High temperature corrosion of thermally sprayed NiCr and FeCr coatings covered with a KCl–K2SO4 salt mixture

Varis, Tommi; Bankiewicz, Dorota; Yrjas, Patrik; Oksa, Maria; Suhonen, Tomi; Tuurna, Satu; Ruusuvuori, Kimmo; Holmström, Stefan

doi:10.1016/j.surfcoat.2014.11.012

Cited by 30 publications

(13 citation statements)

References 14 publications

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“…The HVAF-sprayed coatings in this study appear to exhibit a higher degree of porosity than some of the HVOF-and plasma-sprayed coatings used in previous studies [28,29,31]. However, in this study the cross sections of the coatings are not Fig.…”

Section: Comparison With Other Spraying Techniquescontrasting

confidence: 53%

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: Comparison With Other Spraying Techniquescontrasting

confidence: 53%

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

et al. 2019

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“…Since C22 is only sprayed by laser cladding technology, it has been discussed in the chapter on laser cladding. Diamalloy 4006, sprayed by HVOF-Diamond jet hybrid (DJ), shows excellent corrosion resistance, even better than IN625, in different experimental environments below 650 • C [51], especially in actual boilers. However, failure may occur when the coating is sprayed by HVOF-CJS and the temperature exceeds 750 • C [56].…”

Section: Ni-based Coatingsmentioning

confidence: 99%

“…With the increase of chromium content, the corrosion resistance of NiCr (>45Cr) coating is significantly improved, which is obviously better than IN625 coating [44,47,48,51,56]. The increase in Cr makes chromium oxide easier to form and can be replenished in time, even if it is consumed.…”

Section: Ni-based Coatingsmentioning

confidence: 99%

“…The amorphous phase of the coating protects the coating from corrosion due to the rapid formation of a dense, uniform, and stable high purity passivation film upon solidification. Many related documents mention the role of the amorphous phase of the Fe-based coating in improving the corrosion resistance of the coatings [42,[50][51][52], such as SHS9172 (Fe < 25Cr < 15W < 12Nb < 6Mo < 4C < 3Mn < 2Si wt.%) coatings, which can also obtain good high-temperature corrosion resistance by optimizing parameters of HVOF thermal spraying technology [50].…”

Section: Fe-based Coatingsmentioning

confidence: 99%

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Recent Development of Corrosion Factors and Coating Applications in Biomass Firing Plants

Yuan

Liu

et al. 2020

Coatings

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Due to global warming, biomass fuels are gradually being used to replace fossil fuels. However, high-temperature biomass corrosion is a crucial issue affecting its future application. In this article, different factors affecting boiler performance are summarized from various studies to guide the optimization of boiler parameters in practical applications, such as corrosive components and boiler temperatures. Meanwhile, different coating formation methods and materials are summarized to provide better protection strategies. The potential coating materials for future research are also discussed. The addition of other elements, such as Ti, Mo, and W, has the potential to accelerate the formation of oxide layers during high-temperature corrosion and directly slow down the corrosion rate. Future studies should focus on these elements containing materials.

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“…The rapid development of thermal spray processes offers attractive and cost-effective routes to avoid degradation of low alloy tubes by selecting appropriate coating chemistry and manufacturing process (Ref 16,17). A variety of thermal spray methods including atmospheric plasma spray (APS), arc spray and high-velocity air-fuel (HVOF) have been already used to fabricate corrosion resistant coatings (Ref [18][19][20][21][22]. High-velocity air-fuel (HVAF), a promising method to produce dense and adherent coating, works based on high-velocity impact of molten or semi-molten particles which could be used to apply a wide range of coating materials including Ni-based powders (Ref [23][24][25][26].…”

Section: Introductionmentioning

confidence: 99%

KCl-Induced High-Temperature Corrosion Behavior of HVAF-Sprayed Ni-Based Coatings in Ambient Air

et al. 2018

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KCl-induced high-temperature corrosion behavior of four HVAF-sprayed Ni-based coatings (Ni21Cr, Ni5Al, Ni21Cr7Al1Y and Ni21Cr9Mo) under KCl deposit has been investigated in ambient air at 600°C up to 168 h. The coatings were deposited onto 16Mo3 steel-a widely used boiler tube material. Uncoated substrate, 304L and Sanicro 25 were used as reference materials in the test environment. SEM/EDS and XRD techniques were utilized to characterize the as-sprayed and exposed samples. The results showed that the small addition of KCl significantly accelerated degradation to the coatings. All coatings provided better corrosion resistance compared to the reference materials. The alumina-forming Ni5Al coating under KCl deposit was capable of forming a more protective oxide scale compared to the chromia-forming coatings as penetration of Cl through diffusion paths was hindered. Both active corrosion and chromate formation mechanisms were found to be responsible for the corrosion damages. The corrosion resistance of the coatings based on the microstructure analysis and kinetics had the following ranking (from the best to worst):

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High temperature corrosion of thermally sprayed NiCr and FeCr coatings covered with a KCl–K2SO4 salt mixture

Cited by 30 publications

References 14 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

Recent Development of Corrosion Factors and Coating Applications in Biomass Firing Plants

KCl-Induced High-Temperature Corrosion Behavior of HVAF-Sprayed Ni-Based Coatings in Ambient Air

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