Microstructure evolution and thermal stability of an Fe-based amorphous alloy powder and thermally sprayed coatings

Chokethawai, Komsanti; McCartney, D.G.; Shipway, P.H.

doi:10.1016/j.jallcom.2009.02.035

Cited by 65 publications

(24 citation statements)

References 26 publications

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“…Peak broadening is much likely due to the formation of a finely-structured supersaturated austenitic solid solution, whereas the underlying broad band probably reflects amorphous phase formation [11,12]. In the literature, similar broad bands in the diffraction patterns of thermally sprayed Fe-based alloys have indeed been univocally associated with the presence of significant amounts of amorphous phase, identified e.g., by TEM observation [14]. With regard to Fe-Ni-Cr-Mo-B-C, the narrower particle size distribution and the higher oxygen flow rate, which in turn increases the flame temperature, provide more extensive particle heating and melting, resulting in the observed microstructural changes.…”

Section: Microstructural and Mechanical Characterization Of Coatingsmentioning

confidence: 81%

“…The chemical composition of the present Fe-based powders includes large amounts of Cr in order to form hard fine-grained precipitates, Ni to form an austenitic matrix with superior mechanical and corrosion properties compared to ferritic structure, and B as hardening element by promoting the formation of an amorphous phase and by developing hard fine-grained precipitates [13,14]. The second composition was achieved by a customized addition of Mo in order to evaluate its effect on the properties of the resulting coatings.…”

Section: Introductionmentioning

confidence: 99%

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Microstructural Characteristics and Tribological Behavior of HVOF-Sprayed Novel Fe-Based Alloy Coatings

et al. 2014

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Thermally-sprayed Fe-based coatings have shown their potential for use in wear applications due to their good tribological properties. In addition, these kinds of coatings have other advantages, e.g., cost efficiency and positive environmental aspects. In this study, the microstructural details and tribological performances of Fe-based coatings (Fe-Cr-Ni-B-C and Fe-Cr-Ni-B-Mo-C) manufactured by High Velocity Oxygen Fuel (HVOF) thermal spray process are evaluated. Traditional Ni-based (Ni-Cr-Fe-Si-B-C) and hard-metal (WC-CoCr) coatings were chosen as references. Microstructural investigation (field-emission scanning electron microscope FESEM and X-Ray diffractometry XRD) reveals a high density and low oxide content for HVOF Fe-based coatings. Particle melting and rapid solidification resulted in a metastable austenitic phase with precipitates of mixed carbides and borides of chromium and iron which lead to remarkably high nanohardness. Tribological performances were evaluated by means of the ball on-disk dry sliding wear test, the rubber-wheel dry particle abrasion test, and the cavitation erosion wear test. A higher wear resistance validates Fe-based coatings as a future alternative to the more expensive and less environmentally friendly Ni-based alloys.

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Section: Microstructural and Mechanical Characterization Of Coatingsmentioning

confidence: 81%

Section: Introductionmentioning

confidence: 99%

Microstructural Characteristics and Tribological Behavior of HVOF-Sprayed Novel Fe-Based Alloy Coatings

et al. 2014

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“…The literature suggests that thermal spray can retain the amorphous fraction in the feedstock [7,[13][14][15]. It is suggested that this effect is due to the rapid cooling rates that occur when the molten particles from the spray process are incident on the substrate, on the order of 10 6 k s -1 [8].…”

Section: Resultsmentioning

confidence: 99%

HVOF and Laser-Cladded Fe–Cr–B Coating in Simulated Biomass Combustion: Microstructure and Fireside Corrosion

Reddy

Shipway

Davis³

et al. 2017

Oxid Met

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Biomass is often considered as a low carbon alternative to fossil fuels in the power industry. However, the heat exchangers in biomass plants can suffer from chloride-based aggressive fireside corrosion. A commercially available amorphous Fe-Cr-B alloy was deposited onto a stainless steel substrate by HVOF thermal spray and laser cladding. The controlled environment corrosion tests were conducted in a HCl-rich environment at 700°C for 250 h with and without KCl deposits. The samples were examined with XRD, SEM and EDX mapping to understand the corrosion mechanisms. In the absence of any deposits, the amorphous HVOF coating performed very well with a thin oxide growth, whereas the crystalline laser cladding suffered from *350 lm metal loss. The scales were composed of MnWO 4 , Fe 2 O 3 , Fe 3 O 4 and Cr 2 O 3 . When a KCl deposit was present, the HVOF-sprayed coating delaminated from the substrate and MnCl 2 was found in the scale.

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“…Laser treatment can result in crack formation as well as incomplete amorphisation [9,11]. An HVOF sprayed coating can be significantly different to the bulk material of the same composition as the spraying process can introduce porosity, oxides, regions of unmelted and resolidified material and a lamellar microstructure as well as producing the amorphous phase [18,19]. Such features are known to affect the corrosion behaviour [17] [18,20].…”

Section: Introductionmentioning

confidence: 99%

Corrosion behaviour of crystalline and amorphous forms of the glass forming alloy Fe43Cr16Mo16C15B10

Bakare

Voisey

Chokethawai

et al. 2012

Journal of Alloys and Compounds

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The corrosion behaviour of both crystalline and largely amorphous forms of the Fe-based glass forming alloy, Fe 43 Cr 16 Mo 16 C 15 B 10 alloy was investigated. Two different methods were used to induce transformation to the amorphous form of the alloy: laser melting and HVOF spraying. Both methods produced largely amorphous material, however the high brittleness of the alloy makes it susceptible to cracking during laser treatment, hence this technique is not suitable for largescale application. Potentiodynamic scanning showed that in 0.5M H 2 SO 4 and 3.5% NaCl electrolytes both amorphous forms of the alloy had better corrosion resistance (lower current densities for -200 to +1000mV SCE) compared to the crystalline material. The laser treated material and HVOF coating performed similarly in 3.5% NaCl. In 0.5M H 2 SO 4 the HVOF coating had a lower current density than the laser melted material for almost all of the potential range -300 to +1000mV SCE. The improved corrosion behaviour of the largely amorphous material is attributed to its homogeneity, and particularly to the elimination of the Mo-rich phase that underwent preferential corrosion in the crystalline form of the material.

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Microstructure evolution and thermal stability of an Fe-based amorphous alloy powder and thermally sprayed coatings

Cited by 65 publications

References 26 publications

Microstructural Characteristics and Tribological Behavior of HVOF-Sprayed Novel Fe-Based Alloy Coatings

Microstructural Characteristics and Tribological Behavior of HVOF-Sprayed Novel Fe-Based Alloy Coatings

HVOF and Laser-Cladded Fe–Cr–B Coating in Simulated Biomass Combustion: Microstructure and Fireside Corrosion

Corrosion behaviour of crystalline and amorphous forms of the glass forming alloy Fe43Cr16Mo16C15B10

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