Tribological behavior of HVOF- and HVAF-sprayed composite coatings based on Fe-Alloy+WC–12% Co

Bolelli, Giovanni; Börner, T.; Milanti, Andrea; Lusvarghi, Luca; Laurila, Jussi; Koivuluoto, Heli; Niemi, Kari; Vuoristo, Petri

doi:10.1016/j.surfcoat.2014.03.037

Cited by 64 publications

(40 citation statements)

References 23 publications

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“…Presently, the runner blades made of martensitic stainless steel is widely used and are subjected to a predominantly cavitation phenomenon during the service. The potential of HVAF technology in terms of superior abrasion and slurry wear resistance has been reported recently (Ref [16][17][18][19][20][21]. While the effect of particle velocity, fuel/oxygen ratio, WC grain size, etc., on the performance of coatings processed through different HVOF systems has been studied extensively ( .…”

Section: Introductionmentioning

confidence: 99%

Effect of Spray Particle Velocity on Cavitation Erosion Resistance Characteristics of HVOF and HVAF Processed 86WC-10Co4Cr Hydro Turbine Coatings

et al. 2016

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The hydro plants utilizing silt-laden water for power generation suffer from severe metal wastage due to particle-induced erosion and cavitation. High-velocity oxy-fuel process (HVOF)-based coatings is widely applied to improve the erosion life. The process parameters such as particle velocity, size, powder feed rate, temperature, affect their mechanical properties. The high-velocity air fuel (HVAF) technology, with higher particle velocities and lower spray temperatures, gives dense and substantially nonoxidized coating. In the present study, the cavitation resistance of 86WC-10Co4Cr-type HVOF coating processed at 680 m/s spray particle velocity was compared with HVAF coatings made at 895, 960, and 1010 m/s. The properties such as porosity, hardness, indentation toughness, and cavitation resistance were investigated. The surface damage morphology has been analyzed in SEM. The cohesion between different layers has been examined qualitatively through scratch depth measurements across the cross section. The HVAF coatings have shown a lower porosity, higher hardness, and superior cavitation resistance. Delamination, extensive cracking of the matrix interface, and detachment of the WC grains were observed in HVOF coating. The rate of metal loss is low in HVAF coatings implying that process parameters play a vital role in achieving improved cavitation resistance.

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Section: Introductionmentioning

confidence: 99%

Effect of Spray Particle Velocity on Cavitation Erosion Resistance Characteristics of HVOF and HVAF Processed 86WC-10Co4Cr Hydro Turbine Coatings

et al. 2016

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“…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]. Recent advances in design and development of new HVAF guns have reduced the cost and enhanced the quality of coatings, resulting in booming markets for HVAF technology (Ref [27][28][29].…”

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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“…The corrosion performance of Coatings 2017, 7, 162 3 of 13 the bilayer coating was found to be dependent on the intermediate layer's microstructure [11]. It was also proposed that Cr and Al in NiCr and NiAl coatings, respectively, could form a corresponding passive layer of chromia or alumina to control the corrosion [20][21][22][23]. However, the synergistic effects of Cr and Al in the two-phase NiCoCrAlY microstructure, which contains microgalvanic cells, have not yet been studied.…”

Section: Introductionmentioning

confidence: 99%

“…The high-velocity air fuel (HVAF) process, which has been recently developed, is capable of producing very dense coatings with a minimum number of defects such as in situ oxides. It also ensures that the beneficial elements (e.g., Cr or Al) are preserved for the corrosion protection and not depleted while spraying [22].…”

Section: Introductionmentioning

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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Tribological behavior of HVOF- and HVAF-sprayed composite coatings based on Fe-Alloy+WC–12% Co

Cited by 64 publications

References 23 publications

Effect of Spray Particle Velocity on Cavitation Erosion Resistance Characteristics of HVOF and HVAF Processed 86WC-10Co4Cr Hydro Turbine Coatings

Effect of Spray Particle Velocity on Cavitation Erosion Resistance Characteristics of HVOF and HVAF Processed 86WC-10Co4Cr Hydro Turbine Coatings

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

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

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