JPH03134130A - High damping material of aluminum alloy - Google Patents

Abstract

PURPOSE:To provide a lightweight Al alloy excellent in plastic workability and having superior vibration damping property by incorporating specific amounts of B or graphite grains to Al and regulating loss factor to a specific value or above. CONSTITUTION:A high damping material has a composition consisting of, by weight, 0.1-20% B and the balance Al with inevitable impurities or consisting of 0.5-20% graphite grains and the balance Al with inevitable impurities. In the above composition, loss factor (eta) is regulated to >=0.006. It is desirable that the average grain size of the graphite grains is >=5 mum. By adding B to Al, a fine compound AlB2 uniformly dispersing into a matrix is formed. When vibration is applied to the above material, vibration energy can be rapidly absorbed owing to viscous flow at the interface between the above compound or graphite grains and the Al matrix, and high vibration damping property can be obtained.

Description

[Detailed description of the invention] [Industrial application] The present invention is an aluminum alloy vibration damping material that has excellent vibration damping properties and is used as a structural member that dislikes vibrations in sound equipment, precision equipment, automobiles, etc. It's about materials.

[Conventional technology]

Generally, when an object is vibrated, the amplitude suddenly increases at a certain frequency (fr) (Figure 1). This frequency is called the resonant frequency, and if the maximum amplitude at the resonant frequency is A, then the amplitude that is 1/2 of this energy is Aa.
/J"i (-3 dB in aB representation). If this frequency width (half width) is Δf, the loss coefficient η is expressed by the following equation.

η = Δr / f r A material with a large value of this loss coefficient η has excellent vibration damping ability, and when the external force is removed, the vibration is damped 2 times faster.
The loss coefficient η of ordinary metal materials is 0.001 or less.

Conventionally, Fe-
Cr-based, Mn-Cu-based, Zn-Al-based, Ni-T
Alloys such as i-series are known.

Furthermore, Mg and Mg-Zr based cast materials are also known as vibration damping materials.

[Problem to be solved by the invention]

Fe-Cr series, Mn-Cu series, Zn-Al series, Ni-T
Alloys such as the i-series have high vibration damping properties, but they have a common drawback of high specific gravity, making them unsuitable when attempting to reduce the weight of equipment. On the other hand, Mg and Mg-Zr based cast materials also exhibit great vibration damping properties and have the advantage of having a low specific gravity, but have the disadvantage that they cannot be cold worked at all.

[Means to solve the problem]

In view of the above, as a result of various studies, the present invention has developed an aluminum alloy vibration damping material that has a low specific gravity and is easy to cold work. The remainder consists of Al and unavoidable impurities, and the loss coefficient η
is 0.006 or more, and the second invention is an aluminum alloy vibration damping material characterized in that the
．． This is an aluminum alloy vibration damping material comprising 5 to 2 Qw t% gold, balance Al, and unavoidable impurities, and having a loss coefficient η of 0.006 or more. In the second invention, it is desirable that the average particle size of the graphite particles is 5- or more.

[Effect]

Damping materials are classified into dislocation type, composite phase type, ferromagnetic type, and twin type depending on their vibration damping mechanism, and the vibration damping material according to the present invention falls under the composite phase type.

By adding B to Al, B forms a fine compound of AlBz that is uniformly distributed in the matrix. When vibration is applied to such a material, the vibration energy is quickly absorbed by viscous flow at the interface between the compound and the Al matrix, resulting in extremely high vibration damping properties.

As mentioned above, B is added to form a compound in the Al matrix that is extremely effective in improving vibration damping properties, and the reason for limiting its content to 0.1 to 20-t% is 0.
．． At 1 wt%, the amount of the A I B z compound formed is small and vibration damping properties are poor, and at more than 20-t%, the effect is saturated and plastic working becomes difficult.

By adding graphite to Al, it is uniformly and finely distributed in the matrix. When vibration is applied to such a material, the vibration energy is quickly absorbed by viscous flow at the interface between the graphite particles and the Al matrix, resulting in extremely high vibration damping properties.

As mentioned above, graphite particles are added to improve vibration damping properties, and the content is 0.1 to 20-t.
%, because at 0.1 wt%t%, the amount of graphite particles is small and the vibration damping property is poor, and when it exceeds 20wt%, the effect is saturated, and the graphite particles aggregate and localize, resulting in poor plastic workability and mechanical properties. This is because the physical properties deteriorate.

