In-situ electrogravimetric detection of the cathodic process during the galvanic coupling between lithium and copper. - In: Electrochimica acta, ISSN 1873-3859, Bd. 463 (2023), 142853
With the development of the energy system transformation the quality and efficiency of the rechargeable batteries, particularly the Li ion technology, gain major importance. In spite of the enormous advances, along with many other technological challenges corrosion of the metallic battery parts is often a difficult obstacle for producers and researchers. Li-metal batteries and especially the “anode-free” battery concept could significantly increase the energy density. However, contact corrosion of the Li anode, can occur in this cell configuration since there is a high probability of a three-phase contact between Li-metal, current collector and electrolyte, a condition triggering an intensive Li corrosion. In this work, a new in-situ analytical methodology based on combining electrochemical (ZRA) and microgravimetric (QCM) techniques is proposed for studying the galvanic corrosion. The applicability of this approach is explored in three different electrolyte compositions. Beside the analysis of the conventional electrochemical parameters an in-situ gravimetric detection of the deposited electrolyte decomposition products on the cathode surface is demonstrated. Adsorbed polymer layer on the Cu surface is applied for cathodic inhibition of the galvanic corrosion process, which is studied by means of the novel ZRA-QCM approach.
High-resolution patterning on LTCC by transfer of photolithography-based metallic microstructures. - In: International journal of applied ceramic technology, ISSN 1744-7402, Bd. 0 (2023), 0, S. 1-11
The growing applications and constant miniaturization of electronic devices and of low-temperature co-fired ceramics (LTCC) in various fields, such as aviation, telecommunications, automotive, satellite communications, and military, have led to an increase in the demand for LTCC. Such prospects arise due to the continuous scaling down of components and high-density interconnection in electronics packaging. This paper reports a technique for the transfer of high-resolution microstructures from silicon substrates to LTCC. In this method, gold and copper patterns were formed by photolithography, electrodeposition, and residual layer stripping on silicon substrate. Lithography provides the opportunity to create and transfer complex patterns for use in several different applications and electroplating enables the use of pure metal for excellent electrical properties. The developed structures were transferred onto a top layer of LTCC tape using hot embossing. Then, the subsequent layers were stacked, laminated, and sintered. A resolution of 1.5 μm after free sintering and 4.5 μm after pressure-assisted sintering was achieved. This distinctive method can be useful for several applications requiring high-resolution and superior electrical properties.
Improvement of corrosion behavior of chromium(III) coatings. - In: Galvanotechnik, ISSN 0016-4232, Bd. 114 (2023), 3, S. 311-319
Nickel/Chromium electroplating is widely used in engineering applications, especially for decorative thin ﬁlm plating, abrasion resistance, and corrosion protection . Depositions of metallic chromium from trivalent chromium electrolytes show a lower corrosion resistance than those from hexavalent baths. Therefore, this research work investigated the effect of anodic post-treatment on the corrosion behavior of conventional and micro-cracked chromium (III) based coatings with a series of evaluation methods for corrosion resistance. While the corrosion tests indicated reduced corrosion rates for conventional chromium (III) based coatings, no improvement was observed for micro-cracked chromium coatings.
Electrodeposition of reactive aluminum-nickel coatings in an AlCl3:[EMIm]Cl ionic liquid containing nickel nanoparticles. - In: Journal of the Electrochemical Society, ISSN 1945-7111, Bd. 170 (2023), 7, 072504
The electrodeposition of aluminum-nickel coatings was performed by pulsed direct current in the ionic liquid (IL) 1.5:1 AlCl3:EMIm]Cl containing nickel nanoparticles (Ni NPs), for reactive dispersion coating application. Several electrochemical and characterization techniques were used to shed more light on the mechanism of Ni particle incorporation into the Al matrix. Thus, particle incorporation at the early stage of the deposition would mainly take place via particle adsorption at the substrate. However, as the thickness of the coating increases, it seems that the main mechanism for particle incorporation is via the reduction of ions adsorbed at the particles surface. Although a considerable high incorporation of Ni NPs has been achieved from the IL containing the highest concentration of Ni NPs (i.e. ∼33 wt% from a 20 g/L of Ni NPs bath), a high concentration of NPs in the IL resulted having a negative effect in terms of quality of the coatings, due to solidification of the electrolyte in a poorly conductive compound. Moreover, almost equivalent amounts of Ni and Al (Ni ∼45 wt.%and Al ∼44 wt.%) have been detected in some areas of the coatings. Such a layer composition would be desired for the targeted application.
