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1

Modified Graphite with Tin Oxide as a Promising Electrode for Reduction of Organic Pollutants from Wastewater by Sonoelectrochemical Oxidation

Nsaif Hind Jabbar, Majeed Najwa Saber

Ecological Engineering & Environmental Technology

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2024

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Vol. 25, iss. 1

307--320

EN

Most of the studies on tin oxide coatings as electrode materials were conducted on titanium; in this study, the aim was to create pure tin oxide (SnO2) films on graphite substrate, which is more prevalent than titanium. There is a lack in investigation the effect of SnCl2 and HNO3 concentrations on the prepared SnO2 electrode; therefore, the aim of this work was to study these effects precisely. Also, no previous study investigated the removal of phenol sonoelectrochemically by a SnO2 electrode, which would be accomplished in the present work. The tin dioxide electrode was produced by cathodic electrodeposition using a SnCl2·2H2O solution in the presence of HNO3 and NaNO3 on a graphite plate substrate. The impact of various operating parameters (current density – CD, HNO3 concentration, and SnCl2·2H2O concentration) on the morphology and structure of the SnO2 deposit layer was thoroughly investigated. The physical structures of the SnO2 film were determined by X‐ray diffraction (XRD), surface morphology was characterized using field-emission scanning electron microscopy (SEM), and chemical composition was analyzed using energy-dispersive X-ray spectroscopy (EDX). In a batch reactor, the sonoelectrochemical oxidation of phenol was tested to determine the performance of the best SnO2 electrodes for phenol degradation and any organic byproducts. It was discovered that 10 mA/cm2 , 50 mM of SnCL2·2H2O, and 250 mM of HNO3 were the optimum conditions to prepare SnO2 electrodes, which produced the smallest crystal size, with no appeared cracks, and gave the best phenol removal. The best prepared electrode was tested in the sonoelectrochemical oxidation of phenol with two different electrolytes and different CD, and the results showed that the phenol removal was 76.87% and 64.68% when using NaCl and Na2SO4, respectively, as well as was 63.39, 76.87, and 100% for CD at 10, 25, and 40 mA/cm2, respectively.

2

Preliminary studies on electrodeposition of Zn-Fe-W alloy coatings from citrate-sulphate baths

Shoaib Hafiz Muhammad, Winiarska Katarzyna, Winiarski Juliusz

Ochrona przed Korozją

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2023

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nr 2

44--47

EN

Exploratory studies of the electrodeposition process of zinc coatings containing iron and tungsten were carried out using SEM/EDS and XRD techniques. It was shown that from a citrate-sulphate plating bath composed of (mol dm−3): ZnSO4 – 0.2, FeSO4 – 0.2, Na3Cit (tri-sodium citrate salt) – 0.4, (NH4)2SO4 – 0.1 and Na2WO4 – 0.01 Zn-Fe-W alloys can be obtained on a rotating disc electrode. It was noted that the induced co-deposition of tungsten with iron only occurred at pH > 6.0. Below this value, a Zn-Fe alloy coating was obtained. In the pH range from 5.0 to 9.0, the maximum contents of tungsten (15.96 wt. %) and iron (29.36 wt. %) were shown by the coatings deposited at pH 7.0. The increase in the bath pH from 5.0 to 9.0 resulted in clear changes in the phase composition of the deposited coatings. According to the results of XRD analyzes, the following can be indicated as probable: Fe22Zn78 and Fe7W6. However, the recorded diffractograms are difficult to interpret and it was very difficult to clearly define the type of phases present in the coating without additional tests.

PL

Stosując techniki SEM/EDS i XRD, przeprowadzono rozpoznawcze badania procesu elektroosadzania powłok cynkowych zawierających żelazo i wolfram. Wykazano, że z cytrynianowo-siarczanowej kąpieli galwanicznej o składzie (mol dm−3): ZnSO4 – 0,2, FeSO4 – 0,2, Na3Cit (cytrynian tri-sodu) – 0,4, (NH4)2SO4 – 0,1 i Na2WO4 – 0,01 można otrzymać na wirującej elektrodzie dyskowej powłoki stopowe Zn-Fe-W. Zauważono, że indukowane współosadzanie wolframu z żelazem zachodziło dopiero przy pH > 6,0. Poniżej tej wartości otrzymywało się powłokę stopową Zn-Fe. W zakresie pH od 5,0 do 9,0 maksymalną zawartość wolframu (15,96% mas.) i żelaza (29,36% mas.) wykazały powłoki osadzone przy pH 7,0. Wzrost pH kąpieli od 4,5 do 9,0 powodował wyraźne zmiany w składzie fazowym osadzanych powłok. Zgodnie z wynikami analiz XRD można wskazać jako prawdopodobne występowanie: Fe22Zn78 oraz Fe7W6. Zarejestrowane dyfraktogramy są jednak trudne w interpretacji i jednoznaczne określenie rodzaju faz obecnych w powłoce bez wykonania dodatkowych badań było mocno utrudnione.

