Anodic behavior of iron, cobalt, and nickel silicides in alkaline electrolytes

Rakityanskaya, I. L.; Shein, A. B.

doi:10.1134/s1023193506110073

Cited by 9 publications

(7 citation statements)

References 3 publications

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“…It is known that the high corrosion resistance of the silicides in fluoride-free acid media is due to the surface layer of SiO 2 which prevents selective dissolution of iron (Rakityanskaya and Shein, 2006). Also, Fe(III) ion is stable in acidic media below pH 1 at 25°C (Fig.…”

Section: The Fe-si-h 2 O Systemmentioning

confidence: 97%

Dissolution windows for hydrometallurgical purification of metallurgical-grade silicon to solar-grade silicon: Eh–pH diagrams for Fe silicides

Kim

Osseo‐Asare

2012

Hydrometallurgy

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Section: The Fe-si-h 2 O Systemmentioning

confidence: 97%

Dissolution windows for hydrometallurgical purification of metallurgical-grade silicon to solar-grade silicon: Eh–pH diagrams for Fe silicides

Kim

Osseo‐Asare

2012

Hydrometallurgy

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“…Silicon actively dissolves in alkali media, and a protective film consisting of different metal oxides and hydroxides such as Fe 3 O 4 | γ-Fe 2 O 3 | Fe(OH) 3 forms [85]. Hence, in spite of the high solubility of Si in alkali electrolytes, iron, cobalt, and nickel silicides remain comparably stable in anodic polarization.…”

Section: Electrochemical Oxidation Of Silicidesmentioning

confidence: 97%

“…The results obtained in [81] are quite ambiguous since the assumption that only silica forms on MoSi 2 during anodic oxidation is too simplified. It is doubtful whether SiO 2 protective film can form in oxidation in alkali solutions since iron-subgroup silicides form films of oxides and hydroxides of their metals in alkali electrolytes, while silicon goes into the electrolyte [83][84][85]. As there are no data on the chemical composition of the oxide layer in [81], it is incorrectly to make conclusions that its chemical composition is identical in acid and neutral media.…”

Section: Electrochemical Oxidation Of Silicidesmentioning

confidence: 98%

“…The electrochemical dissolution in alkali electrolytes has quite different mechanism [83][84][85]102]. Silicon actively dissolves in alkali media, and a protective film consisting of different metal oxides and hydroxides such as Fe 3 O 4 | γ-Fe 2 O 3 | Fe(OH) 3 forms [85].…”

Section: Electrochemical Oxidation Of Silicidesmentioning

confidence: 99%

“…It is noted [76,77] that the formation of transition metal silicides (Me 5 Si 3 ) in the thermal treatment of NiMo(W)-Si alloys increases their corrosion resistance. Note that special research interest was focused on the abnormal behavior of MoSi 2 in various electrolytes [78][79][80][81][82][83][84][85]. Numerous studies conducted by Shams El Din [78][79][80][81] deal with extensive analysis of the electrochemistry of MoSi 2 electrode: stationary potential of the electrode in water solutions [78], potentiometric titration in salt melts [78] and electrolytes [79], and anodic oxidation and formation of passivation film [81].…”

Section: Electrochemical Oxidation Of Silicidesmentioning

confidence: 99%

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High-temperature and electrochemical oxidation of transition metal silicides

Chirkin

Lavrenko

Talash

2009

Powder Metall Met Ceram

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546.281:541.138 High-temperature and electrochemical oxidation of transition metal silicides, which are widely used in microelectronics as ohmic contacts and protective coatings for high-temperature alloys, are discussed in this review. The process of oxide film formation during annealing or anodizing is extremely important for both applications of silicides. It is discussed for three disilicides: MoSi 2 , WSi 2 , and TiSi 2 . It has been shown that different types of oxide films may form on the disilicide surface depending on the thermodynamic (formation enthalpies of silicides and associated oxides) and kinetic (diffusion coefficients of silicon in silicide and oxygen diffusivity in oxide) factors: onephase (MoSi 2 ), mixed (WSi 2 ), and multilayer (TiSi 2 ) films. The "silicide pest" phenomenon is discussed in terms of thermodynamic, kinetic, and structural factors influencing the pesting. Analysis of electrochemical oxidation mechanisms for silicides in various electrolyte media reveals numerous similarities between anodic and high-temperature oxidation mechanisms. It is shown that slow silicon transport during anodic treatment at room temperature leads to the formation of multiphase mixed oxide films under electrochemical polarization.Keywords: transition metal silicides, kinetics of high-temperature oxidation, formation mechanism, protective oxide films containing SiO 2 , anodic electrochemical oxidation, electrolyte solutions.Binary refractory compounds of elements from groups 4-6 of the Periodic Table with carbon, boron, nitrogen, and silicon--carbides, borides, nitrides, silicides, and associated composites⎯are very promising materials owing to their excellent, as compared with the initial metals, high-temperature oxidation resistance and chemical stability. These materials are widely used in different engineering areas. New composite materials based on refractory compounds with desired properties constantly show up.Transition metal silicides are widely used in modern engineering. They are remarkable for their significant physical and technical properties: relatively low density, metal conductivity, high corrosion resistance, which are needed in engineering areas using high temperatures, rates, loads, and corrosive media. These are aerospace structures, high-temperature heaters, corrosion protective coatings on refractory alloys, etc. [1]. For example, the high melting temperature combined with the corrosion resistance of semiconducting silicides (Cr, Mn, and Fe disilicides) are the very properties required for thermoelectric generators that convert solar energy into electric energy.

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