A Raman study on the speciation of different metal ions in an AlCl3-based ionic liquid. - In: Journal of the Electrochemical Society, ISSN 1945-7111, Bd. 170 (2023), 7, p072503
The speciation of Cr, Zn and Sn in AlCl3/1-ethyl-3-methylimidazolium chloride containing CrCl2, ZnCl2 and SnCl2, respectively, has been studied by cyclic voltammetry (CV), Raman spectroscopy and density functional theory (DFT) calculations. Addition of the respective metal salt causes the current waves in the CV to decrease, indicating a reaction of the metal salts with Al2Cl7−. Compared to the neat electrolyte, the Raman peaks of Al2Cl7− decrease while the AlCl4− peak increases in intensity, broadens and shifts towards lower wavenumbers. Calculated wavenumbers of metal complexes [Me(AlCl4)3]− reflect these observations. DFT calculations of the Gibbs free energies of formation, solvation and reaction support the formation of the proposed complexes. The central ions are coordinated by three bidentate AlCl4− ligands that are arranged planar-trigonally. Due to the occupied Sn-5s orbital, repulsive forces cause a trigonal-pyramidal geometry in case of the Sn complex. Based on the similarities in the experimental observations and the orbital configuration of Zn2+ compared to Cr2+, the spontaneous formation of the species [Cr(AlCl4)3]− can be assumed.
Electrochemically structured copper current collectors for application in energy conversion and storage: a review. - In: Energies, ISSN 1996-1073, Bd. 16 (2023), 13, 4933, S. 1-33
Copper current collectors (Cu CCs) impact the production technology and performance of many electrochemical devices by their unique properties and reliable operation. The efficiency of the related processes and the operation of the electrochemical devices could be significantly improved by optimization of the Cu CCs. Metallic Cu plays an important role in electrochemical energy storage and electrocatalysis, primarily as a conducting substrate on which the chemical processes take place. Li nucleation and growth can be influenced by the current collector by modulating the local current density and Li ion transport. For example, the commonly used planar Cu CC does not perform satisfactorily; therefore, a high number of different modifications of Cu CCs have been proposed and reported in the literature for minimizing the local current density, hindering Li dendrite formation, and improving the Coulombic efficiency. Here, we provide an updated critical overview of the basic strategies of 3D Cu CC structuring, methodologies for analyzing these structures, and approaches for effective control over their most relevant properties. These methods are described in the context of their practical usefulness and applicability in an effort to aid in their easy implementation by research groups and private companies with established traditions in electrochemistry and plating technology. Furthermore, the current overview could be helpful for specialists with experience in associated fields of knowledge such as materials engineering and surface finishing, where electrochemical methods are frequently applied. Motivated by the importance of the final application of Cu CCs in energy storage devices, this review additionally discusses the relationship between CC properties and the functional parameters of the already-implemented electrodes.
Novel gas phase route toward patterned deposition of sputter-free Pt/Al nanofoils. - In: Advanced Materials Technologies, ISSN 2365-709X, Bd. 8 (2023), 18, 2300448, S. 1-8
This article reports a new approach toward fabrication and directed assembly of nanoparticulate reactive system (Nanofoils) on patterned substrates. Different from current state-of-the-art, gas phase electrodeposition uses nanoparticles instead of atoms to form densely packed multilayered thin films at room temperature-pressure. On ignition, the multilayer system undergoes an exothermic self-propagating reaction. The numerous contact points between two metallic nanoparticulate layers aid in high heat release. Sub-10-nm Platinum (Pt) and Aluminum (Al) particles are synthesized through cathode erosion of metal electrodes in a flow of pure nitrogen gas (spark ablation). Pt/Al bilayer stacks with total thickness of 3–8 µm undergo self-propagating reaction with a 10.3 mm s−1 wavefront velocity on local ignition. The reaction wavefront is captured using high speed videography. Calorimetry studies reveal two exothermic peaks suggesting Pt/Al alloy formation. The peak at 135 ˚C has a higher calorific value of 150 mW g−1 while the peak at 400 ˚C has a 12 mW g−1 exothermic peak. X-ray diffraction study shows reaction-products are cubic Al2Pt with small quantities of orthorhombic Al6Pt and orthorhombic AlPt2. Electron microscopy studies help draw a correlation between film morphology, bimetallic interface, nanoparticle oxidation, and self-propagating reaction kinetics that is significant in broadening our understanding towards nanoparticulate reactive systems.