3

Effect of saccharin addition on formation, wear and corrosion resistance of electrodeposited Ni-Cr coatings

Demir Mehmet, Kanca Erdoğan, Karahan İsmail Hakki

Materials Science Poland

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2023

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Vol. 41, No. 3

111--125

EN

Numerous factors play a pivotal role in shaping the mechanical and corrosion resistance properties of electrodeposited Ni-Cr alloy coatings. This study delves into the deposition of Ni-Cr alloy coatings on AISI 1040 steel, examining the influence of saccharin additives within the electrodeposition bath. Specifically, the concentration of saccharin within the solution was varied over a range of 0 to 2 g/l. Following the electrodeposition process, a comprehensive array of characterization techniques was employed, encompassing 2D surface roughness analysis, scanning electron microscopy, X-ray diffraction, nanoindentation, energy-dispersive X-ray spectroscopy and assessments of wear and corrosion performance. The characterization results of this article reveal a compelling difference between saccharin-free Ni-Cr coatings and their saccharin-modified counterparts. Notably, microcracks, a common occurrence in saccharin-free coatings, were suppressed in the saccharin-modified Ni-Cr coatings. Additionally, the latter exhibited a smoother and more uniform surface texture. A crucial observation was that the introduction of saccharin into the bath was directly associated with an increased incorporation of chromium within the coatings, resulting in higher nanohardness values. Furthermore, the residual stress within the coatings shifted from tensile to compression as saccharin concentrations increased. Concurrently, surface roughness and wear rates exhibited a consistent downward trend with increasing saccharin concentrations in the solution. The most significant findings were seen in the domain of corrosion resistance. Saccharin-modified Ni-Cr coatings outperformed the bare steel substrate and saccharin-free Ni-Cr coatings. Intriguingly, the enhancement of corrosion resistance was not linearly proportional to saccharin concentration; the optimal corrosion resistance was achieved at a concentration of 1 g/l.

4

Synthesis of Mn-Co-Ni Composite Electrode by Anodic and Cathodic Electrodeposition for Indirect Electro-oxidation of Phenol: Optimization of the Removal by Response Surface Methodology

Ahmed Yamama A., Salman Rasha H.

Ecological Engineering & Environmental Technology

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2023

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Vol. 24, iss. 8

107--119

EN

In the present work, Response Surface Methodology (RSM) was utilized to optimize process variables and find the best circumstances for indirect electrochemical oxidation of mimicked wastewater to remove phenol contaminants using prepared ternary composite electrode. The electrodeposition process is used for the synthesis of a ternary composite electrode of Mn, Co, and Ni oxides. The selected concentrations of metal salts of these elements were 0.05, 0.1, and 1.5 M, with constant molar ratio, current density, and electrolysis time of 1:1:1, 25 mA/cm2, and 2 h. Interestedly, the gathered Mn-Co-Ni oxides were deposited at both the anode and cathode. X-ray diffraction (XRD) and scanning electron microscopy (SEM) facilitated the qualitative characterization of surface structure and morphology of the accumulated oxides. The energy dispersive X-ray (EDX) provided a semi-quantitative analysis of deposit composition. The atomic force microscopy (AFM) apparatus quantified the roughness. We examined the efficiency of composite electrodes in coinciding with the removal of Chemical Oxygen Demand (COD) under current densities of 40, 60, and 80 mA/cm2, pH values of 3, 4, and 5, and NaCl concentrations of 1, 1.5, 2 g/l. RSM covered the optimization of process parameters in conjunction with Central Composite Design (CCD). The COD represented the response function in the optimization procedure. The optimal current density, NaCl concentration, and pH magnitude were 80 mA/cm2, 1.717 g/l, and 3, respectively. The efficiency of COD elimination of 99.925% attained after 1 hour of indirect electrochemical oxidation with an energy consumption of 152.380 kWh per kilogram of COD. The COD elimination model is significant based on the correlation coefficient (R2) and F-values, and the experimental data fitted well to a second-order polynomial model with R2 of 98.93%.

