JPH0347933A - Nonevaporation-type getter alloy - Google Patents

Abstract

PURPOSE:To provide the alloy having superior absorptivity even when used at <=300 deg.C and also excellent in crushability by adding specific amounts of Al and Nb and/or Ta to Zr. CONSTITUTION:This nonevaporation-type getter alloy has a composition consisting of, by weight, 5-20% Al, 0.1-15% Nb and/or Ta, and the balance Zr. In the above alloy, Al has a function of forming Zr-Al intermetallic compound to improve crushability, and, crushability is deteriorated when its content is less than 5%, and, when it exceeds 20%, respective contents of Zr or Nb and/or Ta are reduced because Al itself has no gas absorptivity, and as a result, gas absorptivity of the alloy is reduced. Nb and Ta have a function of remarkably increasing the amount of gas absorbed, and, as to their contents, the increase in the amount of absorption is reduced when they are less than 0.1% and, on the other hand, the amount of absorption and crushability are rapidly reduced when they exceed 15%.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a getter material that can trap gas in the form of physical adsorption and chemisorption, and in particular, a non-evaporable getter that can increase the amount of gas absorbed. It concerns alloys.

[Conventional technology 1 Generally, getter materials have traditionally been Zr, Ti, H
Elemental metals such as f, Nb, Ta, Th, and V are known.

The getter material is usually made of 110 ml to provide a large reactive surface area for effective physical and chemical adsorption.
It is used in the form of a powder of about 0 μm, and therefore, crushability is one of the characteristics that the getter material should have. However, these single metals have the disadvantage that they are too ductile and cannot be easily crushed, and even if they can be crushed, they are difficult to become fine, or they are spherical in shape and have a small surface area (which is disadvantageous in terms of gas absorption speed). Become.

In addition, in order to retain gettering ability, an activation treatment is usually performed to decompose oxides on the surface to create an active surface. However, these simple metals form very stable oxides on their surfaces, and creating an active surface requires heating to high temperatures in a vacuum, which is not easy.

Therefore, alloy getter materials have been developed as an alternative to the single metals mentioned above.

84% by weight Z disclosed in Japanese Patent Publication No. 46-39811
The getter material of the r-16wt% 8-he alloy is an intermetallic compound of Zr and A℃, and although this alloy has solved the above-mentioned crushability problem, the absorption rate is low, and it absorbs a large amount of air, especially at room temperature. It takes a considerable amount of time to evacuate the phase;
Addition of Al2 has the disadvantage of reducing the amount of absorption, and since the absorption rate of this alloy does not increase unless the temperature is 300°C or higher, the alloy must be heated to 300°C or higher.

In addition, as described in Japanese Patent Publication No. 1141/1983, a getter material is disclosed in which the above-mentioned single metal and Zr-Al2 alloy are mixed, but this also has the drawback of not having sufficient exhaust capacity at room temperature. are doing.

For this reason, there has been a demand for a getter material that has excellent crushability and also has excellent absorption characteristics when used at temperatures below 300°C.

[Problems to be Solved by the Invention] The present invention aims to solve the above-mentioned drawbacks of the prior art and provide a non-evaporable getter alloy that has excellent absorption characteristics even when used at temperatures below 300°C and has good crushability. This is what it means.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides the following: Aβ: 5 to 20% by weight Nb, Ta: The total weight of one or two types is 0.1 to 15%.
Weight % Zr: Provides a non-evaporable getter alloy characterized by consisting essentially of the balance.

[For use] Getter materials used in the vacuum field are required to have a high absorption rate (and a large amount of absorbed gas).

After the activation treatment, the higher the absorption rate of the getter material, the earlier the desired degree of vacuum can be achieved, and the greater the amount of gas absorbed, the longer it can be used and the higher the degree of vacuum achieved.

The present inventor conducted various studies on getter materials that can be used at room temperature, and found that Zr contains Aβ, Nb and/or Ta.
The present invention was achieved based on the discovery that both the crushability and the gas absorption capacity are improved by adding the following.

The present invention will be explained in detail below.

The present invention is based on a simple metal Zr having getter ability, and has Al2 added thereto to impart crushability, and further Nb and/or Ta is added to increase the gas absorption ability at room temperature.

Al2 is contained in an amount of 5 to 20% by weight. As a result, Zr
- Formation of Al2 intermetallic compound improves crushability,
Powders of 50 to 1100 u can be easily produced. AI! If the content is less than 5% by weight, the grindability is poor, and if it exceeds 20% by weight, A° C. itself has no gas absorption ability, so the amount of Zr, Nb, or Ta decreases, resulting in a decrease in gas absorption ability.

The total weight of one or two types of Nb and Ta is 0.1
~15% by weight. This addition significantly increases the gas absorption capacity of the regetter material.

If it is less than 0.1% by weight, there is little increase in the amount of absorption, and if it exceeds 15% by weight, the amount of absorption and crushability will decrease rapidly.

[Example] Alloys having the compositions shown in Table 1 were arc melted in an argon atmosphere of 500 mbar to produce button-shaped alloys each weighing 30 g.

This is crushed and classified in a mortar, and the particle size is 50 to 100L.
A powder of L was prepared.

Next, weigh 1 g of each of these powders and
After sufficiently evacuation in an atmosphere of approximately Torr, activation was performed at 800° C. for 30 minutes while evacuation was performed, and after cooling to room temperature, gas absorption measurements were performed. Gas absorption measurement has a purity of 6N
Using H2 gas, an initial pressure of 10 kgf/crn'' was applied to a chamber with a known internal volume in an atmosphere of 30°C, and the amount of H2 absorbed was measured from the pressure change in the system due to absorption by the sample.

The measurement results are shown in Table 1 along with comparative examples.

* indicates Comparative example × ○ Good It is possible to secure the getter material on time and maintain it for a long time, and as a result, the installation volume of the getter material in the container etc. is small, making it easy to secure the installation location.

Claims (1)

[Claims] 1 Al: 5-20% by weight Nb, Ta: The total weight of one or two types is 0.1-15% by weight Zr: Substantially the remainder A non-evaporable getter alloy characterized by: