Composite materials capable of hydrogen sorption and methods for the production thereof

Abstract

A powder of a composite material comprising a non-evaporable getter material with a palladium coating continuously sorbs hydrogen. Embodiments in which the coverage of the palladium coating over the particles of the NEG material is complete can sorb hydrogen without the need for an activation treatment. Other embodiments in which the palladium coverage is less than total but greater than about 10% can also sorb gaseous species other than hydrogen. Loose powders, pressed powders, and sintered powders of the composite material are incorporated into getter devices and into the evacuated spaces of double-walled pipes, dewars, and thermal bottles. Methods for preparing powders of these composite materials utilize evaporative, sputter, and CVD deposition techniques. Another method prepares powders of the composite material by a liquid phase impregnation process.

What is claimed is:  
     
         1 . A composite material capable of continuously sorbing hydrogen, said composite material comprising: 
 a plurality of particles of a non-evaporable getter material, said particles being coated over at least about 10% of their surfaces with a coating of one or more species selected from the group consisting of palladium, palladium oxide, palladium-silver alloys containing up to about 30% atomic percent silver, and compounds of palladium and said getter material.    
     
     
         2 . A composite material according to  claim 1 , wherein between about 10% and about 90% of said particles' surfaces are coated with said coating.  
     
     
         3 . A composite material according to claims  1  or  2 , wherein said non-evaporable getter material is selected from the group consisting of: 
 Zr, Ti, Nb, Ta, and V metals;  
 Zr alloyed with either Ti, Cr, Mn, Fe, Co, Ni, Al, Cu, Sn, Si, Y, La, any of the rare earth elements, or mixtures thereof;  
 Ti alloyed with either Zr, Cr, Mn, Fe, Co, Ni, Al, Cu, Sn, Si, y, La, any of the rare earth elements, or mixtures thereof; and  
 any mixture of the aforementioned metals and alloys.  
 
     
     
         4 . A composite material according to  claim 3 , wherein said non-evaporable getter material is selected from the group consisting of Ti—V alloys, Zr—V alloys, Zr—Al alloys, Zr—Fe alloys, Zr—Ni alloys, Ti—V—Mn alloys, Zr—Mn—Fe alloys, Zr—V—Fe alloys, Zr—Ni-A-M alloys, and Zr—Co—A alloys, where A indicates Y, La, any of the rare earth elements, or mixtures thereof, and M indicates Co, Cu, Fe, Al, Sn, Ti, Si, or mixtures thereof.  
     
     
         5 . A composite material according to  claim 2 , wherein between about 25% and about 75% of said particles' surfaces are coated with said coating.  
     
     
         6 . A composite material according to claims  1  or  2 , wherein a thickness of said coating is less than about 5 μm.  
     
     
         7 . A composite material according to claims  1  or  2 , wherein said particles of said non-evaporable getter material have a size less than about 500 μm.  
     
     
         8 . A composite material according to  claim 7 , wherein said particle size is between about 20 μm and about 125 μm.  
     
     
         9 . A method for the preparation of a composite material capable of continuously sorbing hydrogen, comprising: 
 preparing a solution of a palladium compound in a solvent;    mixing a plurality of particles of a non-evaporable getter material into said solution;    evaporating said solvent to create a dried powder; and    thermally treating said dried powder to leave a palladium coating on said plurality of particles.    
     
     
         10 . A method for the preparation of a composite material as in  claim 9  wherein said palladium compound is a palladium salt.  
     
     
         11 . A method for the preparation of a composite material as in  claim 9  wherein said palladium compound is a palladium complex.  
     
     
         12 . A method for the preparation of a composite material as in  claim 9  wherein said palladium coating is palladium metal.  
     
     
         13 . A method for the preparation of a composite material as in  claim 9  wherein said palladium coating is palladium oxide.  
     
     
         14 . A method for the preparation of a composite material as in  claim 9  wherein said palladium coating is a mixture of palladium metal and palladium oxide.  
     
     
         15 . A method according to  claim 9  wherein said plurality of particles of a non-evaporable getter material are hydrogenated before being mixed into said solution and dehydrogenated by said thermal treatment.  
     
     
         16 . A method for the preparation of a composite material capable of continuously sorbing hydrogen, comprising: 
 preparing a thin powder bed of a plurality of particles of a non-evaporable getter material;    placing said thin powder bed into an evacuable chamber;    evacuating said chamber;    evaporating a precursor compound containing palladium within said chamber to deposit said precursor compound on said plurality of NEG particles; and    thermally treating said plurality of NEG particles to leave a palladium coating thereon.    
     
     
         17 . A method for the preparation of a composite material as in  claim 16  wherein said palladium coating is palladium metal.  
     
