Dr. Jörg Ihde (left) and Dr. Uwe Lommatzsch have developed a new coating process for functional nano-layers using a plasma nozzle that works at atmospheric pressure. Image: Dirk Mahler / Fraunhofer

When
manufacturing products, the coating technology is a key innovation
driver for almost all areas of daily life—for example, for making
scratch-proof displays for smartphones or anti-bacterial surfaces in
refrigerators. Other coatings protect components from corrosion or
aging, for example in a solar cell module or a car engine, without the
end user noticing their existence. In industry today, wet chemical
processes or vacuum plasma processes are primarily used for coating
applications. Both have drawbacks. Vacuum units are expensive, limited
to smaller components and applying a coating takes a relatively long
time. Wet chemical processes often involve high resource and energy
consumption with the corresponding environmental damage and can also
cause difficulties in the handling of material combinations for
lightweight construction such as plastics/ metals or aluminum/steel.

“There
has to be another way”, thought Dr. Jörg Ihde and Dr. Uwe Lommatzsch
from the Fraunhofer Institute for Manufacturing Technology and Advanced
Materials IFAM in Bremen. Together with Plasmatreat GmbH, the IFAM team
developed a new kind of plasma coating process that works at ambient
pressure, that is to say, in an open atmosphere.

“And
that poses a major challenge,” explains Ihde. “Because the pressure is
more than 10,000 times higher and the absence of a vacuum reactor, we
had to stop unwanted particles from forming and embedding in the
coating. That was the key to developing robust and efficient industrial
processes using the new plasma system.

One nozzle—various functional coatings

The
central element is a plasma nozzle. The nozzle is no bigger than a
typical spray can. Yet it contains a highly complex coating system.

“In
the nozzle, an electrical discharge generates small flashes—a plasma
that is expelled from the nozzle in the form of a jet. We systematically
feed into the nozzle outlet those materials that are excited and
fragmented in the plasma and then deposited out of the plasma jet as a
functional nano-layer onto the surface,” explains Lommatzsch. “We
achieve extremely high deposition rates, enabling fast and
cost-effective production processes to be realized.”

The
use of a nozzle allows the coating to be applied very precisely and
only where it is needed, thus conserving resources. “We can control the
processes so that the same nozzle can be used to apply coatings with
various functionalities, for corrosion protection or for increasing or
reducing adhesion, for instance,” adds Jörg Ihde. Only very small
amounts of coating material are required and practically all materials
and material combinations can be coated. The process offers, in addition
to the coating qualities and functionalities, even more benefits: it
can be easily integrated into an inline production process, requires
little space and is easy to automate, meaning it can be controlled via a
robot. Yet another advantage: low investment costs and easy on the
environment. The positive characteristics benefit industrial production:
depositing an adhesion-promoting coating on a car window edge before
gluing it in, to replace environmentally damaging chemicals or as a
substitute for thick protective paint on printed circuit boards, which
improves heat dissipation and hence prolongs service life. The process
is already employed in the automotive industry and the energy sector to
provide protection against corrosion and aging.

One
of this year‘s Joseph-von-Fraunhofer prizes was awarded to Dr. Jörg
Ihde and Dr. Uwe Lommatzsch for their development of a
resource-efficient process for the high-rate deposition of functional
nano-layers.

Source: Fraunhofer Institute