toughness. The crystal structure is flexibly taken care of, and workability such as bending is improved.

FIG. 5 shows the concentration distribution in the lengthwise direction of the bridging portion of the eutectic element. Among them, (a) is a hypereutectic composition as in the present invention, and (b) is a hypoeutectic crystal of a comparative example. The composition is shown. As shown in FIG. 5, the hypereutectic composition has a higher yield strength because the solute eutectic element is higher in concentration than the hypoeutectic composition, and the concentration gradient during liquid-phase sintering becomes larger. Therefore, the base powder 1 of Al or its alloy advances in the case of hypereutectic crystal as in the present invention, and the bonding strength with the base powder 1 is also improved.

In the present invention, the base of Al or its alloy is used.
The bridging portion 2 connecting the powders to each other has a higher melting point than Al and a hypereutectic structure of a eutectic element that causes a eutectic reaction with Al. More specifically, when the sintering is performed at a temperature higher than the eutectic temperature, the eutectic element having excellent mechanical strength first solidifies as a solidification nucleus to form a central portion, and then,
A eutectic structure is solidified and precipitated around the core so as to surround the center. This eutectic structure is richer in toughness than the core that forms the core.

Further, as described above, the eutectic structure is gathered in the central part having excellent mechanical strength to form a bridging part (see FIG. 2), and each eutectic structure has a different eutectic structure. It is continuously bonded to the eutectic structure. For this reason, the entire bridging portion has an ideal structure in which primary crystals excellent in hardness and strength are finely dispersed in a tough eutectic matrix.

Since the bridging portion has such a structural morphology in the porous Al sintered material, the strength is higher than that of the base powder, the toughness can be secured, and the bending workability problem can be solved.

Therefore, as the element having a melting point higher than that of Al and undergoing a eutectic reaction with Al, that is, the eutectic element involved in the formation of the bridging portion, Si, Ni, Mn and Cu shown in Table 1 are preferable.

Further, it is desirable to add these eutectic elements as alloy powder with Al, as compared with adding them to the base powder alone. When added as an alloy powder with Al in this way, a bridging portion having the previously mentioned structure can be formed by liquid phase sintering during sintering.

When the bridging portion is added as an alloy powder with Al and the alloy powder is liquid-phase sintered as described above, it is preferable to use an Al alloy powder having the following composition.

The lower limit of the eutectic element is the composition of the eutectic point, but the upper limit is determined from the limit of forming a solid solution with Al as one of the eutectics.

For example, the melting point of Si is 660 ° C. of the melting point of Al.
The higher temperature is 1430 ° C. 11.7% S with Al
The i composition shows a eutectic reaction at 577 ° C. Therefore, Al
It is necessary for Si to be contained at 11.7% or more of the eutectic point, and Si is preferably contained at 15.0% or more. Further, as an upper limit, Si alone does not have a high melting point and liquid phase sintering does not occur, so Si 100% is not included.

Further, Si contributes to the improvement of heat resistance and has a small coefficient of thermal expansion, but if it is too large, the toughness is impaired.

Although the eutectic point of Cu is 33%, the hypereutectic does not contain 33%, and the eutectic point is contained above 33%. 5
If it exceeds 2.5% Cu, a solid solution with Al cannot be formed as one of the eutectic crystals. Especially, if it exceeds this, a hard intermetallic compound is formed, and the eutectic structure is that of intermetallic compounds. Is not desirable. Cu contributes to the improvement of strength and hardness. However, if it is too much, the corrosion resistance is impaired and the workability deteriorates. From this point of view, it is not preferable to exceed 52.5%.

That is, in the eutectic structure, the eutectic of intermetallic compounds is hard but has no viscosity and is vulnerable to fracture.

On the other hand, in the present invention, the bridging portion has a eutectic structure which is partially composed of an Al solid solution having high toughness, and the object of the present invention cannot be achieved unless this structure is obtained.

The composition within the hypereutectic range is arbitrarily selected according to the mechanical properties required for the sintered material. For example, a hyper-eutectic composition containing a large amount of elements is suitable for a flat plate material in which mechanical strength is more important than bending workability, and conversely, a small tubular sintered material in which bending workability is more important than strength. Then, a hypereutectic composition close to the eutectic component is selected.

For this purpose, Si is 15-80.
%, Ni6 to 42%, Mn3 to 20%, Cu35 to 52
% Is preferred.

