6.2 Material- und Oberflächentechnologien
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Erscheinungsjahr
- 2018 (37) (entfernen)
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- Vortrag (19)
- Zeitschriftenartikel (8)
- Posterpräsentation (8)
- Beitrag zu einem Tagungsband (2)
Schlagworte
- Corrosion (9)
- Femtosecond laser (8)
- Laser-induced periodic surface structures (LIPSS) (5)
- MIC (5)
- Methanogens (4)
- Biofilm (3)
- Chalcopyrite (3)
- Environmental Simulation (3)
- Femtosecond laser ablation (3)
- Laser-induced X-ray emission (3)
Organisationseinheit der BAM
- 6 Materialchemie (37)
- 6.2 Material- und Oberflächentechnologien (37)
- 4 Material und Umwelt (6)
- 4.1 Biologische Materialschädigung und Referenzorganismen (6)
- 9 Komponentensicherheit (6)
- 9.5 Tribologie und Verschleißschutz (6)
- 6.1 Oberflächen- und Dünnschichtanalyse (3)
- 6.7 Materialsynthese und Design (3)
- 6.6 Physik und chemische Analytik der Polymere (2)
- 5 Werkstofftechnik (1)
Eingeladener Vortrag
- nein (19)
Der Vortrag gibt den aktuellen Stand der Normung im Bereich der Oberflächen-technik insbesondere der Oberflächenanalytik und der Oberflächenmess- und -prüftechnik wider. Vorgestellt wird der Status technischer Berichte, Normenentwürfe und Normen u.a. zur Charakterisierung von funktionellen Glasoberflächen für bioanalytische Anwendungen, zur Messung der Schichtdicke von Nanomaterialien mittels Ellipsometrie, zur Kalibrierung von Interferometern und Interferenzmikroskopen für die Formmessung, zur Rockwelleindringprüfung zur Bewertung der Schicht-haftung, zu den Grundlagen der Ellipsometrie, zur Messung der Schichtdicke mittels Wirbelstromverfahren, zur Schichtpotentialmessung von Mehrfach-Nickelschichten, zu Filtern und Augenschutzgeräten gegen Laserstrahlung sowie zur Bestimmung der Schichthaftung mittels Zugversuch.
The performance of functional coatings and adhesively joined hybrid components relies strongly on the stability of the polymer-metal interface. With the increasing utilization of multi-material structures in the automotive and aerospace industry, it is of great scientific and technical interest to understand the processes leading to interface degradation and to develop novel strategies to increase corrosion and delamination resistance.
The aim of this project is to develop thin epoxy-based films on aluminium alloy AA2024-T3 as a model system and to investigate their interfacial stability under corrosive and coupled corrosive-mechanical load. Electrochemical and spectroscopic methods were used for the characterisation of the film properties and in situ corrosion experiments were performed by means of AFM. The deformation properties of the aluminium alloy and the model coatings were investigated by means of scanning Kelvin probe force microscopy (SKPFM) utilizing the integrated tensile stage.
The presentation will give a brief overview of the capabilities of the new AFM setup to foster future collaborations and summarize our work on the interface stability of model coatings.
Microbially influenced corrosion (MIC) of iron is usually attributed to sulfate-reducing microorganisms (SRM) which act upon the metal by the reactiveness of hydrogen sulfide, and by withdrawal of the available electrons in electrical contact with the metal. Methanogenic archaea can also cause MIC by directly withdrawing electrons from the iron surface for methanogenesis. However, the mechanistic details and kinetics of the overall process are poorly understood. Precipitation of siderite, a by-product of methanogenesis, (4Fe + 5HCO3 + 5H+ 4FeCO3 + CH4 + 3H2O) can lead to an insulating layer on the metal surface and lower the corrosion rate. Still, the extent of FeCO3 precipitation may be significantly influenced by environmental conditions such as pH and advective processes.
To investigate early stage corrosion processes of stainless steel 1.4301 taking place during the biofilm formation of the organism Shewanella putrefaciens electrochemical impedance spectroscopy (EIS) in a multielectrode approach has been used. The multielectrode array consisted of up to 25 electrically isolated electrodes made of stainless steel wires of diameters ranging from 100 µm to 500 µm. They were connected to a multichannel microelectrode analyzer (MMA) electrically coupled through zero resistance ammeters. Current flow between electrodes in the array as well as changes in impedance of individual electrodes over time were recorded and analyzed with respect to the onset of localized corrosion and biofilm formation. The results were complemented by optical microscopy, SEM and AFM images which were taken immediately after the respective experiment. To verify that the multielectrode arrays correctly indicated the initial stages of the corrosion process and of biofilm formation they were introduced in a flow cell reaction vessel containing test specimens made from stainless steel 1.4301, which were checked regularly for signs of localized corrosion and biofilms. Preceding results with the multielectrode array in solutions containing high amounts of chloride ions and hydrogen peroxide at low pH also showed that it is possible with the MMA to monitor individual electrodes becoming local anodes as local corrosion set in, while the remaining electrodes predominantly acted as cathodes.
Micro-concentrator solar cells offer an attractive way to further enhance the efficiency of planar-cell technologies while saving absorber material. Here, two laser-based bottom-up processes for the fabrication of regular arrays of CuInSe2 and Cu(In,Ga)Se2 microabsorber islands are presented, namely one approach based on nucleation and one based on laser-induced forward transfer.
Additionally, a procedure for processing these microabsorbers to functioning micro solar cells connected in parallel is demonstrated. The resulting cells show up to 2.9% efficiency and a significant efficiency enhancement under concentrated Illumination.
A promising technology in photovoltaics is based on micro-concentrator solar cells, where the photovoltaic active area is realized as an array of sub-millimeter sized thin-film solar cells. Different approaches to produce micro-sized precursors of CIGSe absorbers on molybdenum are presented using 30-fs laser pulses at 790 nm wavelength. On the one hand, a multi pulse surface structuring of the molybdenum or the underlying glass substrate and a subsequent physical vapor deposition (PVD) process were used for a site-selective aggregation of indium droplets. On the other hand, a single pulse laser-induced forward transfer (LIFT) was utilized to selectively deposit combined copper/indium/gallium precursor pixels on the molybdenum back contact of the solar cell. It was demonstrated that a postprocessing of the laser-generated micro-sized precursors results in an array of working CIGSe solar cells with an efficiency of 2.9% for 1 sun Illumination.
To investigate the attachment behavior of bacteria, tailored surfaces are needed. Differences in the chemical charge of the substrate are varied by -COO-, -CH3, -OH, -NH3 terminated functional groups. Regular patterns of them on the surfaces enable bacteria to choose their preferred attachment sides. Tools to tailor the samples are µ-contact printing, self-assembled monolayers and physical vapor deposition. The same concept of preferred sides in patterned surfaces is transferred to the nano- and microroughness which is accomplished by using zinc oxide nanorods synthesis.