Thermodynamic evaluation of Fe-Sn phase diagram

Kumar, K.C. Hari; Wollants, Patrick; Delaey, L.

doi:10.1016/s0364-5916(96)00021-1

Cited by 74 publications

(59 citation statements)

References 21 publications

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“…Table II. 33 The values are consistent with the potential shift observed between the cyclic voltammogram for tin and FeSn 2 . It is thus proposed that the peak observed in the anodic going wave of the cyclic voltammogram for FeSn 2 seen in Figure 5e corresponds to tin oxidation and it is consequently postulated that the tin oxide governs the activity of the FeSn 2 material.…”

Section: Electrochemical Characterization; Cathodic Oxygen Reduction supporting

confidence: 86%

“…This is consistent with literature values for the Gibbs free energy for the formation of FeSn( G f ) shown in Table II. 33 The G f formation of FeSn is consistent with a positive shift in equilibrium potential associated with the formation of Fe(OH) 2 given by Equation 9, calculated using Equations 10 and 11 where n corresponds to the number of electrons and F the Faraday constant (96487 C. mol −1 ). It is thus proposed that peaks observed in the anodic going wave of the cyclic voltammogram for FeSn seen in Figure 5d correspond predominantly to Fe(OH) 2 formation and it is consequently postulated that the iron oxide governs the activity of the FeSn material.…”

Section: Electrochemical Characterization; Cathodic Oxygen Reduction supporting

confidence: 66%

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The Kinetics and Mechanism of Atmospheric Corrosion Occurring on Tin and Iron-Tin Intermetallic Coated Steels

Wint

Geary

McMurray

et al. 2015

J. Electrochem. Soc.

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This paper describes a systematic study into the initiation and propagation of cathodic delamination on pure iron, pure tin and industrially important tin and iron-tin intermetallic (FeSn and FeSn 2 ) coatings for packaging steels, as a function of coating weight. Cathodic disbondment rates for an organic lacquer overcoat applied to the various metallic coatings are determined using an in-situ scanning Kelvin probe technique. Cathodic disbondment was not observed on pure tin and was found to propagate at reduced rates on the FeSn and FeSn 2 intermetallic coatings, relative to pure iron. An explanation of these findings is given in terms of electrocatalytic activity of various metallic surfaces for the cathodic oxygen reduction reaction. It is shown that the relative susceptibility of Fe, Sn, FeSn and FeSn 2 to cathodic disbondment increases with decreasing cathodic overpotential and is independent of metallic coating weight. Tin is traditionally used for the corrosion protection of packaging steel. Conventional tinplate is typically produced by initially electrodepositing a porous layer of pure tin (∼2.8 g.m −2 -11.2 g.m −2 ) onto the cathodic steel substrate, as shown in Figure 1a, and heating above the melting point of tin (reflowing). [1][2][3] Reflowing causes the tin layer to become fully dense (bright tin) and also allows creation of partial or complete iron-tin intermetallic, typically FeSn 2 , as shown in Figure 1b [1][2][3] .Recently the increasing price of tin in the commodities market has resulted in a need to reduce the amount of tin used in tinplate materials (tin coating weight) whilst retaining adequate corrosion resistance. One approach to doing this has been to diffusion anneal the unflowed tin (<1g.m −2 ) in a reducing atmosphere at temperatures above 500 • C 4,5 in such a way that almost all (preferably 90-98%) 6 of the free tin is converted to an iron-tin (FeSn) intermetallic as shown in Figure 1c. It has previously been found that heating to these temperatures leads to increased tin diffusion to the substrate and formation of a continuous FeSn layer which is more uniform and dense than the conventional FeSn 2 layer. 4 The principal purpose of tin in tinplate packaging materials is to provide corrosion resistance. Furthermore, in modern packaging, corrosion resistance is enhanced by using tinplate in conjuction with an organic (laquer or laminate) overcoat. Consequently mechanisms of corrosion driven coating delamination are of particular concern. The aim of the current paper is to present a detailed study of the role of free tin and iron-tin intermetallic layers in resisting atmopheric corrosion, specifically cathodic disbondment, as it affects lacquer coated packaging material.During cathodic delamination the separation of the organic coating from the metal substrate is linked to the cathodic reduction of oxygen. Within the localized corrosion cell anodic metal dissolution located in the vicinity of the defect is coupled to the cathodic delamination front by a thin (<5 μm) gel like electrol...