5

Substrates with different magnetic properties versus iron-nickel film electrodeposition

Białostocka Anna M., Klekotka Marcin, Klekotka Urszula, Żabiński Piotr R., Kalska-Szostko Beata

Chemistry-Didactics-Ecology-Metrology

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2023

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R. 28, NR 1-2

157--170

EN

The hereby work presents the iron-nickel alloys electroplated on the different metallic substrates (aluminium, silver, brass) using galvanostatic deposition, with and without presence of the external magnetic field (EMF). The films were obtained in the same electrochemical bath composition - mixture of iron and nickel sulphates (without presence of additives) in the molar ratio of 2 : 1 (Ni : Fe), the electric current density (50.0 mA/cm2), and the time (3600 s). The mutual alignment of the electric (E) and magnetic field (B) was changeable - parallel and perpendicular. The source of EMF was a set of two permanent magnets (magnetic field strength ranged from 80 mT to 400 mT). It was analysed the surface microstructure, composition, morphology, thickness and the mechanical properties (roughness, work of adhesion). The surface morphology and the thickness of films were observed by Scanning Electron Microscopy (SEM) and Confocal Laser Scanning Microscopy (CLSM). The elemental composition of all FeNi films was measured using Wavelength Dispersive X-Ray Fluorescence (WDXRF). The crystalographic analysis of the deposits was carried out by X-Ray Diffraction. Depending on the used substrate, modified external magnetic field orientation influenced the tribological and physio-chemical properties of the deposited layers. The diamagnetic substrates and EMF application reduced the FeNi thickness and the average crystallites size, in contrast to the paramagnetic substrate. Parallel EMF increased the value of the tribological parameters for CuZn and Ag but decreased for Al. The content of FeNi structure was rising in the case of diamagnetic substrate and the dependence was opposite on the paramagnetic substrate.

6

Tribological properties of the FeNi alloys electrodeposited with and without external magnetic field assistance

Białostocka Anna Maria, Klekotka Marcin, Klekotka Urszula, Kalska-Szostko Beata

Eksploatacja i Niezawodność

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2022

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Vol. 24, no. 4

687--694

EN

The hereby work presents the tribological properties of the iron-nickel alloys and their dependence on the microstructure and thickness of the probes as well as the presence of an external magnetic field during the synthesis. Coatings were electroplated on the brass and copper metallic substrates using galvanostatic deposition in the same electrochemical bath condition (Fe and Ni sulfates) and the electric current density. The surface morphology of the films was observed by Scanning Electron Microscopy. The average composition of all FeNi coatings was measured using Energy Dispersive X-ray Spectroscopy. Tribo-mechanical properties such as microhardness, roughness, and friction coefficient were determined in the obtained structures. The morphology and tribologial properties of the FeNi coatings clearly depend on both the substrate (Cu, CuZn) itself and the presence of an external magnetic field (EMF) applied during the deposition process.

7

Characterization of nanoporous nickel-based films on electrode materials for hydrogen evolution, fabricated by dealloying technique

Bakr A., El-Aziz Ahmed M., Abdel-Karim R.

Ochrona przed Korozją

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2021

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nr 5

134--139

EN

Nanoporous nickel-based films, with a thickness of several μm have been fabricated on Ni substrate by electrodeposition of zinc, heat treatment of modified Zn-rich layer and by selective leaching of the active zinc metal from the electrode material substrate. The fabrication process involved three steps: (i) cathodic deposition of zinc on Ni substrate, (ii) heat treatment process of the surface layer and (iii) dealloying of zinc in alkaline solution on the electrochemical route. SEM and EDS analyses were carried out after each step of the fabrication process. The dealloyed film displays a porous structure with an average pore size of the order of 0.94μm. The electrocatalytic activity of the fabricated surface towards hydrogen evolution reaction (HER) was evaluated by cathodic polarization measurements and the results have been compared to these of pure nickel and commercial porous nickel foam surface. It has been concluded that the nanoporous nickel films fabricated by electrochemical dealloying revealed considerably higher electrocatalytic activity for HER process.

