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European Coatings Conference
Extra
Pre-Conference Tutorial
13 June 2007
Berlin, Germany
Main conference
"New Concepts for Anti-Corrosive Coatings"
14/15 June 2007
Berlin, Germany
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 Welcome
At a Glance
Tutorial
Abstracts
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| Events > New Concepts for Anti-Corrosive Coatings > Abstracts |
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Abstracts
| THURSDAY, JUNE 14th 2007 |
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Session I: Self-Repair
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Self-Healing Polymeric Anti-Corrosion Coatings
Prof. Dr. Scott White, University of Illinois, USA |
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Self-Healing Concepts for protective Coatings
Dr. Ulrike Mock, Fraunhofer IFAM, Germany |
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When considering protective coatings for use in corrosion protection, up-to-date no practically usable coating systems with self-healing properties are known. However, the demand for coatings with excellent durability is tremendous and can best be achieved when self-healing properties are inherent in the system.
In this presentation, the main research activities in the field of self-healing materials are presented. On the one hand this includes systems where materials are leached in order to prevent or stop corrosion processes. On the other hand the most promising approaches focussing on structural self-healing processes are discussed, together with some results that deal with coating materials based on practically usable formulations.
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Self-Healing Multifunction Anticorrosion Coating Based on the Smart Nanocontainers
Dr. Dmitry Shchukin, Max-Planck Insitute of Colloids and Interfaces, Germany |
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Corrosion Inhibition Through Diffusion Control in Epoxy-Silica-Molybdate Hybrids
Dr. Luca Prezzi, SAFE Marine Nanotechnologies, Italy |
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Today's steel surface technology is still based on concepts that date back into the 20th century and includes metallic (galvanized steel), inorganic oxides layers (phosphates, chromates) or other weldable primers. Such layers are applied in industrial conditions and many layers are needed to overcome the problem of pinholes and pores. Today's surface technology is optimized for given substrates and involves difficult multiple layer applications as well as hazardous chemistry without taking advantage of those reactions that lead to the destruction of the interface.
In the present study it was shown that the presence of molybdates in organic-inorganic hybrid networks allows the entrapped "doping anions" to be released at a controlled rate. When such materials are used as coatings for ferrous metal substrates the molybdate anions migrate to the interface coating-metal providing an enhanced mechanism for the passivation of the metal substrate tough including self-reparing features into the polymeric network.
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Session II: Thin Films
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New Silane Based VOC-Free Thin-Film Metal Pretreatment Technology
Dr. Björn Borup, Degussa AG, Germany |
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The basic chemical reactions behind the sol-gel process, hydrolysis and condensation of alkoxysilanes, are well known and since the 1980ies have been a focus of new developments for a range of applications. Due to the sensitivity of alkoxysilanes against hydrolysis and condensation, solvent-free, water-borne and storage-stable sol-gel systems initially posed a challenge, but are now established and commercially available as stabilized silanol-group bearing oligosiloxanes. The innovation to be presented is the development of a modular concept consisting of different multifunctional sol-gel systems resulting in coatings which exhibit customized properties. The presented modular system comprises a base sol-gel binder, and components for pH optimization, for improved weather resistance, hydro- and oleophobic surface properties. This modular system is ideally suited for the formulation of anti-corrosion metal pre-treatment systems.
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The Contribution of Small Particles to Anticorrosion in Thin Film UV-Cured Coatings
Angela Claßen, Sachtleben Chemie GmbH, Germany |
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New developments in anticorrosive coatings are driven by the optimization of economy and ecology. As cost performance ratios have to be met, nanoscalic particles are considered to be too expensive in the established conventional systems. However, for new technologies and special applications like thin film coatings they can play an important role. As chemically active species they provide a huge surface to defend the corrosive attack. But can chemically inert nanoparticles make a significant contribution, too?
Epoxy acrylate and urethane acrylate systems were used in UV-cured coil coating primers as modern systems on their way to be implemented in the market. Adhesion and salt spray tests could be considerably and reproducibly improved by the use of nanoscalic barium sulfates while typical 1 µm-fillers did not show an effect.
