JP3116293B2 - Rotating blade of turbo molecular pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to 10 ^-8 Torr (1.
The present invention relates to a rotor blade of a turbo-molecular pump realizing an ultra-high vacuum of 33 × 10 ⁻⁶ Pa or less.

[0002]

2. Description of the Related Art Heretofore, a rotor blade having oblique slits radially formed in a disk and a stator blade having oblique slits radially opposite to the slits of the rotor blades are coaxially and alternately arranged. 2. Description of the Related Art A turbo-molecular pump which is arranged close to and rotates a rotor blade at a high speed is known (for example, Japanese Patent Application Laid-Open No. 60-24 / 1985).
No. 7075). It is used to obtain a clean ultra-high vacuum that is not contaminated by oil molecules.

[0003] Since the rotor blade needs to increase its peripheral speed to about the thermal motion speed of gas molecules in a vacuum (about several hundred m to 1,000 m per second), it rotates at a high speed of 4000 to 30000 rpm. I have.

[0004] In this case, it is important to rotate the blade at a higher speed and with less vibration, and the material used for the blade needs to be lightweight, high in strength and high in toughness. , And light metals such as magnesium alloys are the materials to be used.

However, titanium alloys are remarkably inferior in machinability, so they are not suitable for moving blades having a complicated structure in which oblique slits are provided radially. Magnesium alloys are inferior in plastic workability, so that quality is poor. Poor stability and toughness.
Therefore, an aluminum alloy is mainly used for the rotor blade.

[0006]

When a rotor blade of a turbo molecular pump is manufactured from an aluminum alloy, JIS20 is used as a high-strength aluminum alloy satisfying the strength required for the rotor blade.
An Al-Cu alloy represented by No. 14 is used.
In this case, solution aging treatment (for example, 175 ° C., 1
Heating for 0 hour, hereinafter referred to as “T6” treatment. ) Is used in a state close to the maximum strength of the alloy.

As a result, the baking operation of the pump (the operation of evacuating the pump while heating the pump to remove oil, water and the like inside the pump) is limited to the temperature of the T6 treatment or lower, and a sufficient baking operation is performed. There was a problem that could not be done.

Further, the turbo molecular pump is often used under severe conditions for exhausting a corrosive gas such as H ₂ S (hydrogen sulfide) gas, and has a corrosion resistance higher than that of the alumite film on the blade surface. There are many needs, such as the desire to form a fluorinated passivation film. However, in the formation of the fluorinated passivation film, it is necessary to heat the rotor blade to a high temperature of 350 ° C. or more,
There is a problem that it is difficult to provide high corrosion resistance because the material strength is reduced.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a rotor blade of a turbo-molecular pump having necessary strength and excellent heat resistance. And

The rotor blade of the turbo-molecular pump according to the present invention for achieving the above object is a turbo-molecular pump made of an aluminum alloy, wherein the aluminum alloy contains 4 wt% or more and 13 wt% or more.
% Of Mn and at least one element of Fe of 4 wt% or more and 12 wt% or less, and a rapidly solidified aluminum powder metal alloy having a total dissolved atomic weight of 16 wt% or less.

The rapidly solidified aluminum powder metallurgy is desirably made of a rapidly solidified powder obtained at a cooling rate of 10 ² K / sec or more.

[0012]

According to the rotor blade of the turbo-molecular pump of the present invention,
The blade has the necessary strength as a moving blade and has excellent heat resistance.

That is, since the rapidly solidified aluminum powder metal alloy is a strength retaining material by forced solid solution and fine dispersion of transition elements without aging precipitation, there is no strength reduction in a high temperature range. It can withstand the existing baking operation and high-temperature treatment for forming a fluorinated passivation film without lowering the strength.

[0014] The addition amount of transition elements such as Mn and Fe needs to be in the above-mentioned range in order to secure the necessary strength as a moving blade. The addition amount of Mn and Fe is 4wt% each.
If it is less than the required value, the strength required for the blade material cannot be obtained. Further, when the addition amount of Mn exceeds 13 wt% and when the addition amount of Fe exceeds 12 wt%, the toughness decreases,
Destruction is caused by abnormal vibration during high-speed rotation.

