JPS5831378B2 - Manufacturing method of aluminum-based sintered alloy sound absorbing material - Google Patents

Description

[Detailed Description of the Invention] The present invention provides a method for producing an aluminum-based sintered alloy sound absorbing material, in particular, it has excellent sound absorbing properties for high frequency sounds such as noise, noise, etc., has excellent mechanical properties and weather resistance, and is lightweight. Moreover, the present invention relates to a method for producing sound absorbing materials that is highly economical.

Currently, noise, noise, vibration noise, etc. from automobiles, high-speed rotating equipment, presses and other metal forming machines, and other vibrating equipment has become a major problem as noise pollution, and it is important to eliminate it from our daily lives. is desired.

For this reason, legal and administrative regulations and guidance are currently in place, but these do not solve the problem, and the fundamental focus is on the development of prevention technology.

For example, soundproof materials are currently being developed as one of the noise prevention technologies, and these materials are incorporated into buildings and used as so-called soundproof walls to achieve the desired effect.

However, soundproofing materials only block sound and do not have the effect of absorbing sound, and furthermore, their mechanical strength is not very high, so they cannot be directly attached to automobiles, vehicles, etc. to absorb sound.

For this reason, sound absorbing materials are currently being developed in place of sound insulating materials.

Therefore, the sound absorbing materials currently being developed can be roughly divided into those that are mainly made of glass fiber, etc., those that are made of metal plates with pores, and those that are a combination of these materials.

Among these, those mainly made of glass fiber have relatively good sound absorption properties, but have poor mechanical strength and weather resistance, and are especially effective at reducing noise generated when directly attached to moving or vibrating automobiles and vehicles. difficult to absorb;
The sound absorbing material itself is easily damaged by external forces such as impact.

In addition, although materials made of metal plates have high mechanical strength, it is difficult to increase sound absorption, and even when combined with glass fiber, the mechanical strength and weather resistance deteriorate, and high-frequency sound waves cannot be absorbed. be.

For this reason, porous copper alloy sintered bodies constructed using powder metallurgy have excellent mechanical strength and weather resistance, as well as good sound absorption properties, so copper alloy sintered bodies have recently been used. Sound absorbing materials have been proposed.

This sound absorbing material has high mechanical strength and has zigzag communication holes, so wave energy such as noise is converted into thermal energy while passing through the communication holes, and noise etc. is almost completely absorbed.

In other words, when the engine compartment of a train, train, automobile, etc. is surrounded by this sound-absorbing material, the noise generated from the engine compartment enters the communication hole, the noise collides with the zigzag wall, and the wave energy changes into thermal energy. The sound is completely muted.

However, the sound absorbing material with this structure is not simply constructed like a normal porous sintered body, but in order to almost completely absorb noise, especially high-frequency sound waves, the pores must be connected.
This communication hole must be thick (and formed in a zigzag pattern), and to satisfy this condition, only a copper alloy sintered body is suitable, and it is almost impossible to use metals or alloys of other compositions. It is said that there is.

Therefore, copper alloy-based sound absorbing materials are expensive and heavy, which severely limits their use.

The present invention aims to solve the above-mentioned drawbacks, and in particular uses A7 or its alloy powder as a raw material, which has sound absorption properties, mechanical properties, and weather resistance that are equal to or better than those of copper alloy-based products, and is lightweight and economical. We propose a manufacturing method for sound-absorbing materials with excellent performance.

That is, the method of the present invention uses A containing 3% or less of Cu in terms of weight percentage and a grain size of 20 to 80 mesh per 100 parts of alloy powder or Al powder having a grain size of 20 to 80 mesh.
A with a particle size of ioo to 325 mesh, including u25 to 45 grains
10 to 30 parts of No. 1 alloy powder are mixed with a hydrocarbon-based dispersant such as white kerosene, and then this mixture is molded into a desired shape under substantially no pressure. 60
It is characterized by being sintered at 0°C.

In addition, in the method of the present invention, 0.7×10"
It can be molded into a desired shape by applying a pressure of 1 kg/- or less, and in this case, sinterability is improved, which is preferable.

The method of the present invention will be explained in detail below.

First, a hydrocarbon-based dispersant such as white kerosene is added dropwise into the raw material powder, and is stirred into the raw material powder.

