ICMCTF 2012! - CD-Lab Application Oriented Coating Development

4:10pm B6-2-9 Stage-gate approach for the development of corrosion
and erosion resistant PVD multilayer coatings, J. Ellermeier
(ellermeier@mpa-ifw.tu-darmstadt.de), U. Depner, T. Troßmann, M.
Oechsner, Zentrum für Konstruktionswerkstoffe - TU Darmstadt, Germany,
K. Bobzin, N. Bagcivan, S. Theiss, R. Weiß, Surface Engineering Institute -
RWTH Aachen University, Germany
Many components need a protection against superimposed corrosion and
wear (abrasion, erosion) loading, e.q. in off-shore applications. The goal of
the research has been to develop PVD multilayer coating by systematically
altering the layer architecture in order to protect components against
corrosive environments and erosive loadings. The development of the PVD
multilayer coatings was staged in four phases. These are investigations of
corrosion-, wear-, combined erosion corrosion-resistance and verification of
the development, for example by field testing.
This paper deals with first phase of the development, i.e. the investigation
of the corrosion resistance of the PVD multilayer coating. Polarisation tests
have been identified to be an adequate tool to investigate the different
multilayer architectures.
The investigated coatings were applied on a plasma nitrided mild steel and
consist of a CrN/CrCN interlayer, different numbers of graded (g) CrCg/aC
layers and an a-C:H top layer. The investigations were focused on the
necessary number of CrCg/aC layers and the thickness of the a-C:H top
layer to achieve excellent corrosion protection. In addition to the influence
of the architecture various substrate pre-treatments like substrate nitriding
and polishing have been investigated regarding their potential to improve
the corrosion resistance as well.
As a result of the PVD multilayer development no corrosion could be
detected when immersing in artificial seawater after more than 500 hours.
The results of the polarization tests were assisted by metallographic and
SEM investigations and GD-OES analyses.
4:30pm B6-2-10 Biomimetics in thin film design – Enhanced properties
by multilayer coatings and nanostructured surfaces, J.M. Lackner
(juergen.lackner@joanneum.at), W. Waldhauser, Joanneum Research
Forschungsges.m.b.H., Institute of Surface Technologies and Photonics,
Functional Surfaces, Austria, L. Major, Polish Academy of Sciences,
Institute for Metallurgy and Materials Science, Poland, C. Teichert,
Montanuniversität Leoben, Austria, P. Hartmann, Joanneum Research
Forschungsges.m.b.H., Institute of Surface Technologies and Photonics,
Functional Surfaces, Austria
Biological materials are highly organized from the molecular to the
nanoscale, microscale and macroscale in a hierarchical manner. Material
and surface properties result from a complex interplay between the surface
structure and the morphology, being optimized by evolution for
multifunctionality in their natural habitat. Understanding these functions
and mimicking them in biologically inspired design using nanotechnology
offers a wide variety for smart materials. Elastic instability based wrinkling
of thin films on soft polymer substrates as well as hard-soft phase
multilayer coatings are two examples for biomimetic design by our PVD
techniques, based on plant leave ridges, cell membrane blebs or mollusc
shells, respectively. Tribological behaviour is drastically enhanced by the
application of Ti, TiN, Cr, CrN, and diamond-like carbon based nanoscaled
multilayer structures on soft substrate materials (austenitic steel, fibre
reinforced polymers), deposited by magnetron sputtering and pulsed laser
deposition techniques. These enhancements are shown to be based on
plastic deformation in nanostructures down to a few nanometers thick metal
layers improving the compound toughness. Fractal (nano-)wrinkles
originating from intrinsic compressive film growth stresses enhance surface
wetting and friction behaviour of Ti, TiN and diamond-like carbon coated
polyurethane polymer surfaces.
Fundamentals and Technology of Multifunctional Thin
Films: Towards Optoelectronic Device Applications
Room: Sunset - Session C5-1/F7-1
Polarisation Phenomena in Thin Films and Devices
Moderator: D. Holec, Montanuniversität Leoben, Austria,
S. Moram, University of Cambridge, UK
1:30pm C5-1/F7-1-1 Recent Advances in the Thin Film Electro-
Acoustic Technology, I. Katardjiev (Ilia.Katardjiev@Angstrom.uu.se), V.
Yantchev, Uppsala University, Angstrom Laboratory, Sweden INVITED
The classical Electro-Acoustic (EA) technology is a highly developed
technology today with applications ranging from telecom, medical, military,
scientific, radio and TV, sensors, pharmaceutical industry, etc. Only the
Thursday Afternoon, April 26, 2012 88
telecom industry consumes billions of RF filters annually. It is based on the
use of single crystalline piezoelectric materials such as quartz and others.
