6.7 Materialsynthese und Design
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Organisationseinheit der BAM
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- 6.1 Oberflächen- und Dünnschichtanalyse (25)
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Eingeladener Vortrag
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Multi-functional coatings are a key requirement for surface engineering. General demands are adhesion and long-term stability under service conditions. The modification of surfaces by means of PVD-, ECD- or hybrid processes allows an add-on functionalization of surfaces by a huge diversity of materials with both lateral and vertical micro-/nano-designs. This fact is a prerequisite for micro- and sensor-systems in lab-on-chip and sensor-on-chip technology. Two layer-based sensor principles are presented, i.e. surface plasmon resonance enhanced spectroscopic ellipsometry (SPREE) for detection of hazardous gases and magneto-optical sensors on smart-coated fiber Bragg gratings (FBG) for structural health monitoring (SHM).
The interdependence of substrate features, coating properties, and layer design is discussed firstly for gas sensitivity and selectivity of SPREE-sensors and secondly for sensitivity and selectivity of magneto-strictive coatings to mechanical strain or external magnetic fields resulting in an optical displacement of the Bragg wavelength of FBG-sensors. Moreover, generic features such long-term stability, crucial process-related fabrication conditions, and effects of operational and environmental parameters are discussed with respect to the sensor performance. It has been shown that appropriate layer design and adapted selection of layer materials (SnOx/Au, Fe/Ni:SnOx/Au; Ni/NiFe-Cu-Cr) result in improved sensor parameters and may enable new sensor applications.
Der Vortrag widmet sich der „ELLIPSOMETRISCHE KLASSIFIZIERUNG VON KOHLENSTOFFSCHICHTEN“ und beschreibt die Punkte: 1. Anwendungen Kohlenstoffschichten–Carbon–based films (DLC) aus dem Vortrag N. Ohtakeet. al. (ISO TC 107, Tokyo 2017),2. Präparation der Kohlenstoffschichten für ISO TC 107 Ringversuch aus Vortrag M. Hiratsuka et. al. (ISO TC 107, Tokyo 2017), 3. Ellipsometrische Charakterisierung von Kohlenstoffschichten, Ergebnisse des Ringversuchs (ISO TC 107, Tokyo 2017) Vortrag Beck et. al. und 4.Deutsche Normungsaktivitäten national/international zur Ellipsometrie DIN NA 062-01-061 (DIN 50989-1)/TC 107 (PWI DE)“ im Einzelnen.
Imaging of surfaces regarding topographical, morphological, micro-structural, and chemical features is a key requirement for quality control for the identification of contaminated, degraded, damaged or deliberately modified surface areas vs. clean, virgin, undamaged or unmodified regions. As optical functions may represent any of these changes on the micro- and nano-scale, imaging ellipsometry (IE) is the technique of choice using either intensity, phase, or/and amplitude contrast for visualization of low-contrast surface modifications [1, 2]. Defects or surface and film features whether native or artificial, intended or unintended, avoidable or unavoidable as well as surface pattern are of interest for quality control. In contrast to microscopic techniques operated at normal incidence, ellipsometry as oblique-incidence technique provides improved contrast for vertically nano-scaled add-on or sub-off features such as ultra-thin transparent films, metallic island films, carbon-based thin films, laser modification or laser induced damage, dried stain, cleaning agent or polymeric residue. Two-sample reference techniques, i.e. referenced spectroscopic ellipsometry (RSE) may further increase sensitivity and decrease measurement time. In case of particulate accumulations depolarization contrast imaging (DCI) may improve the lateral resolution beyond the Abbe limit. This has been proven for silica spheres as reference in terms of single particles, particulate accumulations or particulate monolayers and layer stacks. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used for reference measurements of particle diameter, particle height, or particulate layer/accumulation thickness. It has been shown that single silica particles of 250 nm in diameter, i.e. at least a factor of 4 better than the lateral resolution limit as of now, can be visualized on even substrates. However, the ellipsometric measurement of particle diameters of this size needs further efforts interpretation.
