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.
https://doi.org/10.3390/met13020377
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.
https://doi.org/10.1002/app.53746
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.
Electrochemical deposition of silicon in organic electrolytes. - In: Reference module in chemistry, molecular sciences and chemical engineering, (2023)
Electrodeposition is a versatile instrumental technique, already applied in many industrial fields. However, the deposition of silicon and other reactive elements is still challenging and requires further research and improvement. Accomplishing an efficient electrodeposition of silicon at room temperature is very attractive due to the high number of manufacturing technologies that would benefit from this approach. This work provides an overview of the electrochemical approaches for silicon deposition performed in organic electrolytes. The main factors that impact this process are individually discussed and exemplified with appropriately updated literature sources. Furthermore, the previously available research on characterization of electrodeposited silicon containing layers is provided. These studies are presented in the context of better understanding the structure, composition, and functional properties of the deposited silicon material, which may attract the attention of young academic scientists and process engineers.
https://doi.org/10.1016/B978-0-323-85669-0.00005-2
Innovation processing of circuit boards with FDM printing and selective electrochemical metallization. - In: Meeting abstracts, ISSN 2151-2043, Bd. MA2022-01 (2022), 57, 2369
https://doi.org/10.1149/MA2022-01572369mtgabs
A systematic approach for controlling electrodeposition based on studies of an acidic copper electrolyte. - Ilmenau : Universitätsbibliothek, 2022. - 1 Online-Ressource (122 Seiten)
Technische Universität Ilmenau, Dissertation 2022
Bekannte akademische Erkenntnisse der Elektrochemie, wie die Butler-Volmer Kinetik, und deren Veränderungen ermöglichen unter anderem einen genaueren Einblick in den Mechanismus der Metallabscheidung. Aufgrund eines fehlenden Bindegliedes wurden diesen akademischen Erkenntnissen keine oder nur wenig Beachtung in der industriellen Prozessüberwachung geschenkt. Stattdessen wird die Hull-Zell-Abscheidung als indirekter Ansatz für die Analyse des Abscheidungsverhaltens benutzt. Durch die Entwicklung einer Methode, die die Randelemente-Methode als Grundlage für die Simulation verwendet, werden die kinetischen Parameter - die Austauschstromdichte j0 und der Transferkoeffizient α - aus experimentellen Hull-Zellen-Abscheidungen gewonnen (Rückwärtsbestimmung). Dieser Ansatz wird validiert, indem zyklische voltammetrische Daten eines sauren Kupferelektrolyten in die Simulation eingesetzt und die simulierten Hull-Zellkurven mit experimentellen Kurven verglichen werden. Darüber hinaus wird der Einfluss von Additiven auf das kinetische Verhalten untersucht, ohne die visuellen Informationen und die Möglichkeiten zu verlieren, die strukturellen und physikalischen Eigenschaften der Metallabscheidung zu erhalten. Dieser Ansatz kann zu einem tieferen elektrochemischen Verständnis von industriell benutzten Elektrolyten führen.
https://doi.org/10.22032/dbt.55223
Abscheidung von Aluminiumlegierungen aus ionischen Flüssigkeiten. - In: Galvanotechnik, ISSN 0016-4232, Bd. 113 (2022), 10, S. 1299-1304
Umweltfreundliche Schichten aus Aluminiumlegierungen werden gegenüber Schichten aus bedenklichen Metallen wie Cadmium zunehmend interessanter. Allerdings können sie mittels galvanischer Verfahren nur aus aprotischen Elektrolyten, wie ionischen Flüssigkeiten, abgeschieden werden. Um eine hohe Prozessstabilität zu erzielen, können Multianoden eingesetzt werden.