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Section: Electrochemical Characterization; Cathodic Oxygen Reduction supporting

confidence: 86%

Section: Electrochemical Characterization; Cathodic Oxygen Reduction supporting

confidence: 66%

The Kinetics and Mechanism of Atmospheric Corrosion Occurring on Tin and Iron-Tin Intermetallic Coated Steels

Wint

Geary

McMurray

et al. 2015

J. Electrochem. Soc.

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“…28) approximated the D f G E versus concentration function by the Redlich-Kister polynomials. Figure 3 shows that description 28) practically coincides with the present one. These type polynomials were also used in the earlier study.…”

Section: Comparison With Literature Datasupporting

confidence: 78%

“…Tanaka et al 27) suggested a thermodynamic description of the Fe-Sn melt on the basis of the theory of regular solutions with temperature dependent parameters. However, in the succeeding report 28) it was demonstrated that a symmetric concentration function of D f G E cannot account for appearance of the immiscibility gap. For this reason the authors of Ref.…”

Section: Comparison With Literature Datamentioning

confidence: 99%

Potentialities of Simultaneous Removal of Tin and Copper from Molten Iron through Evaporation

et al. 2004

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The Knudsen-cell mass spectrometry was used to study evaporation and thermodynamics of pure liquid Sn, Fe-Sn and Fe-Cu-Sn molten alloys containing up to 20.3 mol% Sn or up to 5 mol% Cu and Sn in a wide temperature range. The thermodynamic properties of the binary melt were approximated by means of the subregular solution model with temperature dependent parameters. The properties of the ternary melt were represented with accuracy not worse than the experimental one by combination of the characteristics of the binary constituents. The obtained results were applied to assessment of the potentialities of simultaneous copper and tin removal from molten steel by means of evaporation. Combination of vacuum treatment of a 160-tons ladle with blowing through the molten metal neutral gases was considered as an example. Two processes are responsible for removal of copper and tin: transfer into gas bubbles, free-rising from the ladle bottom to its surface, and evaporation from molten metal surface, turbulized by blowing-through gas. It was shown that duration of the treatment necessary for a decrease in Cu concentration from 0.6 to 0.3 wt% amounts to ϳ1.5 h and is not practically affected by variations in tin content in the range of 0.01 to 0.6 wt%. During this time concentration of tin changes insignificantly at any initial content: from 0.6 to ϳ0.51, from 0.1 to ϳ0.086 or from 0.01 to ϳ0.0086 wt%.

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“…Although we cannot separate the effect of phosphorus and tin strictly, tin can be regarded to have d g refinement effect compatible with phosphorus at this composition range. Solid-liquid equilibrium distribution coefficient of solute element in the iron binary phase diagram can be thermodynamically calculated and obtained as 0.32 and 0.20 for phosphorus 15,17) and tin, 17,19) respectively. It is considerable that the difference in this parameter might compensate for the disadvantage of tin having the larger g-loop nose content and smaller A 4 temperature decrease slope than phosphorus since smaller distribution coefficient leads to higher segregation during solidification.…”

Section: G G Grain Refinement By Tinmentioning

confidence: 99%

Evolution of Columnar γ Grain in Low Carbon Steel and Its Refinement by Additional Elements in Thin Slab Casting Simulator

et al. 2008

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Thermodynamic evaluation of Fe-Sn phase diagram

Cited by 74 publications

References 21 publications

The Kinetics and Mechanism of Atmospheric Corrosion Occurring on Tin and Iron-Tin Intermetallic Coated Steels

The Kinetics and Mechanism of Atmospheric Corrosion Occurring on Tin and Iron-Tin Intermetallic Coated Steels

Potentialities of Simultaneous Removal of Tin and Copper from Molten Iron through Evaporation

Evolution of Columnar γ Grain in Low Carbon Steel and Its Refinement by Additional Elements in Thin Slab Casting Simulator

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