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Environmentally-Compliant Sol Gel Coatings
Prof. Dr. Robert Akid, Sheffield Hallam University, United Kingdom |
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Organic-inorganic hybrid coatings are of increasing interest to industry due to their potential widespread applications. The organic component in the matrix offers the advantages of mechanical toughness and flexibility while the inorganic component provides the coating with its hardness and thermal stability properties. This presentation gives a brief outline of the developments undertaken within our research laboratory and within industry collaborative projects of the different environmentally-compliant, fast cure, sol gel coating/pre-treatment systems which offer alternatives to existing anti-corrosion coatings. The functionality of the 1st generation coatings is primarily that of corrosion resistance via the encapsulation of inhibitors. This type of coating has been successfully applied to a variety of substrates including zinc, aluminium, magnesium and steel offering an environmentally-friendly alternative pre-treatment to that of toxic Cr (IV)-based systems and phosphating. A 2nd generation of coating incorporating a specific bacterial strain(s) is now being developed to prevent the formation of biofilms which can subsequently lead to microbial induced corrosion (MIC). A 3rd generation of coating is also being developed which offers the combination of both a sol gel component and a top coat as a single pot system.
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Eco-friendly Conversion Coatings for Automotive and Aerospace Materials
Dr. Abdel Salam Hamdy, Central Metallurgian R&D Institute Cairo, Egypt |
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Aluminum and its alloys are used widely in aerospace, automotive, architectural, lithographic and packaging applications. The demand for weight savings has focused attention on magnesium alloys. However, the use of magnesium alloys is restricted at present by their susceptibility to corrosion, especially in the presence of NaCl.
Chromate has been reported as the most efficient widespread conversion coatings for the corrosion protection of many metallic substrates. However, the waste containing Cr6+has many limitations due to the environmental consideration and health hazards.
This paper reports our recent research to develop environmentally acceptable surface treatments based on silica, ceria, vanadia or molybdate conversion coatings for aluminum alloys, Al-composite and magnesium alloys as alternatives to toxic chromate-based systems.
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| FRIDAY, JUNE 15th 2007 |
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Session III: Polymers
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Self-Assembly of Inorganic/Organic Corrosion Resistant Coatings
Dr. Mark Soucek, University of Akron, USA |
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Corrosion Protection by Thin Polymer Films - Self-Assembled Monolayers and Protective Biopolymers
Dr. Wolfram Fürbeth, DECHEMA e.V., Karl-Winnacker-Institut, Germany |
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In the context of corrosion protection by polymeric coatings ultrathin polymer films may be used to build up a very well defined and highly stable metal/polymer interface. In this way other environmentally more harmful metal pretreatments should be replaced. It could be shown that monolayers of thiophene phosphonic acids may self-assemble on steel surfaces and may afterwards be electropolymerised to obtain a monomolecular conducting polymer film.
On the other hand thin polymer films can also be used as some kind of inhibitor without a further polymer coating on top. For this purpose the use of biopolymers which are secreted by suitable microorganisms is investigated. These biopolymers may especially be helpful against microbially influenced corrosion processes.
For both research topics the principles will be explained and the results obtained so far will be shown.
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ExoPolysaccarides (EPS) as Anti-Corrosive Additives for Coatings
Dr. Jurgen Scheerder, DSM NeoResins, The Netherlands |
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The use of heavy metals and heavy metal based anti-corrosive compounds in organic coatings has been known for decades. However, environmental reasons and health concerns have restricted and even banned the use of these compounds. ExoPolySaccharides (EPS) are large sugar molecules (up to 50,000 sugar units) produced by a variety of microorganisms. It was shown by electrochemical measurements that these polysaccharides, and especially homopolysaccharides , exhibit anti-corrosive properties on steel. In this contribution we would like to report the use of these EPS as anti-corrosive additives when combined with aqueous styrene-acrylic copolymers for anti-corrosive primer applications. The effect of the type (molecular weight, functionality) and the amount of EPS on the anti-corrosive properties will be discussed and a working mechanism will be proposed. The distribution of EPS in the coating as studied by Confocal laser scanning Microscopy (CLSM) will be discussed. These results indicate that when properly selected, EPS can improve the anti-corrosive performance of waterborne primers.