PL

Nanoporowate, warstwy na baize niklu, o grubościach kilku μm wytwarzano na podłożach niklowych poprzez elektroosadzanie cynku, obróbkę cieplną zmodyfikowanych warstw wzbogaconych cynkiem i przez selektywne ługowanie cynku z wytworzonych warstw powierzchniowych. Proces wytwarzania składał się z trzech etapów: (i) katodowego osadzania cynku na podlożu niklowym, (ii) obróbki cieplnej warstwy powierzchniowej i (iii) selektywnego wytrawiania cynku w roztworze alkalicznym na drodze elektrochemicznej. Po każdym etapie procesu wytwarzania przeprowadzano analize SEM i EDS zmodyfikowanej powierzchni. Wyługowane warstwy wykazują porowatą structure z średnimi rozmiarami porów na poziomie 0.94μm. Elektroaktywność katalityczną zmodyfikowanej powierzchni w odniesieniu do reakcji wydzielania wodoru oceniano w pomiarach katodowej polaryzacji a wyniki porównano dla podłoży czystego niklu i komercyjnego, porowatego niklu gąbczastego. Stwierdzono, że nanoporowate warstwy niklowe wytwarzane poprzez selektywne ługowanie wykazywały znacząco wyższą elektroaktywność katalityczną w odniesieniu do reakcji wydzielania wodoru.

8

Optoelectronics applications of electrodeposited p- and n-type Al2Se3 thin films

Faremi A. A., Oluyamo S. S., Olubosede O., Olusola I. O., Adekoya M. A., Akindadelo A. T.

Materials Science Poland

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2021

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Vol. 39, No. 2

166--171

EN

In this paper, energy band gaps and electrical conductivity based on aluminum selenide (Al2Se3) thin films are synthesized electrochemically using cathodic deposition technique, with graphite and carbon as cathode and anode, respectively. Synthesis is done at 353 K from an aqueous solution of analytical grade selenium dioxide (SeO2), and aluminum chloride (AlCl2·7H2O). Junctions-based Al2Se3thin films from a controlled medium of pH 2.0 are deposited on fluorine-doped tin oxide (FTO) substrate using potential voltages varying from 1,000 mV to 1,400 mV and 3 minutes −15 minutes respectively. The films were characterized for optical properties and electrical conductivity using UV-vis and photoelectrochemical cells (PEC) spectroscopy. The PEC reveals a transition in the conduction of the films from p-type to n-type as the potential voltage varies. The energy band gap reduces from 3.2 eV to 2.9 eV with an increase in voltage and 3.3 eV to 2.7 eV with increase in time. These variations indicate successful fabrication of junction-based Al2Se3 thin films with noticeable transition in the conductivity type and energy band gap of the materials. Consequently, the fabricated Al2Se3can find useful applications in optoelectronic devices.

9

Zn-Cr alloy coatings: electrodeposition and properties

Osuchowska Ewa, Buczko Zofia, Olkowicz Klaudia

Journal of KONBiN

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2021

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Vol. 51, iss. 1

29--42

EN

The electrodeposition process of Zn-Cr alloy coatings under the conditions of direct and pulsed current is discussed. The Cr content in the obtained alloy coatings, the current efficiency of the process, surface morphology, structure and wettability as a function of deposition parameters, such as current density, were determined. The Zn-Cr alloy coatings of good quality contained up to 20 wt.% Cr (for direct current) and up to 9 wt.% Cr (for pulse current). All the obtained coatings had a structure typical of zinc coatings (h.c.p.) and had a hydrophobic character. The morphology of the coatings changed significantly under the influence of changes in deposition conditions.

PL

W niniejszej pracy omówiono proces elektroosadzania powłok stopowych Zn-Cr w warunkach prądu stałego i pulsacyjnego. Określono zawartość Cr w otrzymanych powłokach stopowych, wydajność prądową procesu, morfologię powierzchni, strukturę i zwilżalność w funkcji parametrów osadzania, takich jak gęstość prądu. Powłoki stopowe Zn-Cr o dobrej jakości zawierały do 20% wag. Cr (dla prądu stałego) i do 9% wag. Cr (dla prądu pulsacyjnego), Wszystkie otrzymane powłoki miały strukturę typową dla powłok cynkowych (h.c.p.) oraz wykazywały charakter hydrofobowy. Morfologia tych powłok ulegała istotnej zmianie pod wpływem zmian warunków osadzania.

