Changing material hardness at touch of a button

July 19, 2011—German and Chinese researchers in June announced the development of a material that changes its hardness by introducing an electronic signal to the material at the touch of a button.

By changing the electronic signal, the material may be fixed and brittle one moment and soft and malleable the next, according to a news release issued by the Technical University of Hamburg and the Helmholtz Center Geesthacht.

The breakthrough in material science is the result of a collaboration between Dr. Jörg Weißmüller, a professor and researcher at the Technical University of Hamburg, and Chinese research scientist Hai-Jun Jin of the Institute of Metal Research, Shenyang, China.

The material scientists used corrosion to produce the material. Typically using precious metals such as gold or platinum, the researchers placed the metal in an acidic solution. The subsequent corrosion created tiny ducts and holes, or a network of pore channels. They then impregnated the pores with a conductive liquid such as saline or diluted acid.

The unusual "marriage" of liquid and metal, observed Weißmüller, enables the properties of the material to change when triggered by an electric signal.

"For the first time we have succeeded in producing a material which, while in service, can switch back and forth between a state of strong and brittle behavior and one of soft and malleable," he said. "We are still at the fundamental research stage, but our discovery may bring significant progress in the development of so-called smart materials.”

The development could lead to future intelligent materials with the ability of self healing and smoothing out flaws autonomously.