Next, in this state, Cu25~4 is added to the raw material.
Add and mix A1 alloy powder containing 100 to 325 particles of mesh size.

When mixed in this way, the main component A [or A1 alloy powder and the additive component A1 alloy powder are mixed uniformly even if the particle sizes are different, and in particular, the particles of the main component A7 or A1 alloy powder (hereinafter the main component The additive component AJI is placed around the particles (referred to as particles).
? The alloy powder adheres uniformly and completely covers the periphery, and the surface oxide film of the main component particles is reduced by the dispersant during sintering as described later, so that sintering is performed satisfactorily.

That is, in the method of the present invention, due to its properties as a sound absorbing material, the pores are connected and the diameter of the communicating pores is large (the porosity is increased, and the mechanical strength of the sintered body is significantly increased). It is necessary.

Generally, Al or A1 alloy powder (hereinafter simply referred to as A powder, etc.) is commonly used.

) has a surface that is much more easily oxidized than other metals, and the surface is covered with a hard oxide film.
Before sintering, it is necessary to compress the Al powder or the like in advance to destroy and remove the hard oxide film.

However, when compressed, it is not possible to increase the porosity of the sintered body, and it is almost impossible to increase the porosity to about 30 to 40.

From this point of view, only solid bearings made of sintered materials such as powder or impregnated bearings with a maximum porosity of about 2O4 as described in Japanese Patent Publication No. 45-24206 have been proposed in the past.

That is, the method described in this publication uses Al powder etc.
-Cu eutectic alloy powder is mixed and compression molded into the desired shape,
This is a method of sintering near the eutectic point.

With this method, the surface oxide is destroyed during compression, and during sintering, the melt of the eutectic alloy powder diffuses between the powders etc. through the destroyed portion, resulting in some degree of porosity.

However, in this method, the pressure is at least 1.5 mm in order to mechanically destroy the oxide film. OX103kg,/cr
A porosity of about A is required, and the porosity is limited to about 20 porosity at most.

In this regard, in the method of the present invention, since pores with large porosity and communicating with each other are formed in a zigzag pattern, the oxide film on the surface of the main component powder is instantly destroyed due to the difference in coefficient of thermal expansion, and the pores pass through this part. To diffuse the Al-Cu alloy powder, the main component powder is surrounded by AA.
They focused on the fact that it is effective to uniformly surround the -Cu alloy powder.

Therefore, in order to form communicating pores, Al-
It is necessary that Cu be surrounded uniformly, and in this sense it is necessary to make the particles small and to make the particles of the main component powder large.

In addition, in the method described in Japanese Patent Publication No. 45-24206, the eutectic alloy powder is diffused as a liquid phase and this portion remains as pores, making it porous. The dimensions of the pores increase and the porosity increases.

On the other hand, in the method of the present invention, as described later, pores are formed in advance between the main component particles, and the Al-Cu alloy powder on the surface is formed by the main component particles in this state. The pore size and porosity are determined by the size of the main component particles, etc.

In fact, when mixing large main component particle alloy powder and small Al-Cu alloy powder, segregation occurs due to differences in particle size, specific gravity, etc., and for this reason, carbonization of white kerosene etc. in the main component particles occurs. A hydrogen-based dispersant is dropped to wet the surface of the main component powder with the dispersant, and then the A7Cu alloy powder is added.

In addition, it is preferable that the main component particles be 20 to 80 mesh, and that the pore size be as large as possible for a sound absorbing material.
When the thickness is 20 mesh or more, sinterability is impaired, and when it is smaller than 80 mesh, the performance as a sound absorbing material is deteriorated.

The particle size of the Al-Cu alloy powder is set to 100 to 325 mm because dispersibility is considered in relation to the particle size of the main component particles.

Furthermore, the reason why AA gold alloy Al is added to the main component particles is to impart mechanical strength, but if the particle size exceeds 3φ, corrosion resistance deteriorates.

Moreover, the reason why the Cu content of the Al-Cu alloy powder is 25 to 45% is to make the melting point lower than the melting point of the main component particles, and in this sense, those having a eutectic composition are included.