10

Study on Synthesis and Modification of Conical Ni Structures by One-Step Method

Skibińska K., Semeniuk S., Kutyła D., Kołczyk-Siedlecka K., Jędraczka A., Żabiński P.

Archives of Metallurgy and Materials

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2021

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Vol. 66, iss. 3

861--869

EN

In this work the conical Ni structures were obtained from an electrolyte containing NH4Cl as a crystal modifier. This process is called one-step method and allows to cover large areas with micro- and nanostructures during a single electrodeposition. Presence of NH4Cl promotes a vertical direction of structure growth in order to block a horizontal one. Additionally, this method does not require using chromic acid solution, which is dangerous for the environment. Due to the ferromagnetic properties of Ni, obtained coatings could be applied as magnetic devices. The influence of the parameters such as a preparation of copper substrate, a composition of electrolyte and electrodeposition conditions (time, the electrolyte temperature and current density) was investigated in this work.

11

Otrzymywanie powłoki galwanicznej Zn-Ni przy zredukowanej liczbie etapów przygotowania powierzchni. Część I: próby z wykorzystaniem kąpieli laboratoryjnych

Niedbała Jolanta, Wesołowski Jan

Rudy i Metale Nieżelazne Recykling

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2020

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R. 65, nr 9-10

3--11

PL

W pracy przedstawiono wyniki badania możliwości otrzymywania galwanicznej powłoki stopowej Zn-Ni przy zredukowanej liczbie etapów. Zaproponowany ekonomiczny proces pozwoli na zmniejszenie zużycia odczynników i mediów, opóźni korozję elementów linii oraz skróci czas procesu. Przy zredukowanej liczbie etapów i przy zastosowaniu gęstości prądowej równej i wyższej od stosowanej obecnie w galwanizerniach, przeprowadzono próby otrzymywania powłoki Zn-Ni z kąpieli laboratoryjnych i przemysłowych. W części I przedstawiono charakterystykę powłok otrzymanych w skróconym procesie z wykorzystaniem kąpieli laboratoryjnych. Dokonano oceny możliwości wykorzystania zaproponowanych zmian w praktyce charakteryzując właściwości powłok otrzymanych w skróconym procesie.

EN

The paper presents the results of testing the possibility of obtaining a galvanic Zn-Ni alloy coating with a reduced number of stages. The proposed economic process will reduce the consumption of reagents and media, delay the corrosion of line elements and reduce the process time. With a reduced number of stages and using current density equal to and higher than currently used in electroplating plants, tests were carried out to obtain a Zn-Ni coating from laboratory and industrial baths. Part I presents the characteristics of coatings obtained in a shortened process using laboratory baths. The possibility of using the proposed changes in practice was assessed, characterizing the properties of the coatings obtained in the short process.

12

Wytwarzanie i mikrostruktura osadzanych elektrolitycznie stopów Ni-Co i kompozytów TiO2 / Ni-Co

Ledwig Piotr, Dubiel Beata, Kopia Agnieszka

Hutnik, Wiadomości Hutnicze

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2020

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Vol. 87, nr 4

107--113

PL

Stopy Ni-Co oraz kompozyty TiO2/Ni-Co osadzono elektrolitycznie z kąpieli siarczanowo-cytrynianowych o względnej zawartości jonów Co:Ni równej 1:49, 1:24 i 1:9 stosując gęstości prądu 2,5, 5 i 7,5 A/dm2. Wpływ parametrów osadzania na morfologię powierzchni, mikrostrukturę, skład chemiczny i skład fazowy zbadano za pomocą skaningowej i transmisyjnej mikroskopii elektronowej, spektroskopii dyspersji energii charakterystycznego promieniowania rentgenowskiego oraz dyfrakcji promieniowania rentgenowskiego. Wytworzone kompozyty charakteryzowały się globularną morfologią i nanokrystaliczną mikrostrukturą. Wykazano, że w osnowie kompozytów występują pojedyncze nanocząstki oraz aglomeraty TiO2. Zawartość TiO2 w kompozytach wynosiła około 4% mas. Stwierdzono, że wielkość ziarna kompozytów TiO2/Ni-Co zależy od obecności fazy umacniającej, warunków prądowych podczas osadzania oraz stężenia Co w osnowie Ni-Co.

