Studies of the thermal decomposition of copper hydride

Burtovyy, Ruslan; Utzig, E.; Tkacz, M.

doi:10.1016/s0040-6031(00)00594-3

Cited by 35 publications

(22 citation statements)

References 9 publications

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“…The E c vs. t curve of hydrogenated copper shows no potential delay corresponding to dissolution of any second component (not copper). This means that either no hydride is formed at copper hydrogenation or the hydride is unstable, which agrees with the literature data [11].…”

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confidence: 92%

Corrosion of Hydrides of Nickel and Cu30Ni Alloy in Oxygen Containing Solutions

2005

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yan, Sirota, Pchel'nikov. As was shown earlier [1], nickel hydride quickly decomposes at its open-circuit potential E c in an oxygen-saturated sulfuric-acid solution (1 N H 2 SO 4 ), which is accompanied by hydrogen evolution. As a result, attempts to determine the corrosion rate of nickel hydride by using the oxygen compensation (OC) method has failed.In this work, we study the corrosion behavior of the nickel and Cu30Ni alloy hydrides in oxygen-saturated alkaline, neutral, and weakly acidic solutions.Corrosion tests were carried out in oxygen atmosphere by the OC method [2, 3] in a modernized cell with thermal control [4] and additionally by spectrophotometry (SF) [5].We used samples of 1-3 cm 2 surface areas and the following solutions: 1 N NaOH; 0.01 N NaOH + 0.16 N Na 2 SO 4 ; 0.16 N Na 2 SO 4 (pH 7); 10 -3 N H 2 SO 4 + 0.16 N Na 2 SO 4 at 20 ° C.The essence of OC method lies in compensation of oxygen consumed in corrosion by oxygen obtained in electrolyzer. The corrosion rate is estimated from the charge ∆ Q consumed in the electrolyzer for a time ∆ twhere S is the surface area of the sample, m 2 .Hydrides of nickel and alloy were synthesized by hydrogenation (HG) of samples during cathodic polarization in 1 N H 2 SO 4 solution containing 0.2 g/l thiourea ( i HG = 170 A/m 2 , t HG = 0.5-2 h) in a separate cell, i.e., under the conditions of hydride formation, according to [6]. Then, the samples were quickly (10-30 s) washed in twice distilled water, transferred to the working chamber of the OC cell, in which time variations of i c ∆Q/∆tS Ä/m 2 ( ), = E c and the charge Q consumed in the corrosion process were measured.Being placed in the OC cell, nickel hydride immediately begins to uptake oxygen (Fig. 1). Therewith, upon longer nickel hydrogenation, and, correspondingly, for thicker hydride layers, one needs greater charges in order to replenish oxygen consumed in hydride corrosion (curves 1 and 2 ). The corrosion rate i c calculated from the slope of Q vs. t curves (Fig. 2a, curves 1 and 2 ) decreases in time and reaches the value observed for corrosion of original nickel ( i c < 0.1 A/m 2 ). In the process, at first, E c decreases insignificantly, passes a flat Abstract -Corrosion behavior of nickel hydride is studied in alkaline, neutral, and weakly acidic oxygen-containing solutions by compensating oxygen consumed in corrosion and spectrophotometric analysis of solution for nickel. It is shown that in the course of nickel hydride corrosion in alkaline solutions, oxygen is consumed solely in its interaction with hydrogen formed at hydride decomposition, while nickel remains at the surface. It is concluded that, in a pH range from 7 to 14, hydrogen oxidation is limited by its solid-phase diffusion, whereas the rate of nickel hydride decomposition is pH-independent. The difference in the corrosion behavior of the original alloy and its hydride is attributed to the fact that the original alloy evolves copper ions, whereas the hydride evolves hydrogen. 9 8 7 6 5 4 3 2 1 0 50 100 150 200 t , min Q , C 1 2...

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confidence: 92%

Corrosion of Hydrides of Nickel and Cu30Ni Alloy in Oxygen Containing Solutions

2005

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“…Even one-hour hydrogenation by a current of 5 A/dm 2 in 1 N H 2 SO 4 solution doped with 0.2 g/l of thiourea results in the appearance of neither cathodic nor anodic limiting currents observed on nickel hydride [3,4]. This agrees with conclusions that copper during its cathodic polarization either forms no hydride [8,9] or the latter is very unstable [10]. Consequently, quasi-steady-state voltammograms do not fit in with detecting small quantities of hydrogen absorbed by copper.…”

