Research

11 pages, 5143 KiB

Open AccessArticle

Superconducting Niobium Coatings Deposited on Spherical Substrates in Molten Salts

by Anton Dubrovskiy, Maksim Okunev, Olga Makarova and Sergey Kuznetsov

Coatings 2018, 8(6), 213; https://doi.org/10.3390/coatings8060213 - 04 Jun 2018

Cited by 14 | Viewed by 3850

The interaction of substrates from ceramics, beryllium, and carbopyroceram with the electrolyte for the electrodeposition of niobium coatings was investigated. The corrosion resistance of spherical ceramic and beryllium samples with the protective molybdenum films obtained by magnetron sputtering was studied. The exfoliation of [...] Read more.

The interaction of substrates from ceramics, beryllium, and carbopyroceram with the electrolyte for the electrodeposition of niobium coatings was investigated. The corrosion resistance of spherical ceramic and beryllium samples with the protective molybdenum films obtained by magnetron sputtering was studied. The exfoliation of molybdenum film from ceramics and beryllium samples was observed after the experiments due to the interaction of substrates with the melt. It was found that the carbopyroceram did not corrode in the niobium containing melt and this material was chosen as the substrate for the electrodeposition of superconducting niobium coatings. The influence of the oxide ions on the electrochemical behavior of niobium complexes in the NaCl–KCl–NaF–K₂NbF₇ melt was studied. A special form of the cathode was constructed for the electrodeposition of niobium coatings on spherically shaped substrates. Electrodeposition of the niobium coatings on spheres 10 mm in diameter manufactured from carbopyroceram was carried out at 750 °C with the cathodic current density of 5 × 10⁻³–2 × 10⁻² A·cm⁻² and the electrolysis time of 8–12 h. Influence of the cathodic current density on the microstructure of niobium coatings was studied. The roughness, nonsphericity, and superconductive properties of niobium coatings were determined. Full article

(This article belongs to the Special Issue Thin Films and Patterned Structures by Electrochemical Methods)

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9 pages, 2797 KiB

Open AccessArticle

The Gain of Low Thermal Expansivity via Phase Transition in Electroformed Invar

by Yong Bum Park and In Gyeong Kim

Coatings 2018, 8(5), 169; https://doi.org/10.3390/coatings8050169 - 02 May 2018

Cited by 9 | Viewed by 6363

Abstract

In the organic light-emitting diode display industry, Invar exhibits anomalously low thermal expansivity and is, therefore, used as a material for fine metal masks, which are necessary components for the evaporation process of diode materials. We present an electroforming method for fabricating Fe-Ni [...] Read more.

In the organic light-emitting diode display industry, Invar exhibits anomalously low thermal expansivity and is, therefore, used as a material for fine metal masks, which are necessary components for the evaporation process of diode materials. We present an electroforming method for fabricating Fe-Ni alloys with a coefficient of thermal expansion lower than that of conventional Invar. The principle of controlling the thermal expansivity of electroformed Fe-Ni alloys is clarified in terms of the behavior of the phases constituting them. The cause of the Invar anomalies, which has not yet been fully elucidated, is explained by combining the Weiss model based on the electron configurations of Fe atoms and a model that we propose based on atom configurations. Full article

(This article belongs to the Special Issue Thin Films and Patterned Structures by Electrochemical Methods)

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17 pages, 5900 KiB

Open AccessArticle

Alkoxylated β-Naphthol as an Additive for Tin Plating from Chloride and Methane Sulfonic Acid Electrolytes

by Simona P. Zajkoska, Antonio Mulone, Wolfgang E. G. Hansal, Uta Klement, Rudolf Mann and Wolfgang Kautek

Coatings 2018, 8(2), 79; https://doi.org/10.3390/coatings8020079 - 21 Feb 2018

Cited by 9 | Viewed by 5702

Abstract

β-naphthol was one of the first additives introduced for smooth and homogeneous tin electrodeposition. Although it can be oxidized under the plating conditions, forming either 1,2-napthoquinone or polymeric materials based on naphthioxides, it is still in use. In this work, an investigation of [...] Read more.

