KR100721229B1 - Fabrication of getter - Google Patents

Abstract

The present invention relates to a method of manufacturing a getter, and more particularly, to a method of manufacturing a getter through nanopowdering of pure metal powder, not a zirconium alloy powder or a mixed powder thereof. The present invention can produce a getter by a simple method of the pure metal without having to go through the alloying process of the various processes as in the prior art, the getter according to the present invention has a large specific surface area compared to the conventional alloy powder has a large gas absorption capacity, Wide range of activation temperature has an effect that can be applied to diversified products.

Titanium nanopowder, zirconium nanopowder, electroexplosion method, arc plasma method, gas absorption rate, activation temperature

Description

Getter manufacturing method {Fabrication of getter}

1 is a conventional getter manufacturing process diagram

Figure 2 is a getter manufacturing process chart of the present invention

Figure 3 is a TEM photograph of nano titanium powder according to the present invention

4 is a measurement result of the activation temperature of nano-titanium powder and other powders according to the present invention

5 is a hydrogen absorption rate measurement results of nano titanium powder and other powders according to the present invention

The present invention relates to a method of manufacturing a getter, and more particularly, to a method of manufacturing a getter by nano-powdering and then compacting a metal material.

A getter is a substance that absorbs the gas remaining in the vacuum system (contact getter) or forms a gas and a compound (disperse getter) to maintain a high vacuum. In a high vacuum state, high vacuum is maintained only by removing residual gas as well as outgass such as hydrogen introduced from the outside.

Most of the clean metal surfaces have a gettering function, but zirconium (Zr), titanium (Ti), barium (Ba), magnesium (Mg), etc. are used a lot. They are used for maintaining vacuum degree of vacuum tubes and ion pumps.

In addition, the getter is divided into an evaporable getter and a non-evaporable getter. Evaporation type getters have low melting point because the getter material is evaporated in the activation process at high temperature to remove impurities, and barium and other alloys are easily used for evaporation, and vacuum of cathode ray tube is mainly used. It is often used for fats and oils.

Non-evaporable getters are used when evaporative getters are difficult to use, i.e. when the device is contaminated by evaporated getters or when the activation process temperature is too high. Since the non-evaporable getter does not need to evaporate the getter itself like an evaporative getter, a zirconium alloy having a high melting point and excellent gas absorption ability in the solid state is mainly used.

 Such non-evaporable getters have been applied to a wide range of lamps, thermos, vacuum containers, etc. In particular, plasma emission, which requires the field emission display (FED) and the purification of impurity gases, is essential. Used in flat panel displays such as plasma displays (PDPs), they play an important role in increasing the performance, efficiency and lifespan of devices.

 The biggest determinant of the getter's performance is its specific surface, which means the surface area in contact with residual gases in high vacuum. Therefore, the larger the specific surface area, the higher the residual gas absorption capacity can maintain the desired degree of vacuum. In order to increase the specific surface area of powder particles, the particle size is reduced, the porosity is increased, and the surface curvature is increased.However, since the metal powder used as the getter material is highly active (highly oxidizing in the air), the powder particle processing process This is very difficult and there are no examples of applying this method to the actual getter powder.

The materials used in the non-evaporable getters are titanium, zirconium, etc., but their pure metal powders cannot be used alone, which is difficult to activate, and because of their low gas absorption ability, they cannot be used as getters. Zirconium-based alloys are used. That is, Zr-Al alloy which is a zirconium-based binary alloy, Zr-V-Fe alloy which is a ternary alloy is used.

As described above, the getter manufacturing method cannot produce a getter using a pure metal, and also has to go through several steps in order to manufacture an alloy, and has a disadvantage in that the specific surface area is limited.

The present invention is to provide a method for manufacturing a getter from wire rods, ingots, etc. of pure metals without the need to use alloys produced in several steps to improve the disadvantages of the conventional manufacturing method. .

In the present invention, in order to improve the disadvantage of using an alloy produced in a multi-step process, and to produce a getter with a significant increase in specific surface area, using a nano powder manufacturing apparatus of various types such as wire rod, incoating Nanometalized pure metal zirconium or titanium and compacted to obtain a getter.

Hereinafter, the getter manufacturing method of the present invention will be described in detail with reference to the accompanying drawings.

1 is a conventional getter manufacturing process, and FIG. 2 is a getter manufacturing process of the present invention. In order to prepare the getter by the presently known method, the dissimilar metals are dissolved together for alloying, and then to be pulverized (as it is difficult to grind), the hydrogenation treatment is performed first, followed by pulverization and hydrogen The getter is manufactured by going through a degassing step for removal, followed by a rolling step. That is, it must go through the processes of melting, hydrotreating, grinding, degassing and compacting.

However, in the getter manufacturing method of the present invention, nanopowders of various types of pure metal zirconium or titanium, such as wire rods and incoats, are nanopowdered using a nanopowder manufacturing apparatus and then pressed to prepare a getter. That is, manufacturing of the getter is completed only by the process of nanopowdering and compacting the pure metal.