In both the first and second inventions, it is preferable that Ti and B, which are usually added as refining agents for the casting structure, are added in an amount of 0.05 wt% or less. Further, if the impurities contained in the ordinary Al base metal such as Si and Fe are 0.5 wt%, the effects of the present invention will not be particularly impaired.

In the second invention, the reason why the average particle diameter of the graphite particles is 5- or more is because vibration damping properties are small when the particle diameter is less than 5 fm.The larger the graphite particles are, the higher the vibration damping properties are, but when the graphite particles are monovalent or more, the plastic workability is reduced. Since the mechanical properties deteriorate, it is preferably 700- or less.

The A1 alloy having the composition described above is melted and cast using a conventional method, and after being homogenized if necessary, it is used as a casting. Furthermore, it may be used after being subjected to plastic working, that is, rolling, extrusion, drawing, forging, etc. When such plastic working is performed, dislocations are introduced into the material and AlB
A dislocation-type vibration damping mechanism is provided by the interaction between dislocations and intermetallic compounds such as compounds, graphite particles, and Al-Fe systems, and vibration damping properties are further improved. This plastic working may be performed by either hot or cold methods. In addition, when performing plastic working, the annealing treatment that is usually performed does not impair the effect of the composite phase type of the present invention.

The aluminum vibration damping material of the second invention can be manufactured by a method in which graphite particles are dispersed in a molten aluminum material or a partially solidified semi-molten material, or a method in which A1 powder and graphite particles are mixed and molded, followed by sintering.

〔Example〕

The present invention will be explained in more detail below with reference to Examples.

Example 1 An alloy having the composition shown in Table 1 was melted and cast to form an ingot having a thickness of 500 mm, a width L of 200 mm, and a length of 3000 m. After solidifying this, homogenization treatment was performed at 500'C for 10 hours,
It was hot rolled to a thickness of 5 m and further cold rolled to a plate material of 2 cm in thickness.

From this, a test piece with a thickness of 2 mm, a width of 10 mm, and a length of 250 mm was cut out, and the vibration damping property (loss coefficient η) was evaluated by the cantilever vibration method. That is, one end of the test piece was chucked to forcibly vibrate it with an oscillator, and the loss coefficient η at the resonance frequency fr was determined by equation (1). The results are also listed in Table 1.

η=Δr/f r However, Δf has a value range of 3 dB.Table 1 As is clear from Table 1, A due to the first invention alloy composition
It can be seen that all of the No. 1 alloy vibration damping materials (N (Ll~5) exhibit a loss coefficient η of 0°006 or more, and have excellent vibration damping properties. On the other hand, the comparative alloy Nα, which deviates from the No. 1 invention alloy composition,
6.7 had a low loss coefficient, and Nα8 cracked during cold rolling, making it impossible to manufacture a plate.

Example 2 Graphite particles in the amount shown in Table 2 were added to a molten metal containing AAl100 alloy, and cast while mechanically stirring to obtain an ingot with a thickness of 5011III+, a width of 120+nQl, and a length of 300 mm. This was homogenized at 500'C for 10 hours, and the thickness was 2mm, width IQmm, and length 2mm.
A 50-meter test piece was cut out, and the loss coefficient η was determined in the same manner as in Example 1. The results are also listed in Table 2.

It can be seen that it has Table 2. On the other hand, the comparative alloy (N(114)) which deviates from the second invention alloy composition and Nα15 whose average grain size of graphite particles is small have a low loss coefficient η.

〔Effect of the invention〕

As described above, since the present invention is based on aluminum, it is possible to obtain an aluminum alloy vibration damping material that is lightweight, has excellent plastic workability, and has excellent vibration damping properties, and is industrially outstanding. It is effective.

[Brief explanation of the drawing]

Figure 1 shows the resonance curve of vibration.

Claims (3)

[Claims] (1) An aluminum alloy vibration damping material containing 0.1 to 20 wt% of B, the balance being Al and unavoidable impurities, and having a loss coefficient η of 0.006 or more. (2) Contains 0.5 to 20 wt% of graphite particles, with the balance consisting of Al and unavoidable impurities, and has a loss coefficient η of 0.0
1. An aluminum alloy vibration damping material characterized in that the vibration damping material is 0.06 or higher. (3) The aluminum alloy vibration damping material according to claim 2, wherein the graphite particles have an average particle size of 5 μm or more.