The Sulfidation Kinetics of Nickel‐Aluminum Alloys at 700°C in Hydrogen Sulfide‐Hydrogen Atmospheres

Bhide, V. S.; Smeltzer, W. W.

doi:10.1149/1.2127529

Cited by 12 publications

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“…In .such environments sulfidation is often the predominant mode of corrosion attack. There are, however, only few investigations dealing with the high temperature corrosion of nickel aluminides in sulfidizing or mixed atmospheres [6][7][8][9]. Godlewska et al [6] investigated the sulfidation of pseudobinary p-NiAl-a-Cr alloys in sulfur vapor a t 900 and 1000°C.…”

Section: Introductionmentioning

confidence: 99%

Sulfidation behaviour of nickel aluminides

Schramm

Auer

1996

Materials & Corrosion

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The sulfidation behaviour of four nickel aluminium alloys containing 25 to 45 at.% A1 was studied over the temperature range of 750 to 950°C in a gas mixture of Hz-HzS (0.1 to 10 vol.?'~). The sulfidation kinetics were determined using a continous weight gain system. The corrosion products were examined by SEM, EDX and XRD.Sulfidation in Hz-H2S gas mixtures formed bilayered scales consisting of an outer layer of Ni3S2 and an inner layer of NiA13,&5 on all alloys regardless of the different aluminium contents. In H2-H2S gas mixtures the sulfidation kinetic generally followed the parabolic rate law for all alloys. The influence of aluminium content on corrosion rate was relatively low.The influence of low oxygen partial pressure on sulfidation was investigated in H2-H2S-H20 mixtures. In these atmospheres the corrosion mechanism is completely different. Severe attack by rapid internal oxidation destroyed all the alloys except Ni25A1(25 at.%Al). The internal oxidation zone consisted of a mixture of y-Ni3Al and AlZO3. On the alloys containing 36 and 45 at.% A1 local attack occurred, fast growing pocks were observed after an incubation period.Nickel aluminides show this corrosion phenomena only in Hz-H2S-Hz0 mixtures. An interruption of the H2S gas flow stops the running internal oxidation. In flowing Hz-H20 atmospheres no internal oxidation was observed. These facts prove that HzS is necessary for starting and maintaining the internal oxidation of the nickel aluminides.Das Sulfidierungsverhalten von Nickelaluminiden mit Aluminiumgehalten zwischen 25 und 35 At.% wurde in H2-H2S Gasgemischen durch kontinuierliche Registrierung der Massenanderung mit einer Thermowaage untersucht. Im Temperaturbereich von 750-950°C wurde dabei der HzS Gehalt zwischen 0,l und 10 Vol.% variiert. Die Morphologie der Korrosionsprodukte wurde im Rasterelektronenmikroskop (REM), die chemische Zusammensetzung mit EDX und Rontgendiffraktometrie (XRD) bestimmt.Bei der Sulfidierung in Hz-H2S Gasgemischen entstanden auf allen untersuchten Nickelaluminiden eine aufiere Ni3S2-Schicht und eine innere Mischsulfidschicht der Zusammensetzung NiA13,jSj,j. Die Schichtbildung folgte annahrend einer parabolischen Kinetik. Die Sulfidierungsgeschwindigkeit wurde nur gering vom Aluminiumgehalt beeinflufit.Der Einflufi niedriger Sauerstoffpartialdriicke auf die Sulfidierung wurde in H2-HzS-H20 Atmospharen untersucht. In diesen Atmospharen veranderte sich der Korrosionsangriff vollig. Alle Legierungen aufier Ni25A1(25 At.% Al) wurden durch eine rasche innere Oxidation zerstort. Als Reaktionsprodukt blieb ein Konglomerat auf y'-Ni,Al und A1203 zuruck. Nach der Anfangsphase des Korrosionsangriffes wurden auf den Aluminiden rnit 36 und 45 At.% A1 lokale, pockenartige Angriffe beobachtet, die rnit zunehmender Reaktionsdauer sehr schnell wuchsen.Diese Form des Korrosionsangriffes trat ausschliefllich in Hz-HzS-HzO Atmospharen auf. Weiterhin wurde beobachtet, daB ein Entfernen des HzS aus der Versuchsatmosphare zum Stillstand der bereits laufenden inneren Oxidation fuhr...

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Section: Introductionmentioning

confidence: 99%

Sulfidation behaviour of nickel aluminides

Schramm

Auer

1996

Materials & Corrosion

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“…The preparation of alloys, the thermogravimetric sulfidation assembly, and phase identification techniques are described in previous papers (4,5). Typical features of scales and internal sulfidation zones resuiting from sulfidation of -y-phase Ni-A1 alloys con- decreased with increasing aluminum alloy content.…”

Section: Experimental Methods and Resultsmentioning

confidence: 99%

“…Furthermore, AGv(D is a function of supersaturation (as B --as E) and for small supersaturations AGv(oo) = w'(as B --as E) [4] Upon substitution of Eq. [4] into Eq. [3] 1…”

Section: B 4'~-~x~ Xmentioning

confidence: 99%

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Cooperative Precipitation of Sulfides as a Mode of Internal Sulfidation of Nickel‐Aluminum Alloys

Bhide

Smeltzer

1983

J. Electrochem. Soc.

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“…Rapp and his group [13][14] carried out extensive studies pertaining to hot corrosion fluxing mechanisms, different oxide solubilities and electrochemical evaluation methods for hot corrosion resistance. Kinetic studies of various materials at high temperatures under hot corrosion conditions were reported by the earlier workers [15][16]. Natesan et al [17][18] have studied the high temperature corrosion of Ni-based superalloys in coal conversion environments.…”

Section: Propagation Stagementioning

confidence: 99%

The Importance of Hot Corrosion and Its Effective Prevention for Enhanced Efficiency of Gas Turbines

Gurrappa¹,

Yashwanth²,

Mounika³

et al. 2015

Gas Turbines - Materials, Modeling and Performance

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Gas Turbines -Materials, Modeling and Performance 56 the hot corrosion resistance. This is further complicated for marine applications by the aggressivity of the environment, which includes sulphur and sodium from the fuel and various halides contained in seawater. These features are known to drastically reduce the superalloy component life and reliability by consuming the material at an unpredictably rapid rate, thereby reducing the load-carrying capacity and potentially leading to catastrophic failure of components [3][4][5]. Thus, the hot corrosion resistance of superalloys is as important as its high temperature strength in gas turbine engine applications. Recent studies have shown that the high temperature strength materials are most susceptible to hot corrosion and the surface engineering plays a key role in effectively combating the hot corrosion problem [6][7]. Therefore, the two materials (base and coating) must be considered as an integral system and the interface between them is also equally important as it can often be the limiting factor. This chapter explains the critical issue of hot corrosion of superalloy components in gas turbine engines and methodologies to select appropriate materials and coatings for its prevention. It is followed by an assessment of current status of coatings, coating techniques and finally, some of the critical areas that need to be addressed for development of more efficient and smart coatings.

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The Sulfidation Kinetics of Nickel‐Aluminum Alloys at 700°C in Hydrogen Sulfide‐Hydrogen Atmospheres

Cited by 12 publications

References 0 publications

Sulfidation behaviour of nickel aluminides

Sulfidation behaviour of nickel aluminides

Cooperative Precipitation of Sulfides as a Mode of Internal Sulfidation of Nickel‐Aluminum Alloys

The Importance of Hot Corrosion and Its Effective Prevention for Enhanced Efficiency of Gas Turbines

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