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. Non-evaporable sintered 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 2.5% by atoms with respect to the alloy, said amount of the one or more additional element being lower than 10% of the aluminum atomic percentage content in the alloy; wherein said non-evaporable sintered getter alloy has a CO sorption rate from 29% to 66% greater than the CO sorption rate of non-evaporable sintered getter alloys having higher or lower vanadium or aluminum content than the vanadium or aluminum content of the claimed non-evaporable sintered getter alloy.

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

3. The non-evaporable sintered getter alloy according to claim 1, wherein, if present, said one or more additional element is in an amount comprised between 0.1 and 2% by atoms with respect to the alloy.

4. The non-evaporable sintered getter alloy according to claim 1, which is in the form of a sintered powder.

5. A sintered mixture comprising the non-evaporable sintered getter alloy of claim 4 and a metal powder.

6. The sintered mixture of claim 5, wherein the metal powder is at least one selected from the group consisting of metallic titanium powder and metallic zirconium powder.

7. The non-evaporable sintered getter alloy according to claim 4, wherein said powder has a particle size lower than 500 μm.

8. A getter device, comprising: the sintered non-evaporable getter alloy according to claim 1.

9. The getter device according to claim 8, wherein zirconium and vanadium have a ratio Zr/V of their respective atomic amount comprised between 1.5 and 2.

10. Non-evaporable sintered getter alloy able to sorb CO at a rate of 8 l/s 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 2.5% by atoms with respect to the alloy, said amount of the one or more additional element being lower than 10% of the aluminum atomic percentage content in the alloy.

11. The non-evaporable sintered getter alloy according to claim 10, wherein zirconium and vanadium have a ratio Zr/V of their respective atomic amount comprised between 1 and 2.5.

12. The non-evaporable sintered getter alloy according to claim 10, wherein, if present, said one or more additional element is in an amount comprised between 0.1 and 2% by atoms with respect to the alloy.

13. The non-evaporable sintered getter alloy according to claim 10, which is in the form of a sintered powder.

14. A sintered powder mixture comprising the non-evaporable sintered getter alloy of claim 13 and a metal powder.

15. The sintered powder mixture of claim 14, wherein the metal powder is at least one selected from the group consisting of metallic titanium powder and metallic zirconium powder.

16. The non-evaporable sintered getter alloy according to claim 13, wherein said powder has a particle size lower than 500 μm.

17. A getter device, comprising: the non-evaporable sintered getter alloy according to claim 10.

18. The getter device according to claim 17, wherein zirconium and vanadium have a ratio Zr/V of their respective atomic amount comprised between 1.5 and 2.

Description

EXAMPLES

(1) 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 μm.

(2) 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.

(3) 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 — — — —

(4) 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.

(5) 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 3×10.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).

(6) 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

(7) TABLE-US-00003 TABLE 3 Pills 10−3 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