ANTI-ICING COATINGS1 Icing chamber developed at
Fraunhofer IFAM.
2 Analysis of the frost layer using
a measuring comb.
Ice formation on surfaces –
A major challenge
The icing of surfaces is a major and recur-
rent problem which impairs the function of
those surfaces and incurs costs. Consider,
for example, the surfaces of aircraft, ships,
rail vehicles, cars, roller shutters, refrige-
rators, and wind turbines. The effects of
icing include increased weight, impaired
function of equipment, longer maintenance
times and downtimes, and even damage to
persons.
Iced up rotor blades on wind turbines, for
example, result in significantly reduced
energy output. Ice falling off surfaces is
also a danger to people. One strategy to
reduce icing is to use so-called rotor blade
heating systems (hot air or hot wires). Here
the rotor blades of the stationary turbine
are heated so that adherent ice falls off.
During this de-icing period the wind tur-
bine actually consumes power rather than
produces power.
An optimal solution would be a coating on
the rotor blades which prevents ice formati-
on from the outset. The currently available
commercial anti-icing coatings cannot
effectively prevent ice formation on rotor
blades. The latest research strategies are,
however, showing great promise for solving
this problem.
Expertise of Fraunhofer IFAM –
Development and testing of
anti-icing coatings
Development of coatings
New techniques for the nano-struc-
turing of surfaces and their anti-icing
effect
Biomimetic anti-icing coatings based
on anti-freeze proteins
Temporary anti-icing coatings
Hydrophobic coatings
Fraunhofer Institute for
Manufacturing Technology
and Advanced Materials IFAM
- Adhesive Bonding Technology
and Surfaces -
Wiener Straße 12
28359 Bremen, Germany
Institute director
Prof. Dr. rer. nat. Bernd Mayer
Contact
Paint/Lacquer Technology
Dr. Volkmar Stenzel
Phone +49 421 2246-407
www.ifam.fraunhofer.de
© Fraunhofer IFAM
F r A u n h o F E r - I n S T I T u T F ü r F E rT I g u n g S T E c h n I k u n D A n g E wA n D T E M AT E r I A l F o r S c h u n g I FA M
1 2
3 Evaluation of frost adhesion using the frost
adhesion test developed at Fraunhofer IFAM.
4 Test device developed at Fraunhofer IFAM
for carrying out the runback ice test on wing
sections.
3 4
Ice formation – current research
Three different icing scenarios are being
researched:
Frost adhesion test for simulating fros-
ting (Fig. 2 + 3)
Ice-rain test which simulates ice forma-
tion from rainwater
Runback ice test on wing sections (Fig. 4)
All the tests are carried out in the icing
chamber of Fraunhofer IFAM.
Frost adhesion test
Innovative testing technology is supporting
the development of novel anti-frosting coa-
tings. The frost layer that forms is analyzed
using a measuring comb (Fig. 2). The frost
adhesion is then evaluated in the so-called
frost adhesion test, a force test developed
at Fraunhofer IFAM (Fig. 3). It measures the
force required to detach the frost layer.
Ice-rain test
Extensive systematic studies at Fraunhofer
IFAM have shown that superhydrophobic
coatings give ice-free surfaces in the ice-
rain test. This anti-icing effect is, amongst
other things, due to the water-repelling
nature of the surface which hinders the
adhesion of water. The hydrophobicity of
a coating is hence a suitable, albeit not the
sole, parameter for an anti-icing surface.
runback ice test
Runback ice is a phenomenon that occurs
on wing sections of aircraft when thermal
de-icing systems are used. These systems
only de-ice the front edges of the wings.
The melted ice is forced backwards by the
flow of air, where some of this refreezes.
A test device has been developed at
Fraunhofer IFAM which allows this pheno-
menon to be studied (Fig. 4).
new r&D strategies
The Paint/Lacquer Technology section at
Fraunhofer IFAM is currently working on
a variety of strategies for minimizing ice
formation. The extensive knowledge of
surface pre-treatment, coating develop-
ment, and testing is being utilized for
this, as is other internal Fraunhofer IFAM
expertise in the area of plasma technology
for modifying surfaces. Complementing
the aforementioned tests, computer-aided
simulation methods are also being used
to evaluate the adhesion and detachment
mechanisms of ice and frost on coating
surfaces. The findings are allowing accele-
ration of the development work.
Anti-icing tests for coatings
Icing chamber at Fraunhofer IFAM
The novel icing chamber that has been
developed at Fraunhofer IFAM (Fig. 1)
can mimic almost any icing scenario on
surfaces and coatings.
It allows:
Air temperatures down to -20 °C
Substrate temperatures down
to -40 °C
Relative air humidities up to 40 %
Rain simulation via a nozzle system
Maximum wind speeds up to 70 m/s
Visual monitoring via a webcam
Icing test stand –
Testing under real conditions
Coating systems that have been suc-
cessfully tested in the icing chamber are
exposed to the outside weather in an
endurance test. This icing test stand is
on the Brocken in the Harz Mountains
at a height of 1141 meters. The results
attained in the icing chamber in the
laboratory have been found to agree
with the tests under real conditions.