The Influence of Weak Ionic Interactions on Electrode Reactions during Electrodeposition of Re-Ni Alloys

Berkh, O.; Khatchatouriants, Artium; Eliaz, Noam; Gileadi, E.

doi:10.1149/2.0071412jes

Cited by 9 publications

(17 citation statements)

References 41 publications

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“…The electrodeposition process.-In this section we consider the mechanism of the process suggested before 13,14 and its agreement with the results of the present investigation. As pointed out before, [6][7][8] catalysis by freshly deposited Ni can explain the induced codeposition of Re and regularities of the process at long deposition times, i.e.…”

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confidence: 64%

“…Explanation of these phenomena is possible in terms of a catalytic electrode surface that enhances reduction of both Re and Ni and is changed with deposition time. 13,14 Taking into account the deformation of the ReO − 4 anion in the presence of a Ni-Citrate complex in the electrolyte, as shown by Raman spectroscopy, we proposed the existence of a precursor that consists of both the deformed ReO Process (1) is facilitated by the mutual deformation of ReO − 4 and Ni-Cit in precursor. Processes (2) and (3) are catalyzed by the products of process (1).…”

mentioning

confidence: 98%

“…We have supported this hypothesized mechanism by different experiments. 7,[13][14][15] The initial stages of Re-Ni deposition, which are critical for understanding the catalytic mechanism, were studied in our recent work. …”

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confidence: 99%

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Characterization of Re-Ni Films after the Initial Stages of Electrodeposition

Berkh

Burstein

Gladkikh

et al. 2016

J. Electrochem. Soc.

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Re-Ni layers produced in the early stages of electrodeposition from citrate electrolytes were studied by high-resolution X-ray photoelectron spectroscopy (HR-XPS) and time-of-flight secondary-ion mass spectrometry (TOF-SIMS). The deposition time was varied in the range of 2 to 300 seconds. The compositional heterogeneity of the thin Re-Ni alloys and the variations of their composition with deposition time, both in the bulk and on the surface, were shown. The results obtained are indicative of the occurrence of chemical reactions at short deposition times and are in agreement with our previous results obtained in studying the early stages of Re-Ni deposition by electrochemical techniques. The mechanism of the deposition process is discussed. Induced electrodeposition of refractory metals with iron-group metals has drawn the attention of many researchers in view of their high corrosion resistance, stability at high temperatures and wear resistance.1 Induced codeposition of rhenium from aqueous solutions has been studied, 2-5 including Re-Ni alloys from citrate-containing solutions. [6][7][8][9] Induced codeposition of Re from an electrolyte containing ReO − 4 can occur readily. Coatings with a thickness of up to 25 μm were obtained within 60 min deposition at a faradaic efficiency of up to 95%. Moreover, the concentration of Re in the resulting alloy can reach up to 90 at.%. This excludes the possibility of having a precursor similar to that found in the case of W, 1,10-12 since it would require the formation of a complex containing nine molecules of the perrhenate ion, which is totally unlikely. Instead, we have suggested a new mechanism, according to which the Ni 2+ ion is first reduced and deposited on the surface of the substrate. The resulting neutral Ni atoms act as strong reducing agents, helping to reduce the 7-valent ReO − 4 probably to the 5-valent ReO − 3 . This is a typical catalytic process, in which the Ni 2+ ion acts as a catalyst, the concentration of which should not change in the overall reaction. Theoretically, this should lead to a deposit of pure Re, but some Ni is found in the resulting alloy due to entrapment of neutral Ni atoms. This represents a rather unique type of process, where the catalyst is formed in situ as part of the redox process.6-9 The deposition of Re-Ni apparently depends on the high catalytic activity of the freshly deposited nickel. We have supported this hypothesized mechanism by different experiments. 7,[13][14][15] The initial stages of Re-Ni deposition, which are critical for understanding the catalytic mechanism, were studied in our recent work. 13There, the electrodeposition of Re-Ni alloys was investigated at deposition times of 0.05-60 s, unlike in earlier publications, 6-8 where the deposition times were on the scale of minutes and hours. The anomalous faradaic efficiency (AFE) of the deposition process, the composition of the deposits and their morphology were considered. The AFE and the Re-content in the deposits were shown to decrease with deposition time. Anom...

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mentioning

confidence: 98%

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Characterization of Re-Ni Films after the Initial Stages of Electrodeposition

Berkh

Burstein

Gladkikh

et al. 2016

J. Electrochem. Soc.

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“…1,2 These advantages make Re and its alloys attractive to a broad range of industries, including aerospace, nuclear, electrical, chemical, biomedical, and others. [3][4][5] The currently manufacturing processes for Re and its alloy are powder-metallurgy (PM), 6 chemical vapour deposition (CVD), 7 electron beam-physical vapor deposition (EB-PVD), 8 electroplating, 9,10 and electroless plating. 11,12 For PM, CVD and EB-PVD processes, the metal coatings were produced by the expensive devices at vacuum condition.…”

Section: Introductionmentioning

confidence: 99%

Electrodeposition and Thermal Stability of Re<sub>60</sub>Ni<sub>40</sub> Amorphous Alloy

2016

Electrochemistry

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Re 60 Ni 40 alloy was electrodeposited galvanostatically from aqueous solution containing 34 mM ammonium perrhenate, 124 mM nickel sulfamate tetrahydrate and 343 mM citric acid in a three-electrode cell system at bath temperature of 70°C. The deposition mechanisms of the alloy were discussed by cyclic voltammetry and cathodic potentiodynamic tests. Microstructure and morphology of surface and fracture surface of the alloy were examined by ESEM. The phase and chemical composition were tested by XRD and EDS, respectively. The thermal stability of the alloy was estimated by DSC. The results show that electrodeposition of Re-Ni alloy is an anomalous deposition. Many cracks were present on the surface and fracture surface of the alloy. The fracture surface of the alloy exhibited both a fibrous structure and a laminar structure. The chemical composition distribution in the alloy was uniform. The alloy adhered well to the substrate with no evidence of delamination. Re 60 Ni 40 alloy was composed of an amorphous structure, and the deposition rate was about 16.5 µm h −1. The average roughness R a and R q of the alloy surface were 123 + 13 and 158 + 17 nm, respectively. After DSC test, the amorphous Re 60 Ni 40 alloy exhibited a good thermal stability from 25°C to 550°C.

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“…Formation of Re-alloy coatings has been reported mostly for chemical vapor deposition (CVD) and electroplating [6][7][8][9][10][11][12][13][14][15][16][17]. The electroless deposition process may be attractive for many applications due to the uniform formation of thin layers on both conductive and non-conductive surfaces, simplicity and low processing temperature.…”

Section: Introductionmentioning

confidence: 99%