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ADVANCED MATERIALS & PROCESSES • MAY 2014 17
SURFACE ENGINEERING
news
industry
briefs
PPG Industries, Pittsburgh,
completed its acquisition of Hi-
Temp Coatings Technology Co.
Inc., Boxborough, Mass., a
privately-owned supplier of high-
temperature-resistant and
insulative coatings. The acquisition
enhances the product portfolio of
PPG’s protective and marine
coatings business, adding coatings
that withstand extreme
temperatures to protect both
carbon steel and stainless steel
substrates. The coatings are used
in refineries, petrochemical plants,
pulp and paper mills, and power
plants. .
Research and Markets added a
new study, Markets in Wear
Coatings: Hard Chrome and its
Alternatives. This comprehensive
report discusses the various
technologies, industries in which
they are used, and forecasts to
2020. A number of alternatives to
hard chrome are discussed,
dominated by thermal spray, in
particular high-velocity oxy-fuel
(HVOF), which is often favored due
to its high strength and wear
resistance, relatively low cost, and
fast turnaround time. However,
other emerging processes that are
capturing the chrome and HVOF
markets are explored as well.
.
Scientists report that rough zinc
oxide coatings can prevent tiny
silicon parts from adhering to each
other. Xinchun Lu and colleagues
explain that adhesion is a big
concern when designing very
small microelectromechanical
systems (MEMS). Silicon is widely
used in MEMS devices, but is
sticky. The traditional solution is to
either coat silicon with a water-
repellent coating or roughen the
surface. The group combined the
two—using a water-repellent zinc
oxide film with a rough surface.
Thicker films were rougher and
had a lower adhesion force than
thin ones. Low humidity also
helps, according to researchers.
.
Self-mending paint immobilizes military vehicle rust
Developed by The Johns
Hopkins University Applied
Physics Laboratory, Laurel,
Md., in partnership with the
Office of Naval Research
(ONR), Arlington, Va., polyfi-
broblast allows scratches
forming in vehicle paint to
scar and heal before corrosive
effects reach the metal be-
neath. Polyfibroblast is a pow-
der that can be added to
commercial-off-the-shelf
(COTS) paint primers. It is
made up of microscopic poly-
mer spheres filled with an oily
liquid. When scratched, resin
from the broken capsules
forms a waxy, water-repellant
coating across the exposed steel that protects against corrosion. While many self-healing
paints are designed solely for cosmetic purposes, polyfibroblast is being engineered specif-
ically for tactical vehicles used in harsh environments.
From rainstorms to sunlight, tactical vehicles face constant corrosion threats from the
elements, costing the Navy alone roughly $7 billion each year. About $500 million of that
is the result of corrosion to Marine Corps ground vehicles, according to the most recent
Department of Defense reports. Vehicles transported and stored on ships also are subject
to salt spray from the ocean, a leading cause of problems for military hardware. In one lab-
oratory experiment, polyfibroblast showed it could prevent rusting for six weeks inside a
chamber filled with salt fog. , .
Nanocoating increases aircraft engine service life
Researchers at University West, Sweden, are using nanoparticles in the heat-insulat-
ing surface layer that protects aircraft engines from heat. In tests, this increased the coat-
ing’s service life by 300%. A heat-insulating surface layer is sprayed on top of metal
components, shielding the engine from excessive heat. The temperature can be increased,
leading to increased efficiency, reduced emissions, and decreased fuel consumption. The
group hopes to control the structure of the surface layer in order to increase its service
life and insulating capability.
“The base is a ceramic powder, but we have also tested adding plastic to generate pores
that make the material more elastic,” says Nicholas Curry. The ceramic layer is subjected
to great stress when the enormous changes in temperature make the material expand and
contract. It is important to make the layer elastic. Over the past few years, research has fo-
cused on further refining the microstructure for industry use.
New technique binds organic compounds to metal surfaces
Queen’s University (Ontario, Canada) researchers developed a new process that allows
organic compounds to bind to metal surfaces. “Imagine pouring vegetable oil onto a metal
surface and expecting it to stay,” says Hugh Horton. “We have created a bond through a
chemical absorption process that allows that to happen.” In the new process, the bond be-
tween the metal and organic coating occurs through carbon instead of sulfur, which gives
much greater strength and resistance to oxidation. The technology is being patented and
commercialized by PARTEQ and Green Centre Canada. For more information: Hugh Hor-
ton, 613/533-2470, , .
Adding polyfibroblast powder to COTS paint primers allows
scratches forming in vehicle paint to scar and heal before the
effects reach the metal beneath.