High temperature corrosion of coatings and boiler steels in reducing chlorine-containing atmosphere

Uusitalo, Mikko A.; Vuoristo, Petri; Mäntylä, T.

doi:10.1016/s0257-8972(02)00472-3

Cited by 89 publications

(66 citation statements)

References 22 publications

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“…The results showed that inward diffusion of Al occurred fairly rapidly and the Al concentration deceased from 10 wt.% in the as-deposited condition to about 4.1 wt.% after 625 hours and to 2 wt.% after 8760 hours (1 year), suggesting that these coatings have limited service life and a diffusion barrier interlayer coating is required to shut-off inward diffusion of Al. Consistent with these results a significant reduction of Al content in the Ni-20Cr-10Al nanocrystalline coating was observed in the first few hundred cycles of thermal exposure [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20].…”

Section: -2supporting

confidence: 61%

“…Hence, a systematic research effort is required to understand the factors (including coating chemistry) affecting the grain growth kinetics in the Ni-based nanocrystalline coatings. Sintering modeling indicated that the initial relative density of the as-processed coatings must be greater than 98% in order to achieve full density in less than two days of thermal exposure at 750º C. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] Figure 5-6 Representative backscatter SEM images of commercial coating A1 on 91 substrate material in the as-received condition (top left); after 1000 hours at 455º C (top right); after 1000 hours at 524º C) (bottom left); after 1000 hours at 593º C (bottom right) [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] Figure 5-7 Representative backscatter SEM Images of nanocrystalline coating B1 (Fe-37Ni-25Cr) on 91 substrate material in the as-received condition (top left); after 600 hours at 455º C (top right); after 600 hours at 524º C (bottom left); after 1000 hours at 593º C (bottom right) [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]…”

Section: Excutive Summarymentioning

confidence: 99%

“…The critical Al content is reduced from 5 wt.% to 3.5 wt.% Al for nanocrystalline coatings with grain size of ≈60 nm because of a greater Al diffusion kinetics through grain boundaries [2][3][4][5][6][7][8][9][10][11][12][13][14][15].…”

Section: -2mentioning

confidence: 99%

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Computation Modeling and Assessment of Nanocoatings for Ultra Supercritical Boilers

Shingledecker¹,

Gandy²,

Cheruvu³

et al. 2011

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The authors and project managers would like to acknowledge the guidance and support of Vito Cedro III, NETL project manager and Patricia Rawls, former project manager.iii ABSTRACT Forced outages and boiler unavailability of coal-fired fossil plants is most often caused by fire-side corrosion of boiler waterwalls and tubing. Reliable coatings are required for Ultrasupercritical (USC) application to mitigate corrosion since these boilers will operate at a much higher temperatures and pressures than in supercritical (565° C @ 24 MPa) boilers.Computational modeling efforts have been undertaken to design and assess potential Fe-Cr-Ni-Al systems to produce stable nanocrystalline coatings that form a protective, continuous scale of either Al 2 O 3 or Cr 2 O 3 . The computational modeling results identified a new series of Fe-25Cr-40Ni with or without 10 wt.% Al nanocrystalline coatings that maintain long-term stability by forming a diffusion barrier layer at the coating/substrate interface. The computational modeling predictions of microstructure, formation of continuous Al 2 O 3 Advanced coatings, such as MCrAl (where M is Fe, Ni, or Co) nanocrystalline coatings, have been processed using different magnetron sputtering deposition techniques. Several coating trials were performed and among the processing methods evaluated, the DC pulsed magnetron sputtering technique produced the best quality coating with a minimum number of shallow defects and the results of multiple deposition trials showed that the process is repeatable.scale, inward Al diffusion, grain growth, and sintering behavior were validated with experimental results.The cyclic oxidation test results revealed that the nanocrystalline coatings offer better oxidation resistance, in terms of weight loss, localized oxidation, and formation of mixed oxides in the Al 2 O 3The fire-side corrosion test results showed that the nanocrystalline coatings with a minimum number of defects have a great potential in providing corrosion protection. The coating tested in the most aggressive environment showed no evidence of coating spallation and/or corrosion attack after 1050 hours exposure. In contrast, evidence of coating spallation in isolated areas and corrosion attack of the base metal in the spalled areas were observed after 500 hours. These contrasting results after 500 and 1050 hours exposure suggest that the premature coating spallation in isolated areas may be related to the variation of defects in the coating between the samples. It is suspected that the cauliflower-type defects in the coating were presumably responsible for coating spallation in isolated areas. Thus, a defect free good quality coating is the key for the long-term durability of nanocrystalline coatings in corrosive environments. Thus, additional process optimization work is required to produce defect-free coatings prior to development of a coating application method for production parts. scale, than widely used MCrAlY coatings. However, the ultra-fine grain structure in these coatings, consisten...

