Hydrogen Generation in Submerged Friction Stir Welding of

Aluminum

Paul FlemingVanderbilt University

Overview

Background FSW, SFSW, Aluminum and Hydrogen

Experiment Discussions Future Research

Friction Stir Welding

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

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

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

Article from physics.com (May 16, 2007): “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

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:

2Al + 3H2O → Al2O3 + 3H2

Our research

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

http://www.fuelcellstore.com/products/h2interpower/bz12-16.html

PEMFC 1.2 W

Experiment 1

Weld reprocessed three times Voltage on fuel cell recorded

(Play Video)

Experiment 1

Experiment 2

Resistor (985 Ohms) added as load path between terminals of fuel cell

Voltage measured across resistor

Experiment 2

Discussion

Technology is potentially useful: As a means of safely storing hydrogen and

releasing without the use of chemicals As a means of regenerative braking, where the

friction provides the braking force and hydrogen is collected and used later as fuel

As a useful byproduct of a process which is itself useful (submerged FSW)

Future Research

Improve apparatus and determine the total amount of hydrogen which can be collected during normal submerged FSW

References 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.

http://www.webelements.com/webelements/elements/text/Al/chem.html

http://www.physorg.com/news98556080.html