High-temperature corrosion performance of HVAF-sprayed NiCr, NiAl, and NiCrAlY coatings with alkali sulfate/chloride exposed to ambient air

Jafari, Reza; Sadeghimeresht, Esmaeil

doi:10.1016/j.corsci.2019.06.021

Cited by 59 publications

(12 citation statements)

References 61 publications

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“…In this study, the corrosion performance was evaluated by comparing the thickness of formed corrosion layer on the coatings' surface, which were measured by using ImageJ software [41]. This method does not involve the common errors associated with the mass change records due to the remaining salt deposits and formation of volatile compounds during the test [42].…”

Section: Hot Corrosion Testmentioning

confidence: 99%

Development of hybrid electrodeposition/slurry diffusion aluminide coatings on Ni-based superalloy with enhanced hot corrosion resistance

Zakeri

Balashadehi

Rouhaghdam

2021

jcc

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Ni/Co-modified aluminide coatings were prepared on the Hastelloy-X superalloy by a combined process of electrodeposition and slurry aluminizing. In this regard, pure layers of Ni and Ni-50wt.%Co were initially applied via electrodeposition process and successive aluminization was carried out by a slurry technique. The scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques were used for the microstructural and chemical composition characterization of the specimens. The results of these analyses revealed that a compact and dense aluminide coating was formed with a two-layered structure containing the outer Al-rich β phase and inner interdiffusion zone. Moreover, the presence of pre-electrodeposited layers inhibited the outward diffusion flux of elements from the substrate and effectively suppressed the formation of Kirkendall pores. The hot corrosion studies of the obtained coatings indicated that the addition of a pre-electrodeposited layer could enhance the high-temperature corrosion performance of the coatings when exposed to sulfate salt.

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Section: Hot Corrosion Testmentioning

confidence: 99%

Development of hybrid electrodeposition/slurry diffusion aluminide coatings on Ni-based superalloy with enhanced hot corrosion resistance

Zakeri

Balashadehi

Rouhaghdam

2021

jcc

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“…It is known that KCl is more corrosive than K 2 SO 4 with higher stability. 86 Therefore, it is a good strategy to use some additives (i.e., ammonium sulfate) to convert alkali metal chlorides into sulfates through heterogeneous reactions, thus reducing the concentration of highly corrosive chlorinecontaining substances, especially in waste incinerators with high chlorine content. 87 2.2.…”

Section: Fireside Corrosion On Heat Transfer Tubesmentioning

confidence: 99%

Application of Coatings to Alleviate Fireside Corrosion on Heat Transfer Tubes during the Combustion of Low-Grade Solid Fuels: A Review

et al. 2020

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To address the energy and environmental issues related to the use of traditional fossil fuels, the thermal utilization of low-grade solid fuels such as low-rank coal, biomass, and municipal solid waste has gradually attracted much attention. During the combustion of the low-grade solid fuels, one of the major operation problems is the fireside corrosion on heat transfer tubes, which easily causes the frequent replacement of tubes and shutdown of boilers, largely reducing the energy and economic performances. In this review, the causes and mechanisms of corrosion were first clarified to provide a basis for mitigating the losses induced by the fireside corrosion, followed by the introduction of the preparation and properties of coatings, which show great potential to resist the invasion of corrosive species by attaching the reinforced surface to the tubes. To demonstrate the feasibility of the coating for hightemperature corrosion resistance, 94 kinds of coatings in more than 60 literature contributions were statistically analyzed. It was found that over 90% of anticorrosion coatings were prepared from thermal spraying techniques, and approximately three-quarters of the anticorrosion coatings were made of NiCr-based alloys. Many methods were reported to evaluate the corrosion resistance of coatings in literature, including mass gain/loss method, ash deposition method, contact angle method, and ash adhesion method. As for exploring the anticorrosion mechanisms of coatings, it was found that the protection was achieved by the formation of dense oxide scale, such as Cr 2 O 3 , NiO, MoO 2 , and so on. Furthermore, the application status of coatings in power plants was also summarized. According to the pilot-scale tests listed in literature, the obvious similarity is that the adopted technologies were mainly High velocity oxy-fuel (HVOF) spraying or cold spraying techniques, with almost all of the coated materials being NiCr-based alloys as well as a small portion of Fe/Co-based alloys. This indicates that the NiCr-based coatings prepared by HVOF spraying technique have been widely applied in power plants. In order to promote the large-scale application of anticorrosion coatings, it is prospective to focus on several key research aspects: (1) predicting the corrosion conditions from fuel compositions, (2) developing costeffective coatings, (3) establishing the systematic evaluation methods by laboratory tests, (4) achieving in-depth understanding of the anticorrosion mechanisms, and (5) conducting a comprehensive economic analysis.

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“…It can be seen that higher amount of un-melted particles are attached to the surface without flattening, compared to the lower deposited layers. This could be attributed to the insufficient particle hammering near the top surface of the coating [59]. Also, the coating contains some pin holes on the surface which can be caused by low impact energy of the un-melted particles.…”

Section: Characterization Of the Coatingsmentioning

confidence: 99%

Study on production of modified MCrAlY powder with nano oxide dispersoids as HVOF thermal spray feedstock using mechanical milling

Zakeri

Ghadami

Rouhaghdam

et al. 2020

Mater. Res. Express

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This paper investigates NiCoCrAlY-CeO 2 nanocomposite powders prepared by mechanical milling process. At first, micron-sized ceria powder was pre-milled to obtain nano-sized powders and then 1 wt% CeO 2 was mixed with the conventional NiCoCrAlY powder and milled under three sets of parameters. The conventional and milled powders were deposited on low carbon steel substrates by HVOF thermal spray technique. X-ray diffraction (XRD), scanning electron microscopy (SEM), fieldemission scanning electron microscopy (FESEM) and image analyzing method were used to characterize the prepared powders and coatings. Microstructural characterization showed that the milled powders underwent morphological and phase transitions. Through the microstructural and compositional analyses, it was found that a homogeneous distribution of CeO 2 nano-dispersoids in the NiCoCrAlY matrix was obtained. The resulting coatings showed that by using optimized milling parameters, required particle size and suitable morphology for thermal spray can be achieved.

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High-temperature corrosion performance of HVAF-sprayed NiCr, NiAl, and NiCrAlY coatings with alkali sulfate/chloride exposed to ambient air

Cited by 59 publications

References 61 publications

Development of hybrid electrodeposition/slurry diffusion aluminide coatings on Ni-based superalloy with enhanced hot corrosion resistance

Development of hybrid electrodeposition/slurry diffusion aluminide coatings on Ni-based superalloy with enhanced hot corrosion resistance

Application of Coatings to Alleviate Fireside Corrosion on Heat Transfer Tubes during the Combustion of Low-Grade Solid Fuels: A Review

Study on production of modified MCrAlY powder with nano oxide dispersoids as HVOF thermal spray feedstock using mechanical milling

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