Electrocatalysis of lithium (poly-) sulfides in organic ether-based electrolytes. - In: Journal of the Electrochemical Society, ISSN 1945-7111, Bd. 167 (2021), 16, 166520, insges. 9 S.
https://doi.org/10.1149/1945-7111/abd60c
Method for contact resistance determination of copper during fast temperature changes. - In: Journal of materials science, ISSN 1573-4803, Bd. 56 (2021), 5, S. 3827-3845
https://doi.org/10.1007/s10853-020-05490-w
Formation of CuCrCoFeNiO high entropy alloy thin films by rapid thermal processing of Cu/CrNiO/FeCo multilayers. - In: Surface and coatings technology, ISSN 1879-3347, Bd. 405 (2021), 126563
https://doi.org/10.1016/j.surfcoat.2020.126563
Radius and roundness measurement of micro spheres based on a set of AFM surface scans. - In: Measurement science and technology, ISSN 1361-6501, Bd. 32 (2021), 4, 044005, S. 1-11
Micro coordinate measuring machines have been developed for the traceable characterisation of small complex parts, due to the demand in research and industry. These machines require geometrically well characterised probing spheres of ever smaller radii. Currently, there is no established procedure for the measurement of such spheres below radii of 500 [my]m. In this paper we, therefore, propose and investigate an approach which is based on a set of AFM surface scans in conjunction with a stitching algorithm. The strategy was implemented on a nano measuring machine and investigated on a ruby sphere with a radius of 150 [my]m. Although the strategy can generally be applied to the characterisation of a full sphere, we limit ourselves to the measurement of one greate circle (equator). The technique enables the measurement of micro spheres with a high lateral and vertical resolution. The mean radius of the ruby sphere was measured with a standard deviation of 3.7 nm over 6 repetitions. As our experiments have shown, the measurement procedure is at the moment mainly influenced by the shape of the AFM tip which requires further attention.
https://doi.org/10.1088/1361-6501/abcff4
Influence of different Ni coatings on the long-term behavior of ultrasonic welded EN AW 1370 cable/EN CW 004A arrestor dissimilar joints. - In: Welding in the world, ISSN 1878-6669, Bd. 65 (2021), 3, S. 429-440
The increasing demand for energy-efficient vehicles requires suitable methods for cost and weight reduction. This can be achieved by the replacement of copper by aluminum, in particular for the on-board power systems. However, the complete substitution is restricted by the mechanical and physical material properties of aluminum as well as challenges in the aluminum copper interface. The challenges concern the corrosion vulnerability and the occurrence of brittle intermetallic compounds (IMC) which can negatively influence the mechanical properties and the electrical conductivity. Therefore, current investigations focus on the one hand on the realization of dissimilar aluminum copper joints by suitable joining technologies, like ultrasonic welding, and on the other hand on the assurance of a sufficient prevention against harmful corrosion effects. In cases where the joint cannot be protected against corrosion by sealing, nickel coatings can be used to protect the joint. In the present study, the influence of electroless, electroplated, and sulfamate nickel coatings was investigated regarding the long-term stability. The joints were performed as industry-related arrester connections, consisting of EN AW 1370 cables and EN CW 004A terminals. The samples were exposed to corrosive as well as electrical, thermal, and mechanical stress tests according to current standards and regulations.
https://doi.org/10.1007/s40194-020-01030-x
Ni-Cu-Zn ferrites with high Curie temperature for multilayer inductors with increased operating temperatures. - In: International journal of applied ceramic technology, ISSN 1744-7402, Bd. 18 (2021), 1, S. 129-137
https://doi.org/10.1111/ijac.13623
Electrocodeposition of Ni composites and surface treatment of SiC nano-particles. - In: Surface and coatings technology, ISSN 1879-3347, Bd. 406 (2021), 126663, insges. 8 S.
https://doi.org/10.1016/j.surfcoat.2020.126663
Determination of transport parameters in [EMIm]Cl-based ionic liquids - diffusion and electrical conductivity. - In: Electrochimica acta, ISSN 1873-3859, Bd. 366 (2021), 137370
The density, electrical conductivity and diffusion coefficients of anions and cations in the ionic liquid AlCl3/1-ethyl-3-methylimidazolium chloride, [EMIm]Cl, were determined to study physical correlations of these important parameters. The density was measured for different molar ratios of AlCl3:[EMIm]Cl from 0.5:1 to 2.0:1 at ambient temperature. The diffusion coefficient of the electrochemically active heptachloroaluminate complex, Al2Cl7-, was measured for a molar ratio of 2:1 in the range of 25˚C to 100˚C. The corresponding current density and potential transients were discussed regarding the decomposition of the [EMIm]+ cation and deviation from the theoretical Cottrell behavior. The electrical conductivity was measured for molar ratios of 1.5:1 and 2:1 in the range of 25˚C to 100˚C. Both the diffusion coefficient and electrical conductivity can be described well by an Arrhenius law. The diffusion coefficients of AlCl4-, Al2Cl7- and [EMIm]+ were estimated from the Nernst-Einstein and Stokes-Einstein relation. The results indicate a strong impact of ion pairing in these electrolytes.
https://doi.org/10.1016/j.electacta.2020.137370
A dynamic bolus phantom for the evaluation of the spatio-temporal resolution of MPI scanners. - In: Journal of magnetism and magnetic materials, ISSN 1873-4766, Bd. 519 (2021), 167446
Magnetic particle imaging (MPI) is a tomographic imaging method to determine the spatial distribution of magnetic nanoparticles (MNP) within a defined volume. To evaluate the spatio-temporal resolution of existing MPI scanners, enabling the consistent comparison of the performance of different scanner setups, we developed dynamic MPI measurement phantoms based on segmented flow. These segmented flow phantoms comprise a defined bolus of ferrofluid tracer material, which can be pumped through a tube system with defined velocities. Using a hydrophobic organic carrier oil, cylindrically shaped boluses of different diameter, length, and flow velocity can be emulated. Moving boluses were imaged by different MPI scanner types and the correlation of spatial resolution und velocity of the bolus was investigated. For all bolus dimension and flow velocity combinations investigated, we observed a decreasing spatial resolution and increasing blurring for increasing bolus velocity and decreasing bolus volume.
https://doi.org/10.1016/j.jmmm.2020.167446
Coordinate transformation and its uncertainty under consideration of a non-orthogonal coordinate base. - In: Measurement science and technology, ISSN 1361-6501, Bd. 32 (2021), 4, 045001, insges. 6 S.
Nanopositioning and nanomeasuring machines are 3D coordinate measuring systems with nanometer precision at measurement volumes in the cubic centimeter range. The coordinate base is formed by an interferometer system with a common mirror corner. The orthogonality deviations of the mirror corner require a coordinate transformation of the measuring axes. The uncertainty of the coordinate transformation must be taken into account in the overall measurement uncertainty budget. Starting from a complete transformation model, the result of model simplications on the transformation behaviour is analysed and discussed.
https://doi.org/10.1088/1361-6501/aba3f5