Transcript Hydrogen generation in friction stir welding of aluminum

Hydrogen Generation in Submerged
Friction Stir Welding of Aluminum
Paul Fleming
Vanderbilt University
Overview
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Background
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FSW, SFSW, Aluminum and Hydrogen
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Experiment
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Discussions
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Future Research
Friction Stir Welding
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Recently (1991)
developed solid state
welding technique
Uses mechanical stirring
to join metals
Yields high weld strength
Can be used to join
aluminum
Submerged Friction Stir Welding
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The case when the
joining process is run
underwater
Has been shown to
be useful to prevent
overheating
May produce lower
grain sizes
Aluminum and Hydrogen
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Aluminum in its pure form will react with air or water
In the case of water the reaction often leads to a release of
hydrogen
Typically however, an oxide skin develops on the surface of
aluminum which prevents the reaction from continuing through
the aluminum
However, several researchers have proposed uses of this
reaction for hydrogen generation
An example technology
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Article from physics.com (May 16, 2007):
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“New process generates hydrogen from aluminum
alloy to run engines, fuel cells”
Jerry Woodall at Purdue uses gallium to prevent
the development of the “skin” or oxide layer.
The reaction continues therefore until all
aluminum is used
Another example
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The paper, “Hydrogen gas generation in the wet cutting of
aluminum and its alloys”, shows that when aluminum is cut
underwater there is a fresh surface revealed which reacts
with the water and hydrogen is released.
Experiments were conducted in the paper and the gas
released during underwater cutting was confirmed to be
hydrogen.
Also provides a probable chemical reaction:
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2Al + 3H2O → Al2O3 + 3H2
Our research
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Demonstrate that hydrogen is released during
submerged FSW, a technology which is useful
in and of itself
Build an apparatus which can perform
submerged FSW and collect the resulting
Hydrogen
Attempt to discern the total amount of hydrogen
released
Research Apparatus
Block Diagram
PEMFC 1.2 W
http://www.fuelcellstore.com/products/h2interpower/bz12-16.html
Experiment 1
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Weld reprocessed three times
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Voltage on fuel cell recorded
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(Play Video)
Experiment 1
Experiment 2
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Resistor (985 Ohms) added as load path
between terminals of fuel cell
Voltage measured across resistor
Experiment 2
Discussion
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Technology is potentially useful:
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As a means of safely storing hydrogen and
releasing without the use of chemicals
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As a means of regenerative braking, where the
friction provides the braking force and hydrogen is
collected and used later as fuel
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As a useful byproduct of a process which is itself
useful (submerged FSW)
Future Research
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Improve apparatus and determine the total
amount of hydrogen which can be collected
during normal submerged FSW
References
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Ted Clark. An analyis of microstructure and corrosion resistance of underwater friction stir processed 304l
stainless steel. Technical report, BYU, 2007.
George E. Cook, Reginald Crawford, Denis E. Clark, and Alvin M. Strauss. Robotic friction stir welding.
Industrial Robot, 31(1):55–63, November 2004.
Jerome J. Cuomo and Jerry M. Woodall. Solid state renewable energy supply, November 1982. US Patent
4,358,291.
Douglas C. Hofmann and Kenneth S. Vecchio. Submerged friction stir processing (sfsp): An improved method
for creating ultra fine grained bulk materials. Materials Science & Engineering, 402:234–241, 2005.
Terry Khaled. An outsider looks at friction stir welding. Technical report, Federal Aviation Administration, 2005.
Kunio Uehara, Hideo Takeshita, and Hiromi Kotaka. Hydrogen gas generation in the wet cutting of aluminum
and its alloys. Journal of Materials Processing Technology, 127:174–177, 2002.
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http://www.webelements.com/webelements/elements/text/Al/chem.html
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http://www.physorg.com/news98556080.html