Effect of water vapor on the oxidation behavior of HVAF‐sprayed NiCr and NiCrAlY coatings

Sadeghimeresht, Esmaeil; Eklund, Johan; Simon, Julien Phother; Liske, Jesper; Markocsan, Nicolaie; Joshi, Shrikant V.

doi:10.1002/maco.201710005

Cited by 13 publications

(4 citation statements)

References 55 publications

(58 reference statements)

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“…1. (Mass gains of NiCr and NiCrAlY coatings are the same as presented in [11].) A 304L bulk sample was exposed for reference and exhibited a lower mass gain compared to the coated samples and was close to 0 mg/cm 2 (slightly negative value possibly due to Cr evaporation).…”

Section: % O 2 + 20% H 2 O + Nmentioning

confidence: 98%

“…The performance of HVAF-sprayed NiCr and NiCrAlY coatings in water vapourcontaining environment was therefore recently investigated by exposing them in 5% O 2 + 20% H 2 O + N 2 (bal.) at 600 °C for 168 h [11]. It was shown that both coatings formed thin protective oxides in the nanometre range.…”

Section: Oxidation In Water Vapour: Absence Of Kclmentioning

confidence: 99%

“…More recently, a new thermal spraying technique, HVAF (high-velocity air fuel), has been developed which can produce coatings with even lower degree of porosity (i.e. denser coating layer), minimal oxide formation during spraying and thus, reduced elemental depletion of the powder feedstock [10,11]. This is due to the relatively low particle temperature and dwell time compared to HVOF [10,12,13].…”

Section: Introductionmentioning

confidence: 99%

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High-Temperature Corrosion of HVAF-Sprayed Ni-Based Coatings for Boiler Applications

et al. 2019

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The present study investigates the initial corrosion behaviour of HVAF-sprayed NiCr, NiAl and NiCrAlY coatings in two different environments, O 2 + H 2 O and O 2 + H 2 O + KCl at 600 °C for up to 168 h in order to evaluate the possibility of utilizing such coatings in biomass-and waste-fired boilers. SEM/EDX analysis showed that all coatings displayed a protective behaviour in O 2 + H 2 O. Upon addition of KCl (O 2 + H 2 O + KCl), the corrosion behaviour of the NiCr coating drastically changed as it formed a thick oxide layer and displayed major chlorine diffusion down to the substrate. The NiCrAlY coating displayed a significantly better corrosion resistance with only minor oxide formation. The NiAl coating exhibited a protective behaviour similar to when exposed in the absence of KCl indicating that a thin protective oxide has formed on the coating surface. The performance of the NiAl and NiCrAlY coatings is promising for future studies with long-term exposures in more corrosive environments such as in a biomass-and waste-fired boiler.

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Section: % O 2 + 20% H 2 O + Nmentioning

confidence: 98%

Section: Oxidation In Water Vapour: Absence Of Kclmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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High-Temperature Corrosion of HVAF-Sprayed Ni-Based Coatings for Boiler Applications

et al. 2019

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“…For many years, the group's research focus was oriented towards the development of thermal barrier coatings (TBCs) primarily for aero-engine and land-based gas turbine applications [6][7][8][9]. The addition of ASPS and HVAF facilities in the past few years, along with the growing expertise of the team, has enabled expansion of the research base further into new areas of wear [10], corrosion [11], and repair [12]. Initial efforts to develop biocompatible [13], hydrophobic [14], and luminescent coatings [15] have also yielded extremely encouraging results.…”

Section: Introductionmentioning

confidence: 99%

Advanced Coatings by Thermal Spray Processes

Joshi

Nylén

2019

Technologies

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Coatings are pivotal in combating problems of premature component degradation in aggressive industrial environments and constitute a strategic area for continued development. Thermal spray (TS) coatings offer distinct advantages by combining versatility, cost-effectiveness, and the ability to coat complex geometries without constraints of other in-chamber processes. Consequently, TS techniques like high-velocity oxy-fuel (HVOF) and atmospheric plasma spray (APS) are industrially well-accepted. However, they have reached limits of their capabilities while expectations from coatings progressively increase in pursuit of enhanced efficiency and productivity. Two emerging TS variants, namely high-velocity air-fuel (HVAF) and liquid feedstock thermal spraying, offer attractive pathways to realize high-performance surfaces superior to those hitherto achievable. Supersonic HVAF spraying provides highly adherent coatings with negligible porosity and its low processing temperature also ensures insignificant thermal ‘damage’ (oxidation, decarburization, etc.) to the starting material. On the other hand, liquid feedstock derived TS coatings, deposited using suspensions of fine particles (100 nm–5 µm) or solution precursors, permits the production of coatings with novel microstructures and diverse application-specific architectures. The possibility of hybrid processing, combining liquid and powder feedstock, provides further opportunities to fine tune the properties of functional surfaces. These new approaches are discussed along with some illustrative examples.

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Advances in Corrosion-Resistant Thermal Spray Coatings for Renewable Energy Power Plants. Part I: Effect of Composition and Microstructure

2019

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Power generation from renewable resources has attracted increasing attention in recent years owing to the global implementation of clean energy policies. However, such power plants suffer from severe high-temperature corrosion of critical components such as water walls and superheater tubes. The corrosion is mainly triggered by aggressive gases like HCl, H 2 O, etc., often in combination with alkali and metal chlorides that are produced during fuel combustion. Employment of a dense defect-free adherent coating through thermal spray techniques is a promising approach to improving the performances of components as well as their lifetimes and, thus, significantly increasing the thermal/electrical efficiency of power plants. Notwithstanding the already widespread deployment of thermal spray coatings, a few intrinsic limitations, including the presence of pores and relatively weak intersplat bonding that lead to increased corrosion susceptibility, have restricted the benefits that can be derived from these coatings. Nonetheless, the field of thermal spraying has been continuously evolving, and concomitant advances have led to progressive improvements in coating quality; hence, a periodic critical assessment of our understanding of the efficacy of coatings in mitigating corrosion damage can be highly educative. The present paper seeks to comprehensively document the current state of the art, elaborating on the recent progress in thermal spray coatings for high-temperature corrosion applications, including the alloying effects, and the role of microstructural characteristics for understanding the behavior of corrosion-resistant coatings. In particular, this review comprises a substantive discussion on high-temperature corrosion mechanisms, novel coating compositions, and a succinct comparison of the corrosion-resistant coatings produced by diverse thermal spray techniques.

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Effect of water vapor on the oxidation behavior of HVAF‐sprayed NiCr and NiCrAlY coatings

Cited by 13 publications

References 55 publications

High-Temperature Corrosion of HVAF-Sprayed Ni-Based Coatings for Boiler Applications

High-Temperature Corrosion of HVAF-Sprayed Ni-Based Coatings for Boiler Applications

Advanced Coatings by Thermal Spray Processes

Advances in Corrosion-Resistant Thermal Spray Coatings for Renewable Energy Power Plants. Part I: Effect of Composition and Microstructure

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