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Implant coating promotes bone growth
Researchers at Uppsala University, Sweden, developed
a responsive coating for implants to improve their inte-
gration into bone and to prevent rejection. Neutron scat-
tering experiments at the Institut Laue-Langevin (ILL),
France, show how a protein that promotes bone growth
binds to this surface and can be released in a controlled
way. Gels made by modifying hyaluronan, a biological
molecule, can coat implants. Research shows the coated
titanium surfaces can bind protein molecules that pro-
mote bone formation. These can be released slowly once
the surface comes in contact with a solution of calcium
ions. This process stimulates bone growth on implants.
The gel layers, a few millionths of a millimeter thick, were
characterized using neutron reflection at ILL, providing a
detailed surface image. BMP-2, the protein that encour-
ages bone growth, was bound to the gel. The protein layer
was stable in water, but could be released slowly by adding
solutions containing calcium, a process that was observed
in real time using neutron reflection to track the amount
of protein at the surface.
Coating offers grease-free lubrication and corrosion protection
Researchers at the INM – Leibniz Institute for New Materials, Germany, developed a
functional coating that lubricates without grease and protects against corrosion at the same
time. It is suitable as a coating for metals and metal alloys such as steel, aluminum, or mag-
nesium. “We incorporated platelet-like solid lubricants and platelet-like particles in a
binder. When this mixture is applied to a surface, it produces a well-ordered structure in
which these various particles are arranged in a roof tile pattern,” says Carsten Becker-Will-
inger, head of the Nanomers Program Division. This forms a so-called transfer film be-
tween the low-friction coating and the object through which surfaces can slide with
minimal friction. “The particular mixture ratio means that our composite has a very low
coefficient of friction. If we only used a solid lubricant, the coefficient of friction would be
considerably higher,” says Becker-Willinger.
Moth eyeballs inspire low-glare coating
Work by University of California Irvine scientists could reduce glare from solar panels
and electronic displays, as well as dangerous glints on military weapons. “We found a very
simple process and a tiny bit of gold can turn a transparent film black,” says chemistry pro-
fessor Robert Corn. The team was initially worried when they noticed what appeared to be
soot on a flexible film designed to coat various products. Via painstaking tests, however,
they realized they accidentally discovered a way to fabricate a surface capable of eliminat-
ing glare. The material can also keep grime in raindrops and other moisture from sticking.
A repeating pattern of cones modeled on moth eyeballs at the nanoscale was etched on
Teflon and other nonstick surfaces. A thin layer of gold was
then applied over the cones and the shine from the gold
and any light reflecting onto it was all but obliterated. The
material is also highly hydrophobic. For more information:
Robert Corn, 949.824.1746, , .
UC Irvine undergraduate chemistry student George Auwaijan
sports a pair of sunglasses coated with a new material invented by
researchers that mimics the pattern of moth eyeballs to reduce glare.
Courtesy of Gabriel Loget/UC Irvine.
ADVANCED MATERIALS & PROCESSES • JUNE 2014 15
SURFACE ENGINEERING
news
industry
briefs
Rice University, Houston,
scientists mixed very low
concentrations of diamond
particles (roughly 6 nm in
diameter) with mineral oil to test
the nanofluid’s thermal
conductivity and how temperature
affects its viscosity. They found it
to be much better than nanofluids
that contain higher amounts of
oxide, nitride or carbide ceramics,
metals, semiconductors, carbon
nanotubes, and other composite
materials. In tests, researchers
dispersed nanodiamonds in
mineral oil and found that a very
small concentration—one-tenth of
a percent by weight—raised the
thermal conductivity of the oil by
70% at 373°K (211°F). .
NEI Corp., Somerset, N.J.,
introduced NANOMYTE SuperCN
Plus, a functionally graded coating
that imparts superhydrophobic
properties to the underlying
substrate while providing greater
abrasion resistance compared to
existing superhydrophobic
coatings. The coating consists of a
hard and abrasion-resistant outer
layer that transitions to a softer
material closer to the substrate.
Due to its graded structure, the
coating maintains its
superhydrophobicity and high
contact angle even after moderate
damage. Additionally, it exhibits
good adhesion to the substrate.
.
Researchers at the University of
Arkansas report achieving the
highest efficiency ever in a 9 mm2
solar cell made of gallium
arsenide. After coating cufflink-
sized cells with a thin layer of zinc
oxide, the team reached a
conversion efficiency of 14%. A
small array of these cells—as few
as nine to 12—generates enough
energy for small LEDs and other
devices. Better yet, surface
modification can be scaled up and
cells can be packaged in large
arrays of panels to power large
devices such as homes, satellites,
or even spacecraft. .
A gel-coated titanium surface
binds proteins that promote
bone formation. Courtesy of
Ida Berts.