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METAL FOAM CAN TAKE
THE HEAT
Researchers at North Carolina
State University, Raleigh, determined
that lightweight composite metal
foams (CMFs) are significantly more
effective at insulating against heat
than the conventional base metals and
alloys that comprise them and also
exhibit greater thermal stability. CMFs
are hollow spheres made of materials
such as carbon steel, stainless steel, or
titanium embedded in a matrix of steel,
aluminum, or metallic alloys.
In one test, researchers exposed
samples of steel-steel CMF, measuring
2.5 × 2.5 in. and 0.75 in. thick, to a fire
with an average temperature of 800°C
for 30 minutes on one side. It took eight
minutes for the steel-steel CMF to reach
800°C through the entire thickness of
the sample, but it took only four min-
utes for a piece of bulk stainless steel
with the same dimensions to reach
the same temperature throughout.
Researchers also found that the CMF
made entirely of stainless steel expands
80% less than bulk stainless steel at
200°C, and the differential increases at
higher temperatures. Additionally, the
CMF expands at a fairly constant rate,
whereas conventional bulk metals and
alloys expand more rapidly as tempera-
ture increases. The findings demon-
strate that CMF is promising for use in
storing and transporting nuclear mate-
rial, hazardous materials, explosives,
and other heat-sensitive materials, as
well as for space exploration. .
FOLDABLE 3D MATERIAL
CHANGES SHAPE AND SIZE
Researchers at Harvard University,
Cambridge, Mass., designed a novel 3D
material that is versatile, tunable, and
self-actuated. Inspired by an origami tech-
nique called snapology, the structure is
made from extruded cubes with 24 faces
and 36 edges. By folding certain edges,
Afsaneh Rabiei examines a sample of composite metal foam.
BRIEF
The University of British Columbia, Canada, received $11 million from
Vancouver-based diamond pioneer and philanthropist Stewart Blusson
and his wife, Marilyn, to support quantummaterials research. In recogni-
tion, the UBC Quantum Matter Institute has been renamed the Stewart
Blusson Quantum Matter Institute. The Institute will move to a new
facility later this year and will include 20 professors by 2019. .
which act like hinges, the material can
be deformed into many different shapes.
The team connected 64 of these individ-
ual cells to create a 4 × 4 × 4 cube that can
grow and shrink, change its shape glob-
ally, change the orientation of its micro-
structure, and fold completely flat. As the
system changes shape, it also changes
stiffness. These actuated changes inmate-
rial properties add a fourth dimension
to the structure. While the Harvard team
used pneumatic actuators that were pro-
grammed to bend specific hinges, the
material can be embedded with any type
of actuator—including thermal, dielectric,
or even water—eliminating the need for
external input.
“This researchdemonstrates anew
class of foldable materials that is also
completely scalable,” explains gradu-
ate student Johannes T.B. Overvelde.
“It works from the nanoscale to the
meter-scale and could be used to make
anything from surgical stents to porta-
ble pop-up domes for disaster relief.”
.
EMERGING TECHNOLOGY
A D V A N C E D M A T E R I A L S & P R O C E S S E S | M A Y 2 0 1 6
1 4
From left, UBC President Martha Piper, Stewart and
Marilyn Blusson, and Andrea Damascelli. Courtesy
of Don Erhardt.
Harvard researchers designed a
new type of foldable material that is
versatile, tunable, and self-actuated.
Courtesy of Johannes Overvelde/
Harvard SEAS.