Effect of Structure on the Electrochemical Oxidation Rate of Copper and Nickel Sulfides / Nechvoglod O. V.,Selivanov E. N.,Mamyachenkov S. V. // . - 2012. - V. 326-328, l. . - P. 383-387.

ISSN/EISSN:

1012-0386 / нет данных

Type:

Proceedings Paper

Abstract:

Synthesized samples were crystallized at 10 - 1000 K/sec (v(cooling)) to study the effect of sulfides structure on the electrochemical oxidation rates. The methods of X-ray, optical and electronic microscopy are used to analyze the phase composition, and the methods of voltamperometry and chronoamperometry are used to study the laws of electrochemical oxidation. Slow cooling of the samples with sulfide phase (Cu1,96S, Ni3S2) leads to crystallization of the metal (Ni, Cu). High cooling rate leads to crystallization of non-equilibrium phases, increasing of proportion of the sulfide phase and decreasing of metallic component up to complete disappearance. It is shown that electrochemical oxidation of copper and nickel sulfides proceeds stepwise: Me2S -> Me2-XS -> Me1+XS -> MeS -> Me2+ + S. Experiments have revealed the rates of electrochemical oxidation of granular sulfides that exceed the rates established for the slowly cooled samples. The rates of the electrochemical oxidation of Ni3S2 at potential of 1500 mV are 8.8.10(-8) g/sec.mm(2) (at v(cooling) = 10 K/sec) and 1.3.10(-7) g/sec.mm(2) (at v(cooling) = 1000 K/sec). The rates of the electrochemical oxidation of Cu2S at potential of 1000 mV are 2.8.10(-8) g/sec.mm(2) (at v(cooling) = 10 K/sec) and 4.3.10(-8) g/sec.mm(2) (at v(cooling) = 1000 K/sec). It is found that the forming of a passivation layer effects the rate of the electrochemical oxidation of copper sulfide and nickel sulfide. Non-equilibrium phase composition and refinement provide greater reactivity of sulfides in the conditions of anodic polarization. The oxidation and passivation of metallic phase along with sulfide phases proceed from the surface of Me2S - Me alloys. As for the samples crystallized at 1000 K/sec only anodic oxidation of sulfides occurs due to a lack of metallic phase. The compositions of passivation films and potentials providing the extraction of sulfur in the elemental state from the sulfides crystallized at high rates were determined.

Author keywords:

copper sulfide; nickel sulfide; dispersion; electrochemistry; passivation; rate of oxidation

DOI:

10.4028/www.scientific.net/DDF

Web of Science ID:

ISI:000309370400066

Соавторы в МНС:

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Другие поля

Поле	Значение
Editor	Ochsner, A and Murch, GE and Shokuhfar, A and Delgado, JMPQ
Booktitle	DIFFUSION IN SOLIDS AND LIQUIDS VII
Series	Defect and Diffusion Forum
Note	7th International Conference on Diffusion in Solids and Liquids (DSL 2011), Algarve, PORTUGAL, JUN 26-30, 2011
Publisher	TRANS TECH PUBLICATIONS LTD
Address	LAUBLSRUTISTR 24, CH-8717 STAFA-ZURICH, SWITZERLAND
Language	English
Research-Areas	Science \& Technology - Other Topics; Materials Science
Web-of-Science-Categories	Nanoscience \& Nanotechnology; Materials Science, Multidisciplinary
Author-Email	pcmlab@mail.ru
ResearcherID-Numbers	Selivanov, Evgeniy/T-7296-2017
Number-of-Cited-References	10
Usage-Count-Since-2013	11
Doc-Delivery-Number	BCA15