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Taniguchi, Shigeji; Andoh, Atsushi

doi:10.1023/a:1020577107126

Cited by 42 publications

(16 citation statements)

References 6 publications

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“…1b, 3b, 4b and Refs. 31,32), and was thought to be the main reason for the relatively long lifetimes for the coating systems produced with pre-oxidation at intermediate pO 2 (Fig. 2).…”

Section: Tgo Growth Ratementioning

confidence: 99%

“…30 The low growth rate and larger grain size of the a-Al 2 O 3 layer developed for the intermediate pO 2 pre-oxidation treatments was attributed to the formation of h-Al 2 O 3 during pre-oxidation. 31,32 It is thought that at the onset of oxidation less a-Al 2 O 3 nuclei (and thus grains) are formed by sympathetic nucleation on h-Al 2 O 3 , as compared with the direct nucleation of a-Al 2 O 3 (in the presence of initially segregated Y 15 ). The low a-Al 2 O 3 growth rate after prolonged oxidation outweighed the rapid growth rate of the h-Al 2 O 3 during pre-oxidation (cf.…”

Section: Tgo Growth Ratementioning

confidence: 99%

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Development of a Pre-Oxidation Treatment to Improve the Adhesion between Thermal Barrier Coatings and NiCoCrAlY Bond Coatings

Nijdam

Marijnissen²,

Vergeldt³

et al. 2006

Oxid Met

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High-temperature coating systems, consisting of a Rene´N5 superalloy, a Ni-23Co-23Cr-19Al-0.2Y (at.%) bond coating (BC), and a yttria (7 wt%)-stabilized zirconia (YSZ) thermal-barrier coating (TBC), were thermally cycled to failure for seven different controlled pre-oxidation treatments and one commonly employed industrial pre-oxidation treatment to establish the preferred microstructures of the thermally-grown oxide (TGO) on a NiCoCrAlY bond coating after pre-oxidation. It was found that the failure of the coating system occurred along the TGO/BC interface when the TGO attained a critical thickness, except if a NiAl 2 O 4 spinel layer developed contiguous to the TBC/TGO interface. Then, the coating system failed at a smaller TGO thickness along the NiAl 2 O 4 /a-Al 2 O 3 interface. The value for the TGO thickness at failure increased for a larger area fraction of Y-rich oxide pegs at the TGO/BC interface after pre-oxidation. A desired slow-growing oxide layer on the BC surface was promoted when the presence of the oxides NiAl 2 O 4 , h-Al 2 O 3 , Y 3 Al 5 O 12 at the TGO surface after pre-oxidation was avoided. The a-Al 2 O 3 layer, which developed adjacent to the BC upon thermal cycling, grew at a low rate if the initial oxide at the onset of oxidation consisted of h-Al 2 O 3 instead of a-Al 2 O 3 . Based on these results a pre-oxidation treatment is proposed for which the lifetime of the entire coating system during service is enhanced.

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“…1b, 3b, 4b and Refs. 31,32), and was thought to be the main reason for the relatively long lifetimes for the coating systems produced with pre-oxidation at intermediate pO 2 (Fig. 2).…”

Section: Tgo Growth Ratementioning

confidence: 99%

Section: Tgo Growth Ratementioning

confidence: 99%

Development of a Pre-Oxidation Treatment to Improve the Adhesion between Thermal Barrier Coatings and NiCoCrAlY Bond Coatings

Nijdam

Marijnissen²,

Vergeldt³

et al. 2006

Oxid Met

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“…Taniguchi and Andoh [21] have improved oxidation resistance at 1,100°C by both deposition of additional Al and pre-oxidation. In this study, it was thought that a pre-oxidation treatment at 1,100°C in air should lead to a stable a-Al 2 O 3 oxide scale and limit further oxidation even at lower temperatures.…”

Section: Pre-oxidation Treatment Of Fibersmentioning

confidence: 99%

Oxidation of FeCrAlY Fibers at Low Oxygen Potentials

et al. 2008

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The oxidation of Fe-15Cr-5Al-0.3Y (wt.%) coupons and 22-lm-diameter fibers has been studied in a helium atmosphere containing *150 ppm oxygen at temperatures of 750-950°C. Thermogravimetric analysis was used to follow kinetics, and oxide scales were analyzed with scanning-electron microscopy, electron-microprobe analysis, and photostimulated luminescence. The observed kinetics behavior of the coupons and fibers is attributed to effects of both transitional aluminas and aluminum depletion in the alloy. Distinct differences are observed with the fibers as compared to the coupons at 900 and 950°C, but similar behavior is observed at 850°C. Pre-oxidation treatments of the fibers at 1,100°C in air formed a thin layer of a-Al 2 O 3 and slowed oxidation dramatically at 850°C. The fibers showed aluminum depletion and formed mixed alumina-chromia scales, which appeared adherent and protective.

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“…The pre-oxidation treatment of high-temperature alloys is one of the most common methods used to improve the oxidation resistance of alloys in aggressive atmospheres [1,2]. Earlier investigations of Co-Re-Cr model alloys have shown rather poor oxidation resistance during exposure to laboratory air [3,4].…”

Section: Introductionmentioning

confidence: 99%

The Effect of Pre-Oxidation Treatment on the High-Temperature Oxidation of Co–Re–Cr Model Alloys at Laboratory Air

et al. 2010

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The aim of a pre-oxidation treatment at low oxygen partial pressure is to promote the formation of a Cr 2 O 3 (or Al 2 O 3 ) scale in such a way that the oxide layer can reliably prevent the contact of oxygen with the metallic substrate also at high oxygen partial pressure. In this study, the pre-oxidation treatment was applied to the two alloys Co-17Re-23Cr and Co-17Re-30Cr (at.%). Pre-oxidation of the Co-Re-xCr alloys was found to be non-protective for the metallic substrate at high oxygen partial pressure despite the formation of a Cr 2 O 3 layer. Different kinds of Cr 2 O 3 scale damage were observed depending on the Cr concentration. The Cr 2 O 3 scale formed on the alloy Co-17Re-23Cr loses its protective properties as a result of cation transport by lattice and grain boundary diffusion, while the Cr 2 O 3 scale formed on the alloy Co-17Re-30Cr degraded as a consequence of scale cracking. In addition, the effect of alloying with Si was investigated and found to be promising.

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Cited by 42 publications

References 6 publications

Development of a Pre-Oxidation Treatment to Improve the Adhesion between Thermal Barrier Coatings and NiCoCrAlY Bond Coatings

Development of a Pre-Oxidation Treatment to Improve the Adhesion between Thermal Barrier Coatings and NiCoCrAlY Bond Coatings

Oxidation of FeCrAlY Fibers at Low Oxygen Potentials

The Effect of Pre-Oxidation Treatment on the High-Temperature Oxidation of Co–Re–Cr Model Alloys at Laboratory Air

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