NON-EVAPORABLE GETTER ALLOYS PARTICULARLY SUITABLE FOR HYDROGEN AND CARBON MONOXIDE SORPTION

Abstract

Getter devices with improved sorption rate based on powders of ternary alloys particularly suitable for hydrogen and carbon monoxide sorption are described, said alloys having a composition comprising zirconium, vanadium and aluminum as main constituent elements.

Claims

1-15. (canceled)

16: Non-evaporable getter alloy consisting of: a. vanadium from 18 to 40% by atoms; b. aluminum from 5 to 25% by atoms; c. optionally one or more additional element selected from the group consisting of iron, chromium, manganese, cobalt, and nickel; and d. zirconium in the amount to balance the alloy to 100% by atoms, wherein, if present, said one or more additional element is in an amount comprised between 0.1 and 3% with respect to the alloy, said amount being lower than 10% of the aluminum atomic percentage content in the alloy.

17: The non-evaporable getter alloy according to claim 16, wherein zirconium and vanadium have a ratio Zr/V of their respective atomic amount comprised between 1 and 2.5.

18: The non-evaporable getter alloy according to claim 16, wherein, if present, said one or more additional element is in an amount comprised between 0.1 and 2% with respect to the alloy.

19: Non-evaporable getter alloy consisting of: i) vanadium from 18 to 40% by atoms; ii) aluminum from 5 to 25% by atoms; iii) optionally one or more additional element selected from the group consisting of iron, chromium, manganese, cobalt, and nickel; iv) impurities in an amount lower than 1% by atoms with respect to the alloy, v) zirconium in the amount to balance the alloy to 100% by atoms; and wherein, if present, said one or more additional element is in an amount comprised between 0.1 and 3% with respect to the alloy, said amount being lower than 10% of the aluminum atomic percentage content in the alloy.

20: The non-evaporable getter alloy according to claim 16, which is in the form of a powder.

21: A mixture, comprising: the non-evaporable getter alloy according to claim 20; and a metal powder.

22: The mixture of claim 20, wherein the metal powder is at least one selected from the group consisting of metallic titanium powder and metallic zirconium powder.

23: The non-evaporable getter alloy according to claim 20, wherein said powder has a particle size lower than 500 m.

24: The non-evaporable getter alloy according to claim 20, wherein said powder has a particle size lower than 300 m.

25: A getter device, comprising: the non-evaporable getter alloy according to claim 16.

26: The getter device according to claim 25, wherein said non-evaporable getter alloy is in the form of pills of compressed powder.

27: The getter device according to claim 25, wherein zirconium and vanadium have a ratio Zr/V of their respective atomic amount comprised between 1.5 and 2.

28: The getter device according to claim 25, wherein said non-evaporable getter alloy powder is in the form of a single compressed and sintered body getter element.

29: The getter device according to claim 28, wherein said getter device is a getter pump, a cartridge for a getter pump, or a pump comprising at least one pumping element.

30: A process, comprising: removing hydrogen and carbon monoxide with the getter device according to claim 25.

31: A hydrogen-sensitive system comprising the getter device according to claim 25, wherein the hydrogen-sensitive system is selected from the group consisting of a vacuum chamber, a cryogenic liquids transportation, a solar receiver, a vacuum bottle, a vacuum insulated flow line, an electronic tube, a dewar, an oil pipe, a gas pipe, a collecting solar panel, and an evacuated glass.

Description

EXAMPLES

[0041] Several polycrystalline ingots have been prepared by arc melting of appropriate mixtures of the high purity metallic constituent elements in an argon atmosphere. Each ingot has been then grinded by ball milling under argon atmosphere and subsequently sieved to the desired powder fraction, i.e. less than 300 m.

[0042] 1 g of each alloy listed in table 1 (see below) were pressed in a die in order to obtain the samples (pill) labeled as sample A, B, C (according to the present invention) and comparative samples labeled from 1 to 7.

TABLE-US-00001 TABLE 1 Zr V Al Ni Cr Mn Fe Comparative 1 50 35 15 Comparative 2 57 35.8 7.2 Comparative 3 57 35.8 7.2 Comparative 4 57 35.8 7.2 Comparative 5 57 35.8 7.2 Sample A 52.5 32.3 15.2 Sample B 53 27 20 Sample C 58.5 34.5 7 Comparative 6 63 17 20 Comparative 7 40 20 40

[0043] They have been compared in their sorption performance versus hydrogen and carbon monoxide in form of getter powder compressed pills (diameter 10 mm and height 3 mm) and in form of sintered getter disk, obtained after press and pressing and sintering process Temperature lower than 1250 C.

[0044] The test for H.sub.2 and CO sorption capacity evaluation is carried out on an ultra-high vacuum bench. The getter sample is mounted inside a bulb and an ion gauge allows to measure the pressure on the sample, while another ion gauge allows to measure the pressure upstream of a conductance located between the two gauges. The getter is activated with a radiofrequency oven at 500 C.10 min; afterwards it is cooled and kept at 25 C. A flow of H.sub.2 or CO is passed on the getter through the known conductance, keeping a constant pressure of 310.sup.6 torr. Measuring the pressure before and after the conductance and integrating the pressure change in time, the pumping speed and the sorbed quantity of the getter can be calculated. The recorded data have been reported in table 2 (for sintered disks) and in table 3 (for compressed pills).

TABLE-US-00002 TABLE 2 Sintered H.sub.2 CO sorption sorption rate (l/s) rate (l/s) Comparative 1 10.0 4.8 Comparative 2 11.0 6.0 Comparative 3 10.0 5.2 Comparative 4 7.5 5.3 Comparative 5 5.6 5.0 Sample A 19 8 Sample B 17 8 Comparative 6 6.3 6.2 Comparative 7 6.8 4.7

TABLE-US-00003 TABLE 3 Pills 103 H.sub.2 CO sorption sorption rate (l/s) rate (l/s) Sample A 2 1.5 Sample B 1.7 1 Sample C 3.5 2.3 Comparative 6 1.2 0.5 Comparative 7 0.5 0.3