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

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.

1 . A getter composition which is reactivatable by treatment at a temperature lower than that of a previous exposure to reactive gases, the composition comprising a mixture of powders of: 
 a first component comprising titanium or a mixture of titanium and at least one of nickel and cobalt, wherein nickel and/or cobalt are present up to 50% by weight of the first component; and    a second component comprising a non-evaporable getter alloy comprising zirconium, vanadium, iron, and at least one further component selected from the group consisting of manganese, component A and mixtures thereof, wherein the weight percentages of elements of the second component are in the following ranges:    zirconium from 60 to 90%;    vanadium from 2 to 20%;    iron from 0.5 to 15%;    manganese from 0 to 30%; and    component A from 0 to 10%;    wherein component A is selected from the group consisting of yttrium, lanthanum, Rare Earths, and mixtures thereof.    
   
   
       2 . The getter composition according to  claim 1 , wherein the getter alloy further contains up to 5% by weight of other transition elements.  
   
   
       3 . The getter composition according to  claim 1 , wherein the getter alloy comprises zirconium, vanadium, iron, and manganese, and the weight percentages of these elements in the alloy are in the following ranges: 
 zirconium from 60 to 90%;    vanadium from 2 to 20%;    iron from 0.5 to 15%; and    manganese from 2.5 to 30%.    
   
   
       4 . The getter composition according to  claim 3 , wherein the getter alloy has a weight percent composition of Zr 72.2%-V 15.4%-Fe 3.4%-Mn 9%.  
   
   
       5 . The getter composition according to  claim 1 , wherein the getter alloy comprises zirconium, vanadium, iron, and component A, and the weight percentages of these elements in the alloy are in the following ranges: 
 zirconium from 60 to 90%;    vanadium from 2 to 20%;    iron from 0.5 to 15%; and    component A from 1 to 10%.    
   
   
       6 . The getter composition according to  claim 5 , wherein the getter alloy has a weight percent composition of Zr 76.7%-V 16.4%-Fe 3.6%-A 3.3%.  
   
   
       7 . The getter composition according to  claim 1 , wherein the getter alloy comprises zirconium, vanadium, iron, manganese and component A, and the weight percentages of these elements in the alloy are in the following ranges: 
 zirconium from 60 to 85%;    vanadium from 2 to 20%;    iron from 0.5 to 10%;    manganese from 2.5 to 30%; and    component A from 1 to 6%.    
   
   
       8 . The getter composition according to  claim 7 , wherein the getter alloy has a weight percent composition of Zr 70%-V 15%-Fe 3.3%-Mn 8.7%-A 3%.  
   
   
       9 . The getter composition according to  claim 1 , wherein the powders of the first component have a particle size of up to about 40 μm.  
   
   
       10 . The getter composition according to  claim 1 , wherein the powders of the second component have a particle size comprised between about 10 and 250 μm.  
   
   
       11 . The getter composition according to  claim 10 , wherein the powders of the second component have a particle size of about 128 μm.  
   
   
       12 . The getter composition according to  claim 1 , wherein a weight ratio between the powders of the first and second components is comprised between about 1:4 and 4:1.  
   
   
       13 . The getter composition according to  claim 12 , wherein the ratio is comprised between about 1:2 and 2:1.  
   
   
       14 . The getter composition according to  claim 13 , wherein the ratio is about 3:2.  
   
   
       15 . The getter composition obtained by subjecting the composition of  claim 1  to an oxidation treatment.  
   
   
       16 . The getter composition according to  claim 15 , wherein the oxidation treatment is equal to a frit-sealing treatment foreseen for production of a device in which the composition will be contained.  
   
   
       17 . The getter composition according to  claim 16 , wherein the oxidation treatment comprises exposure to air at 450° C. for 20 minutes.  
   
   
       18 . A getter device employing composition according to  claim 1 .  
   
   
       19 . The device according to  claim 18 , comprising solely powders of the getter composition.  
   
   
       20 . The device according to  claim 19 , wherein the powders of the getter composition have been compressed at a value of pressure higher than 5000 Kg/cm 2 .  
   
   
       21 . The device according to  claim 20 , wherein the compressed powders have been sintered by thermal treatment at a temperature comprised between about 700 and 1000° C. under vacuum or inert atmosphere.  
   
   
       22 . The device according to  claim 18 , the powders of the getter composition are supported on a mechanical substrate.  
   
   
       23 . The device according to  claim 22 , wherein the substrate is a metallic strip or sheet.  
   
   
       24 . The device according to  claim 23 , wherein the powders have been cold-rolled on the metallic strip or sheet.  
   
   
       25 . The device according to  claim 23 , wherein the powders of the getter composition have been screen-printed on the metallic strip or sheet.  
   
   
       26 . The device according to  claim 22 , wherein the substrate is a container provided with at least an open portion to allow contact between the powders of getter composition and a space from which gaseous impurities must be removed.