New metallic bubble wrap offers big benefits over other protective materials

July 8, 2013 by Matt Shipman, North Carolina State University
Researchers at North Carolina State University have developed a new metallic bubble wrap that is lighter, stronger and more flexible than sheet metal and more heat- and chemical-resistant than plastic or other polymer-based bubble wraps. Credit: Afsaneh Rabiei

Researchers at North Carolina State University have developed a new metallic bubble wrap that is lighter, stronger and more flexible than sheet metal and more heat- and chemical-resistant than plastic or other polymer-based bubble wraps. Potential applications include automobile body panels, the wing edges of airplanes, suitcases, helmets and cases for computers and other electronic devices.

"This material does exactly what sheet metal and other bubble wraps do, but better," said Dr. Afsaneh Rabiei, professor of mechanical and aerospace engineering and the lead researcher on the project. "And it won't cost businesses and consumers very much because producing it requires just a few steps."

Rabiei developed the metallic bubble wrap to offer protection in areas that are only a few millimeters thick. To be effective, such materials must be thin enough to fit inside tightly spaced product linings, flexible enough to withstand twisting and bending, and strong enough to protect the contents inside.

To create the bubble wrap, Rabiei started with a of aluminum and used a studded roller to dot the material with small indentations. Then she deposited a foaming agent—such as or titanium —into the indentations. When heated, such agents decompose and create bubbles.

Rabiei covered the aluminum with another sheet, sandwiching the foaming agent in its indentation troughs. She ran a heavy roller over the two sheets to bond them together. In the final step, she placed the combined sheet into a furnace, where the heat broke down the foaming agent and created in the material. The process is akin to causing batter to rise when baking a cake.

The researchers applied a variety of to the metallic bubble wrap to evaluate its properties and compare it with the original bulk sheet metal. The bubble wrap, which weighs about 20 to 30 percent less than the , offered a 30 to 50 percent increase in bending strength. The tensile strength—essentially the material's breaking point—was nearly identical to the non-bubbled metal.

"The way we created this material could be used for any sheet metal, not just aluminum," Rabiei said. "We plan to further develop our metallic bubble wrap and hope it eventually offers better protection for products and the public."

Rabiei announced the creation of the bubble wrap June 24 at the 8th International Conference on Porous Metals and Metallic Foams in Raleigh, N.C. A paper on the invention is forthcoming in the conference's proceedings.

Rabiei's keynote presentation, including the metallic bubble wrap and its method of processing, was picked as one of the technical highlights of the conference by the audience. A poster presentation on the topic received the first place poster award.

Explore further: Tiny bubbles in your metallic glass may not be a cause for celebration

More information: "Introduction of a New Type of Metal Foam (Metallic Bubble Wrap)" Di Miao and Afsaneh Rabiei, North Carolina State University. Presented: June 24 at the 8th International Conference on Porous Metals and Metallic Foams in Raleigh, N.C.

Abstract: New type of metallic foam is processed in the form of thin sheet metals with longer lifetime and more reliable properties than currently used sheet materials. The current closed cell metallic foams are highly porous and non-uniform and their deformation behavior is not predictable, particularly in a thin sheet form. The new material has combined rolling processing technique with careful placement of foaming agent to produce thin sheet metal foams (a metallic version of bubble wraps) with regular pore structure and possibility of further addition of reinforcement. Design and manufacturing of the processing tools, processing of metallic bubble wrap sheets and full evaluation of the mechanical, micro-structural and physical properties of the processed material are reported in this study.

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1 / 5 (4) Jul 08, 2013
This is not a new technology. Texas Instruments Metals made "bumpy" sheet metal cases with bonded aluminum and heat-produced chemical voids in the 1980's. At best, this is a rediscovery of that process for a different use.
1 / 5 (4) Jul 08, 2013
Just because something isn't new doesn't mean it isn't important. The Vikings got to Newfoundland. They didn't stay or make significant use of their discovery or widely inform others. It may not have been practical for them using means available to them or maybe they misjudged the potential of the discovery. So for Western civilization, Columbus discovered the new world. And his importance to world history is huge whereas that of the Vikings is comparably less.
1.2 / 5 (5) Jul 09, 2013
Roller pressure welding? O.K. but a molecularly clean oxide free surface sounds expensive, unless pressure itself just blasts through any surface film.

From a Google search: "Cold welding is a solid state welding process which uses pressure at room temperature to produce coalescence of metals with substantial deformation at the weld. Welding is accomplished by using extremely high pressures on extremely clean interfacing materials. Sufficiently high pressure can be obtained with simple hand tools when extremely thin materials are being joined. When cold welding heavier sections a press is usually required to exert sufficient pressure to make a successful weld. Indentations are usually made in the parts being cold welded. The process is readily adaptable to joining ductile metals. Aluminum and copper are readily cold welded. Aluminum and copper can be joined together by cold welding."

Old science report: http://www.ieeegh...ding.pdf

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