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- Haftfestigkeit (4)
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Die Bestimmung der Haftfestigkeit von Lackierungen, Beschichtungen oder Klebeverbunden ist ein wichtiges Analyseinstrument bei der Beurteilung von entsprechenden Fertigungsabläufen. Unter Verwendung einer neuen Zentrifugentechnologie wurde in einem AiF Forschungsprojekt OKTETT die gesamte Prozesskette Vorbehandlung - Verklebung - Prüfung validiert.
Die Bestimmung der Haftfestigkeit von Lackierungen, Beschichtungen oder Klebungen ist wichtig für die Beurteilung von entsprechenden Fertigungsabläufen. Unter Verwendung einer neuen Zentrifugentechnik wurde jetzt ein neues Mehr-Proben-Konzept zur schnellen Validierung von Klebverbindungen entwickelt.
SMT4-CT98-2238 - A certified reference material for the scratch test - REMAST - Synthesis report
(2002)
Single Femtosecond Laser-Pulse-Induced Superficial Amorphization and Re-Crystallization of Silicon
(2021)
Superficial amorphization and re-crystallization of silicon in <111> and <100> orientation after irradiation by femtosecond laser pulses (790 nm, 30 fs) are studied using optical imaging and transmission electron microscopy. Spectroscopic imaging ellipsometry (SIE) allows fast data acquisition at multiple wavelengths and provides experimental data for calculating nanometric amorphous layer thickness profiles with micrometric lateral resolution based on a thin-film layer model. For a radially Gaussian laser beam and at moderate peak fluences above the melting and below the ablation thresholds, laterally parabolic amorphous layer profiles with maximum thicknesses of several tens of nanometers were quantitatively attained. The accuracy of the calculations is verified experimentally by high-resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray spectroscopy (STEM-EDX). Along with topographic information obtained by atomic force microscopy (AFM), a comprehensive picture of the superficial re-solidification of silicon after local melting by femtosecond laser pulses is drawn.
Thermo-mechanical fatigue (TMF) testing plays an increasingly important role in the design, the reliability assessment and the lifecycle management of safety critical components used, for instance, for power generation, in the process industry and in aeronautical and automotive applications, with a view to increasing the fuel efficiency, safety and service intervals, while reducing production (and material) costs. In a European Commission funded research project (acronym: TMF-Standard) of the 5th Framework Programme, 20 European laboratories have undertaken a joint research effort to establish a validated code-of-practice (CoP) for strain-controlled TMF testing. Starting from a survey of the testing protocols and procedures previously used by the partners, a comprehensive pre-normative research activity into various issues has been completed, addressing the dynamic temperature control, the effects of deviations in nominal temperatures and phase angles, the influences of temperature gradients, as well as the practicalities of test interruption and restart procedures. Meaningful allowable tolerances for the various test parameters were identified and practical recommendations as to the test techniques were formulated. From this a preliminary CoP was compiled and used to guide an extensive round robin exercise among the project partners. From the statistical analysis of that exercise, a validated CoP was derived dealing with strain-controlled constant amplitude TMF of nominally homogeneous metallic materials subjected to spatially uniform temperature fields and uniaxial mechanical loading. It is intended to give advice and guidance on the appropriate test setup, testing procedures and the analysis of results, in particular for newcomers in the field of strain-controlled TMF. This paper highlights some of the results of the TMF-Standard project. Moreover, commonalities and differences of the present CoP with respect to the standard documents for strain-controlled TMF, which have been developed at ISO and ASTM levels, are presented in this paper.
High-accuracy film thickness measurements in the range below 100 nm can be made by various complex methods like spectral ellipsometry (SE), scanning force microscopy (SFM), grazing incidence X-ray reflectometry (GIXR), or X-ray fluorescence analysis (XRF). The measurement results achieved with these methods are based on different interactions between the film and the probe. A key question in nanotechnology is how to achieve consistent results on a level of uncertainty below one nanometre with different techniques.
Two different types of thickness standards are realised. Metal film standards for X-ray techniques in the thickness range 10 to 50 nm are calibrated by GIXR with monochromatised synchrotron radiation of 8048 eV. The results obtained at four different facilities show excellent agreement. SiO2 on Si standards for SE and SFM in the thickness range 6 to 1000 nm are calibrated by GIXR with monochromatised synchrotron radiation of 1841 eV and with a metrological SFM. Consistent results within the combined uncertainties are obtained with the two methods. Surfaces and interfaces of both types of standards are additionally investigated by transmission electron microscopy (TEM).
The multiple-sample approach by means of centrifugal adhesion testing (CAT-technology) allows the determination of bonding strength of adhesive-bonded joints on a statistical basis of up to eight samples. Therefore, it is obvious to ensure the continuous handling and identical processing of an octet of samples within the entire process chain of wet-chemical cleaning, plasma-chemical pre-treatment, bonding of samples, and testing of bonding strength. Within the multiple-sample bonding set-up (MPKV-technology) a defined bonding pressure can be adjusted regardless the actual number of samples. A comparison of single- and multiple-sample approach is made for bonding strength of selected adhesives, double-sided adhesive tapes and different material combinations [stainless steel (V2A) vs. stainless steel, polyamide (PA), or polypropylene (PP)]. It is shown that both technologies improve reliability of results
The combination of acoustically levitated droplets, mid-IR laser evaporation, and subsequent post-ionization by secondary electrospray ionization was applied for monitoring the enzymatic digestion of various proteins. Acoustically levitated droplets are an ideal, wall-free model reactor, readily allowing compartmentalized microfluidic trypsin digestions. Time-resolved interrogation of the droplets yielded real-time information on the progress of the reaction and thus provided insights into reaction kinetics. After 30 min of digestion in the acoustic levitator, the obtained protein sequence coverages were identical to the reference overnight digestions. Importantly, our results clearly demonstrate that the applied experimental setup can be used for the real-time investigation of chemical reactions. Furthermore, the described methodology only uses a fraction of the typically applied amounts of solvent, analyte, and trypsin. Thus, the results exemplify the use of acoustic levitation as a green analytical chemistry alternative to the currently used batch reactions.