EN

TiO2/Ni-Co composites were electrodeposited from citrate-sulfate bath with varying Ni:Co ratios. Effect of deposition conditions on chemical composition, surface morphology, microstructure and phase composition were investigated using scanning and transmission electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction. Manufactured composites were characterized by typical cauliflower surface morphology and nanocrystalline structure. Nanocrystalline TiO2 particles were embedded in the Ni-Co matrix both in the form of dispersive nanoparticles and clusters. The concentration of nc-TiO2 in composites was about 4 wt. %. Grain size of TiO2/Ni-Co composites depended on the content of strengthening phase, deposition current conditions and Co concentration in the Ni-Co matrix.

13

MHD Supported Electroreduction of Formate Nickel Complexes with Simultaneous Incorporation of TiO2 Particles

Mech K.

Archives of Metallurgy and Materials

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2020

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Vol. 65, iss. 1

219--227

EN

The present work concerns analysis of the possibilities of synthesis of Ni-TiO2 composite coatings from electrolytes containing formate nickel complexes. A magnetic field was applied as an additional factor enabling modification of properties of the synthesized coatings through its influence on electrode processes. The presented data describes the effect of electrode potential, TiO2 concentration in the electrolyte as well as the value of the magnetic field induction vector on the deposition rate, composition, current efficiency, structure, surface states and morphology of synthesized coatings. The studies were preceded by thermodynamic analysis of the electrolyte. The obtained results indicated possibilities of synthesis of composites containing up to 0.97wt.% of TiO2. Depending on applied electrolysis conditions current efficiency amounted to from 61.2 to 75.1%.

14

Innowacyjne hydrofobowe cynkowe powłoki galwaniczne jako proekologiczna ochrona antykorozyjna

Chat Karolina, Rudnik Ewa

Rudy i Metale Nieżelazne Recykling

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2019

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R. 64, nr 2

21--24

PL

Metale i ich stopy są podstawowymi materiałami inżynierskimi. Stosowane są one powszechnie jako konstrukcje, elementy różnorodnych urządzeń czy pokrycia dachowe. Jednak samorzutne, zazwyczaj stopniowe, niszczenie metali w wyniku elektrochemicznego lub chemicznego oddziaływania z otaczającym środowiskiem prowadzi do pogorszenia wyglądu zewnętrznego wyrobów i osłabienia konstrukcji metalowych, a w konsekwencji do awarii i katastrof. Szacuje się, że roczne straty korozyjne na świecie w przeliczeniu na jednego mieszkańca to 1000–1500 USD, co stanowi nawet 6–8% PKB, uwzględniając bezpośrednie i pośrednie skutki korozji. Procesy korozyjne stanowią bardzo poważny problem gospodarczy, w związku z tym istotne jest prawidłowe zabezpieczenie metali, np. poprzez nanoszenie metalowych powłok ochronnych. Metalem najczęściej stosowanym na powłoki jest cynk. Cynkowanie elektrolityczne umożliwia otrzymanie równomiernych warstw ochronnych o żądanej grubości i estetycznym wyglądzie zewnętrznym. Najnowsze badania wskazują, że poprzez nadanie odpowiedniej morfologii powierzchni w mikro- i nanoskali możliwe jest otrzymanie warstw cynkowych o właściwościach superhydrofobowych. Dzięki temu woda bardzo łatwo spływa z powierzchni materiału, a poprzez zmniejszenie kontaktu powłoka-elektrolit powstawanie ognisk korozyjnych jest ograniczone. W pracy przedstawiono elektrochemiczną metodę otrzymywania powłok cynkowych o właściwościach hydrofobowych. Poprzez odpowiedni dobór składu elektrolitu oraz warunków osadzania, uzyskano warstwy o różnorodnej morfologii powierzchni, co przekłada się na podwyższoną odporność korozyjną powłok.