β-naphthol was one of the first additives introduced for smooth and homogeneous tin electrodeposition. Although it can be oxidized under the plating conditions, forming either 1,2-napthoquinone or polymeric materials based on naphthioxides, it is still in use. In this work, an investigation of its more stable form, alkoxylated β-naphthol (ABN), on tin plating is undertaken. For this purpose, chloride based (pH ~5) and methane sulfonic acid (MSA, pH ~0.5) electrolytes, including ABN, were prepared. Reaction kinetics were studied by polarization, Tafel measurements, and cyclic voltammetry. Tin electrodeposits were obtained on flat brass substrates. Surface morphology and preferred crystal orientation were studied by Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD). In both studied electrolytes ABN acts as an inhibitor but in the case of the chloride electrolyte it is more pronounced. In the MSA electrolyte this effect was overlaid by the presence of tin-citrate complexes. In the chloride-based electrolyte, ABN has a grain refining effect, while in the MSA electrolyte an increase of ABN concentration leads to a slight enlargement of the average grain size. X-ray analysis shows a constant decrease of the (101) intensity with increasing concentration of ABN for the sample deposited from both baths. Full article

(This article belongs to the Special Issue Thin Films and Patterned Structures by Electrochemical Methods)

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11 pages, 13468 KiB

Open AccessArticle

Investigation of Electrochemically Deposited and Chemically Reduced Platinum Nanostructured Thin Films as Counter Electrodes in Dye-Sensitized Solar Cells

by Chih-Hung Tsai, Yu-Chen Hsiao and Ping-Yuan Chuang

Coatings 2018, 8(2), 56; https://doi.org/10.3390/coatings8020056 - 01 Feb 2018

Cited by 5 | Viewed by 5470

Abstract

In this paper, we demonstrated that platinum (Pt) counter electrodes (CEs) fabricated using electrochemical deposition and chemical reduction can replace conventional high-temperature thermally decomposed Pt electrodes. In this study, Pt electrodes were fabricated using thermal decomposition, electrochemical deposition, and chemical reduction, and the [...] Read more.

In this paper, we demonstrated that platinum (Pt) counter electrodes (CEs) fabricated using electrochemical deposition and chemical reduction can replace conventional high-temperature thermally decomposed Pt electrodes. In this study, Pt electrodes were fabricated using thermal decomposition, electrochemical deposition, and chemical reduction, and the influence of the different Pt counter electrodes on the efficiency of the dye-sensitized solar cells (DSSCs) was analyzed. The properties of the various Pt CEs were analyzed using scanning electron microscopy (SEM), surface area analysis, X-ray diffraction (XRD), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV). DSSCs with various Pt CEs were characterized using current density-voltage (J-V), incident photo-current conversion efficiency (IPCE), and EIS measurements. The results show that the power conversion efficiencies of these three types of DSSC devices were between 7.43% and 7.72%. The DSSCs based on the Pt electrode fabricated through electrochemical deposition exhibited the optimal power conversion efficiency. Because the processes of electrochemical deposition and chemical reduction do not require high-temperature sintering, these two methods are suitable for the fabrication of Pt on flexible plastic substrates. Full article

(This article belongs to the Special Issue Thin Films and Patterned Structures by Electrochemical Methods)

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6159 KiB

Open AccessArticle

Ammonia Generation via a Graphene-Coated Nickel Catalyst

by Fei Lu and Gerardine G. Botte

Coatings 2017, 7(6), 72; https://doi.org/10.3390/coatings7060072 - 27 May 2017

Cited by 4 | Viewed by 6449

Abstract

A novel graphene-coated Ni electrode was developed in this investigation to improve corrosion resistance while unexpectedly enhancing the ammonia generation rate in the electrochemically induced urea to ammonia (eU2A) process, which is an electrochemical onsite ammonia generation method. The development of the electrode [...] Read more.

A novel graphene-coated Ni electrode was developed in this investigation to improve corrosion resistance while unexpectedly enhancing the ammonia generation rate in the electrochemically induced urea to ammonia (eU2A) process, which is an electrochemical onsite ammonia generation method. The development of the electrode is crucial for the eU2A reactions since in the ammonia generation process, the concentration of ammonia is inevitably high on the surface of the electrode, leading to severe corrosion of the electrode and the loss of generated ammonia as well. In this paper, the graphene was derived from raw coal by using the chemical vapor deposition method and self-lifted onto a Ni electrode to form a protective layer for corrosion prevention. Transmission electron microscopy showed the synthesized graphene had few-layers and Raman spectroscopy indicated that the coating of graphene was stable during the eU2A reaction. As a result, the ammonia corrosion of the Ni electrode was dramatically reduced by ~20 times with the graphene coating method. More importantly, a higher ammonia generation rate (~2 times) was achieved using the graphene-coated Ni working electrode compared to a bare Ni electrode in the eU2A process. Full article

(This article belongs to the Special Issue Thin Films and Patterned Structures by Electrochemical Methods)

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3203 KiB

Open AccessArticle

Statistical Determination of a Fretting-Induced Failure of an Electro-Deposited Coating

by Kyungmok Kim

Coatings 2017, 7(4), 48; https://doi.org/10.3390/coatings7040048 - 31 Mar 2017

Cited by 5 | Viewed by 4654

Abstract

This paper describes statistical determination of fretting-induced failure of an electro-deposited coating. A fretting test is conducted using a ball-on-flat plate configuration. During a test, a frictional force is measured, along with the relative displacement between an AISI52100 ball and a coated flat [...] Read more.

