The electronic structure of passive films formed on stainless steels

Hakiki, N.B.; Boudin, S.; Rondot, B.; Belo, M. Da Cunha

doi:10.1016/0010-938x(95)00084-w

Cited by 413 publications

(275 citation statements)

References 36 publications

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“…The electronic band structure model proposed in previous work 7,16 considers that the flat band potentials of the inner (Cr oxide) and outer (Fe oxide) layers of the passive films are characterized by the same flat band potential situated at about -0.5 V. It was assumed that under an applied potential the passive film acts as a Schottky barrier above and below this flat band potential. Consequently the inner film-metal interface is in an accumulation condition at potentials higher than -0.5 V. This may be not true if we consider that the more accurate flat band potential of the metal-chromium oxide interface is situated at about 0.5 V, i.e.…”

Section: Passive Filmsmentioning

confidence: 99%

“…Under certain conditions, the electronic structure of these films can be more accurately described as a bi-layer composed of a ntype outer region containing iron oxide and hydroxide and a p-type inner region containing chromium oxide. 6,7 Nickel oxide is also present in both alloys mainly in the external layers of the film, although a much larger Ni/Fe ratio is found in the case of the Alloy 600.…”

Section: Introductionmentioning

confidence: 95%

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Semiconducting properties of oxide and passive films formed on AISI 304 stainless steel and Alloy 600

Ferreira¹,

Belo²,

Hakiki³

et al. 2002

J. Braz. Chem. Soc.

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Estudaram-se as propriedades semicondutoras de filmes passivos formados em aço inoxidável AISI 304 e em ligas de base Ni (Alloy 600) em soluções tampão de borato. Os filmes foram estudados por medidas de capacidade (Mott-Schottky ) e de fotocorrente. Estudaram-se também filmes formados em aço inoxidável AISI 304 por oxidação ao ar, à temperatura de 350ºC. Os resultados mostram que a estrutura electrónica dos filmes é comparável à de uma heterojunção do tipo p-n, onde as cargas de espaço desenvolvidas nas interfaces filme -metal e filme -electrólito devem ser consideradas. O estudo electroquímico está de acordo com os resultados analíticos que demonstram que os filmes de óxido são, em todos os casos, compostos por uma região interna rica em óxido de crómio e por uma região externa rica em óxido de ferro.The semiconducting properties of passive films formed on AISI 304 stainless steel and Alloy 600 in borate buffer solution were studied by capacitance (Mott-Schottky approach) and photocurrent measurements. Oxide films formed on 304 stainless steel in air at 350 ºC have also been studied. The results obtained show that, in all cases the electronic structure of the films is comparable to that of a pn heterojunction in which the space charges developed at the metal-film and film-electrolyte interfaces have also to be considered. This is in accordance with analytical results showing that the oxide films are in all cases composed of an inner region rich in chromium oxide and an outer region rich in iron oxide.

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Section: Passive Filmsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 95%

Semiconducting properties of oxide and passive films formed on AISI 304 stainless steel and Alloy 600

Ferreira¹,

Belo²,

Hakiki³

et al. 2002

J. Braz. Chem. Soc.

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“…Since the space charge region developed in the passive film and the Helmholtz layer can be considered as two capacitors in series, the measured capacitance of the film/electrolyte interface can be expressed as [44]:…”

Section: Capacitance Measurementsmentioning

confidence: 99%

“…In this way, the space charge capacitance of pand n-type semiconductors is given by Equations 5 and 6, respectively [44,47,49].…”

Section: Capacitance Measurementsmentioning

confidence: 99%

“…Contrarily, as oxygen vacancies may be assumed as electron donors [65,66], a decrease in N D for the films formed at 900 ºC might be related to two factors: first, an increase in the thickness of the formed oxide film, corroborated by the high C 1 and R 1 values (Table 1) and the higher mass gain (Figure 5), and second, the oxidation of the magnetite, which changes the conductive properties of the oxides. In fact, the presence of donor vacancies prevents migration of cations from the substrate metal and penetration of harmful anions, such as Cl -, from the electrolyte, thereby improving corrosion resistance [44,67,68].…”

Section: Capacitance Measurementsmentioning

confidence: 99%

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Characterization of thermal oxide films formed on a duplex stainless steel by means of confocal-Raman microscopy and electrochemical techniques

2015

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ElsevierSánchez Tovar, R.; Leiva García, R.; García Antón, J. (2015). Characterization of thermal oxide films formed on a duplex stainless steel by means of confocal-Raman microscopy and electrochemical techniques. Thin Solid Films. 576:1-10. doi:10.1016/j.tsf.2014.12.024. Regarding the electrochemical properties of these films, the corrosion resistance of the film tends to be lower with the heat treatment temperature, probably due to a more porous and heterogeneous scale. Mott Schottky plots show the n-type semiconductive behaviour of the films with donor densities that decrease with the enhancement of the temperature.

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Corrosion resistance for biomaterial applications of TiO2 films deposited on titanium and stainless steel by ion-beam-assisted sputtering

Pan

Leygraf

Thierry³

et al. 1997

J. Biomed. Mater. Res.

148

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The high corrosion resistance and good biocompatibility of titanium and its alloys are due to a thin passive film that consists essentially of titanium dioxide. There is increasing evidence, however, that under certain conditions extensive titanium release may occur in vivo. An ion-beam-assisted sputtering deposition technique has been used to deposit thick and dense TiO2 films on titanium and stainless steel surfaces. In this study, using the following measurements these TiO2 films have been investigated in a phosphate-buffered saline solution: (1) open-circuit potential versus time of exposure, (2) electrochemical impedance spectroscopy, (3) potentiodynamic polarization, and (4) Mott-Schottky plot. A higher electrical film resistance, lower passive current density, and lower donor density (in the order of 10(15) cm-3) have been measured for the sputter-deposited oxide film on titanium in contrast to the naturally formed passive oxide film on titanium (donor density in the order of 10(20) cm-3). The improved corrosion protection of the sputter-deposited oxide film can be explained by a low defect concentration and, consequently, by a slow mass transport process across the film. As opposed to TiO2 on titanium, a deviation from normal n-type semiconducting Mott-Schottky behavior was observed for TiO2 on stainless steel.

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The electronic structure of passive films formed on stainless steels

Cited by 413 publications

References 36 publications

Semiconducting properties of oxide and passive films formed on AISI 304 stainless steel and Alloy 600

Semiconducting properties of oxide and passive films formed on AISI 304 stainless steel and Alloy 600

Characterization of thermal oxide films formed on a duplex stainless steel by means of confocal-Raman microscopy and electrochemical techniques

Corrosion resistance for biomaterial applications of TiO2 films deposited on titanium and stainless steel by ion-beam-assisted sputtering

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