Binary aluminum alloys from 1-ethyl-3-methylimidazolium-based ionic liquids for cathodic corrosion protection. - In: Metals, ISSN 2075-4701, Bd. 13 (2023), 2, 377, S. 1-15
Aluminum cannot provide continuous cathodic corrosion protection under ambient conditions due to the formation of an insulating oxide layer and therefore it should be alloyed. Binary aluminum alloys with Cr, Zn and Sn from AlCl3/1-ethyl-3-methylimidazolium chloride ([EMIm]Cl) containing CrCl2, ZnCl2 or SnCl2 have been deposited and their morphology and composition were investigated using SEM/EDS. The corrosion behavior of alloys with 2–4 wt% Cr, Zn or Sn was investigated using potentiodynamic polarization in 3.5 wt% NaCl solution, neutral salt spray test (NSS) and environmental exposure (EE). Pure aluminum provides excellent corrosion protection of steel in a chloride-containing environment, but not under ambient conditions. AlCr alloys show poor corrosion protection while AlZn alloys provide excellent corrosion protection in the NSS test and superior cathodic protection in the EE test compared to aluminum. AlSn alloys are highly active at even low tin contents and dissolve rapidly in chloride-containing electrolytes. However, a slightly improved cathodic protection in the EE test compared to pure aluminum has been observed. The results prove the necessity of alloying aluminum to achieve effective cathodic corrosion protection under mild atmospheric conditions.
Alkyds with artistic applications based on drying oils, multifunctional polyalcohols and different polybasic acids. - In: Journal of applied polymer science, ISSN 1097-4628, Bd. 140 (2023), 16, e53746, S. 1-12
Today's requirements in the art field have challenged researchers to create artistic paintings with attractive appearance and long-term color stability. Alkyd-based art mediums have become an important group in the art field, because of their similar characteristics to traditional oils and exceptional drying properties. In this work, high solid alkyd-based art mediums have been synthesized by the monoglyceride and acidolysis processes. Multifunctional polyols and high unsaturated fatty acid sources were compared and used for alkyd synthesis. The use of a non-traditional oil of Peruvian origin is proposed. Resins have been characterized according to their physicochemical (acid number, viscosity, color and density) and drying properties. Drying tendencies were verified with the use of quartz crystal microbalance. Also, the behavior of the art mediums mixed with commercial oil paintings and a dry pigment, have also been evaluated. Results indicate that resins containing the polyol with the highest functionality are more viscous and have fewer tendencies to yellowing, while non-traditional Peruvian oil is the best option for creating light-colored art mediums. Alkyd mediums prepared by the monoglyceride method gave to oil paintings better characteristics and drying behavior on canvas.
Innovative Fertigung von Leiterplatten durch FDM-Druck und selektive Kunststoffmetallisierung. - In: WOMag, ISSN 2195-5891, Bd. 12 (2023), 4, S. 9-11
Mit Hilfe von additiven Fertigungsverfahren lassen sich Kunststoffe mit unterschiedlichen Eigenschaften zu einem Produkt kombinieren. Dies erlaubt es, die Grundeinheiten von elektrischen Leiterplatten mittels Drucktechnik herzustellen, wobei der Aufwand weitgehend unabhängig von der hergestellten Stückzahl ist. Durch Drucken mit metallisierbaren Kunststoffen gelingt es, Leiterbahnen mit akzeptabler Leitfähigkeit auf elektrisch isolierendem Trägermaterial zu erzeugen. Die bisherigen Entwicklungen sind auf die Verwendung von Kunststoff mit einer maximalen Temperaturbelastung bis etwa 100 ˚C beschränkt. Um die bestehenden Verfahren der Leiterplattentechnik nutzen zu können, muss diese Temperaturobergrenze deutlich erhöht werden.