Improving process monitoring of ultrasonic metal welding using classical machine learning methods and process-informed time series evaluation. - In: Journal of manufacturing processes, ISSN 2212-4616, Bd. 77 (2022), S. 54-62
Ultrasonic metal welding (USMW) is an industrially applied joining technology that is highly complex since the weld quality is influenced by numerous factors. The relationships between these factors and the quality remain partly unavailable resulting in a need for improvement in process monitoring and quality management. This work focuses on exploring the relationships between tensile shear strength (TSS) of Cu-sheet welds and process curves from welding machine and additional vibration sensors at sonotrode and anvil. Discovered relationships would enable an improved process monitoring, when valid for a broad parameter range. To ensure the latter, examinations are carried out on a central composite design of experiments (DoE) data set. For the whole data set as well as for single data points, the process curves are examined in detail comprising visualizations and discussions of revealed trends. These trends are related to process physics to clarify their relevance for the TSS. Based on physical process knowledge, more than 700 features are extracted from the curves. The extraction approach is not limited to the present setup and enables a quantitative evaluation of the relation between TSS and process curves. Most important features are derived from the generator power and the anvil vibration. Finally, linear regression as well as multi-layer perceptron regression are used to predict the TSS based on the most relevant features. Comparing the obtained regression results with the reference model, that is the polynomial regression model from standard DoE evaluation, a prediction improvement of nearly 50% is achieved. These results suggest the employed signals as a suited basis for an improved USMW process monitoring.
https://doi.org/10.1016/j.jmapro.2022.02.057
Anodic dissolution of aluminum and anodic passivation in [EMIm]Cl-based ionic liquids :
Anodische Auflösung und Passivierung von Aluminium in ionischen Flüssigkeiten auf Basis von [EMIm]Cl. - In: WOMag, ISSN 2195-5891, Bd. 11 (2022), 1/2, S. 27-29
Aluminiumabscheidung und -auflösung in ionischen Flüssigkeiten auf Basis von [EMIm]Cl : Kinetik des Ladungstransfers und der geschwindigkeitsbestimmende Schritt. - In: WOMag, ISSN 2195-5891, Bd. 11 (2022), 3, S. 22-25
Wichtiger Wettbewerbsfaktor Thüringer Unternehmen. - In: Wirtschaftsspiegel, ISSN 2190-409X, Bd. 18 (2022), 1, S. 24-25
Recent advances in 2D heterostructures as advanced electrode materials for potassium-ion batteries. - In: Small structures, ISSN 2688-4062, Bd. 3 (2022), 3, 2100221, insges. 19 S.
Owing to the cost-effectiveness, Earth abundance, and suitable redox potential, potassium-ion batteries (PIBs) stand out as one of the best candidates for large-scale energy storage systems. However, the large radius of K+ and the unsatisfied specific capacity are the main challenges for their commercial applications. To address these challenges, constructing heterostructures by selecting and integrating 2D materials as host and other materials as guest are proposed as an emerging strategy to obtain electrode materials with high capacity and long lifespan, thus improving the energy storage capability of PIBs. Recently, numerous studies are devoted to developing 2D-based heterostructures as electrode materials for PIBs, and significant progress is achieved. However, there is a lack of a review article for systematically summarizing the recent advances and profoundly understanding the relationship between heterostructure electrodes and their performance. In this sense, it is essential to outline the promising advanced features, to summarize the electrochemical properties and performances, and to discuss future research focuses about 2D-based heterostructures in PIBs.
https://doi.org/10.1002/sstr.202100221
Aligned deposition of bottom-up grown nanowires by two-directional pressure-controlled contact printing. - In: Nanotechnology, ISSN 1361-6528, Bd. 33 (2022), 23, 235301, S. 1-9
Aligned large-scale deposition of nanowires grown in a bottom-up manner with high yield is a persisting challenge but required to assemble single-nanowire devices effectively. Contact printing is a powerful strategy in this regard but requires so far adequate adjustment of the tribological surface interactions between nanowires and target substrate, e.g. by microtechnological surface patterning, chemical modifications or lift-off strategies. To expand the technological possibilities, we explored two-directional pressure-controlled contact printing as an alternative approach to efficiently transfer nanowires with controlled density and alignment angle onto target substrates through vertical-force control. To better understand this technology and the mechanical behavior of nanowires during the contact printing process, the dynamic bending behavior of nanowires under varying printing conditions is modeled by using the finite element method. We show that the density and angular orientation of transferred nanowires can be controlled using this three-axis printing approach, which thus enables potentially a controlled nanowire device fabrication on a large scale.
https://doi.org/10.1088/1361-6528/ac56f8
Influence of carboxylic acids on the performance of trivalent chromium electrolytes for the deposition of functional coatings. - In: Electrochimica acta, ISSN 1873-3859, Bd. 411 (2022), 140054
As a direct consequence of the restrictions on the use of hexavalent chromium compounds, the demand for a suitable replacement has arisen. In this work the electrodeposition of thick chromium layers (>1µm) from a trivalent electrolyte is investigated with the aim to identify an electrolyte composition for the deposition of hard functional coatings. These layers can be used to surface finish tribological components experiencing high wear rates or mechanical stress in applications such as coating printing cylinders, feed rollers or piston rods. The influence of different carboxylic acids (malonic acid, malic acid, glycolic acid) on the deposition has been studied. The effect of current density on the current efficiency was investigated using in-situ microgravimetry. For a technical application the electrolyte containing malonic acid was the most promising one and was further investigated regarding the properties of the deposits, such as surface morphology, crack formation, composition, thickness and hardness, aiming at properties as close as possible to those of hexavalent chromium. In comparison to hexavalent chromium, the layer of trivalent chromium showed the same properties in terms of crack formation, hardness and layer thickness (> 1 µm).