In addition, 1 part of Al-Cu alloy powder was added to 100 parts of main component particles.
The reason why the amount is 0 to 30 parts is because if it is less than 10 parts, the bonding between the main component particles will be insufficient, and if it is more than 30 parts, even if the bonding property is improved, the porosity will decrease and the corrosion resistance will also deteriorate.

Next, A7-Cu alloy powder is mixed with the main component particles, and the mixed powder is molded into a desired shape under substantially no pressure.

In this case, even if the powder is molded in a substantially non-pressurized state, a dispersant such as white kerosene is present in the mixed powder, so that it can be easily molded into the desired shape.

Further, some kind of container may be used during molding, and in this case, the material may be sintered together with the container as described below.

Also, instead of molding in a non-pressure state as described above, 0,7
It is safe to apply a pressure of about
%, and by pressurizing a part of the oxide film around the main component particles is destroyed, sintering progresses through the destroyed part, and the mechanical strength is improved.

Finally, the molded body formed as described above is placed in a non-oxidizing atmosphere.
For example, in a reducing atmosphere or an inert atmosphere, the temperature condition is 550℃.
Heat and sinter at ~b.

When sintered in this way, small diameter A is formed around the main component particles.
The l-Cu alloy powder surrounds and flows in a molten state, and this exerts a binder effect, for example, to bond the particles of the main component to each other.

In addition, at this time, since the dispersant present in the mixed powder is made of hydrocarbon, the dispersant is thermally decomposed during sintering, and at this time, at least a part of the oxide film around the main component particles is reduced. The melted eutectic alloy diffuses through this portion, and the base material can also be strengthened.

Furthermore, when molding is performed under pressure instead of under no pressure, a portion of the oxide film around the main component particles is destroyed, and diffusion and sinterability are improved through these cracks.
A sound absorbing material with excellent mechanical strength can be obtained.

Further, in the atmosphere during sintering as described above, it is particularly preferable that the atmosphere be of high purity.

This high-purity non-oxidizing atmosphere means that oxygen, hydrogen, and other oxidizing media are hardly present in the atmosphere, and
For example, a near-complete vacuum state and an atmosphere with a dew point of -50 to -70°C are preferred.

The reason for this is that the eutectic alloy that melts around the main component particles is oxidized by even a small amount of oxidizing medium, and these oxidized inclusions are present in the melted portion, preventing the solid bonding as described above.

As explained in detail above, the method of the present invention is to make the main component particles as large as possible and sinter them with AlCu alloy powder interposed around the large particles, thereby forming communicating pores as gaps surrounded by the main component particles. It is.

Therefore, the shape of the communicating pores, which influences the sound absorption characteristics, depends on the shape of the main component particles.

In this respect, with the method of the present invention, even if the shape of the main component particles is not spherical but irregular, the Al-Cu alloy will adhere around the main component particles after sintering. The shape of the main component particles becomes almost spherical, the shape of the communicating pores becomes uniform, and from this as well, a product with excellent sound absorption properties can be obtained.

Next, an example will be described.

Example 1 First, white kerosene as a dispersant was mixed into 100 parts by weight of An powder having a particle size of 20 to 40 mesh until the powder became slightly moist as a whole.

Next, 20 parts of Al-Cu eutectic alloy powder having a particle size of -100 mesh was added to the Al powder in this state and mixed.

In addition, in the same way as above, white kerosene was added to 00 parts by weight of AAA1 having a particle size of 20 to 40 mesh,
Similarly, a comparative example was prepared by adding and mixing AlCu eutectic alloy powder with a particle size of 20 to 40.

When the microstructures of the compound blended according to the method of the present invention and the comparative example were examined as described above, the former was as shown in Figure 1, and the latter was as shown in Figure 2.

That is, in the case of the method of the present invention, as shown in FIG.
The periphery of the large-diameter A7 powder 1 is completely and uniformly covered with Al-Cu based eutectic alloy powder 2.

On the other hand, in the case of the comparative example, as shown in FIG.
Since powder 3 and A, g-Cu-based eutectic alloy powder 40 particles are almost the same, there is no segregation in specific gravity difference during mixing;
It was difficult to uniformly disperse both particles.

Example 2 Two types of mixed powder mixed as in Example 10 were mixed at 10×20×
Filled in a ceramic container with a size of 5 cr/L,
Both were molded under no pressure and sintered in a hydrogen atmosphere under the following conditions.