[0015] Even when the added amounts of Mn and Fe are within the specified ranges, ordinary ingot metallurgy is used.
Cooling rate is slow (10K
/ Sec) and because the solid solubility limit of the element is low, required performance cannot be obtained in both strength and toughness. Therefore, if the cooling rate is 1
0 ² K / sec or more and the powder metallurgy method (Powder
It is necessary to manufacture the alloy by metallurgy.

When an aluminum alloy containing both elements of Mn and Fe is used, the total addition amount must be 16% by weight or less. If the content exceeds 16% by weight, the toughness of the material decreases.

In the case of an aluminum alloy containing only the Fe element, the heat resistance can be further improved by adding Cr, Mo, V, and Zr as the third element.

[0018]

Embodiments of the present invention will be described below.

(Example 1) 5 in which the content of Mn was changed
Various types of aluminum alloys were prepared, and powders classified into particles having a particle size of 104 μm or less as a rapidly solidified powder by an atmospheric atomizing method were used as raw materials. The cooling rate in the atmospheric atomization method was 10 ³ K / sec. Each powder raw material was subjected to vacuum hot pressing at a heating temperature of 400 ° C. to obtain an extruded billet (φ200), which was further subjected to hot extrusion to form a φ100 billet.
A round bar having an outer diameter of 90 mm was manufactured by machining and electric discharge machining.

As a comparative material, JI prepared by ordinary ingot metallurgy and subjected to T6 treatment (175 ° C., 10 hours)
An S2014 alloy and an aluminum alloy were prepared by powder metallurgy at a cooling rate of 10 K / sec, and rotor blades were manufactured in the same manner as described above.

Each of the rotating blades was rotated at 20,000 rpm and 25,000 rpm in the atmosphere, and the following various evaluation tests were performed.

High-speed rotation test This is for determining the strength of the material.

Air blowing test This is for determining the toughness of the material.

Rotation test after baking Test was performed after heating at 250 ° C. for 1 hour. This is to determine the softening characteristics of the material.

Rotation test after high-temperature heating As a base treatment, fluoridation passivation film formation by electroless Ni-P plating and fluorination treatment was assumed, and the maximum temperature of 350 ° C. applied in this base treatment was added for 80 minutes. Later. This is for the purpose of judging the softening characteristics of the material in the same manner as described above.

The results of the evaluation test are shown in Table 1.

[0027]

[Table 1]

From the results shown in Table 1, it was confirmed that the blade of the present invention made of an Al-Mn alloy had the necessary strength, toughness and heat resistance.

(Example 2) 8 in which the content of Fe was changed
A variety of aluminum alloys were prepared and made into a rapidly solidified powder at a cooling rate of 10 ³ K / sec by an atmospheric atomization method, and a rotor blade was manufactured in the same manner as in Example 1, and the same evaluation test was performed.

Table 2 shows the results of the evaluation test.

[0031]

[Table 2]

From the results shown in Table 2, it was confirmed that the blade of the present invention made of an Al-Fe alloy had the necessary strength, toughness and heat resistance. In addition, in the case of the alloy to which Cr was added as the third element, it was confirmed that the heat resistance was improved. It was confirmed that the alloy containing Fe and Mn also had the necessary strength, toughness and heat resistance.

[0033]

As described above, according to the present invention, there is an effect that a rotor blade of a turbo-molecular pump having necessary strength, toughness and heat resistance can be obtained. In particular, since the heat resistance can be improved, there is an effect that the temperature limit in the baking operation of the turbo-molecular pump is relaxed, and a pump provided with corrosion resistance such as a fluorinated passivation film can be obtained.

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F04D 19/04

Claims (2)

(57) [Claims] In a rotor blade of a turbo molecular pump made of an aluminum alloy, the aluminum alloy contains 4 wt% or more,
3 wt% or less of Mn and 4 wt% or more and 12 wt% or less of F
e. A moving blade of a turbo-molecular pump comprising a rapidly solidified aluminum powder metal alloy containing at least one solute atom of e and having a total eluted atomic weight of 16% by weight or less. 2. The rapidly solidified aluminum powder metallurgy alloy,
The rotor blade of the turbo-molecular pump according to claim 1, wherein a rapidly solidified powder obtained at a cooling rate of 10 ² K / sec or more is used as a raw material.