https://doi.org/10.1016/j.electacta.2022.140054
Disentangling faradaic, pseudocapacitive, and capacitive charge storage: a tutorial for the characterization of batteries, supercapacitors, and hybrid systems. - In: Electrochimica acta, ISSN 1873-3859, Bd. 412 (2022), 140072
Today's electrochemical energy storage technologies aim to combine high specific energy and power, as well as long cycle life, into one system to meet increasing demands in performance. These properties, however, are often characteristic of either batteries (high specific energy) or capacitors (high specific power and cyclability). To merge battery- and capacitor-like properties in a hybrid energy storage system, researchers must understand and control the co-existence of multiple charge storage mechanisms. Charge storage mechanisms can be classified as faradaic, capacitive, or pseudocapacitive, where their relative contributions determine the operating principles and electrochemical performance of the system. Hybrid electrochemical energy storage systems can be better understood and analyzed if the primary charge storage mechanism is identified correctly. This tutorial review first defines faradaic and capacitive charge storage mechanisms and then clarifies the definition of pseudocapacitance using a physically intuitive framework. Then, we discuss strategies that enable these charge storage mechanisms to be quantitatively disentangled using common electrochemical techniques. Finally, we outline representative hybrid energy storage systems that combine the electrochemical characteristics of batteries, capacitors and pseudocapacitors. Modern examples are analyzed while step-by-step guides are provided for all mentioned experimental methods in the Supplementary Information.
https://doi.org/10.1016/j.electacta.2022.140072
Thin film nanostructuring at oblique angles by substrate patterning. - In: Surface and coatings technology, ISSN 1879-3347, Bd. 436 (2022), 128293, insges. 12 S.
It is demonstrated that, besides classical nanocolumnar arrays, the oblique angle geometry induces the growth of singular structures in the nanoscale when using wisely designed patterned substrates. Well-ordered array of crosses, cylindrical nanorods or hole structures arranged in square or hexagonal regular geometries are reported as examples, among others. The fundamental framework connecting substrate topography and film growth at oblique angles is presented, allowing the use of substrate patterning as a feasible thin film nanostructuring technique. A systematic analysis of the growth of TiO2 thin films on 4 different lithographic patterned substrates in 4 different scale lengths is also presented. A first conclusion is the existence of a height-based selective growth in the initial stages of the deposition, by which the film preferentially develops on top of the tallest substrate features. This behavior is maintained until the film reaches a critical thickness, the so-called Oblivion Thickness, above which the film topography becomes gradually independent of the substrate features. A general formula relating the spatial features of the pattern, the coarsening exponent and the Oblivion Thickness has been deduced.
https://doi.org/10.1016/j.surfcoat.2022.128293
Scavenging of bacteria or bacterial products by magnetic particles functionalized with a broad-spectrum pathogen recognition receptor motif offers diagnostic and therapeutic applications. - In: Acta biomaterialia, ISSN 1878-7568, Bd. 141 (2022), S. 418-428
Sepsis is a dysregulated host response of severe bloodstream infections, and given its frequency of occurrence and high mortality rate, therapeutic improvements are imperative. A reliable biomimetic strategy for the targeting and separation of bacterial pathogens in bloodstream infections involves the use of the broad-spectrum binding motif of human GP-340, a pattern-recognition receptor of the scavenger receptor cysteine rich (SRCR) superfamily that is expressed on epithelial surfaces but not found in blood. Here we show that these peptides, when conjugated to superparamagnetic iron oxide nanoparticles (SPIONs), can separate various bacterial endotoxins and intact microbes (E. coli, S. aureus, P. aeruginosa and S. marcescens) with high efficiency, especially at low and thus clinically relevant concentrations. This is accompanied by a subsequent strong depletion in cytokine release (TNF, IL-6, IL-1β, Il-10 and IFN-γ), which could have a direct therapeutic impact since escalating immune responses complicates severe bloodstream infections and sepsis courses. SPIONs are coated with aminoalkylsilane and capture peptides are orthogonally ligated to this surface. The particles behave fully cyto- and hemocompatible and do not interfere with host structures. Thus, this approach additionally aims to dramatically reduce diagnostic times for patients with suspected bloodstream infections and accelerate targeted antibiotic therapy. - Statement of significance - Sepsis is often associated with excessive release of cytokines. This aspect and slow diagnostic procedures are the major therapeutic obstacles. The use of magnetic particles conjugated with small peptides derived from the binding motif of a broad-spectrum mucosal pathogen recognition protein GP-340 provides a highly efficient scavenging platform. These peptides are not found in blood and therefore are not subject to inhibitory mechanisms like in other concepts (mannose binding lectine, aptamers, antibodies). In this work, data are shown on the broad bacterial binding spectrum, highly efficient toxin depletion, which directly reduces the release of cytokines. Host cells are not affected and antibiotics not adsorbed. The particle bound microbes can be recultured without restriction and thus be used directly for diagnostics.
https://doi.org/10.1016/j.actbio.2022.01.001