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confidence: 75%

The anodic behavior of hydrogenated copper in sodium hydroxide solutions

Sirota

Pchel'nikov

2005

Prot Met

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Alloys of the copper-nickel system are widely used in various industry branches, in particular in marine shipbuilding including desalting plants with their corrosive sea-water steam, not so rarely containing hydrogen sulfide. Under some operation conditions hydrogen can evolve at the alloy surface. Penetrating into the alloy, it may affect its corrosion-electrochemical and mechanical properties. In NaOH solutions, we have already investigated the anodic behavior of two characteristic objects of the Ni-H system, namely, α -phase (Ni-0.03 at. % H) [1, 2] and β -phase (hydride N 2 H) [3,4].In the present work, we use the same solution (1 N NaOH) to investigate the electrochemical behavior of cathodically hydrogenated copper.Similarly to the previous works, the potential range chosen should make the absorbed hydrogen selectively dissolve anodically, leaving copper immune. According to literature data, copper begins to dissolve at a potential of -0.2 V (SHE) [5,6]. Hence, one may suppose that in a still lower potential range, only the electrochemical dehydrogenation of copper can be observed.The experiments were carried out in 1 N NaOH (Sodu Wodorotlenek cz grade (Poland)) solution in bidistilled water in an atmosphere of high-purity N 2 at a temperature of 20 ° C. Prior to starting the experiment, a copper sample was ground by abrasive paper, finishing with the paper No. 0. The sample was then washed with bidistilled water, dried with filtering paper, and placed into a cell with a preliminarily deaerated electrolyte. The potential was measured relative to a reference silver-chloride electrode and recalculated to the standard hydrogen electrode. The electrochemical measurements were carried out with the use of a PI-50-1 potentiostat, a PR-8 programmer, a PDA-1 recorder, and a IPT 1 coulometer.The hydrogenation was carried out galvanostatically ( i c = 5 × 10 2 A/m 2 , t c = 1 h). On stopping it, without changing the solution, the sample underwent voltammetry, deenergized chronopotentiometry, and some special transient electrochemical measurements. Figure 1 shows cathodic (1) and anodic (2) voltammetric curves of copper consecutively plotted by stepwise (0.02 V on each step) changing the polarization. The discharge of water hydrogen occurs at a noticeable rate, starting from -0.8 V with a Tafel's slope of 0.15 to 0.17 V. Copper starts to ionize at E = -0.3 V. The anodic curve exhibits two distinctly pronounced current peaks.Abstract -The anodic behavior of cathodically hydrogenated copper in 1 N NaOH solution is investigated with the use of its free-corrosion chronopotentiometry ( E cor ) and cyclic voltammetry (CVA). The former proves that while being cathodically hydrogenated, copper, unlike nickel, does not form hydride. An analysis of the CVAs shows that during anodic dissolution of hydrogenated copper, two forms of adsorbed hydrogen are ionized, while the ionization is limited by the diffusion in solid phase. Under the same hydrogenation conditions, copper sorbs ten times less hydrogen than nickel does. -1.0 -0.5 ...

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“…Decomposition to copper and hydrogen starts already during the synthesis and completes at room temperature within one day 1–3. To keep it for a longer time it needs to be stored at –60 °C 4,5. Thus, the synthesis of well‐crystallized samples, purification and characterization of copper hydride is a challenge.…”

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confidence: 99%

Reinvestigation of Crystal Structure and Non‐Stoichiometry in Copper Hydride, CuH_1–x (0 ≤ x ≤ 0.26)

Auer

Kohlmann

2014

Zeitschrift anorg allge chemie

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Copper hydride and deuteride were reinvestigated by X-ray and neutron powder diffraction, revealing a pronounced phase width with respect to the hydrogen (deuterium) content. Synthesis from aqueous copper(II) sulfate with hypophosphoric acid solutions yields samples with a broad distribution of compositions and variations of up to 6.5 % in unit cell volume. The result is a metrical distortion with (hkl) dependent asymmetry and broadening of powder diffraction reflections. Patterns of such samples were described using a model with five copper hydride (deuteride) phases with different lattice parameters. A method for developing and refining reasonable multiphase models despite high correlation of parameters is described. Simulta-* Prof. Dr. H. Kohlmann

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Studies of the thermal decomposition of copper hydride

Cited by 35 publications

References 9 publications

Corrosion of Hydrides of Nickel and Cu30Ni Alloy in Oxygen Containing Solutions

Corrosion of Hydrides of Nickel and Cu30Ni Alloy in Oxygen Containing Solutions

The anodic behavior of hydrogenated copper in sodium hydroxide solutions

Reinvestigation of Crystal Structure and Non‐Stoichiometry in Copper Hydride, CuH_1–x (0 ≤ x ≤ 0.26)

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Studies of the thermal decomposition of copper hydride

Cited by 35 publications

References 9 publications

Corrosion of Hydrides of Nickel and Cu30Ni Alloy in Oxygen Containing Solutions

Corrosion of Hydrides of Nickel and Cu30Ni Alloy in Oxygen Containing Solutions

The anodic behavior of hydrogenated copper in sodium hydroxide solutions

Reinvestigation of Crystal Structure and Non‐Stoichiometry in Copper Hydride, CuH1–x (0 ≤ x ≤ 0.26)

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Reinvestigation of Crystal Structure and Non‐Stoichiometry in Copper Hydride, CuH_1–x (0 ≤ x ≤ 0.26)