Chloridation and oxidation of iron, chromium, nickel and their alloys in chloridizing and oxidizing atmospheres at 400–700°C

Zahs, A.; Spiegel, M.; Grabke, H. J.

doi:10.1016/s0010-938x(99)00142-0

Cited by 295 publications

(183 citation statements)

References 26 publications

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“…Gibbs free energies for metal chloride formation (and partial pressures of metal chlorides) at different temperatures (ranging from 550 to 850°C) for Fe, Ni, Cr, and Al are presented in Table 2, extracted from results given but other authors (Ref 29-33). A comparison of the Gibbs free energies of formation of the different divalent chlorides shows that the highest negative values correspond to CrCl 2 followed by FeCl 2 and NiCl 2 (Ref 22,31). According to these data, a less reactive behavior is expected for nickel than for iron and chromium.…”

Section: Cross-section Analysismentioning

confidence: 95%

“…The CrCl 2 can then be oxidized to form Cr 2 O 3 and the Cl 2 ; this latter diffuses inward to attack again the metal at the scale/metal interface. If the temperature is higher, volatilization of CrCl 2 is preponderant and the scale can be Cr depleted (Ref 22,(30)(31)(32)(33)(34) The AlCl 3 will diffuse outward due to its high volatility and be transferred into aluminum oxides subsequently at the outer part of the coating (scale). In these circumstances, aluminum moves toward to the outer surface of the coating.…”

Section: Cross-section Analysismentioning

confidence: 99%

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Performance of NiCrAlY Coatings Deposited by Oxyfuel Thermal Spraying in High Temperature Chlorine Environment

Habib

Damra

Carpio

et al. 2014

J. of Materi Eng and Perform

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A microcrystalline Ni-22Cr-10Al-1Y (wt.%) coating was deposited on AISI 304 stainless steel by the oxyfuel thermal spray technique. The deposited coating was subjected to heat treatment to improve the microstructure characteristics and its corresponding high-temperature properties. The isothermal high-temperature corrosion behavior at 650 and 700°C in synthetic air and in the presence of 1% Cl 2 was investigated using thermogravimetric analysis, x-ray diffraction, and scanning electron microscopy with energy-dispersive x-ray spectroscopy. The results indicated that the deposited NiCrAlY coating possessed acceptable oxidation-corrosion resistance at 650°C owing to the formation of extensive amounts of the protective oxide of Cr 2 O 3 ; NiO and a lesser amount of a Cr 1.12 Ni 2,88 metallic phase are also formed. At 700°C, the coating lost its protective characteristic because of the excessive consumption of thermodynamically stable phases by oxidation-chlorination process. In this case, the steel base and the coating were attacked by chlorine during the exposure time; the mass gain of the NiCrAlY coating was slightly higher and provided only a limited protection up to 11 h; thereafter, breakdown of the layer of oxides occurred and this is attributed to the formation of non-protective oxides mainly b-Fe 2 O 3 and Fe 21.33 O 32 and the depletion of chromium.

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Section: Cross-section Analysismentioning

confidence: 95%

Section: Cross-section Analysismentioning

confidence: 99%

Performance of NiCrAlY Coatings Deposited by Oxyfuel Thermal Spraying in High Temperature Chlorine Environment

Habib

Damra

Carpio

et al. 2014

J. of Materi Eng and Perform

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“…The thermodynamic stability of metal chlorides and oxides at a given temperature depends on the partial pressures of oxygen and chlorine 18 . The thermodynamic phase stability diagram for the Fe-OCl system at 540 C can be calculated using chemical reaction and equilibrium software and is shown in Previous work has included the development of custom experimental rigs 20 which attempt to replicate fluidized bed combustors as well tests in which samples are exposed to gas flows containing HCl or similar gases 21,22 .…”

Section: Figure 3 Equilibrium Vapor Pressures Of Cr and Fe Chlorides mentioning

confidence: 99%

“…Figure 3 also shows that iron chloride can be expected to diffuse outwards at a greater rate than chromium chloride due to its higher vapor pressure. It is important to note that the values presented are for pure metal chlorides; in the case of alloys, mixed chlorides will form and their vapor pressures can only be estimated from those presented here 18 . As chromium chlorides are less volatile than iron chlorides, they are oxidised closer to the metal surface 19 .…”

mentioning

confidence: 99%

Porosity-Based Corrosion Model for Alkali Halide Ash Deposits during Biomass Co-firing

O’Hagan¹,

O’Brien²,

Griffin

et al. 2015

Energy Fuels

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Publication InformationO'Hagan, CP, O'Brien, BJ, Leen, SB, Monaghan, RFD. (2015) 'A porosity-based corrosion model for alkali halide ash deposits during biomass co-firing'. Energy & Fuels,. PublisherAmerican Chemical Society AbstractThis paper presents a physics-based model to describe accelerated corrosion due to alkali halidecontaining deposits, which form on superheater tube walls during biomass co-firing. Increased rates of corrosion during the co-firing of peat with biomass have been identified as a limiting factor on the level of biomass which is viable to use at elevated temperatures. In the present work a synthetic salt, representative of a 70:30 peat-biomass mix, has been applied to pure iron samples in air at 540 C and 600 C. The corrosion layers have been examined using scanning electron microscopy (SEM), optical microscopy and energy dispersive X-ray (EDX) spectroscopy elemental mapping to provide insight into the material degradation and structure of the corrosion layer. Two distinct types of oxide are found to form on the iron substrate. Initially, a compact, uniform oxide layer forms over the substrate. As the process continues, this oxide layer degrades, leading to spalling which sees the broken oxide pieces mix with the salt layer. Additional test samples were examined without deposits as controls to highlight the accelerated rate of corrosion. Two modelling techniques are examined; the widely-used labyrinth factor method (LFM) and the newly proposed porosity-based corrosion method (PCM). The PCM method uses measurements of porosity and pore radius, coupled with a physically-based corrosion mechanism, to predict corrosion rates. Results from the two modelling techniques are compared and both agree satisfactorily with experimental measurements for times of up to 28 days.

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“…The inward penetration of chlorine-containing gases though the spinel forms FeCl 2 , which migrates outward towards the higher oxygen partial pressures at the ash/gas interface, where it decomposes to Fe 2 O 3 and Cl 2 . The Cl 2 penetrates back through the porous oxide to form more metal chlorides at the alloy surface, completing a cycle first called active oxidation by Lee and McNallan [71] and later studied in detail by Grabke and co-workers [72]. The difference between the oxidizing environment at the gas/scale interface and the reducing environment at the tube/scale interface is illustrated by experiments by Salmenoja and Mäkelä [67].…”

Section: Fluxing Of Otherwise-protective Cr 2 Omentioning

confidence: 99%

Improving Heat Recovery In Biomass-Fired Boilers

Keiser¹,

Sharp²,

Singbeil

et al. 2013

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Chloridation and oxidation of iron, chromium, nickel and their alloys in chloridizing and oxidizing atmospheres at 400–700°C

Cited by 295 publications

References 26 publications

Performance of NiCrAlY Coatings Deposited by Oxyfuel Thermal Spraying in High Temperature Chlorine Environment

Performance of NiCrAlY Coatings Deposited by Oxyfuel Thermal Spraying in High Temperature Chlorine Environment

Porosity-Based Corrosion Model for Alkali Halide Ash Deposits during Biomass Co-firing

Improving Heat Recovery In Biomass-Fired Boilers

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