X-ray induced photoelectron spectroscopic study of calcium phosphate glasses containing iron

Tricker, M. J.; Winterbottom, Ann P.; Bishay, A.; Moutran, R. F.

doi:10.1016/0022-3093(74)90134-3

Cited by 3 publications

(2 citation statements)

References 6 publications

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“…However, it is not entirely clear ~ if such ~/ slowing down of the cathodic process is connected with a simple blocking of the cathodic areas by the adsorbed colloidal particles or is rather due to some intrinsic properties of the protective film. The photoelectron spectroscopy being unable to distinguish between glassy and crystalline calcium-iron phosphates (19), the only indication concerning the film structure, provided by XPS analyses, is the very low bound water content. This might be the reason for which the film repair on iron exposed to (NaPO3)JCaC12 solutions apparently does not involve oxide formation.…”

Section: Discussionmentioning

confidence: 99%

On the Nature of Surface Films Formed on Iron in Aggressive and Inhibiting Polyphosphate Solutions

Koudelka

Sánchez

Augustyński

1982

J. Electrochem. Soc.

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The corrosion behavior of pure iron in diluted (inhibiting) and moderately concentrated (aggressive) polyphosphate solutions has been re-examined in the light of the results of surface analyses of iron samples by means of x-ray photoeleetron spectroscopy. The passive film responsible for the anodic control of the corrosion of iron in diluted (NaPO3)x solutions appears much like an air-formed oxide film with, in addition, some inclusions of iron phosphate. The photoelectron spectra of iron samples exposed to (NaPO3)x/CaC12 solutions suggest the reversion of polyphospharos to orthophosphates as being an essential step in the formation of the protective film. A possible mechanism of the growth of such a film, composed of a mixture of calcium and iron orthophosphates, is proposed.Among various inorganic ions acting as corrosion inhibitors of iron or steel, polyphosphates (metaphosphates) possess a rather unique property of being effective when added in small amounts to even concentrated chloride solutions (1-3). However, the effectiveness of polyphosphates depends to a large extent on the simultaneous presence in the solution of some divalent cations, principally Ca 2+ and Zn 2+ (1, 2, 4), as well as on the concentration of dissolved oxygen (2, 5) and on the rate of stirring or flow (1,5,6). It is to be mentioned that high concentrations of polyphosphate increase, in a significant manner, the corrosion rate of iron in water, which is in contrast with the behavior of most of other inhibiting ions.There has been a large variety of interpretations tending to explain the mechanism by which polyphosphates exert their inhibiting action. These include: (i) adsorption of hexametaphosphate or of a complex thereof on the metal or metal oxide surface (6); (ii) formation of a film of adsorbed oxygen favored by the interaction between polyphosphate and ferrous oxide initially present on the iron surface (2, 7) (iii) deposition on the local cathodic areas of the metal of a protective glassy phosphate coating, proceeding through the migration of a calcium phosphate complex present in the solution either as a cation or as a positively charged colloidal particle (8); (iv) formation of a calcium carbonate film induced by the presence of polyphosphate ions in the solution (9). The latter hypothesis has, however, been rejected by Uhlig et al. (2) who argued that such a film would be dissolved by polyphosphate. As a matter of fact, small amounts of polyphosphate added to water have been extensively used for the prevention against and elimination of calcium Carbonate scale (10).Enhanced efficiency of polyphosphate in reducing the corrosion rate (especially in chloride solutions), obtained by the conjoint use of the divalent Ca2+ or Zn2+ ions, has been connected with the formation on the cathodic areas of a diffusion barrier layer impeding access of oxygen to the iron surface (2). According to Uhlig et al.(2), such film, supposed to contain both calcium and phosphorus (8, 11), would exert a mixed (anodic and cathodic) control of the corr...

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Section: Discussionmentioning

confidence: 99%

On the Nature of Surface Films Formed on Iron in Aggressive and Inhibiting Polyphosphate Solutions

Koudelka

Sánchez

Augustyński

1982

J. Electrochem. Soc.

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“…-Spectre ESCA d'un échantillon de verre au phosphate de calcium : a) Avant décapage à l'argon. b) Après ce décapage[28]. les fibres de verre A montrent généralement un appauvrissement très net (50 %) de la teneur superficielle en calcium, indépendamment du vieillissement[30], mais cette teneur augmente avec la température…”

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Analyse chimique des solides non cristallins en surface et en couches minces

Tousset

1977

Rev. Phys. Appl. (Paris)

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Second harmonic generation optimization in thermally poled borophosphate glasses and characterization by XANES and XPS

Nazabal

Fargin

Labrugère³

et al. 2000

Journal of Non-Crystalline Solids

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X-ray induced photoelectron spectroscopic study of calcium phosphate glasses containing iron

Cited by 3 publications

References 6 publications

On the Nature of Surface Films Formed on Iron in Aggressive and Inhibiting Polyphosphate Solutions

On the Nature of Surface Films Formed on Iron in Aggressive and Inhibiting Polyphosphate Solutions

Analyse chimique des solides non cristallins en surface et en couches minces

Second harmonic generation optimization in thermally poled borophosphate glasses and characterization by XANES and XPS

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