28-Apr - They called it
CuproGraf,
merging the Latin name for copper and that for graphene. It is the
new material that has an electrical
resistivity that is
almost 7 percent lower than that of pure copper materials obtained
with the same non-optimized hot rolling process. The discovery is
anticipated
in a preprint posted at ChemRxiv, a widely used preprint
server for chemistry papers.
The researchers -- a team from the Italy's Research Councile in
Palermo led by
Mario Pagliaro and
Rosaria Ciriminna
and from the University of Milan led by
Cristina Della Pina
with the doctoral student
Matteo Formenti -- have
developed a completely new chemical process: and for the first
time they have managed to disperse graphene within the crystal
lattice of copper. All the other methods used to create composite
materials based on copper and graphene make use of physical or
chemical methods that simply functionalize the surface of the
copper with layers of graphene. In CuproGraf, graphene is instead
trapped homogeneously within the crystal lattice of copper. The
result is that the encapsulated graphene molecules are physically
and chemically stabilized, while interacting with the crystal
lattice of copper atoms increases its conductivity.
Made of 99.5% copper and 0.5% graphene, in fact, the CuproGraf
powder withstood without problems the temperature of 800°C of hot
rolling followed by milling to which researchers from the
Polytechnic of Milan
Riccardo Casati and
Giorgia Lupi
subjected the CuproGraf powder to obtain a metal bar whose
electrical resistivity was then measured by physicist
Carlo
Fanciulli from the CNR of Lecco. Compared to a pure copper
bar obtained with the same process, the CuproGraf bar showed a
resistivity 6.78% lower than that obtained with the same method
from pure copper powder: 2.06 microhm centimeter for CuproGraf and
2.21 for copper. The resistivity of pure copper obtained by
electrolysis followed by an optimized metallurgical process to
create oxygen-free copper materials through induction melting is
1.7241 microhm centimeter.
"
If the results obtained with the optimized metallurgical
process to create oxygen-free copper and CuproGraf materials are
confirmed, this is a discovery of great applicative importance
- say Pagliaro, Della Pina and Ciriminna". They add: "
The
manufacturing process of CuproGraf is simple, substantially free
of harmful emissions and easily scalable to an industrial level.
The quality of graphene used is very low, and the process is
conducted entirely in the aqueous phase starting from a simple
and inexpensive copper salt dissolved in water".
Conversion of CuproGraf into
metal bars uses a
metallurgical process called hot rolling followed by milling,
which the researchers believe can be optimized by reducing, for
example, the volume of air trapped in the interstices between the
micrometric metal grains of the optimized bars obtained in the
laboratory. From high-voltage cables to electric vehicles to
household appliances,
copper is the electrical conductor
used in nearly all electrical and electronic devices. Copper foil,
for example, is used in electronics, including computers, digital
cameras, cell phones, and lithium batteries. Only silver has a
higher conductivity than copper, and in applications where
particularly high conductivity is required, such as aircraft
electrical systems, silver-plated copper wire is used. Isolated by
mechanical exfoliation of graphite in 2004, graphene is an
allotropic form of carbon consisting of a two-dimensional atomic
crystal composed of carbon atoms arranged in a hexagonal lattice.
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