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Section: -2supporting

confidence: 61%

Section: Excutive Summarymentioning

confidence: 99%

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Computation Modeling and Assessment of Nanocoatings for Ultra Supercritical Boilers

Shingledecker¹,

Gandy²,

Cheruvu³

et al. 2011

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“…Protective coatings are an efficient method preventing chloride corrosion, which has been used in the case of waste heat boilers. Coatings based on chromium and nickel alloys are thought to be the most efficient and the most frequently used ones; however, they are really expensive [6][7][8]. Significantly cheaper hybrid coatings based on oxides such as aluminum [9] are a promising alternative to metallic coatings.…”

Section: Resultsmentioning

confidence: 99%

“…In oxidizing atmosphere chromium forms chromium oxide (Cr 2 O 3 ) which is wellmatched to Al 2 O 3 ceramics. Chromium oxide obtained on the surface of a composite layer protects the structure and the entire material from oxidation [6].…”

Section: Metal-ceramic Functionally Graded Materials -Manufacturing mentioning

confidence: 99%

Metal-ceramic functionally graded materials – manufacturing, characterization, application

Chmielewski¹,

Pietrzak²

2016

Bulletin of the Polish Academy of Sciences Technical Sciences

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Abstract. Functionally graded materials (FGMs) belong to a new, continuously developing group of materials, finding application in various branches of industry. The idea of freely designing their construction profile, restricted only by the available manufacturing techniques, enables obtaining materials with composition and structure gradients having unprecedented properties. In this paper, selected results of works carried out by the authors and relating to the application of the developed metal-ceramic composites were presented in order to manufacture functionally graded materials for target purposes. Gradient structures with various construction profiles that can play different roles were produced on the basis on the following material pairs: Cr-Al2O3, NiAl-Al2O3 and Cu-AlN. Manufacturing conditions, microstructure characteristics and selected properties, crucial from the point of view of future applications, were presented.

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High temperature alloy chloridation at 850°C. Part I: Comparison of Ni‐based and Fe‐based alloy behaviour

Chevalier¹,

Ched'Homme

Bekaddour

et al. 2007

Materials & Corrosion

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Eight alloys were tested under Ar/Cl 2 atmosphere at 850 C for 15 min and 1 h. Their gross and net weights were evaluated together with the base metal consumption. Macroscopic and microscopic micrographs, associated with chemical analyses and X-ray diffraction gave the composition and microstructure of the corrosion products. Huge differences were observed if one compared the nickel based alloy behaviour to that of the iron based alloy. Molybdenum and tungsten could also play a role, but it was not clearly defined until now. A tentative evaluation of the best candidates will be given, according the experimental conditions of this work and the chosen criteria. A corrosion index was established after each observation and helped to classify the different material behaviour under chloridation. The Ni-based alloys possessed the best chloridation behaviour in the present conditions, followed by the Ni-based alloys containing more Cr and finally by the Fe-based materials. The chloridation behaviours were discussed according to the volatility of the chlorides species formed on the different alloys.

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High temperature corrosion of coatings and boiler steels in reducing chlorine-containing atmosphere

Cited by 89 publications

References 22 publications

Computation Modeling and Assessment of Nanocoatings for Ultra Supercritical Boilers

Computation Modeling and Assessment of Nanocoatings for Ultra Supercritical Boilers

Metal-ceramic functionally graded materials – manufacturing, characterization, application

High temperature alloy chloridation at 850°C. Part I: Comparison of Ni‐based and Fe‐based alloy behaviour

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