Solid hydrogen fuel elements and methods of making the same

Abstract

A hydrogen fuel element ( 10, 110, 210 ) includes a heat-generating pyrotechnic charge ( 12 ) which comprises any suitable pyrotechnic material and an ammonia borane encasement ( 16, 116 ). The encasement partly (encasement 16 ) or wholly (encasement 116 ) encases the pyrotechnic charge ( 12 ). An ignition train ( 14 ) is powered by electrical leads ( 28 a , 28 b ) to ignite pyrotechnic charge ( 12 ) to heat both the ammonia borane binder it contains and the encasement ( 16, 116 ), which itself includes or is made entirely of ammonia borane. Hydrogen is evolved from the heated ammonia borane binder and encasement. The hydrogen fuel element ( 10, 110 ) may be encased within a suitable housing ( 30 ) which may be made of a carbon open-cell foam.

1 . A solid hydrogen fuel element comprising a pyrotechnic charge and a coherent, self-sustaining ammonia borane encasement at least partly encasing the pyrotechnic charge.  
   
   
       2 . The fuel element of  claim 1  wherein the encasement fully encases the pyrotechnic charge.  
   
   
       3 . The fuel element of  claim 1  or  claim 2  wherein the pyrotechnic charge includes a binder which upon being heated to its activation temperature releases hydrogen.  
   
   
       4 . The fuel element of  claim 3  wherein the binder comprises ammonia borane.  
   
   
       5 . The fuel element of  claim 1  or  claim 2  wherein the ammonia borane encasement is made by a process of molding ammonia borane into a hollow shape by placing the ammonia borane into a suitably shaped mold and applying sufficient pressure to the ammonia borane within the mold to render the encasement as a coherent, self-sustaining body, and placing the pyrotechnic charge within the encasement.  
   
   
       6 . The fuel element of  claim 5  including applying a pressure of at least about 2,000 psi.  
   
   
       7 . The fuel element of  claim 5  including applying a pressure of from about 2,000 to 10,000 psi.  
   
   
       8 . The fuel element of  claim 5  wherein the pyrotechnic charge is made by a process of admixing an incoherent pyrotechnic charge with a binder to form an admixture of the binder and the incoherent pyrotechnic charge.  
   
   
       9 . The fuel element of  claim 6  wherein the binder is present in the admixture in a quantity which is sufficient, upon application of sufficient pressure to the admixture, to render the incoherent pyrotechnic charge as a coherent, self-sustaining body, but which quantity is not so great as to preclude reliable ignition and burning of the pyrotechnic charge.  
   
   
       10 . The fuel element of  claim 9  including applying to the admixture a pressure of at least about 2,000 psi.  
   
   
       11 . The fuel element of  claim 10  wherein the binder comprises ammonia borane.  
   
   
       12 . The fuel element of  claim 8  wherein the pyrotechnic composition comprises one or more fuel/oxidizer couples and wherein the fuel is selected from the group consisting of one or more of aluminum, boron, silicon, titanium, zirconium and molybdenum, and the oxidizer is selected from one or more of cupric oxide; Fe 3 O 4 ; Fe 2 O 3 ; tin dioxide and titanium dioxide.  
   
   
       13 . The fuel element of  claim 8  wherein the pyrotechnic composition is selected from the group consisting of one or more of the following fuel/oxidizer couples: aluminum/cupric oxide; aluminum/Fe 3 O 4 ; aluminum/Fe 2 O 3 ; silicon/cupric oxide; silicon-boron/Fe 3 O 4  and silicon-boron/Fe 2 O 3 .  
   
   
       14 . The fuel element of  claim 8  wherein the pyrotechnic material comprises a thermite.  
   
   
       15 . The solid hydrogen fuel element of  claim 1  or  claim 2  further comprising an ignition train positioned in energy transfer relationship with the pyrotechnic charge.  
   
   
       16 . The fuel element of  claim 15  wherein the ignition train is embedded in the encasement.  
   
   
       17 . The fuel element of  claim 15  wherein the ignition train is positioned within the pyrotechnic charge.  
   
   
       18 . The fuel element of  claim 15  wherein the ignition train is embedded within the encasement and extends into contact with the pyrotechnic charge.  
   
   
       19 . The fuel element of  claim 15  further comprising a housing enclosing the ammonia borane encasement, which housing is pervious to hydrogen gas generated by the fuel element.  
   
   
       20 . A method of making a solid hydrogen fuel element comprising subjecting ammonia borane to a pressure sufficient to form it into a coherent, self-sustaining hollow encasement of ammonia borane, and at least partly encasing a pyrotechnic material within the encasement.  
   
   
       21 . The method of  claim 20  including fully encasing the pyrotechnic material within the ammonia borane encasement.  
   
   
       22 . The method of  claim 20  or  claim 21  wherein the pressure is at least about 2,000 psi.  
   
   
       23 . The method of  claim 20  or  claim 21  wherein the pressure is from about 2,000 to about 10,000 psi.  
   
   
       24 . The method of  claim 20  or  claim 21  further comprising admixing a binder with the pyrotechnic material, the binder comprising a pyrolytic hydride characterized by evolving hydrogen at least when heated to a temperature sufficiently high to evolve hydrogen from ammonia borane.  
   
   
       25 . The method of  claim 20  or  claim 21  further comprising mounting an ignition train in signal transfer communication with the pyrotechnic charge.  
   
   
       26 . The method of  claim 25  wherein the ignition train is mounted within the ammonia borane encasement.  
   
   
       27 . The method of  claim 25  wherein the ignition train has an output end and mounting the output end in contact with the pyrolytic material.  
   
   
       28 . The method of  claim 25  further comprising enclosing the ammonia borane encasement within a housing which is pervious to the flow of hydrogen gas from the interior to externally of the housing.