Although Ni enhances high temperature strength, it is expensive. Compared with this, Mn is inexpensive, contributes to the improvement of corrosion resistance and workability, and also achieves the improvement of high temperature strength.
However, compared with Cu, the effect of adding strength is less, and in this sense, the additive addition of Cu and Mn is preferable.

When the eutectic element is blended as an Al alloy, the blending amount is selected according to the required porosity. If the blending amount increases, the liquid phase amount increases and the sintering proceeds, so that the porosity tends to decrease. In this respect, if the bridging portion is composed of a hypoeutectic composition, the bridging portion needs to be thicker to secure the strength because the strength is inferior. Therefore, the blending amount must be increased. . In this case, the amount of liquid phase becomes excessive, and it becomes difficult to secure the porosity with air permeability necessary for the sound absorbing material, the filtering material, and the like.

Next, as described above, between the base powder 1 and
Protrusions or protrusions 4 are formed on the inner wall surface of the pores 3 formed between the bridging portions 2. These protrusions 4 etc. are
It is formed by adding one or more peritectic elements of W, V or Ti and sintering.

That is, the peritectic element is an element having a peritectic reaction with Al and having a peritectic temperature near the melting point of Al. This peritectic element is added as a fine metal powder as compared with powders such as base powder and eutectic element. When added and sintered in this manner, many fine projections and protrusions are formed on the inner wall surface of the pores.
The peritectic element that undergoes a peritectic reaction with l is one of W, V, and Ti.
Species or one or more species are preferred.

When a large number of fine projections or protrusions are formed on the inner surface of the pores in this manner, the shape of the pores becomes complicated and the surface area can be remarkably increased.

As a result, the sound absorption characteristics are further improved, and the filtering effect is also improved in applications such as filter media.

For this purpose, when the peritectic element to be added is added as a metal powder, the metal powder must be a finer powder such as a base powder.
During the liquid phase sintering of the fine powder, the fine powder shape must be completely retained while maintaining the convex portions.

A peritectic element that meets these conditions forms a stable intermetallic compound with Al, and this intermetallic compound is a base.
It is necessary for the Al powder side to have some solid solubility in the peritectic reaction.

By the way, as peritectic elements satisfying this condition, those shown in Table 1 can be exemplified.

[0067]

[Table 1]

Such fine powders of peritectic elements, when mixed with powders of eutectic elements and the like and base powders, have a higher content of base powders and eutectic elements than powders of peritectic elements. Since the powder is a coarse powder, the peritectic element powder accumulates around the base powder and the eutectic element powder.

When solid phase sintering or liquid phase sintering with a eutectic element is performed below the melting point of the base powder, the peritectic element powder is in the form of protrusions or around the base powder or the eutectic element powder. Sinter into a convex shape.

Since the powder of the peritectic element needs to maintain the solid shape to some extent even after sintering, it is required to have a high degree of purity such that the melting point does not fall below the sintering temperature.

The purpose of forming the projections or projections is to increase the surface area and improve the attenuation rate due to diffuse reflection of sound. For this purpose, it must be provided in a convex shape or a protrusion shape on the inner surface of the pores of the sintered material. Therefore, the grain size of the peritectic element powder must be fine.

[0072]

EXAMPLES Next, examples will be described.

Base powder, Al alloy powder for bridging formation containing a eutectic element, and powders such as peritectic elements having the composition, particle size and blending amount shown in Table 2 were mixed, and then baked as shown in Table 3. Sintering was performed under binding conditions (sintering time, temperature, atmosphere).

As a result, the porous A having the characteristics shown in Table 3 was obtained.
1 sintered material was obtained. As shown in FIG. 1, this porous Al sintered material is composed of a base powder, a bridging portion and a projection portion, the base powder having the composition shown in Table 2, and the bridging portion having the composition In accordance with the composition of the Al alloy powder for forming the bridging portion of No. 2, the test numbers 1, 2,
Each protrusion of 3 was composed of the peritectic element itself.

In addition, sample No. 21 in Table 2 and Table 3,
Each of the sintered materials 22 and 23 is a comparative example. In particular, Sample No. 21 has an eutectic composition of Al—Cu alloy, 22 has a hypoeutectic composition, and 23 has a composition exceeding the upper limit of hypereutectic.

