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SM ISO690:2012 DANILCHUK, V.. Effect of anode processes on mechanical properties and rate of Co-W and Fe-W electrodeposition nanocrystalline coatings. In: Materials Science and Condensed Matter Physics, Ed. 9, 25-28 septembrie 2018, Chișinău. Chișinău, Republica Moldova: Institutul de Fizică Aplicată, 2018, Ediția 9, p. 279. |
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Materials Science and Condensed Matter Physics Ediția 9, 2018 |
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Conferința "International Conference on Materials Science and Condensed Matter Physics" 9, Chișinău, Moldova, 25-28 septembrie 2018 | ||||||
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CZU: 539.2+544.6+66 | ||||||
Pag. 279-279 | ||||||
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The effective method of obtaining Co-W and Fe-W coatings, including nanocrystalline coatings, is their electrodeposition from citrated and gluconate solutions. In the technology of electrodeposition the choice of anodes plays a important role [1]. The presents work is devoted to the role of anodes in the electrodeposition of nanocrystalline Co-W and Fe-W coatings. The effect of insoluble (Pt, graphite) and soluble (tungsten, combined cobalt-tungsten anode, ensuring the stability of tungsten and cobalt concentrations in the electrolyte) of the anodes on the deposition rate (current efficiency) and microhardness of Co-W coatings, electrodeposited from bor-gluconate electrolyte in a wide range of long-term operation of the electrolyte (Q, A•h/l) are researched.A significant influence of anodic processes on both the deposition rate and the microhardness of coatings with a change in Q is shown. An model of anodic processes influence based on the mechanism of induced codeposition, the first stage of which is the formation of an intermediate of a "metal-precipitant" (Co, Fe), is proposed. In addition to participation in the reduction process with the formation of the alloy, the complex of the ―metal-precipitant‖ is oxidized at the anode. The influence of different parameters (the concentration of the bath components, pH, temperature,cathodic current density, volume current density, hydrodynamic conditions, insoluble and soluble anodes) on therate of electrodeposition and microhardness of the coatings has been investigated. The given research determinethe conditions ensuring high deposition rate, microhardness and bath efficiency. It was shown, that thedeposition rate, tungsten content and microhardness reach the maximum values at pH 6.5, regardless on theconcentration of bath components. Also, it was detected the macroscopic size effect of microhardness, which islinked to the fact that for a fixed cathodic current density microhardness depends on volume current density. Inaddition, different anodes (Pt, graphite, W and Co–W, steel) were investigated to reveal the anode influence onreaching the maximum values of the current efficiency and microhardness. It is shown, that using steel, as anode, in electrodeposition of iron-tungsten coatings, the current efficiency is significantly increased in comparison with use of insoluble anode (graphite). When Fe-W coatings were obtained from citrate electrolyte containing Fe(II) and tungstate, the maximum rate of electrodeposition was obtained (25 μm/hour at 2 A/dm2) |
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