Water vapor effects on the cyclic oxidation resistance of alumina forming alloys

Onal, K.; Maris-Sida, M.C.; Meier, G. H.; Pettit, F. S.

doi:10.3184/096034003782748757

Cited by 30 publications

(24 citation statements)

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“…Nominally, at higher Al contents, a lower mass gain would be expected as a protective Al-rich oxide scale would be expected to form. However, the presence of H 2 O appears to inhibit the formation of a protective alumina scale, similar to observations in wet air [20]. As noted in Figures 9 and 10, this study is not complete and internal oxidation penetration depth may be more revealing than mass gain when comparing composition effects and cast versus wrought alloys.…”

Section: Oxidation In Steam and Effect Of Microstructurementioning

confidence: 48%

“…Superalloys with higher Al contents, >3wt.%, can form a protective external alumina scale, which is more stable than chromia such that these alloys do not experience volatilization [19]. However, even alumina-forming alloys and coatings can experience increased scale spallation in the presence of H 2 O [20,21]. Several studies have examined high temperature environmental effects of simple oxidizing environments on crack growth rates and fatigue life, which is extremely important for wrought and cast superalloys [22][23][24].…”

Section: Introductionmentioning

confidence: 99%

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Oxidation of Superalloys in Extreme Environments

Pint¹,

Unocic²,

Dryepondt³

2010

7th International Symposium on Superalloy 718 and Derivatives (2010)

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With the current interest in increased efficiency and reduced emissions, materials in power generation systems are increasingly exposed to more aggressive environments and higher temperatures. It is important to understand how these environments can increase corrosion rates, possibly reducing performance and likely shortening component lifetimes. Superalloys like 718 and its derivatives primarily rely on the formation of an external Cr-rich oxide layer or scale for environmental protection at typical application temperatures (≤700°C). While many laboratory oxidation and creep experiments are conducted in ambient air, the application environment for these alloys often involves combustion products, such as H 2 O and CO-CO 2 . The effect of these environments is not completely understood, especially the impact of long-term exposures, typically required of superalloy components in turbines. Air and fuel impurities, especially S and Na, can result in accelerated degradation such as the well known hot corrosion attack. While the effect of environment on crack growth has been studied, less information is available on the effect of environment on creep and fatigue properties. Initial work is being conducted to better understand the role of environment on creep properties, eventually including in-situ testing. Examples are given from steam and wet air environments and comparisons of different superalloy compositions with cast versus wrought microstructures.

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Section: Oxidation In Steam and Effect Of Microstructurementioning

confidence: 48%

Section: Introductionmentioning

confidence: 99%

Oxidation of Superalloys in Extreme Environments

Pint¹,

Unocic²,

Dryepondt³

2010

7th International Symposium on Superalloy 718 and Derivatives (2010)

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“…Oxide spallation increased by the formation of aluminum hydroxide (34)(35) and by the weakness of the scale/alloy interface (32)(33). In the present study, oxide spallation occurred during cooling.…”

Section: Ecs Transactions 25 (25) 3-19 (2010)mentioning

confidence: 68%

“…Recently, the effects of small noble metals (palladium, rhodium, platinum) additions on the oxidation behavior of the Al 2 O 3 -forming heat-resistant alloys have been also studied (25)(26)(27)(28)(29)(30)(31). On the other hand, water vapor usually has adverse effects on the oxidation resistance of Al 2 O 3 -forming alloy (32)(33)(34)(35). Cr 2 O 3 -forming heat-resisting alloys have also served in oxidizing atmospheres at temperatures up to 1473K (36)(37)(38)(39)(40)(41)(42)(43)(44)(45), however, the Cr 2 O 3 have volatile property during high-temperature oxidation.…”

Section: Introductionmentioning

confidence: 99%

High-Temperature Oxidation Resistance of Al₂O₃- and Cr₂O₃-Forming Heat-Resisting Alloys with Noble Metals and Rare Earths

Amano

2010

ECS Trans.

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High-temperature oxidation behavior of Al 2 O 3 -and Cr 2 O 3 -forming heat-resisting alloys with noble metals (Pd, Pt) and rare earths (Y, Lu) was studied in oxidizing atmospheres (oxygen, oxygen-water vapor) for 18ks at 1473, 1573 and 1673K, by mass gain measurements, amount of spalled oxide, observation of surface appearance, XRD, SEM, EPMA, and TEM. For Al 2 O 3 -forming alloys, noble metal additions did not decrease mass gain, however, increased oxide adherence in both oxidation conditions. On the other hand, yttrium addition decreased mass gain in both oxidation conditions. After oxidation at 1673K, water vapor caused alumina scale spallation, however, 0.5mass% platinum addition showed good oxide adherence. For Cr 2 O 3 -forming alloy, rare earth or silicon addition decreased mass gain, and both rare earth and silicon addition markedly decreased mass gain after oxidation in oxygen for 18ks at 1473 and 1573K. Oxide spallation was amplified by the addition of silicon.

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“…Many researches have already been performed, not only at low pressure and temperatures above room temperature, but also by air or during electrochemical oxidation and plasma formation [8][9][10][11][12] Liu et al focused on the research of the corrosion phenomena for a single-crystal Ni-base superalloy at 900 and 1000°C in an air and oxidation was found to be occurred in two steps. It is noted that first oxidation is controlled by NiO growth and the second by Al 2 O 3 growth until Al 2 O 3 layer formed beneath NiO layer [13].…”

Section: Introductionmentioning

confidence: 99%

Preparation of oxide powder by continuous oxidation process from recycled Fe-77Ni alloy scrap

Yun

Park

Jung

et al. 2015

IOP Conf. Ser.: Mater. Sci. Eng.

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Abstract. The oxidation behavior of Fe-77Ni alloy scrap was studied under a 0.2 atm oxygen partial pressure at the temperature range of 400°C to 900°C. The oxidation rate was found to be increased with an increase of temperature and followed the parabolic rate law with linearly proportional to temperature. Microstructure and cross-sectional area of the oxide layer were examined by SEM, EDX, and XRD. It could be speculated that rate-limiting step was controlled by diffusion through either the spinel structure or the NiO layer, both of which were present in this alloy during oxidation at elevated temperatures. In the long run, oxide powder less than 10 m from Fe-77Ni alloy scrap was obtained using ball-milling and sieving processes and recovery ratio approached up to 97% for 15 hours.

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Water vapor effects on the cyclic oxidation resistance of alumina forming alloys

Cited by 30 publications

References 0 publications

Oxidation of Superalloys in Extreme Environments

Oxidation of Superalloys in Extreme Environments

High-Temperature Oxidation Resistance of Al₂O₃- and Cr₂O₃-Forming Heat-Resisting Alloys with Noble Metals and Rare Earths

Preparation of oxide powder by continuous oxidation process from recycled Fe-77Ni alloy scrap

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Water vapor effects on the cyclic oxidation resistance of alumina forming alloys

Cited by 30 publications

References 0 publications

Oxidation of Superalloys in Extreme Environments

Oxidation of Superalloys in Extreme Environments

High-Temperature Oxidation Resistance of Al2O3- and Cr2O3-Forming Heat-Resisting Alloys with Noble Metals and Rare Earths

Preparation of oxide powder by continuous oxidation process from recycled Fe-77Ni alloy scrap

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High-Temperature Oxidation Resistance of Al₂O₃- and Cr₂O₃-Forming Heat-Resisting Alloys with Noble Metals and Rare Earths