     
         18 . A method for the preparation of a composite material as in  claim 16  wherein said palladium coating is palladium oxide.  
     
     
         19 . A method for the preparation of a composite material as in  claim 16  wherein said palladium coating is a palladium compound further including one or more elements of said NEG material.  
     
     
         20 . A method for the preparation of a composite material as in  claim 16  wherein said precursor compound is an organometallic palladium compound.  
     
     
         21 . A method according to  claim 16  wherein said plurality of particles of a non-evaporable getter material are hydrogenated before preparing said thin powder bed and dehydrogenated by said thermal treatment.  
     
     
         22 . A method for the preparation of a composite material capable of continuously sorbing hydrogen, comprising: 
 preparing a thin powder bed of a plurality of particles of a non-evaporable getter material;    placing said thin powder bed into an evacuable chamber;    evacuating said chamber; and    heating a wire of a palladium compound within said chamber to cause a portion of said wire to evaporate and deposit on said plurality of NEG particles.    
     
     
         23 . A method for the preparation of a composite material as in  claim 22  wherein said palladium compound is a palladium-silver alloy.  
     
     
         24 . A method for the preparation of a composite material as in  claim 22  wherein said palladium compound is palladium metal.  
     
     
         25 . A method according to  claim 22  wherein said plurality of particles of a non-evaporable getter material are hydrogenated before preparing said thin powder bed.  
     
     
         26 . A method for the preparation of a composite material capable of continuously sorbing hydrogen, comprising: 
 preparing a thin powder bed of a plurality of particles of a non-evaporable getter material;    placing said thin powder bed into an evacuable chamber;    evacuating said chamber; and    sputtering a target of a palladium compound within said chamber to cause a portion of said target to deposit on said plurality of NEG particles.    
     
     
         27 . A method for the preparation of a composite material as in  claim 26  wherein said palladium compound is a palladium-silver alloy.  
     
     
         28 . A method for the preparation of a composite material as in  claim 26  wherein said palladium compound is palladium metal.  
     
     
         29 . A method according to  claim 26  wherein said plurality of particles of a non-evaporable getter material are hydrogenated before preparing said thin powder bed.  
     
     
         30 . A thermal insulation device, comprising: 
 a sealable enclosure in which a high degree of vacuum is maintained; and    a plurality of particles of a non-evaporable getter material disposed within said enclosure, said particles being coated over at least about 10% of their surfaces with a coating of one or more species selected from the group consisting of palladium, palladium oxide, palladium-silver alloys containing up to about 30% atomic percent silver, and compounds of palladium and said getter material.    
     
     
         31 . A thermal insulation device as recited in  claim 30  wherein said sealable enclosure is a volume enclosed between an inner wall and an outer wall of an insulated pipe.  
     
     
         32 . A thermal insulation device as recited in  claim 30  wherein said sealable enclosure is a volume enclosed between an inner wall and an outer wall of a dewar.  
     
     
         33 . A thermal insulation device as recited in  claim 30  wherein said scalable enclosure is a volume enclosed between an inner wall and an outer wall of a thermal bottle.  
     
     
         34 . A battery, comprising: 
 a casing;    an anode disposed within said casing;    a cathode disposed within said casing;    an electrolyte disposed between said anode and said cathode; and    a plurality of particles of a non-evaporable getter material disposed within said casing, said particles being coated over at least about 10% of their surfaces with a coating of one or more species selected from the group consisting of palladium, palladium oxide, palladium-silver alloys containing up to about 30% atomic percent silver, and compounds of palladium and said getter material.    
     
     
         35 . A pressed and sintered pellet of a composite material capable of continuously sorbing hydrogen, comprising: 
 a plurality of particles of a non-evaporable getter material, said particles being coated over at least about 10% of their surfaces with a coating of one or more species selected from the group consisting of palladium, palladium oxide, palladium-silver alloys containing up to about 30% atomic percent silver, and compounds of palladium and said getter material.    
     
     
         36 . A getter device, comprising: 
 a substrate having a surface; and    a plurality of particles of a non-evaporable getter material deposited on said surface of said substrate, said particles being coated over at least about 10% of their surfaces with a coating of one or more species selected from the group consisting of palladium, palladium oxide, palladium-silver alloys containing up to about 30% atomic percent silver, and compounds of palladium and said getter material.    
     
     
         37 . A getter device, comprising: 
 a container having an opening; and    a plurality of particles of a non-evaporable getter material disposed within said container, said particles being coated over at least about 10% of their surfaces with a coating of one or more species selected from the group consisting of palladium, palladium oxide, palladium-silver alloys containing up to about 30% atomic percent silver, and compounds of palladium and said getter material.