The effect of surface implantation of yttrium and cerium upon the oxidation behaviour of stainless steels and aluminized coatings at high temperatures

“…The limitations of coating application to improve the oxidation resistance of aluminaforming steels were previously described by Pint [3]. Nevertheless, the reasons why surface doping is inefficient in the case of alumina-forming steels, whereas they are beneficial to improve the oxidation resistance of chromia-forming alloys [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21], are still unclear.…”

Section: Introductionmentioning

confidence: 99%

Influence of the mode of introduction of a reactive element on the high temperature oxidation behavior of an alumina-forming alloy. Part III: The use of two stage oxidation experiments and in situ X-ray diffraction to understand the oxidation mechanisms

Chevalier¹,

Issartel²,

Cueff³

et al. 2006

Materials and Corrosion

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International audienceThe aim of this work was to investigate several different yttrium introduction routes to improve the high temperature oxidation resistance of a Fe-20Cr-5Al model alloy. Y2O3 sol-gel coatings, Y2O3 metal-organic chemical vapor deposition (MOCVD) coatings, yttrium. ion implantation and yttrium as alloying element (0.1 wt.%) were the different methods of introduction of the reactive element. Both isothermal and cyclic oxidation tests showed that the surface introduction of yttrium or yttrium oxide did not drastically improve the oxidation behavior of the steel. Complementary experiments were performed to understand the lack of major beneficial effects of the so-treated samples. Two stage oxidation experiments under 200 mbar O-16(2) and O-18(2) followed by secondary neutral mass spectrometry (SNMS) were performed to understand the alumina scale growth mechanisms, according to the introduction route of the reactive element. The results exhibited that the yttrium induced an increase of the inward transport of oxygen through the alumina scale compared to the untreated specimen. Nevertheless, the outward transport of aluminum was generally observed, except for the specimen containing Y as alloying element, which exhibited only a single O-18 peak close to the metal/oxide interface. Phase transformations during the oxidation at 1100 degrees C were registered by in-situ X-ray diffraction (XRD). The untreated alloy was only covered by a thin layer of alpha-Al2O3. For implanted specimens, yttrium was incorporated in Y3Al5O12 and YAlO3 phases. All the YAlO3 is transformed into Y3Al5O12 after less than 10 h. For the MOCVD or the sol-gel coated samples, the primary formed YAlO3 phase was progressively transformed into Y3Al5O12. For the Fe-20Cr-5Al-0.1Y alloy, no yttrium containing phases could be detected, even after 40 h of oxidation test at 1100 degrees C

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“…The RE elements can be added to heat resistant alloys either in elemental form or as oxide dispersions 5,6 . The REs can also be introduced into the surface by ion implantation techniques or applied superficially by a variety of techniques [7][8][9][10][11][12][13][14] . Application of RE oxides to metallic surfaces can be done by immersion in aqueous RE nitrate solutions followed by thermal decomposition of the solid nitrate to oxide.…”

Section: Introductionmentioning

confidence: 99%

Rare earth oxide coatings to decrease high temperature degradation of chromia forming alloys

Fernandes

Ramanathan

2004

Mat. Res.

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The addition of small quantities of reactive elements such as rare earths (RE) to chromia or alumina forming alloys improves the high temperature oxidation resistance. Traditionally, these elements are alloying additions or are added as oxides to form a dispersion. The alloys can also be coated with RE oxides. Several methods can be used to coat alloy substrates with RE oxides and the sol-gel process is considered to be quite efficient, as it generates the very small oxide particles. This paper presents the influence of surface coatings of Ce, La, Pr, and Y oxide gels on the oxidation behavior of an Fe-20Cr alloy at 1000 °C. The morphology of the rare earth (RE) oxide coatings varied with the nature of RE. The oxidation rate of RE oxide coated Fe-20Cr was significantly less than that of the uncoated alloy. The extent of influence the RE oxide coating exercised on the oxidation rate decreased in the following order: La, Ce, Pr, Y. The scale formed in the presence of RE oxide was very thin, fine grained and adherent chromia. A direct correlation between rare earth ion radius and the extent of influence on chromia growth rate at 1000 °C was observed.

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The effect of surface implantation of yttrium and cerium upon the oxidation behaviour of stainless steels and aluminized coatings at high temperatures

Cited by 25 publications

References 3 publications

The effect of yttrium ion implantation on the sulphidation of incoloy 800H

The effect of yttrium ion implantation on the sulphidation of incoloy 800H

Influence of the mode of introduction of a reactive element on the high temperature oxidation behavior of an alumina-forming alloy. Part III: The use of two stage oxidation experiments and in situ X-ray diffraction to understand the oxidation mechanisms

Rare earth oxide coatings to decrease high temperature degradation of chromia forming alloys

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