Corrosion Behavior of HVOF-Sprayed and Nd-YAG Laser-Remelted High-Chromium, Nickel-Chromium Coatings

Tuominen, Jari; Vuoristo, Petri; Mäntylä, T.; Ahmaniemi, S.; Vihinen, Jorma; Andersson, Peter

doi:10.1361/105996302770348899

Cited by 43 publications

(24 citation statements)

References 7 publications

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“…In an effort to further improve the corrosion behaviour of coatings, a number of researchers have investigated the use of laser surface melting (LSM) [8][9][10][11]. LSM of thermally sprayed coatings has been shown to be able to significantly improve corrosion performance.…”

Section: Introductionmentioning

confidence: 99%

“…LSM of thermally sprayed coatings has been shown to be able to significantly improve corrosion performance. This improvement is attributed to elimination of interconnected porosity as well as a general homogenisation of the structure [8,9]. However, some LSM treatments produce no significant effects on corrosion performance [10] and in other cases LSM effects, such as the inhomogeneities produced by overlapping tracks, can degrade corrosion resistance [11].…”

Section: Introductionmentioning

confidence: 99%

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The effects of microstructural features on the performance gap in corrosion resistance between bulk and HVOF sprayed Inconel 625

Ahmed¹,

Bakare²,

McCartney³

et al. 2010

Surface and Coatings Technology

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A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription. AbstractIt is commonly observed that there is a performance gap between the corrosion resistance of thermally sprayed coatings and the equivalent bulk material. This is attributed to the significantly modified microstructure of the sprayed coatings. However, currently there is no detailed understanding of which aspects of microstructural modification are primarily responsible for this performance gap. In this work several deliberately microstructurally modified versions of the Ni-based superalloy Inconel 625 were produced. These were subjected to potentiodynamic electrochemical testing in 0.5M H 2 SO 4 to investigate the links between specific microstructural features and electrochemical behaviour. Samples were prepared by high velocity oxy-fuel (HVOF) thermal spraying, laser surface remelting using a high power diode laser and conventional powder sintering. Microstructural features were examined by optical and scanning electron microscopy and X-ray diffraction.Potentiodynamic testing was carried out on the following forms of Inconel 625: wrought sheet; HVOF sprayed coatings; sintered powder compacts; laser melted wrought sheet and HVOF sprayed coatings. Using the corrosion behaviour, i.e. passive current density, of the wrought sheet as a baseline, the performance of different forms of Inconel 625 were compared. It is found that a fine dendritic structure (with associated microsegregation) produced by laser remelting wrought sheet has no significant effect on corrosion performance.Up to 12% porosity in sintered powder samples increases the passive current density by a factor of only around 2. As observed previously, the passive current density of HVOF sprayed coatings is 20 -40 times greater. However, HVOF coatings subjected to laser surface remelting are found to have a passive current density close to that of wrought material. It is concluded that, whilst porosity in coatings produces some decrease in corrosion resistance, the main contributing factor is the galvanic corrosion of localised Cr-depleted regions which are associated with oxide inclusions within HVOF sprayed samples.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The effects of microstructural features on the performance gap in corrosion resistance between bulk and HVOF sprayed Inconel 625

Ahmed¹,

Bakare²,

McCartney³

et al. 2010

Surface and Coatings Technology

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“…11) Especially, most of thermal spray processes such as conventional flame spray, HVOF, plasma spray, and cold spray have widely used the Ni or nickel alloy particles (e.g., Ni 20 Cr, NiCrAlY, and NiCoCrAlY) for the surface treatment such as reclamation for a re-work and repair of damaged parts and bond coats. 10,[12][13][14] Therefore, the mechanical, tribological, and thermal properties of the thermal spray coatings were reported in the previous literature. 10,12,13) In particular, Ni 20 Cr particles dealt with in the present study have been widely used as a bond coat for a ceramic coating which can enhance corrosion resistance.…”

