The Growth of Ferrous Sulfide on Iron

Meussner, R.A.; Birchenall, C. E.

doi:10.5006/0010-9312-13.10.79

Cited by 80 publications

(37 citation statements)

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“…The microstructure reported b:r Narita and Nishida and other studies as well, [see Ref. (1,9)] is duplex in that a small equiaxed layer exists underneath overgrowing columnar grains. We have demonstrated that this microstructural feature is directly a result of specimen purity and that it effects the pressure range where the "a" to "c" growth transformation occurs.…”

Section: Microstructure--inmentioning

confidence: 88%

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Evolution of Scale Microstructure and the Pressure Dependence of the Sulfidation Rate of Iron

McKee

Druschel

1983

J. Electrochem. Soc.

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The sulfidation rate of iron to Fe,_xS has been measured, and the microstructural features of this sulfide have been carefully studied. The measurements were made at 700~ in pure sulfur vapor covering the pressure range from 1-103 Pa; 700~ is a temperature in the midrange of previous measurements, and was selected to facilitate a study of the general aspects of the microstructure and growth rate of this highly nonstoichiometric sulfide of iron. We find that the growth direction and microstructure of the scale are pressure dependent, and contrary to previously reported results, we find no evidence to suggest that the growth rate of iron sulfide is any different in pure sulfur vapor than in HJH2S mixtures.In a series of experiments, we have measured the sulfidation rate of iron in pure sulfur vapor. From the literature that is available, there is a clear indication that microstructural as well as physical property characteristics are influenced by gas purity and composition. Our effort has not been simply to survey the reaction kinetics (i.e., to determine the complete temperature and pressure dependence), but to look very carefully at a temperature in the midrange of data that exist and to investigate the pressure dependence thoroughly. Therefore, we have been extremely careful in measuring the specimen reaction temperature and fixing the sulfur pressure in a reliable and reproducible manner. Two aspects of the iron-sulfur reaction were of particular importance when we initiated our study. First, both Fryt, Bhide, Smeltzer, and Kirkaldy (i) and Narita and Nishida (2) had suggested that a transformation in growth direction of the scale forming on the metal occurred as the pressure was varied; this is not a common occurrence in metal oxidation and we felt that it was important to verify this observation. Second, it also had been suggested that hydrogen, ionizing in hydrogen-hydrogen sulfide mixtures [see Worrell and Turkdogan (3) and Zelouf and Simkovich (4)] might somehow play a part in the sulfide defect structure; this idea is important to the overall evaluation of sulfidation processes, and can be tested by carefully comparing measurements in H2/H2S and pure sulfur vapor; we have provided accurate measurements in sulfur vapor for such a comparison.Toward these aims then we report our results of a study using pure iron I in which we measured the rate of sulfidation using a multispecimen technique, to insure reproducibility and to provide specimens for mierostructural observations. The sulfur pressure was varied from 0.1 to 1000 Pa, and a systematic comparison of the pressure dependence of the microstructure is now available. ExperimentalWe describe several features of our experimental technique that we believe are important in considering 1 Marz grade iron, supplied by MRC, total metal impurities less than I0 ppm, oxygen + carbon less than 60 ppm. the merit of our overall results. The three principle areas are (i) the measurement of the specimen temperature, (if) the general care that went into assuring that the ...

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Section: Microstructure--inmentioning

confidence: 88%

“…Fryt et al (1) used H J H 2 S at 700~ but stopped at 0.1 Pa for the sulfur partial pressure. Meussner and Birchenall (9) attempted, but were unable, to measure a sulfidation use this to discuss the reported (3,4) ,'hydrogen effect" and the anisotropy in growth direction (2).…”

Section: Microstructure--inmentioning

confidence: 96%

Evolution of Scale Microstructure and the Pressure Dependence of the Sulfidation Rate of Iron

McKee

Druschel

1983

J. Electrochem. Soc.

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“…However, examination of the data published by Berkowitz, 5 8 relevant to the experimental conditions used by Hauffe and Rahmel 40 and by Meussner and Birchenall,46 shows that the majority of sulphur molecules will be present as S 2' rather than SM S6' &c., i.e. n = 2.…”

Section: - [Fe Vacancies] Oc (As)l/xnmentioning

confidence: 96%

“…Accordingly, it would appear incorrect to assume (at least under the experimental conditions used for Mrowec's analysis) the complete ionisation of vacancies, implicit in the papers of Hauffe and Rahmel 40 and of Meussner and Birchenall. 46 It will be clear that the exponent of the sulphur term in these expressions is, in fact, made up of the reciprocal of the product of two terms-a term (x) associated with the degree of association of the defects (either 3, 2, or I, depending upon whether the vacancies in FeS are considered to be dinegative, uninegative, or neutral), and a sulphur activity term (n) associated with the dominant molecular species present in the sulphur vapour (n = 2 ••• 8);…”

Section: The Sulph£dation Of Metals and Alloys: Straffordmentioning

confidence: 97%

“…Some of the limitations of these marker studies both in oxidation and sulphidation experiments have been illustrated and discussed by Cagnet and Moreau, 2 8 Meussner and Birchenall, 46 Mrowec,55 and by Kofstad et al 29 During the sulphidation of iron, according to equation (21) and the Wagner model (see Fig. 2), the rational constant (and therefore kp, the parabolic rate constant) will be dependent on the rate of diffusion of the iron defects, which in tUfn is governed by the sulphur chemicalpotential (or activity) difference that exists between the two interfaces, equation [18].…”

Section: The Sulph£dation Of Metals and Alloys: Straffordmentioning

confidence: 98%

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