EN

Metals and their alloys are fundamental engineering materials. They are commonly used as constructions, elements of various devices or roof coverings. However, spontaneous, usually gradual, destruction of metals due to electrochemical or chemical reactions with the surrounding environment leads to a deterioration of the appearance of products and weakening of the metal structures, thus to failures and catastrophes. It is estimated that the global annual corrosion losses reach 1000–1500 USD per habitant, what corresponds even to 6–8% of GDP, taking into account the direct and indirect effects of corrosion. Corrosion processes are very serious economic problems, therefore it is important to properly protect the metals, by application of metallic protective coatings as example. One of the most commonly used is zinc coating. Electrodeposition enables obtaining uniform protective layers of the desired thickness and aesthetic appearance. Recent studies indicate that special surface morphology in the micro- and nanoscale gives zinc layers with superhydrophobic properties. It results in very easy water flow from the surface of the material, and by reducing the contact between coating and electrolyte the formation of corrosive cells is limited. The paper presents the electrochemical method of obtaining zinc coatings with hydrophobic properties. Through appropriate selection of the electrolyte composition and deposition conditions, layers with various surface morphologies and thus with improved corrosion resistance of the coatings.

15

Comparative studies of the electroreduction of zinc ions from gluconate solutions

Rudnik Ewa, Chat Karolina

Metallurgy and Foundry Engineering

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2019

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Vol. 45, no. 1

19--31

EN

This study considers the role of chloride and sulphate anions in the cathodic reduction of zinc ions from gluconate solutions (chloride, sulphate, chloride-sulphate). Cyclic potentiodynamic and potentiostatic polarization measurements, as well as chronoamperometric experiments, were performed. Electrochemical results were correlated with the speciation of the baths. The experiments revealed the inhibiting effect of sulphate ions on the cathodic process caused by the formation of stable neutral ZnSO4 complex in the sulphate-gluconate bath. It resulted in zinc deposition under a limiting current, with the release of metal cation as a rate-determining step. The less stable ZnGlu+ complex dominated both chloride-containing baths, thus the metal deposition ran under activation control. Independent of the solution composition, the nucleation of zinc occurred according to the instantaneous model.

PL

W artykule przedstawiono rolę anionów chlorkowych i siarczanowych w katodowej redukcji jonów cynku z roztworów glukonianowych (chlorkowy, siarczanowy, chlorkowo-siarczanowy). Przeprowadzono pomiary cyklicznej polaryzacji potencjodynamicznej i potencjostatycznej oraz eksperymenty chronoamperometryczne. Wyniki elektrochemiczne skorelowano ze składem jonowym roztworów. Eksperymenty wykazały hamujący wpływ jonów siarczanowych na proces katodowy w kąpieli siarczanowo-glukonianowej spowodowany tworzeniem się stabilnego obojętnego kompleksu ZnSO4. W rezultacie, w elektrolicie siarczanowym osadzanie cynku zachodziło w warunkach prądu granicznego, a etapem powolnym było uwalnianie jonu metalu z kompleksu. W obecności jonów chlorkowych dominujący kompleks stanowił mniej trwały ZnGlu+, a redukcja jonów cynku zachodziła w warunkach kontroli aktywacyjnej. Niezależnie od składu roztworu stwierdzono natychmiastowe zarodkowanie cynku.

16

Synthesis and characterization of high-efficiency low-cost solar cell thin film

Immanuel W. Christopher, Deborrah S. Paul Mary, Inbanathan S. S. R., Sree D. Nithyaa

Materials Science Poland

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2019

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Vol. 37, No. 1

127--135

EN

Polycrystalline chalcogenide semiconductors play a vital role in solar cell applications due to their outstanding electrical and optical properties. Among the chalcogenide semi-conductors, CdZnS is one kind of such important material for applications in various modern solid state devices such as solar cells, light emitting diode, detector etc. Due to their applications in numerous electro-optic devices, group II-VI semiconductors have been studied extensively. In recent years, major attention has been given to the study of electrical and optical properties of CdZnS thin films. In this work, Cd1−xZnxS thin films were prepared by chemical bath deposition technique. Phase purity and surface morphology properties were analyzed using field emission scanning electron microscope (FE-SEM) and X-ray diffraction (XRD) studies. Chemical composition was studied using energy dispersive spectrophotometry (EDS). Optical band gap property was investigated using UV-Spectroscopy. Electrical conductivity studies were performed by two probe method and thermoelectric power setup (TEP) to determine the type of the material. This work reports the effect of Zn on structural, electrical, microstructural and optical properties of these films.

17

Investigation of the structural, optical and photoluminescence properties of electrosynthesized hexagonal nanocrystalline Cd0.3Zn0.7S thin film

Dhaygude H. D., Fulari V. J.

