The sulphidation properties of pre-oxidized yttrium-ion-implanted Incoloy 800H

Abstract. The transport processes in chromium oxide reviewed here, are related to the basic ionic processes in oxides. Solid state science has been effective in describing the complicated diffusion-controlled oxide growth of chromium and chromia-forming alloys. Additions of reactive elements to chromia-forming alloys have a remarkably beneficial effect and this effect is also related to ionic transport processes in crystal lattices. Chromia-forming alloys are widely used in coal handling and conversion systems due to their good high-temperature corrosion properties; for industrial applications the requirement is that a good adherent protective oxide with a low diffusion of defects is formed. Recently, improved knowledge has been gained of the identity of the moving species and the values of the corresponding diffusion coefficients in chromia scales. STEM measurements give experimental support for the theory of grain-boundary segregation and blocking of grain-boundary diffusion by reactive elements.In this paper the current ideas on the transport processes in chromia and the role of rare earth additions on the corrosion behaviour are reviewed. In addition calculations on crystal lattices and grain boundaries are discussed. The calculations on chromia have been beneficially influenced by earlier theoretical considerations on nickel oxide. Consequently, results on (doped) nickel oxide as well as chromium oxide are discussed.

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“…Recent oxidation measurements on chromium at 900 "C and < Po2 < 1 bar, also show k, to be independent of the oxygen partial pressure [ 7 ] .…”

Section: The Oxidation Of Pure Chromiummentioning

confidence: 99%

“…Ion implantation in 20Cr-25Ni-Nb-stabilised steel did not result in an oxide layer with a higher chromium content [29]. Ion implantation can also be applied to improve the sulphidation corrosion resistance of chromiaforming alloys, if a pre-oxidising treatment is applied, as shown in [30].…”

Section: The Electrical Conductivity Of Chromium Oxidementioning

confidence: 99%

The reactive element effect; ionic processes of grain-boundary segregation and diffusion in chromium oxide scales

Polman¹,

Fransen²,

Gellings³

1989

J. Phys.: Condens. Matter

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“…Modification of the "natural" oxide may be realized by ion implantation of yttrium and/or cerium for instance [1,2] and by the sol-gel method [3] and may result in a reasonably good protection against sulphidation. The direct application of a different oxide for protective purposes was carried out by Bennett [4] who applied the chemical vapour deposition (CVD) technique for the coating of several stainless steels with SiO2.…”

Section: Introductionmentioning

confidence: 99%

The protective properties of thin alumina films deposited by metal organic chemical vapour deposition against high-temperature corrosion of stainless steels

Morssinkhof

Fransen

Heusinkveld

et al. 1989

Materials Science and Engineering: A

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High-temperature corrosion and mechanical properties of protective scales on Incoloy 800H: The influence of preoxidation and ion implantation

1990

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Coatings, obtained by preoxidation of Incoloy 800H at low P02 show good sulphidation resistance due to the higher chromia content in the oxide scale. Yttrium-ion implantation of Incoloy 800H has also a beneficial effect on sulphidation, if preoxidation is applied. The reason for this is presumably the segregation of yttrium to grain boundaries of the oxide. Furthermore, the oxidation kinetics of Incoloy 800H are independent of the partial pressure of the oxygen. Mechanical testing of the preformed oxide scale/substrate combinations in air at 600~ by means of constant-extension-rate experiments shows that preoxidation at low partial pressures of oxygen leads to earlier scalecracking.

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The sulphidation properties of pre-oxidized yttrium-ion-implanted Incoloy 800H

Abstract: ABSTRACT

Cited by 7 publications

References 8 publications

The reactive element effect; ionic processes of grain-boundary segregation and diffusion in chromium oxide scales

The reactive element effect; ionic processes of grain-boundary segregation and diffusion in chromium oxide scales

The protective properties of thin alumina films deposited by metal organic chemical vapour deposition against high-temperature corrosion of stainless steels

High-temperature corrosion and mechanical properties of protective scales on Incoloy 800H: The influence of preoxidation and ion implantation

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