This paper describes statistical determination of fretting-induced failure of an electro-deposited coating. A fretting test is conducted using a ball-on-flat plate configuration. During a test, a frictional force is measured, along with the relative displacement between an AISI52100 ball and a coated flat specimen. Measured data are analyzed with statistical process control tools; a frictional force versus number of fretting cycles is plotted on a control chart. On the control chart, critical number of cycles to coating failure is statistically determined. Fretted surfaces are observed after interrupting a series of fretting tests. Worn surface images and wear profiles provide that the increase on the kinetic friction coefficient after a steady-state sliding is attributed to the substrate enlarged at a contact surface. There is a good agreement between observation of worn surfaces and statistical determination for fretting-induced coating failure. Full article

(This article belongs to the Special Issue Thin Films and Patterned Structures by Electrochemical Methods)

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4462 KiB

Open AccessArticle

Static and Dynamic Magnetization Investigation in Permalloy Electrodeposited onto High Resistive N-Type Silicon Substrates

by Kenedy Freitas, José R. Toledo, Leandro C. Figueiredo, Paulo C. Morais, Jorlandio F. Felix and Clodoaldo I. L. De Araujo

Coatings 2017, 7(2), 33; https://doi.org/10.3390/coatings7020033 - 20 Feb 2017

Cited by 3 | Viewed by 5733

Abstract

The present study reports on the development of permalloy thin films obtained by electrodeposition onto low-doped n-type silicon substrates. While changing from non-percolated clusters into percolated thin films upon increasing the electrodeposition time, the static and dynamic magnetic properties of the as-obtained structures [...] Read more.

The present study reports on the development of permalloy thin films obtained by electrodeposition onto low-doped n-type silicon substrates. While changing from non-percolated clusters into percolated thin films upon increasing the electrodeposition time, the static and dynamic magnetic properties of the as-obtained structures were investigated. We found the experimental magnetic results to be in very good agreement with the simulations performed by solving the Landau-Lifshitz for the dynamics of the magnetic moment. For short electrodeposition times we found the static and dynamic magnetization behavior of the as-formed nanoclusters evidencing vortex magnetization with random chirality and polarization, which is explained in terms of dipolar interaction minimization. Indeed, it is herein emphasized that recent applications of ferromagnetic materials in silicon-based spintronic devices, such as logic and bipolar magnetic transistors and magnetic memories, have revived the possible utilization of low cost and simple electrodeposition techniques for the development of these upcoming hetero-nanostructured devices. Full article

(This article belongs to the Special Issue Thin Films and Patterned Structures by Electrochemical Methods)

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3840 KiB

Open AccessCommunication

Local Electrical Response in Alkaline-Doped Electrodeposited CuInSe₂/Cu Films

by Javier A. Barón-Miranda, Octavio Calzadilla, Liliana E. Arvizu-Rodríguez, Jose L. Fernández-Muñoz, Cesia Guarneros-Aguilar, Fabio Chale-Lara, Ulises Páramo-García and Felipe Caballero-Briones

Coatings 2016, 6(4), 71; https://doi.org/10.3390/coatings6040071 - 20 Dec 2016

Cited by 2 | Viewed by 5647

Abstract

The local electrical response in alkaline-doped CuInSe₂ films prepared by single-step electrodeposition onto Cu substrates was studied by current-sensing atomic force microscopy. The CuInSe₂ (CIS) films were prepared from single baths containing the dopant ions (Li, Na, K or Cs) and [...] Read more.

The local electrical response in alkaline-doped CuInSe₂ films prepared by single-step electrodeposition onto Cu substrates was studied by current-sensing atomic force microscopy. The CuInSe₂ (CIS) films were prepared from single baths containing the dopant ions (Li, Na, K or Cs) and were studied by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and photocurrent response. Increased crystallinity and surface texturing as the ion size increased were observed, as well as an enhanced photocurrent response in Cs-doped CIS. Li- and Na-doped films had larger conductivity than the undoped film while the K- and Cs-doped samples displayed shorter currents and the current images indicated strong charge accumulation in the K- and Cs-doped films, forming surface capacitors. Corrected current-sensing AFM IV curves were adjusted with the Shockley equation. Full article

(This article belongs to the Special Issue Thin Films and Patterned Structures by Electrochemical Methods)

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