18-12-2012, 06:19 PM
Nanotechnology Applications in Future Automobiles
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ABSTRACT
It is rare for a single technology to have the power to
dramatically influence almost every major industry in the
world. Nanotechnology falls into this category and offers
fundamentally new capabilities to architect a broad array of
novel materials, composites and structures on a molecular
scale. This technology has the potential to drastically redefine
the methods used for developing lighter, stronger, and
high-performance structures and processes with unique and
non-traditional properties.
This paper focuses on some of the automotive applications
for nanotechnology and showcases a few of them that are
believed to have the highest probability of success in this
highly competitive industry.
No discussion of nanotechnology is complete without
touching upon its health and environmental implications. This
paper addresses some of the safety issues and the precautions
that we as an automotive industry need to take in the
production, processing, storage and handling of such minute
particles.
INTRODUCTION
A huge amount of research and development activity has
been devoted to nano-scale related technologies in recent
years. The National Science Foundation projects
nanotechnology related products will become a $1 trillion
industry by 2015 [1]. Nano-scale technology is defined as any
technology that deals with structures or features in the
nanometer range or that are less than 100 nanometers, about
one-thousandth the diameter of a human hair, and larger than
about 1 nm, the scale of the atom or of small molecules.
Below about 1 nm, the properties of materials become
familiar and predictable, as this is the established domain of
chemistry and atomic physics. It should be noted that
nanotechnology is not just one, but many wide ranging
technologies in many technical disciplines including but not
limited to chemistry, biology, physics, material science,
electronics, MEMS and self-assembly. Nano-structures have
the ability to generate new features and perform new
functions that are more efficient than or cannot be performed
by larger structures and machines.
NANOPARTICLE THERMAL
MATERIALS
In spite of advances in efficiency of vehicle powertrain
systems and electronics, the removal of waste heat continues
to be an important challenge. With increasing focus on
reduced component size and mass, the traditional approach of
increasing the area available for heat exchange with a cooling
fluid (air, water/ethylene glycol) to manage higher heat loads
is not acceptable. Increasing thermal power densities requires
innovations in new coolants and thermal coupling materials.
The concept of using nano-fluids as a means of improving
coolant performance was proposed over a decade ago [2].
Reports of up to 100% increase in liquid thermal conductivity
with the addition of nanometer scale particles motivated a
large amount of scientific/technical inquiry in the ensuing
years [3].
Nano-fluids are a solid-liquid composite containing
nanoparticles with sizes in the 1-100 nm range dispersed and
suspended in a liquid. A variety of nanoparticle solids have
been used as additives, including metals such as copper and
gold, alumina, SiC and CuO ceramics and carbon nano-tubes.
The surprisingly large increases in liquid thermal
conductivity have been reported for relatively small particle
loadings (<10% by volume). In addition, there have also been
reports of higher critical heat flux (dry-out) for nano-fluids
used in liquid-vapor phase cooling applications. These
observations have been made for a number of liquids,
including water/ethylene glycol, alcohols and oils. The results
defy conventional experience which requires much higher
volume loading of larger particles to produce slurries with
comparable increases in effective liquid thermal conductivity.
These observations have stimulated numerous theories
attempting to understand and describe the phenomena, but the
nature of the thermal enhancement mechanism still remains
controversial. This situation is further aggravated by
inconsistent results from different laboratories, and some
claims that if carefully measured, the enhancements are
smaller and explained by established theories.
DISPLAYS USING
NANOTECHNOLOGY
Displays with improved performance and unique features are
made possible by nanotechnology. Additionally, lower cost
light emission sources, such as lasers are possible in the near
future. Display technology, under rapid development for
consumer electronic devices and home entertainment
systems, is also being pursued for automotive applications.
Improved performance, longer life, higher energy efficiency,
unique presentation features, reduced package size and
innovation become the value proposition for implementing
this new technology.
Automotive displays are expected to directly utilize nanotechnology
in a variety of ways. Light emitting devices, such
as LEDs, OLEDs (Organic Light Emitting Diode),
fluorescent or field-emissive displays, electro-luminescent
and perhaps lasers, are utilizing nano-phosphors and nanolayers
to improve their performance. For example, silver
nanoparticles on the cathode surface allow surface plasmon
localization. This provides a strong oscillator decay channel
that generates a two-fold increase of intensity for flexible
OLED displays. Optical thin films, non-linear holographic
reflectors, micro-lenses, and light conversion films are
examples of materials that modulate or redirect
electromagnetic radiation. Light projection systems, flatpanel
displays, including cameras and other optical detectors
that provide the input signals are all expected to benefit from
nanotechnology developments.
HOW NANO-COMPOSITES WORK
Nanoparticles have an extremely high surface-to-volume ratio
which dramatically changes their properties when compared
with their bulk sized equivalents. It also changes the way in
which the nanoparticles bond with the bulk material. The
result is that the composite can be many times improved with
respect to the component parts.
WHY NANO-COMPOSITES?
Polymers reinforced with as little as 2% to 6% of these
nanoparticles via melt compounding or in-situ polymerization
exhibit dramatic improvements in properties such as thermomechanical,
light weight, dimensional stability, barrier
properties, flame retardancy, heat resistance and electrical
conductivity.
CURRENT APPLICATIONS OF NANOCOMPOSITES
Applications of nano-composite plastics are diversified such
as thin-film capacitors for computer chips; solid polymer
electrolytes for batteries, automotive engine parts and fuel
tanks; impellers and blades, oxygen and gas barriers, food
packaging etc. with automotive and packaging accounting for
a majority of the consumption. [9] The automotive segment is
projected to generate the fastest demand for nano-composites
if the cost/performance ratio is acceptable. Some automotive
production examples of nano-composites include the
following: Step assist - First commercial application on the
2002 GMC Safari and Chevrolet Astro van; Body Side
Molding of the 2004 Chevrolet Impala (7% weight savings
per vehicle and improved surface quality compared with TPO
and improved mar/scuff resistance); Cargo bed for GM's
2005 Hummer H2 (seven pounds of molded-in-color nanocomposites);
Fuel tanks (Increased resistance to permeation);
under-hood (timing gage cover (Toyota) and engine cover
(Mitsubishi).