Characterization of a magnesium fluoride conversion coating on Mg-2Y-1Mn-1Zn screws for biomedical applications. - In: Materials, ISSN 1996-1944, Bd. 15 (2022), 22, 8245, S. 1-18
MgF2-coated screws made of a Mg-2Y-1Mn-1Zn alloy, called NOVAMag® fixation screws (biotrics bioimplants AG), were tested in vitro for potential applications as biodegradable implants, and showed a controlled corrosion rate compared to non-coated screws. While previous studies regarding coated Mg-alloys have been carried out on flat sample surfaces, the present work focused on functional materials and final biomedical products. The substrates under study had a complex 3D geometry and a nearly cylindrical-shaped shaft. The corrosion rate of the samples was investigated using an electrochemical setup, especially adjusted to evaluate these types of samples, and thus, helped to improve an already patented coating process. A MgF2/MgO coating in the µm-range was characterized for the first time using complementary techniques. The coated screws revealed a smoother surface than the non-coated ones. Although the cross-section analysis revealed some fissures in the coating structure, the electrochemical studies using Hanks’ salt solution demonstrated the effective role of MgF2 in retarding the alloy degradation during the initial stages of corrosion up to 24 h. The values of polarization resistance (Rp) of the coated samples extrapolated from the Nyquist plots were significantly higher than those of the non-coated samples, and impedance increased significantly over time. After 1200 s exposure, the Rp values were 1323 ± 144 Ω.cm2 for the coated samples and 1036 ± 198 Ω.cm2 for the non-coated samples, thus confirming a significant decrease in the degradation rate due to the MgF2 layer. The corrosion rates varied from 0.49 mm/y, at the beginning of the experiment, to 0.26 mm/y after 1200 s, and decreased further to 0.01 mm/y after 24 h. These results demonstrated the effectiveness of the applied MgF2 film in slowing down the corrosion of the bulk material, allowing the magnesium-alloy screws to be competitive as dental and orthopedic solutions for the biodegradable implants market.
https://doi.org/10.3390/ma15228245
Hollow platinum-gold and palladium-gold nanoparticles: synthesis and characterization of composition-structure relationship. - In: Journal of nanoparticle research, ISSN 1572-896X, Bd. 24 (2022), 12, 245, insges. 15 S.
Hollow palladium-gold (PdAu) and platinum-gold (PtAu) alloy nanoparticles (NPs) were synthesized through galvanic replacement reactions. PdAu NPs denoted PdAu-99.99 and PdAu-98 were produced using palladium precursors with different purity degree: Na2PdCl4 ≥ 99.99% and Na2PdCl4 98%, respectively. The effect of the addition time of the gold palladium precursor solution on the size of the generated NPs was evaluated. Two types of particles, with a rough and a smooth surface, were identified in the suspensions of PtAu and PdAu NPs by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and scanning transmission electron microscopy (STEM). The atomic percentage of gold, platinum, palladium, and cobalt (atomic %) in the nanoparticles was determined by energy dispersive X-ray spectroscopy (EDX). PtAu NPs (26-42 nm) contain Pt (41 at%), Au (36 at%), and Co (23 at%). Two groups of hollow palladium gold NPs (30-50 nm) with a different residual cobalt content were produced. PdAu-99.99 NPs consisted of Pd (68 at%), Au (26 at%), and Co (6 at%), whereas PdAu-98 NPs were composed of Pd (70 at%), Au (22 at%), and Co (8 at%). The hollow structure of the NPs was confirmed by EDX line scanning. Selected area electron diffraction analysis (SAED) revealed the formation of PtAu and PdAu alloys and it was used in estimating the lattice parameters, too.
https://doi.org/10.1007/s11051-022-05619-9
Tribological and mechanical performance of Ti2AlC and Ti3AlC2 thin films. - In: Advanced engineering materials, ISSN 1527-2648, Bd. 24 (2022), 10, 2200188, S. 1-11
Mn+1AXn (MAX) phases are novel structural and functional materials with a layered crystal structure. Their unique properties such as good machinability, high electrical conductivity, low friction, and corrosion resistance are appealing for many engineering applications. Herein, Ti2AlC and Ti3AlC2 MAX thin films are synthesized by magnetron sputtering and subsequent thermal annealing. A multilayer approach is used to deposit single-element nanolayers of titanium, aluminum, and carbon onto silicon substrates with a double-layer-diffusion barrier of SiO2 and SixNy. Ti2AlC and Ti3AlC2 thin films (thickness ≈500 nm) are formed via rapid thermal annealing and verified by X-Ray diffraction. Nanoindentation tests show hardness values of about 11.6 and 5.3 GPa for Ti2AlC and Ti3AlC2, respectively. The tribological behavior of the Ti2AlC and Ti3AlC2 thin films against AISI 52100 steel balls under dry sliding conditions is studied using ball-on-flat tribometry. The resulting coefficient of friction (CoF) for Ti2AlC and Ti3AlC2 ranges between 0.21-0.42 and 0.64-0.91, respectively. The better tribological behavior observed for Ti2AlC thin films is ascribed to its smaller grain size, reduced surface roughness, and higher hardness.
https://doi.org/10.1002/adem.202200188