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Getter compositions reactivatable at low temperature after exposure to reactive gases at higher temperature

Inactive Publication Date: 2005-08-04
SAES GETTERS SPA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0021] The inventors have found that the compositions of the invention, in contrast to the NEG alloys alone and in contrast to the known compositions of a NEG alloy with a metal, can be exposed to reactive gases (such as atmospheric gases) at relatively high temperatures, e.g., about 4

Problems solved by technology

However, in some cases, it is impossible to treat an alloy for its activation or reactivation at a temperature higher than that at which it has been previously exposed to gases.
In any case, during these operations the NEG alloy surface reacts with more or less intensity with the gases being present, with consequent at least partial deactivation of the alloy, such that the residual sorption velocity and capacity may result in being insufficient

Method used

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  • Getter compositions reactivatable at low temperature after exposure to reactive gases at higher temperature
  • Getter compositions reactivatable at low temperature after exposure to reactive gases at higher temperature
  • Getter compositions reactivatable at low temperature after exposure to reactive gases at higher temperature

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0054] A pellet having a thickness of 0.5 mm and a diameter of 4 mm is prepared, employing 0.10 g of powdered titanium having a particle size of less than 40 μm and 0.15 g of powdered alloy having a weight percent composition Zr 70%-V 15%-Fe 3.3%-Mn 8.7%-MM 3% with a particle size of about 125 μm. The pellet is produced by compression only under 10,000 Kg.

[0055] The thus produced pellet is treated in air at 450° C. for 20 minutes to simulate the conditions of a frit-sealing treatment. The pellet is then activated by thermal treatment under vacuum at 350° C. for two hours.

[0056] A carbon monoxide (CO) sorption test at room temperature is carried out on the thus-treated pellet, following the procedure described in the standard ASTM F 798-82, by operating with a CO pressure of 4×10−5 hPa. The results of the test are graphically shown as curve 1 in FIG. 1, as sorption speed (designated as S and measured in cc / s×g, namely cm3 of gas sorbed in a second per gram of alloy) as a function o...

example 2

[0057] The test of Example 1 is repeated, but in this case the pellet is subjected, after its formation by compression, to a sintering treatment under inert atmosphere at 870° C. for 40 minutes. A CO sorption test is carried out on the pellet, the results of which are shown in FIG. 1 as curve 2.

example 5

[0060] A pellet having a thickness of 0.5 mm and diameter of 4 mm is prepared, employing 0.10 g of powder of titanium having a particle size of less than 40 μm and 0.15 g of powder of an alloy having a weight percent composition Zr 72.2%-V 15.4%-Fe 3.4%-Mn 9% with a particle size of about 125 μm. The mixture of powders is compressed in a suitable mold under 10,000 Kg, and the pellet is then subjected to a thermal treatment of sintering at 870° C. for 40 minutes under vacuum.

[0061] Upon exposure to air (having the effect of passivating the pellet), the thus-produced pellet is activated by thermal treatment under vacuum at a temperature of 350° C. for 2 hours. A carbon monoxide (CO) sorption test at room temperature is carried out on the pellet, as described in Example 1. The results of the test are graphically shown as curve 4 in FIG. 2, as sorption speed (S) as a function of the quantity of sorbed gas (Q).

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Abstract

Compositions containing non-evaporable getter alloys are provided which, after having lost their functionality in consequence of exposure to reactive gases at a first temperature, can then be reactivated by a thermal treatment at a second temperature that is lower than the first temperature.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is a continuation of International Application No. PCT / IT2003 / 000522, filed Aug. 28, 2003, which was published in the English language on Mar. 25, 2004, under International Publication No. WO 2004 / 024965 A2 and the disclosure of which is incorporated herein by reference.BACKGROUND OF THE INVENTION [0002] The present invention is directed to compositions containing non-evaporable getter alloys which, after having lost their functionality as a consequence of an exposure to reactive gases at a first temperature, can then be reactivated by means of a thermal treatment at a second temperature, lower than the first one. [0003] Non-evaporable getter alloys, also known as NEG alloys, can reversibly sorb hydrogen and irreversibly sorb gases such as oxygen, water, carbon oxides and, in the case of some alloys, nitrogen. [0004] These alloys are employed in a number of industrial applications which require the maintenance of vacuum...

Claims

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Application Information

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IPC IPC(8): B01J20/02B01J20/34B22F1/00C01B3/00C22C1/04F04B37/02F04F99/00H01J7/18
CPCC22C14/00B01J20/3433F04F99/00H01J7/183Y02E60/327C22C16/00C22C1/0458C01B3/0047B22F2999/00B22F2998/10B22F1/0003B01J20/3483B01J20/0203B01J20/02B22F1/0088B22F3/02B22F3/1007B22F2201/03B22F2201/10B22F2201/20B01J20/3078Y02E60/32B22F1/09B22F1/145
Inventor GALLITOGNOTTA, ALESSANDROTOIA, LUCABOFFITO, CLAUDIO
Owner SAES GETTERS SPA