[0076]

[Table 2]

[0077]

[Table 3]

With respect to each Al sintered material thus obtained, mechanical properties such as tensile strength and bending, porosity, and sound absorption coefficient were examined, and the results are shown in Table 3.

Bending indicates the minimum curvature when each Al sintered material having a thickness of 2.5 mm is wound around a round rod having a predetermined outer diameter and no crack is generated in the Al sintered material. Therefore,
The smaller the bending, the better the bending workability.

The sound absorption coefficient indicates the normal incident sound absorption coefficient of sound of 1000 to 1600 Hz when an air layer of 50 mm is arranged behind the sintered material.

Sample numbers 1, 2, and 3 are sample numbers 2 of the comparative example.
Tensile strength and bending workability are remarkably improved as compared with Nos. 1, 22 and 23, and since many protrusions are formed on the inner wall surface of the pores in Sample Nos. 1, 2 and 3, the sound absorption coefficient is remarkably improved. .

[0082]

As described in detail above, in the Al sintered material according to the present invention, a bridging portion for forming a connecting connection between the base powders of Al or its alloy is formed, and this bridging portion is Al. It is composed of a hypereutectic structure that has a higher melting point and contains a eutectic element that has a eutectic reaction with Al and has a eutectic point or more. Furthermore, minute projections or projections are formed on the inner wall surface of the pores formed between the base powders, and these projections or projections are made of peritectic elements that undergo peritectic reaction with Al.

Therefore, with this Al sintered material, the mechanical strength can be secured, the bending workability, which has been a problem in the past, can be improved, and the bridging portion itself can be made thin. The sound absorption coefficient as a sound absorbing material and the filtration efficiency as a filtering material can be increased. Therefore, it is suitable as a sound absorbing material, a filtering material, an adsorbing material, etc. for high-speed trains, automobiles, and industrial equipment.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an enlarged part of the structure of a porous Al sintered material according to one embodiment of the present invention.

FIG. 2 is an explanatory diagram schematically showing the structure of a bridging portion of the porous Al sintered material shown in FIG.

FIG. 3 is an explanatory view showing in cross section a precipitation mode of a primary crystal structure or a eutectic structure in one structure of the bridging portion shown in FIG.

FIG. 4 is an explanatory view showing in cross section a precipitation mode of a primary crystal structure and a eutectic structure shown in FIG. 3 in one structure of a bridging portion of a comparative example.

5 is a graph showing the concentration distribution of the eutectic element in the length direction of the bridging portion shown in FIG. 2 together with the bridging portion of the comparative example shown in FIG.

FIG. 6 is a state diagram of Al and a eutectic element that causes a eutectic reaction with Al.

[Explanation of symbols]

 1 Base powder 2 Bridging part 3 Pore 4 Protrusion or convex part

Claims (6)

[Claims] 1. A porous aluminum sintered material in which pores forming infinitely bent communication holes are formed between base powders made of aluminum or an alloy thereof, wherein between the base powders, Due to the bridging portion having a eutectic element having a melting point higher than that of aluminum and performing a eutectic reaction with aluminum at a eutectic point or higher and the balance being substantially aluminum, and the structure being a hypereutectic structure, A porous aluminum sintered material, characterized in that the porous aluminum sintered material is connected to and bonded to each other, and further, a plurality of projections or projections are formed on the inner wall surface of the pores. 2. The porous aluminum sintered material according to claim 1, wherein the projections or projections are made of a peritectic element having a peritectic reaction with aluminum and having a peritectic temperature near the melting point of aluminum. 3. The eutectic element is more than 11.7% to 1
Si of less than 00%, Ni of more than 42.0% over 5.7%, Mn of less than 25.3% over 2.0% or 3
The porous aluminum sintered material according to claim 1 or 2, which is composed of one kind or more than 52.5% of Cu in excess of 3%. 4. The hypereutectic structure is composed of a unit structure composed of a central part made of a compound of the eutectic element and aluminum and a eutectic structure surrounding the central part, and one of the eutectic structures. Is composed of a solid solution in which the eutectic element is solid-dissolved in aluminum.
The porous aluminum sintered material described. 5. The porous aluminum sintered material according to claim 1, wherein in each of the unit structures, a surrounding eutectic structure is bonded and connected between the unit structures. . 6. The porous aluminum sintered material according to claim 1, wherein the peritectic element is one or more of W, V and Ti. .