High temperature alloy chloridation at 850°C. Part I: Comparison of Ni‐based and Fe‐based alloy behaviour

Chevalier, Sébastien; Ched'Homme, S.; Bekaddour, A.; Amilain-Basset, K.; Buisson, Laurent

doi:10.1002/maco.200604012

Cited by 5 publications

(2 citation statements)

References 28 publications

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“…Stringer and Wright [26] attributed the spallation to poor adhesion of the cobaltous oxide scale to the metal surface due to the growth of oxide takes place at scale/gas interface rather than the scale/metal interface. According to Zahs et al [18,27] , the worse adhesion of the scales in chlorine based environment is attributed to the existence of CoCl 2 Á2H 2 O at the substrate-scale interface [23], but this phase was not found by XRD and hydrogenated HCl was the only viable chlorine-containing substance. There were three types of oxides identified on the surface of the exposed coating, i.e.…”

Section: Discussion Corrosion Behaviour Of the Bare Surfacesmentioning

confidence: 99%

Laser Clad and HVOF-Sprayed Stellite 6 Coating in Chlorine-Rich Environment with KCl at 700 °C

et al. 2017

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Laser clads and HVOF coatings from a stellite 6 alloy (Co-Cr-W-C alloy) on 304 stainless steel substrates were exposed both bare and with KCl deposits in 500 ppm HCl with 5% O 2 for 250 h at 700°C. SEM/EDX and PXRD analyses with Rietveld refinement were used for assessment of the attack and for analysis of the scales. The bare samples suffered from scale spallation and the scale was mostly composed of Cr 2 O 3 , CoCr 2 O 4 and CoO, although due to dilution haematite (Fe 2 O 3 ) was detected in the scale formed on the laser clad sample. A small amount of hydrated HCl was detected in bare samples. While the corrosion of the bare surfaces was limited to comparatively shallow depths and manifested by g and M 7 C 3 carbide formation, the presence of KCl on the surface led to severe Cr depletion from the HVOF coating (to 1 wt%). Both inward and outward diffusion of elements occurred in the HVOF coating resulting in Kirdendall voids at the coatingsteel interface. The laser clad sample performed significantly better in conditions of the KCl-deposit-induced corrosion. In addition to the oxides, CoCl 2 was detected in the HVOF sample and K 3 CrO 4 was detected in the laser clad sample. Thermodynamic calculations and kinetic simulations were carried out to interpret the oxidation and diffusion behaviours of coatings.

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Section: Discussion Corrosion Behaviour Of the Bare Surfacesmentioning

confidence: 99%

Laser Clad and HVOF-Sprayed Stellite 6 Coating in Chlorine-Rich Environment with KCl at 700 °C

et al. 2017

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“…Previous studies dealing with supercritical water and chlorine environments described that the corrosion rate is determined by the instability of the oxidic passivation layer in presence of chloridic species and the high polar character of the supercitical fluid [27,28]. The properties of the protective chrome oxide layer on metal surfaces is therefore an important factor for corrosion resistance of those materials [29].…”

Section: Properties Of the Passivation Layermentioning

confidence: 98%

Different corrosion behaviour of autoclaves made of nickel base alloy 718 in ammonobasic and ammonoacidic environments

Hertweck

Steigerwald

Alt

et al. 2014

The Journal of Supercritical Fluids

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High temperature alloy chloridation at 850°C

Chevalier¹,

Ched'Homme²,

Bekaddour³

et al. 2007

Materials & Corrosion

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The resistance of eight alloys against chloridation was tested at 850 C in Ar/Cl 2 (2.5% Cl 2 ) for 15 min. Pre-oxidation treatments were performed for 1 h and 8 h at 850 C in order to produce a thin, adherent and protective oxide scale able to improve the chloridation behaviour of the tested materials. The chloridised sample morphologies were compared to the morphologies observed on the non pre-oxidised samples. The alloys containing a large amount of iron did not exhibit any chloridation resistance, even after preoxidation, and were severely damaged. The nickel based alloys gave interesting results but were also attacked by chloride, probably by the "active oxidation" mechanism. The duration of the pre-oxidation treatment plays an important role, since the 8 h pre-oxidation appears more beneficial than the 1 h pre-oxidation, to delay the chloridation, probably because of the best quality of the oxide layer grown during 8 h. For the nickel based materials, the effects of chloride appear less severe than for the iron-based alloys, but are not stopped. The "active oxidation" mechanism is proposed to be responsible for the degradation of the tested materials.

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High temperature alloy chloridation at 850°C. Part I: Comparison of Ni‐based and Fe‐based alloy behaviour

Cited by 5 publications

References 28 publications

Laser Clad and HVOF-Sprayed Stellite 6 Coating in Chlorine-Rich Environment with KCl at 700 °C

Laser Clad and HVOF-Sprayed Stellite 6 Coating in Chlorine-Rich Environment with KCl at 700 °C

Different corrosion behaviour of autoclaves made of nickel base alloy 718 in ammonobasic and ammonoacidic environments

High temperature alloy chloridation at 850°C

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