The paper addresses the “Functional coatings for mechanical applications: characterization and standardization” and the following points are discussed in more detail:
1. Mechanic alapplications (coatings for tools and components, system features vs. material parameters)
2. Mechanical characterization (instrumented indentation testing (IIT), centrifugal adhesion testing (CAT), state of standardization)
3. Topometric characterization (white light interference microscopy (WLIM, 3D), mechanical stylus (MS, 2D), state of standardization)
4. Optical characterization (spectroscopic ellipsometry (SE), inter-laboratory comparison, state of standardization)
Auf dem Weg zu Industrie 4.0: Bestimmung von Messunsicherheitsbudgets in der Oberflächentechnik
(2019)
Vorgestellt wurde die Bestimmung von Messunsicherheitsbudgets für sehr unterschiedliche physikalische Größen, die in der Oberflächentechnik von hoher Relevanz sind: Stufenhöhe h, Schichtdicke d, Eindringhärte HIT und Haftfestigkeit. Die Unterschiede betreffen die Art der Prüfmethodik (optisch zerstörungsfrei vs. mechanisch invasiv/zer-störend), die laterale Größe des Integrationsgebietes der Messung (lokal:nano bis sub-mikro vs. global: mikro bis makro) und die Art der Bestimmung von Messunsicherheitsbudgets (physikalische Größen: direkt rückführbar; Werkstoffkenngröße: genormt; Systemkenngröße: genormt).
Im Rahmen von Industrie 4.0 werden ausgehend der geforderten Spezifikation des beschichteten Produkts (Mittelwert mit Vertrauensbereich oder Mindestwert) durchgehende Toleranzbänder zur Oberflächenmodifizierung/Beschichtung des Substrats, einhergehend mit Prozessfenstern, die diese Toleranzbänder garantieren, erforderlich, die zuverlässig erfasst werden müssen. Die Frage der anzuwendenden Mess- und Prüftechnik und die damit notwendige Betrachtung von Messunsicherheitsbudgets ist für die Digitalisierung von Konditionierungs-, Zustands-, Regel- und Steuergrößen unverzichtbar. Mit Blick auf die Einhaltung von Prozessfenstern und die dafür notwendige Prozessführung wird technologisches Kern-Know-how digitalisiert, das es unbedingt zu schützen gilt. Nur lokale Netze können diese Sicherheit garantieren, in globalen Netzen ist die Datensicherheit bestenfalls maximierbar.
Mechanische, topometrische und optische Charakterisierung von Schichten mit Stand der Normung
(2019)
Der Vortrag „MECHANISCHE, TOPOMETRISCHE UND OPTISCHE CHARAKTERISIERUNG VON SCHICHTEN MIT STAND DER NORMUNG“ widmet sich unterschiedlichen Beschichtungssystemen und deren mechanischer, topometrischer und optischer Charakterisierung. Über die entsprechenden aktuellen Normen wird informiert. Es betrifft Verfahren wie die Instrumentierte Eindringprüfung (IIT), Centrifugal Adhesion Testing, Weißlichtinterferenzmikroskopie, Tastschnittverfahren und Ellipsometrie (SE).
The oxides, hydroxides, and oxo-hydroxides of iron belong to the most abundant materials on earth. They also feature a wide range of practical applications. In many environments, they can undergo facile phase transformations and crystallization processes.
Water appears to play a critical role in many of these processes. Despite numerous attempts, the role of water has not been fully revealed yet. We present a new approach to study the influence of water in the crystallization and phase transformations of iron oxides.
The approach employs model-type iron oxide films that comprise a defined homogeneous nanostructure. The films are exposed to air containing different amounts of water reaching up to pressures of 10 bar. Ex situ analysis via scanning electron microscopy, Transmission electron microscopy, selected area electron diffraction, and X-ray diffraction is combined with operando near-ambient pressure X-ray photoelectron spectroscopy to follow water-induced changes in hematite nd ferrihydrite. Water proves to be critical for the nucleation of ematite domains in ferrihydrite, the resulting crystallite orientation, and the underlying crystallization mechanism.
The aim of this study is to develop nanometer-thin epoxy-based films on aluminium alloy AA2024-T3 as a model coating system for high resolution corrosion studies. Spin coating was used for the layer-by-layer (LbL) deposition of poly-(ethylenimine) (PEI) and poly([o-cresyl glycidyl ether]-co-formaldehyde) (CNER) bilayers. The film chemistry and the cross-linking process were characterized by means of Fourier-transform infrared spectroscopy (FTIR).
Ellipsometric data confirmed the linear increase of film thickness. The potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) results indicate the improvement of the film barrier properties with increasing film thickness. Mapping of the topography and the volta potential was performed by means of scanning Kelvin probe force microscopy (SKPFM).
The results indicate the presence of a homogeneous film structure, while the intermetallic phases can still be identified below the coating. The SKPFM Analysis confirmed that the model films are suitable for investigation of corrosion processes at the coating/metal interface.