Activated aluminum fuel
Aluminum can be used as a fuel source when reacted with water if its native surrounding oxide coating is penetrated with a gallium-based eutectic. When discrete aluminum objects are treated in a heated bath of eutectic, the eutectic penetrates the oxide coating. After the aluminum objects are treated, the aluminum objects can be reacted in a reactor to produce hydrogen which can, for example, react with oxygen in a fuel cell to produce electricity, for use in a variety of applications.
1. A method of fabricating activated aluminum reactable to produce hydrogen, the method comprising:
exposing a cold worked aluminum object to a eutectic alloy including indium and gallium, wherein, prior to exposing the cold worked aluminum object to the eutectic alloy, the cold worked aluminum object contains greater than 87 percent, by mass, of a plastically deformed and non-recrystallized aluminum alloy, and the cold worked aluminum object includes a high energy grain boundary having an energy greater than about 0.5 J/m 2 ;
through disruptions in an aluminum oxide layer on an outer surface of the cold worked aluminum object, diffusing the eutectic alloy from the outer surface of the cold worked aluminum object into a volume of the cold worked aluminum object; and
recovering at least a portion of the eutectic alloy from the aluminum oxide layer on the outer surface of the cold worked aluminum object.
2. The method of claim 1 , further comprising creating the disruptions in the aluminum oxide layer on the outer surface of the cold worked aluminum object.
3. The method of claim 2 , wherein creating the disruptions in the aluminum oxide layer on the outer surface of the cold worked aluminum object includes thermally expanding the cold worked aluminum object.
4. The method of claim 3 , wherein thermal expansion of the cold worked aluminum object creates mechanical stress in excess of the tensile yield stress of the aluminum oxide layer.
5. The method of claim 3 , wherein thermally expanding the cold worked aluminum object includes placing the cold worked aluminum object into a bath of the eutectic alloy heated to greater than about 75 degrees C. greater than an initial temperature of the cold worked aluminum object.
6. The method of claim 1 , wherein exposing the cold worked aluminum object to the eutectic alloy includes immersing the cold worked aluminum object in a bath of the eutectic alloy.
7. The method of claim 1 , wherein the outer surface of the cold worked aluminum object is exposed to the eutectic alloy for a first predetermined period, and the eutectic alloy diffuses from the outer surface to the volume of the cold worked aluminum object for a second predetermined period, at least a portion of the second predetermined period occurring outside of the first predetermined period.
8. The method of claim 7 , wherein the first predetermined period is less than the second predetermined period.
9. The method of claim 1 , wherein recovering the eutectic alloy from the outer surface of the cold worked aluminum object includes centrifuging the cold worked aluminum object.
10. The method of claim 1 , wherein diffusing the eutectic alloy from the outer surface of the cold worked aluminum object into the volume of the aluminum object includes diffusing the eutectic alloy along grain boundaries of the aluminum alloy of the cold worked aluminum object.
11. The method of claim 1 , wherein the cold worked aluminum object is one or more of extruded and forged.
12. The method of claim 1 , wherein the cold worked aluminum object is a sphere.
13. A method of fabricating activated aluminum reactable to produce hydrogen, the method comprising:
heating a bath of a eutectic alloy of gallium and indium to about 100-200 degrees C.;
placing a cold worked aluminum object having a temperature below 100 degrees C. into the bath, wherein, prior to placing the cold worked aluminum object into the bath, the cold worked aluminum object contains greater than 87 percent, by mass, of a plastically deformed and non-recrystallized aluminum alloy, and the cold worked aluminum object includes a high energy grain boundary having an energy greater than about 0.5 J/m 2 ;
leaving the cold worked aluminum object in the bath for a predetermined time for the eutectic alloy to penetrate an aluminum oxide layer on an outer surface of the cold worked aluminum object and wet grain boundaries with the eutectic alloy into a volume of the cold worked aluminum object; and
removing the cold worked aluminum object with the wetted grain boundaries from the bath.
14. The method of claim 13 , further comprising recovering at least a portion of the eutectic alloy from the outer surface of the cold worked aluminum object, and returning the recovered eutectic alloy to the heated bath.
15. The method of claim 13 , further comprising, with the cold worked aluminum object removed from the bath, resting the cold worked aluminum object.
16. The method of claim 13 , wherein the cold worked aluminum object is a sphere.