(1) Atmosphere Hydrogen flow (dew point -50°C) (2) Sintering temperature 580°C (3) Sintering time 60 minutes (4) Temperature increase rate 10°C 7/min As a result, the first method according to the present invention Al-C in the figure
Only the U-based eutectic alloy powder is completely melted, and this molten alloy is bonded to achieve the required mechanical strength (tensile strength of 4 kg).
/m17t), all pores were in communication, and the porosity was around 45.

On the other hand, in the comparative example, the alloy powder particles 4 in FIG. 2 were only melted and fell apart when pulled out from the container, and could not be formed into a plate shape.

Example 3 For the two types of mixed powder mixed as in Example 10, pressure was applied during molding, and this pressure was adjusted to 0.2.0.3.0.4.
．． 0.5.0.6.0.7.0.8.0.9, and 1. It was sintered under the same conditions as in Example 2, with the OX being changed to 103 kg/-, and its porosity was determined.

As a result, the results shown in FIG. 3 were obtained.

As is clear from Figure 3, in the case of the comparative example, the molding pressure was 0.
．． 5 X 103ky/cr/! Below L, Alj-C
Because the u-based eutectic alloy hardly diffused into the A1 alloy, the liquid phase of the eutectic alloy dripped during sintering, making it impossible to form a sintered body.

On the contrary, in the case of the method of the present invention, a completely sintered body could be constructed in all cases.

Also, looking at the porosity, according to the method of the present invention, 0.7ky
/cwi or less, a ratio of about 34 to 41% is easily obtained, whereas in the comparative example it was about 25 to 31%.

Furthermore, when we conducted a water permeability test using the conventional method for these two types and two systems, we found that all of the products made by the method of the present invention had good water permeability and that the pores were connected, but the comparative example showed that the water permeability was good. There was almost no water content, and the pores were hardly connected.

Furthermore, the relationship between sound absorption coefficient and frequency was determined by changing the actual sound frequency for the method of the present invention and the comparative example.

As a result, the method according to the present invention had a sound absorption coefficient of at least 80 for sounds with frequencies of 500H2 or higher, especially from 1000 to 1500H2, whereas the comparative example could hardly absorb such high-frequency sounds. However, it was only able to absorb sounds of about 500H2 or less.

The high-frequency sound mentioned above corresponds to the vibration sound emitted from the current Tokai Sanba Shinkansen.

[Brief explanation of the drawing]

Figure 1 is a distribution diagram of each powder particle of the mixed powder mixed by the method of the present invention, Figure 2 is a distribution diagram of a comparative example with the same relationship as Figure 1, and Figure 3 is a distribution diagram of the comparison example between the method of the present invention and the comparative example. It is a graph showing the relationship between molding pressure and porosity. 1... Large-diameter Al powder particles as main component, 2...
・Added small diameter AA-Cu alloy particles, 3...
- AI powder particles, 4...Al-Cu-based eutectic alloy particles.

Claims (1)

[Claims] 1. For 100 parts of A1 alloy powder containing 3% or less of Cu and a particle size of 20 to 80 mesh or Al powder having a particle size of 20 to 80 mesh, a powder containing Cu of 25 to 45 and a particle size of 10
10 to 30 parts of A1 alloy powder of 0 to 325 mesh is mixed with a hydrocarbon dispersant such as white kerosene, and this mixture is molded into a desired shape under substantially no pressure, and then a molded body is formed. A method for producing an aluminum-based sintered alloy sound absorbing material, which comprises sintering the above at 550 to 600°C in a non-oxidizing atmosphere. 2. For 100 parts of A1 alloy powder containing 3% or less Cu and a fineness of 20 to 80 mesh or Al powder having a fineness of 20 to 80 mesh, a powder containing 25 to 45% Cu and a fineness of 100 to 325 mesh AA alloy powder 10-30
1. Add and mix a hydrocarbon-based dispersant such as white kerosene,
The mixture is molded into a desired shape under a pressure of 0.7 x 10'' kg, /'crA or lower, and then the molded body is sintered at 550-600°C in a non-oxidizing atmosphere. A method for manufacturing an aluminum-based sintered alloy sound absorbing material.