The powdering of pure metals is nanopowdered using known nanopowderization methods such as electroexplosion, arc plasma, and gas phase spraying. In addition, the press powder may press a nano powder of pure metal to a desired size using a press.

As such, the getter manufacturing method of the present invention is very simple and no further explanation is required for the manufacturing method itself. Therefore, hereinafter, the properties of the getter manufactured according to the present invention will be described based on the measurement result.

First, the specific surface area, which is one of the main characteristics of the getter, was measured. FIG. 3 is a TEM photograph of nano-titanium powder prepared by an electroexplosive method. The particle size of the getter was measured using a spherical powder having a particle size of about 100 nm or less.

The following table is a comparison table comparing the oxygen content and specific surface area of the nano-titanium powder prepared by the present invention with the oxygen content and specific surface area of the Zr-V-Fe alloy powder and Ti powder prepared by the conventional method. .

          -Oxygen content and specific surface area comparison table-

Getter powder Oxygen content (wt%) Specific surface area (m2 / g) Zr-V-Fe Alloy Powder 0.5609 0.4809 Ti powder 0.7456 0.8264 Nano- Ti 4.4875 8.1960

When the specific surface area of the particles representing the contact surface with the residual gas in high vacuum increases, oxygen adhering to the surface increases, and the specific surface area of the nano titanium powder is much larger than that of other powders. That is, the specific surface areas of the nano titanium powder, the titanium general powder, and the zirconium alloy powder are 8.1960 m 2 / g, 0.8264 m 2 / g, and 0.4809 m 2 / g, respectively. That is, the getter according to the present invention was found to have a specific surface area of about 10-17 times that of the conventional alloy powder. This means that the contact surface with the residual gas in high vacuum is relatively large nanopowder.

Next, we measured the other major characteristics of the getter: activation temperature and hydrogenation pumping speed. 4 shows the activation temperature measurement result. The activation temperature was measured by heating the nano titanium and other powders to the corresponding temperature for 10 minutes in a vacuum exhaust process, maintaining the temperature at each temperature for 10 minutes, and then cooling to room temperature. As the surface is formed and absorbs the residual gas in the chamber, the build-up pressure decreases, and if not activated, the pressure does not change or increases. The increase in pressure is due to the release of gases such as moisture, oxygen, nitrogen, etc. adhering to the powder. Each of these powders was activated from about 200 ° C., except for nano powder, zirconium alloy powder and titanium general powder were activated at about 300 ° C. In other words, no further pressure reduction occurs, and the temperature at this time is called an activation temperature.

In contrast, nano titanium powder shows a tendency to continue to decrease in pressure with increasing temperature. This is because the specific surface area is large and the amount of surface oxygen is high, and the lowest pressure is shown at 400 ° C. or higher, which means that the gas absorption capacity is the largest. In this way, if the range of the activation temperature is wide, it is possible to give the absorption capacity to fit each product. In addition, the nano-powder did not show a pressure increase at 300 ° C. or higher, that is, a decrease in absorption capacity, which is observed in other powders to be compared.

5 is a measurement result of the hydrogen absorption rate.

The hydrogen absorption rate was measured using a device according to the carbon monoxide measurement method specified in ASTM-F798, a standard of the American Society for Testing and Materials. The powders were heated to respective temperatures, cooled to room temperature, hydrogen gas was supplied at a constant pressure, and the hydrogen absorption rate was measured by the orifice method. In the orifice method, when an orifice (D> d) with a diameter d is inserted in the middle of the oil pipe (D) in which fluid flows at a constant flow rate, the flow velocity in front of and behind the orifice changes and a pressure difference occurs. If there is a substance that absorbs the fluid later, the pressure difference increases further, and the increase in the pressure difference is a method of measuring the absorption rate.

The measured hydrogen absorption rate was 2.51L / sec · g at 450 ℃ for titanium titanium getter, 0.44L / sec · g for general titanium powder, and 1.31L / sec · g for Zr alloy at 350 ℃. . Therefore, the nano titanium powder showed about 5.7 times higher than general titanium powder and about 2 times higher than commercial zirconium alloy getters.

Although the present invention has been described above based on the pure metal material, the present invention can be applied to an alloy material, which also belongs to the scope of the present invention.

The present invention can produce the getter by a simple method without having to go through the conventional alloying process of various processes, and there is an effect that the getter can be manufactured using only pure metal.

In addition, the getter according to the present invention has a specific surface area of about 10-17 times that of a conventional alloy powder, and thus is about 5.7 times higher than that of titanium powder, which was not used as a conventional getter, and about 2 times higher than a commercial zirconium alloy getter. With the absorption capacity of, when applied to high vacuum products, it is possible to minimize the layout space in the product and to facilitate the product design.

In addition, the getter of the present invention has a wide range of activation temperature when the product is mounted on the product has a wide selection range of activation temperature has the effect that can be applied to the diversified products.

Claims (3)

Nanopowdered pure metal materials and powdered powder to produce high vacuum getter The method of manufacturing a high vacuum getter according to claim 1, wherein the pure metal is zirconium. The method of claim 1, wherein the pure metal is titanium.

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