The combination of acoustic waves and low losses in these materials allows
the fabrication of compact, low cost devices with extreme performance.
Typical EA devices are RF filters, resonators, oscillators, delay lines,
various sensors (physical, chemical and biochemical), etc. Amongst the
major drawbacks of the EA technology are the limited choice of
piezoelectric materials (and hence properties) as well as its incompatibility
with the IC technology. Further, the explosive development of mobile
communications in recent years has necessitated the use of larger
bandwidths thus requiring higher frequencies of operation. This is where the
classical EA technology becomes expensive due to increased fabrication
costs.
In view of the requirements for high bandwidth, miniaturization and low
cost, the so called thin film electro-acoustic (TEA) technology has been
recently developed for applications in the microwave region. It makes use
of thin piezoelectric films that are grown using the planar technology which
makes the IC and the TEA technologies fully compatible with each other.
The material of choice so far is AlN while others are currently being
developed. The deposition methods employed (PVD, CVD, etc) allow
tuning various properties of the thin films (composition, crystallographic
structure and texture, roughness, density, stress, etc) which in turn allows to
tailor these properties in view of the application in mind. Thus, for instance,
the design of filters with a large bandwidth requires the synthesis of highly
c-textured AlN films, while in view of resonator operation in liquids
(biochemical sensors) excitation of shear waves is needed which in turn
requires either films with a c-axis tilted under a certain angle relative to the
surface normal or even better, highly a-textured films. In a different
perspective, certain applications may require high piezoelectric constants
while others may require low losses (both acoustic and electrical) or to
exhibit high functional stability with temperature variation, etc. In other
words, the race is on for the synthesis of thin piezoelectric films with
various functional properties in view of the broad range of potential
applications.
The talk will focus on recent advances in the area in terms of both film
synthesis and application development.
2:10pm C5-1/F7-1-3 Asymmetric electrical properties for dual-gate
InGaZnO TFT under gate bias and light illumination, T.C. Chen
(a49136@gmail.com), NSYSU, Taiwan
The electrical properties and degradation behavior of a-IGZO TFT with
dual gate structure was investigated in this paper. The increase of the oncurrent
for dual-gate TFT compared with single gate TFT indicates that the
dual-gate structure is applicable for the current-driven AMOLED display.
With dual gate structure, the IGZO TFT exhibits asymmetric electrical
properties under top gate or bottom gate operation. For bottom gate
operation, the application of the negative bias by top gate will induce a
parallel Vt shift, whereas the positive top gate bias merely increase the on
current. For top gate operation, the different electrical properties compared
with the bottom gate operation indicate that the gate control area dominates
the difference under measurement. Furthermore, the instability of dual-gate
IGZO TFT under light illumination was investigated. The asymmetric light
sensitivity under bottom gate and top gate operation was caused by the
illumination and the gate control area. With the different light sensitivity for
top and bottom gate operation, the dual gate IGZO TFT can be used as a
light sensor and apply in the touch panel technology without Black Matrix
in comparison with the a-Si TFT.
2:30pm C5-1/F7-1-4 A systematic ab-initio study of the piezoelectricity
in wurtzite nitride alloys: ScAlN, ScGaN, ScInN, YAlN, YInN, C.
Tholander (chtho@ifm.liu.se), F. Tasnádi, I. Abrikosov, Linköping
University, Sweden
New types of piezoelectric materials need to be intelligently designed to
further improve the performance of modern wireless telecommunication
devices, satellites, sensors or optoelectronic devices together with opening
new future commercial applications in biomedical engineering,
neuroscience and bio-nanotechnology. Our recent physical explanation on
the origin of the enhanced piezoelectric effect in wurtzite ScAlN alloys [1]
has introduced a simple, free-energy landscape based phenomena in finding
new materials with giant piezoelectric response. Here, we present a
systematic ab-initio investigation of this strategy on several wurtzite IIIA-
IIIB nitride alloys. The special quasirandom structure (SQS) approach
provides a successful computational scheme to model substitutional random
alloys and predict thermodynamics and, in case of special care, also
mechanical and electronic properties. The here presented results will bring a
refined understanding of the applicability of the free energy flattening
phenomena in the wurtzite IIIA-IIIB nitride alloys and indicate more
general rules/strategies in searching for new piezoelectric materials. These
new rules and refined strategy will be introduced and discussed by our
comparative study.