Materials Science Poland

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2019

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Vol. 37, No. 3

300--303

EN

In this paper, Cd0.3Zn0.7S thin film has been electrodeposited from aqueous bath containing CdSO4, ZnSO4, Na2S2O3 and EDTA, having pH ~ 14. The structural, optical, morphological, surface wettability and photoluminescence properties of the film were investigated. The XRD pattern showed that the film consisted of mixed phases of CdS and ZnS with polycrystalline structure. The bandgap of the film was evaluated as 2.69 eV. The AFM study revealed that the Cd0.3Zn0.7S thin film contained spherical grains with root mean square roughness of 6.09 nm. The water contact angle measurement showed that the thin film was hydrophilic in nature. Moreover, the PL study revealed that the excitation wavelength was 460 nm.

18

Structure and Properties of Zn/MoS2 Composite Coatings Produced by Electrochemical Reduction

Szmigielska K., Trzaska M.

Archives of Metallurgy and Materials

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2019

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Vol. 64, iss. 4

1653--1659

EN

The report presents research efforts on the synthesis of Zn/MoS2 composite coatings by electrochemical reduction from a sulphate-borate bath containing MoS2 powder as a dispersion phase at various concentrations. The structure of the Zn/MoS2 composite coatings was characterised and the effect of MoS2 particles embedded on their microhardness was evaluated. The coatings produced are characterized by a compact, homogeneous structure and a good connection to a steel substrate. The incorporation of MoS2 particles into the zinc matrix has an influence on the structure and morphology of the Zn/MoS2 composite coatings. It was found that the presence of MoS2 particles increases surface roughness along with coating hardness. The incorporation of the MoS2 particles into the zinc matrix slightly improves the corrosion resistance compared to Zn coatings, making the corrosion potential shift towards more electropositive values.

19

Structure and Properties of Nanocomposite Nickel/Graphene Oxide Coatings Produced by Electrochemical Reduction Method

Cieślak G., Trzaska M.

Archives of Metallurgy and Materials

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2019

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Vol. 64, iss. 4

1479--1486

EN

The paper presents the results of research on nanocomposite nickel/graphene oxide (Ni/GO) coatings produced by electrochemical reduction method on a steel substrate. Discussed is the method of manufacturing composite coatings with nickel matrix and embedded graphene oxide flakes. For comparative purposes, the studies also included a nanocrystalline Ni coating without embedded graphene oxide flakes. Graphene oxide was characterized by Raman spectroscopy, infrared spectroscopy (FTIR) and transmission (TEM) and scanning (SEM) electron microscopy. Results of studies on the structure of nickel and composite Ni/GO coatings deposited in a bath containing different amount of graphene oxide are presented. The coatings were characterized by scanning electron microscopy, light microscopy, Raman spectroscopy and X-ray diffraction. The adhesion of the prepared coatings to the substrate was examined by the scratch method. The microhardness of the coatings was measured using the Vickers method on perpendicular cross-sections to the surface. Corrosion tests of the coatings were investigated using the potentiodynamic method. The influence of graphene oxide on the structure and properties of composite coatings deposited from baths with different content of graphene oxide was determined.

20

Electrorefining of Indium Metal From Impure In-Sn Alloy in Fluoride Molten Salt

Lee Hyun-Gyu, Choi Sang-Hoon, Sim Jae-Jin, Lim Jae-Hong, Hyun Soong-Keun, Lee Jong-Hyeon, Park Kyoung-Tae

Archives of Metallurgy and Materials

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2019

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Vol. 64, iss. 3

899--905

EN

In this study, molten salt electrorefining was used to recover indium metal from In-Sn crude metal sourced from indium tin oxide (ITO) scrap. The electrolyte used was a mixture of eutectic LiF-KF salt and InF3 initiator, melted and operated at 700°C. Voltammetric analysis was performed to optimize InF3 content in the electrolyte, and cyclic voltammetry (CV) was used to de-termine the redox potentials of In metal and the electrolyte. The optimum initiator concentration was 7 wt% of InF3 , at which the diffusion coefficients were saturated. The reduction potential was controlled by applying constant current densities of 5, 10, and 15 mA/cm2 using chronopotentiometry (CP) techniques. In metal from the In-Sn crude melt was deposited on the cathode surface and was collected in an alumina crucible.