Corrosion behavior of plasma-sprayed coatings on a Ni-base superalloy in Na2SO4-60 Pct V2O5 environment at 900 °C

Singh, Harpreet; Puri, D.; Prakash, S.

doi:10.1007/s11661-005-0294-x

Cited by 19 publications

(10 citation statements)

References 41 publications

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“…NiCrAlY (Praxair NI-343) powder was used as a bond coat before applying the final coating of Ni 3 Al powder in order to enhance the bond strength and reduce the effect of thermal expansion coefficient mismatch between the top coat and the substrate alloy. The details of coating powders and porosity (2.25-4%) measurement of as-sprayed coatings are reported in the earlier publications of the authors [14,15]. The detailed characterisation of these coatings has already been published elsewhere [15].…”

Section: Experimental Workmentioning

confidence: 99%

Hot corrosion of a plasma sprayed Ni₃Al coating on a Ni‐base superalloy

Singh¹,

Puri²,

Prakash³

et al. 2007

Materials & Corrosion

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Ni 3 Al metallic powder was prepared by the mechanical mixing of pure nickel and aluminium powders and deposited on a Ni-base superalloy namely Superni 75 by the shrouded plasma spray process. Hot corrosion behaviour of Ni 3 Al coated and uncoated superalloy specimens was evaluated in a simulated environment of fossil fuel boilers comprising of Na 2 SO 4 -60%V 2 O 5 by accelerated corrosion tests. The accelerated testing was done under cyclic conditions for 50 cycles, with each cycle consisting of 1 h heating in the silicon carbide furnace and cooling for 20 min in air. The coated superalloy was also subjected to air oxidation for 50 cycles to get an idea about its oxidation behaviour and adherence of the Ni 3 Al coating and its oxide scale with the substrate superalloy. The oxide scales were characterised by X-ray diffraction (XRD), scanning electron microscopy/energy dispersive X-ray (SEM/ EDAX) analyses and electron probe microanalysis (EPMA). The uncoated superalloy suffered an accelerated corrosion in the form of spallation of its oxide scale, whereas the oxide scale formed on the Ni 3 Al coated specimen was intact during the air as well as the molten salt oxidation. Furthermore, the coating was found successful in preventing the internal oxidation of the substrate superalloy. The coating maintained its adherence to the substrate superalloy during the exposure to both the environments of the study. The XRD analysis revealed the presence of oxides like Al 2 O 3 , NiO and NiAl 2 O 4 in the oxide scale of the coated superalloy. The XRD results were further supported by the SEM/EDAX and EPMA analyses.

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Section: Experimental Workmentioning

confidence: 99%

Hot corrosion of a plasma sprayed Ni₃Al coating on a Ni‐base superalloy

Singh¹,

Puri²,

Prakash³

et al. 2007

Materials & Corrosion

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“…Plasma sprayed Ni-22Cr-10Al-1Y coatings were utilized by Singh [50] to increase the hot corrosion and oxidation resistance of boiler steels, and by Singh [51], Singh et al [52][53][54] and Prakash et al [55] of some Ni-based and Fe-based superalloys. They observed a considerable improvement in the hot corrosion and oxidation resistance of the base alloys.…”

Section: Mcraly Coatingsmentioning

confidence: 99%

“…Singh [50] deposited the Ni-20Cr coatings on boiler steels by a plasma spray process and evaluated their oxidation and hot corrosion performance in simulated laboratory tests at 900 C, whereas Singh [51], Singh et al [52][53][54] and Prakash et al [55] did the same on some Ni-based and Fe-based superalloys. The coatings were tested in the actual boiler environment also by Singh [50].…”

Section: Nickel-chromium Coatingsmentioning

confidence: 99%

“…Sidhu and Prakash [72] and Singh [50] conducted studies to evaluate the hot corrosion behaviour of plasma-sprayed Ni 3 Al coatings on boiler steels in oxidation and molten salt environments at 900 C, whereas Singh [51], Singh et al [52][53][54] and Prakash et al [55] did the same on some Ni-based and Febased superalloys. The coatings were found to be effective in decreasing the corrosion rate in air as well as in molten salt (Na 2 SO 4 -60%V 2 O 5 ) environment, due to the formation of the protective oxide scales consisting of protective oxides such as Al 2 O 3 , NiO and NiAl 2 O 4 .…”

Section: Nickel Aluminide Coatingsmentioning

confidence: 99%

“…Studies on the oxidation and hot corrosion resistance of the Stellite-6 coatings on some boiler steels were conducted by Singh [50] in simulated as well as in actual boiler conditions, whereas Singh [51], Singh et al [52][53][54] and Prakash et al [55] investigated the oxidation and hot corrosion behaviour of some plasma sprayed Stellite-6 coated Ni-based and Febased superalloys. The coatings were found to be effective in all the environments.…”

Section: Cobalt Based Coatingsmentioning

confidence: 99%

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Use of plasma spray technology for deposition of high temperature oxidation/corrosion resistant coatings – a review

Singh¹,

Sidhu

Puri

et al. 2007

Materials & Corrosion

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109

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High temperature oxidation is one of the main failure modes of the hot-section components in gas turbines, boilers, waste incinerations, diesel engines, coal gasification plants, chemical plants and other energy generation systems. In such applications the use of Fe-, Ni-and Co-based alloys, especially of superalloys is well known. The superior mechanical strength and good corrosion resistance of the superalloys at high temperature make them favorites for such applications. However, the presence of combustion gases constitutes an extreme environment and hot corrosion is inevitable when superalloys are used at high temperatures for long durations of time. Therefore these alloys need to be protected against this type of oxidation. Several countermeasures have been suggested in the literature to combat the same. One such countermeasure against hot corrosion and oxidation constitutes the deposition of protective coatings on these alloys. Among the various techniques used for deposition of coatings, plasma spraying is a versatile technology that has been successful as a reliable cost-effective solution for many industrial problems. It allows the spraying of a wide range of high performance materials from superalloys and refractory intermetallic compounds to ceramics with continuously increasing commercial applications. Furthermore it does not cause deterioration of the substrate alloys, and relatively thick coatings can be formed with high deposition rates. In this paper the technique of plasma spraying has been detailed and the role of plasma sprayed coatings to arrest high temperature oxidation has been discussed with the help of a comprehensive literature survey. The main focus of this investigation is the studies related to plasma sprayed NiCrAlY, Ni-Cr, Nickel aluminide and Co-based coatings.

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