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Intelligent Corrosion Protection by Conducting Polymers Without Draw-Backs
Dr. Michael Rohwerder, Max Planck Institut für Eisenforschung GmbH, Germany |
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The potential of conducting polymer coatings for corrosion protection is a topic of current controversy. A number of possible protection mechanisms are proposed. In this presentation the focus will be on intelligent self-healing. The trigger for the release is the potential decrease that occurs during delamination at the polymer/metal interface. It will be shown that the efficacy of conducting polymers for corrosion protection very much depends on how they are applied and on the conditions of the corrosion experiment, i.e. depending on the exact conditions a conducting polymer may have excellent protection capability or may lead to a disastrously enhanced corrosive attack. This paper will discuss how to counteract the negative properties.
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Electroactive Polymers (EAPs) as Alternative Pretreatment Replacement Coatings for Chromium and Cadmium Based Coatings
Dr. Peter Zarras, U.S. Navy, USA |
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Both hexavalent chromium and cadmium are currently used by the plating industry as pretreatment coatings for aluminum and steel alloys. The Naval Air Warfare Center Weapons Division (NAVAIR-WD) has investigated electroactive polymers (EAPs) as alternatives pretreatment coatings. Several electroactive polymers (EAPs) were synthesized and coated onto aluminum and high strength steel coupons. Poly(2,5-bis-(N-methyl-N-hexylamino)phenylene vinylene (BAM-PPV) has been extensively investigated as a pretreatment coating for aluminum alloys. BAM-PPV coated onto Al 2024-T3 substrates have repeatedly survived 336 hours neutral salt fog spray (ASTM B117). This test is the current military requirement for alternatives to hexavalent chromium based pretreatment coatings. Additional EAP coatings (e.g. polypyrrole and polythiophene derivatives) were synthesized and coated onto high strength steels. These EAP coated high strength steel coupons were exposed to neutral salt fog spray but after 24 hours extensive corrosion was evident. The coating of these EAP polymers onto high strength steel coupons is still being optimized.
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Session IV: Test Methods
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Approaches to Accelerated Corrosion Testing of Organic Coatings by Use of Electrochemical Methods
Dr. Peter Plagemann, Fraunhofer Institute for Manufacturing Technology and Applied Materials Research, Germany |
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It is only natural, that evaluating the corrosion protection performance of coatings requires long times as the testing period is related to the required life time of the coating. However, from a business perspective, short testing times are needed to accelerate new developments reaching the market.
Often, it is attempted to reduce evaluation times by using more severe test conditions. But this can lead to changes in the corrosion or degradation mechanism, the obtained results are not relevant for real live aging and thus reliability of the product.
An interesting alternative is to use evaluation methods, which allow detection of corrosion effects in an early stage and not only after obvious defects are observable. Several different techniques can be used, but in this presentation we will focus on electrochemical methods and show examples, why these techniques are especially useful.
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Ion Permeability - a New Test Method for Corrosion Prevention Coatings
Dipl. Ing. Peter Heinze, Ph Ionen Permeabilität, Germany |
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Corrosion prevention coatings conduct the corrosion current at an electrolytic corrosion depending on quality over ion migration by pores more or less well.
A measure for this quality is the ion permeability.
A new method allows the measuring of this size objectively with low effort in short time. Measuring principle: The measuring cell consists of two rooms filled with electrolytes. Both rooms are separated by the free coating film.
In both rooms are electrodes attached to a voltage source with the chosen electrical tension. The pH value in the cathode room is measured constantly.
The ion permeability then calculates itself from the amount of OH Ions, the measuring area and the measuring time period.
With this measuring corrosion prevention coatings can be classified qualitatively and fast optimized when required.
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Fast Evalutation of Corrosion Protection Offered by Organic Primers. Formulation of Low-Curing-Temperature Powder Coatings
Dr. Santiago Garciá Espallargas, Universidad Polítecnica de Valencia, Spain |
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In this study new epoxy primers have been formulated with the principal objective of reducing
the curing time and temperature. The coatings were obtained by copolymerization of epoxy
resin based on Bisphenol-A with Meldrum acid initiated by erbium (III)
trifluoromethanesulfonate. The mechanical, thermal, kinetic and anticorrosive properties of the
primers have been studied and compared to those given by a commercial powder coating (otolylbiguanide
/ epoxy resin), finding out that they offer a very fast curing rate while, at the same
time, excellent adhesion to steel substrates, good mechanical properties, and improved
anticorrosive properties. In order to evaluate the anticorrosive properties, an accelerated
electrochemical technique (named AC/DC/AC) has been used showing its ability to evaluate
much faster than other techniques (salt fog spray and EIS) the anticorrosive properties of
powder coatings.
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