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Fore! Glass golf clubs are playing through
What do some high-end golf clubs and a
living room window have in common? The
answer is glass, but the clubs use metallic
glass, which can be bent considerably and
spring back to original form. An interna-
tional team of scientists hopes their discov-
eries will lead to glass that is both stronger
and more ductile.
“We used an experimental technique
called nanoindentation to repeatedly sample
the initial formation of shear bands,” says Seth
Imhoff at Los Alamos National Laboratory,
N.M. “Essentially it uses a tiny needle to push
on the surface of a sample in a very controlled
way. Even though the force is small, the tip of
the needle concentrates stress in one small
region until a single shear band is generated
in order to relieve some stress.”
By repeating this process many times, scientists sample many local atomic arrange-
ments and their specific critical stress levels. This evidence challenges the current assump-
tion of only a single type of initiation site, or STZ (shear transformation zone).
Identification of multiple types of STZs could lead to new opportunities for controlling
the strength and ductility of bulk metallic glasses and, of course, more durable high-per-
formance golf clubs.
Manufacturing a solution to planet-clogging plastics
Researchers at Harvard’s Wyss Insti-
tute, Boston, developed a method to carry
out large-scale manufacturing of every-
day objects—from cell phones to food
containers and toys—using a fully
degradable bioplastic isolated from
shrimp shells. The objects exhibit many
of the same properties as those created
with synthetic plastics, without the envi-
ronmental threat. It also trumps most
bioplastics on the market today in posing
no threat to trees or competition with the
food supply.
The bioplastic was developed from
chitosan, a form of chitin, a long-chain
polysaccharide responsible for the
hardy shells of shrimps and other crus-
taceans, armor-like insect cuticles,
tough fungal cell walls, and flexible but-
terfly wings. The majority of available
chitin in the world comes from dis-
carded shrimp shells, and is either
thrown away or used in fertilizers, cos-
metics, or dietary supplements.
The Wyss team, led by Javier Fernan-
dez and Don Ingber, developed a new way
to process the material so that it can be
news
industry
briefs
Steelhead Composites, Denver,
purchased and installed a heavy-
duty CNC neck forming machine
made by MJC Engineering and
Technology, Huntington Beach,
Calif. It is designed to manufacture
high-pressure cylinders, including
aluminum vessels to 42 cm (16.7
in.) in diameter and to 3 m (10 ft)
in length. A seamless aluminum
tube is shaped to form a bottle
with a domed end and port
openings. The bottle is then
wrapped with carbon fiber
composite using state-of-the-art
filament winding capabilities.
Composite overwrapped pressure
vessels are available as high
pressure, light weight gas storage
containers for high-pressure
compressed natural gas and
hydrogen, for example. The
machine can also manufacture
lightweight hydraulic
accumulators.
,
.
Exelis Inc., Salt Lake City, received
a contract worth more than $34
million from Sikorsky Aircraft
Corp. to produce major structural
airframe components for four
production-representative CH-53K
heavy lift helicopters. Designated
as system demonstration test
articles, the aircraft will enable the
U.S. Marine Corps to evaluate the
new helicopter system in 2017.
Exelis will fabricate and assemble
the composite sponsons, tail rotor
pylon, and horizontal stabilizer.
,
.
The first flight test CH-53K
aircraft being delivered for
evaluation. Courtesy of Sikorsky
Aircraft Corp.
METALS POLYMERS CERAMICS
ADVANCED MATERIALS & PROCESSES • MAY 2014 10
A piece of metallic glass was bent around
onto itself with a 1-mm radius and glued into
place. It would spring back to a flat piece if
the glue were removed.
A series of chess pieces made of chitosan
bioplastic demonstrates a new way to
mass-manufacture large, 3D objects with
complex shapes made of fully compostable
materials. Courtesy of Harvard’s Wyss Institute.