A Comparative Study on Ni-Based Coatings Prepared by HVAF, HVOF, and APS Methods for Corrosion Protection Applications

Sadeghimeresht, Esmaeil; Markocsan, Nicolaie; Nylén, Per

doi:10.1007/s11666-016-0474-9

Cited by 50 publications

(9 citation statements)

References 54 publications

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“…high velocity oxy-fuel (HVOF) [13][14], or atmospheric plasma spraying (APS) [16] have their own unique lamellar structures, and some in flight oxidation of the sprayed particles and certain process-dependent pore content is inevitable, making them less attractive for highly aggressive environments [17]. In comparison, coatings produced by the high velocity air-fuel (HVAF) method can be characterized by a relatively denser microstructure with less amount of oxides than the above thermal spray methods [18]. Although even the HVAF coatings are not entirely free from pores either [19], [20], among the above-mentioned processes, HVAF has the lowest flame temperature and highest flame velocity (T<1800 °C, V= 700-1500 m/s) [21].…”

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confidence: 99%

Chlorine-induced high temperature corrosion of HVAF-sprayed Ni-based alumina and chromia forming coatings

et al. 2018

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Chlorine-induced corrosion of HVAF-sprayed Ni21Cr and Ni5Al coatings was investigated in 5 vol.% O2 + 500vppm HCl + N2 with and without KCl at 600°C up to 168 h. Both coatings were protective in the absence of KCl. With KCl, Ni21Cr degraded through a two-stage mechanism: 1) formation of K2CrO4 followed by diffusion of Clthrough the oxide grain boundaries to yield chlorine and a nonprotective oxide, and 2) inward diffusion of chlorine though defects in the non-protective oxide, leading to breakaway oxidation. Cl-/Cl2 could not diffuse through the protective alumina scale formed on Ni5Al, hence the corrosion resistance increased.

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confidence: 99%

Chlorine-induced high temperature corrosion of HVAF-sprayed Ni-based alumina and chromia forming coatings

et al. 2018

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“…In a previous work performed in ambient air (in the absence of water vapor), the above two coatings had shown much better corrosion protection behavior, as reflected in their lower recorded mass gains (0.014 ± 0.004 and 0.008 ± 0.002 mg cm −2 for NiCr and NiCrAlY, respectively, after 168 h of exposure at 600 °C). The results obtained in the present study confirmed the detrimental effect of water vapor on the corrosion performance of the coatings.…”

Section: Resultsmentioning

confidence: 81%

“…Typically, the in situ oxides formed during thermal spraying are attributed to the particles being exposed to high temperature in ambient air environment in‐flight during the spraying process and/or because of pre‐existing oxygen in the feedstock material . The influence of the above is minimal in the investigated samples, as the dwell time in the HVAF process is short and the temperature (<1800 °C) is lower compared to other thermal spray processes, for example, HVOF (>2200 °C) and APS (>5000 °C) …”

Section: Resultsmentioning

confidence: 99%

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

Sadeghimeresht

Eklund

Simon

et al. 2018

Materials & Corrosion

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Isothermal oxidation behavior of NiCr and NiCrAlY coatings deposited onto low alloy 16Mo3 steel by high‐velocity air fuel (HVAF) process was investigated in 5% O2 + 20% H2O + N2 at 600 °C for 168 h. Whereas NiCrAlY showed lower mass gain compared to NiCr, both coatings succeeded in maintaining the integrity with the substrate during the exposure without any breakaway oxidation. A thin Cr‐rich oxide scale (Cr2O3) formed on NiCr, and a thin mixed oxide scale (Al2O3 with NiCr2O4) formed on NiCrAlY significantly increasing the oxidation protection in the presence of water vapor.

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“…The choice of the materials was to study the effect of the different alloying elements added to Ni and Fe on the corrosion performance of the bilayer coatings. More detailed information about the powders could be found in previous works [17,23,24]. …”

Section: Methodsmentioning

confidence: 99%

Electrochemical Behavior of Bilayer Thermal-Spray Coatings in Low-Temperature Corrosion Protection

Sadeghimeresht

Markocsan

2017

Coatings

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Cr 3 C 2 -NiCr coatings are greatly used to protect critical components in corrosive environments and to extend their lifetime and/or improve functional performance. However, the pores formed during spraying restrict the coating's applicability area for many corrosion protection applications. To overcome this technical challenge, bilayer coatings have been developed, in which an additional layer (the so-called "intermediate layer") is deposited on the substrate before spraying the Cr 3 C 2 -NiCr coating (the so-called "top layer"). The corrosion behavior of the bilayer coating depends on the composition and microstructure of each layer. In the present work, different single-layer coatings (i.e., Cr 3 C 2 -NiCr, Fe-and Ni-based coatings) were initially sprayed by a high-velocity air fuel (HVAF) process. Microstructure analysis, as well as electrochemical tests, for example, open-circuit potential (OCP) and polarization tests, were performed. The potential difference (∆E) had a great influence on galvanic corrosion between the top and intermediate layers, and thus, the coatings were ranked based on the OCP values (from high to low) as follows: NiCoCrAlY > NiCr > Cr 3 C 2 -NiCr > NiAl > Fe-based coatings (alloyed with Cr) > pure Ni. The Ni-based coatings were chosen to be further used as intermediate layers with the Cr 3 C 2 -NiCr top layer due to their capabilities to show high OCP. The corrosion resistance (R p ) of the bilayer coatings was ranked (from high to low) as follows: NiCoCrAlY/Cr 3 C 2 -NiCr > NiCr/Cr 3 C 2 -NiCr > NiAl/Cr 3 C 2 -NiCr > Ni/Cr 3 C 2 -NiCr. It was shown that splat boundaries and interconnected pores are detrimental for corrosion resistance, however, a sufficient reservoir of protective scale-forming elements (such as Cr or/and Al) in the intermediate layer can significantly improve the corrosion resistance.

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A Comparative Study on Ni-Based Coatings Prepared by HVAF, HVOF, and APS Methods for Corrosion Protection Applications

Cited by 50 publications

References 54 publications

Chlorine-induced high temperature corrosion of HVAF-sprayed Ni-based alumina and chromia forming coatings

Chlorine-induced high temperature corrosion of HVAF-sprayed Ni-based alumina and chromia forming coatings

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

Electrochemical Behavior of Bilayer Thermal-Spray Coatings in Low-Temperature Corrosion Protection

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