Section: Introductionmentioning

confidence: 99%

“…10,[12][13][14] Therefore, the mechanical, tribological, and thermal properties of the thermal spray coatings were reported in the previous literature. 10,12,13) In particular, Ni 20 Cr particles dealt with in the present study have been widely used as a bond coat for a ceramic coating which can enhance corrosion resistance. El-Hadj et al 15) conducted numerical analysis to elucidate the influence of gas temperature on the flattening of impinging molten droplets during the thermal spray process.…”

Section: Introductionmentioning

confidence: 99%

Flattening Characteristics of Ni<SUB>20</SUB>Cr Thermal-Sprayed Coating Layers on Preheated SCM415 Substrates

Shin

Lee

Wi³

et al. 2011

Mater. Trans.

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The preheating effect of SCM415 steel substrates on the flattening behavior of Ni 20 Cr flame-sprayed particles was investigated in a temperature range from 278 K to 523 K. In the present study, we calculated the particle temperature and velocity distributions of the continuous and discrete phases before collision with the substrate by using a computational fluid dynamics (CFD) code of Fluent (ver. 6.3.26). Particle velocity and gas temperature decreased rapidly in the radial direction while the particles traveled toward the substrate, suggesting that substrate size and distance from the nozzle should be carefully controlled to improve coating quality. The conventional flame spray gun was used to accelerate molten particles and K-type thermocouples were used to monitor the substrate temperature during a preheating process. Commercially available nickel-based Ni 20 Cr particles with a mean diameter of 45 mm and 20 mm were used for experiments to examine the particle size effect on the coating characteristics. Herein we present FE-SEM images of coated layers on the substrates. As the substrate preheating temperature increased, the flatter surface morphology was seen at the interface between substrate and coating layer because of better wetting and corresponding higher shear adhesion strength. Moreover, the splat morphology was significantly dependent on the particle size.

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“…Laser treatment can seal the coating by remelting either a thin surface layer or the entire thickness of the coating, hence eliminating porosity in the treated region [29,30]. The corrosion resistance of various thermal sprayed coatings has been improved by such laser treatment [28,[31][32][33][34]; however, the technique has not previously been applied to the problem of metal dusting.…”

Section: Introductionmentioning

confidence: 99%

Inhibition of metal dusting using thermal spray coatings and laser treatment

Voisey

Liu

Stott

2006

Surface and Coatings Technology

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Alloy 600 and Alloy 800H are susceptible to metal dusting. Both alloys were thermally sprayed with two different corrosion resistant coatings: Ni50Cr and Ni31Cr11Al0.6Y. Laser remelting was used to enhance further the effectiveness of these coatings to resist metal dusting by eliminating interconnected porosity and improving coating adhesion.Uncoated, coated and laser-treated coated samples of Alloy 600 and Alloy 800H were exposed to a mixed gas atmosphere (20% H 2, 80% CO at 650°C). Samples were examined in plan and cross-section using optical and scanning electron microscopy, electron probe microanalysis and X-ray diffraction. The extent of carbon deposition was tracked by mass difference measurements at intervals during exposure.The thermally sprayed coatings enhanced metal dusting resistance by acting as physical barriers to carbon ingress. The NiCrAlY coating performed well on both substrates. The NiCr coating itself underwent metal dusting and spalled from Alloy 800H due partly to CTE mis-match stresses. Laser treatment of both coatings successfully eliminated interconnected porosity and hence enhanced metal dusting resistance.

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Corrosion Behavior of HVOF-Sprayed and Nd-YAG Laser-Remelted High-Chromium, Nickel-Chromium Coatings

Cited by 43 publications

References 7 publications

The effects of microstructural features on the performance gap in corrosion resistance between bulk and HVOF sprayed Inconel 625

The effects of microstructural features on the performance gap in corrosion resistance between bulk and HVOF sprayed Inconel 625

Flattening Characteristics of Ni<SUB>20</SUB>Cr Thermal-Sprayed Coating Layers on Preheated SCM415 Substrates

Inhibition of metal dusting using thermal spray coatings and laser treatment

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