Cyclic Corrosion and Chlorination of an FeCrAl Alloy in the Presence of KCl

Israelsson, Niklas; Unocic, Kinga A.; Hellström, Kristina; Svensson, Jan‐Erik; Johansson, Lars‐Gunnar

doi:10.1007/s11085-015-9554-3

Cited by 29 publications

(41 citation statements)

References 37 publications

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“…are present. In line with this, recent investigations have addressed the performance of preformed oxides 5,6,7,8 as well as coatings 9,10 on some commercial alloys as a way to improve their corrosion resistance. Some of these investigations provide indications of the ability of the preformed oxides or coatings to delay the onset of corrosion attack by the corrosive KCl deposit.…”

Section: Introductionmentioning

confidence: 95%

Pre-oxidation and its effect on reducing high-temperature corrosion of superheater tubes during biomass firing

Okoro

Kvisgaard

Montgomery

et al. 2017

Surface Engineering

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Superheater tubes in biomass-fired power plants experience high corrosion rates due to condensation of corrosive alkali chloride-rich deposits. To explore the possibility of reducing the corrosion attack by the formation of an initial protective oxide layer, the corrosion resistance of pre-oxidised Al and Ti-containing alloys (Kanthal APM and Nimonic 80A, respectively) was investigated under laboratory conditions mimicking biomass firing. The alloys were pre-oxidised at 900 °C for 1 week. Afterwards, pre-oxidised samples, and virgin non-pre-oxidised samples as reference, were coated with a synthetic deposit of KCl and exposed at 560 °C for 1 week to a gas mixture typical of biomass firing. Results show that pre-oxidation could hinder the corrosion attack; however, the relative success was different for the two alloys. While corrosion attack was observed on the pre-oxidised Kanthal APM, the pre-oxidised Nimonic 80A remained unaffected suggesting protection of the alloy from the corrosive environment.

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Section: Introductionmentioning

confidence: 95%

Pre-oxidation and its effect on reducing high-temperature corrosion of superheater tubes during biomass firing

Okoro

Kvisgaard

Montgomery

et al. 2017

Surface Engineering

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“…These types of steels are of course also intended for corrosive environments, such as when salt deposits are present on the material surface, making the results relevant also from a technological point of view [26][27][28][29][30][31][32].…”

Section: The Potential Of In-situ Esem Exposuresmentioning

confidence: 99%

In-situ investigation of the initial stages of KCl-induced corrosion of a chromia-forming steel at 450ºC using an environmental scanning electron microscope

et al. 2015

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In the present work, the initial stages of KCl-induced high temperature corrosion of a chromia-forming alloy (42Fe25Ni22CrWCuNbN), Sanicro 25, is investigated by means of in-situ Environmental Scanning Electron Microscope (ESEM) exposures in an O 2 /H 2 O gaseous environment up to 1 hour at 450°C. Prior to the exposures, KCl particles were sprayed on the samples. In order to perform reliable in-situ ESEM exposures, temperature calibration of the ESEM hot stage was done. Additionally, the in-situ results were validated by reference tube furnace exposures, and the feasibility of the ESEM technique for obtaining dynamic information regarding the chlorine-induced corrosion process of the steel was discussed. Relatively large oxide crusts, with sizes of several microns, formed in the vicinity of the KCl particles. In-between the KCl particles, a thin double oxide scale (20-100 nm), consisting of a top layer rich in iron oxide and a bottom layer rich in chromia, developed all over the surface of the alloy. Metal chloride was present beneath the thin base oxide, at the alloy/oxide interface, which shows the corrosive nature of KCl towards alloy Sanicro 25 in the studied environment. However, no extensive corrosion occurred at these locations after the short exposure times used in this work (1 h).

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“…Previous results also indicate that KCl itself may interact with the alloy, to cause alloy chlorination. 40 Alloy chlorination leads to weak adhesion of the oxide scale and eventual spallation, which results in rapid oxidation of the uncovered base material.…”

Section: Energy and Fuelsmentioning

confidence: 99%

Mitigation of Fireside Corrosion in Power Plants: The Combined Effect of Sulfur Dioxide and Potassium Chloride on the Corrosion of a FeCrAl Alloy

et al. 2014

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The corrosion behavior of a FeCrAl alloy (Kanthal APMT) was investigated in 5% O 2 with 40% H 2 O plus 300 ppm of SO 2 at 600°C in the presence or absence of KCl, and the results were also compared to exposures performed without SO 2 and KCl. The influence of preoxidation was also examined. The kinetics was followed using mass gain measurements, and the formed corrosion products were examined using XRD, SEM/EDX, AES, IC, and SIMS. The oxidation rate of Kanthal APMT was very low in O 2 /N 2 /H 2 O + 300 ppm of SO 2 , and the outward alumina growth appeared to be suppressed. Interestingly, no sulfur was detected at the scale/metal interface. KCl strongly accelerated the corrosion of Kanthal APMT in O 2 /H 2 O/N 2 at 600°C , forming K 2 CrO 4 and gaseous HCl. Chromate formation depletes the protective scale in Cr, triggering the formation of a fast growing iron-rich scale. Adding SO 2 suppressed the corrosion due to the conversion of the corrosive KCl to the stable K 2 SO 4 . If any K 2 CrO 4 was formed on the surface of the material initially, it was also rapidly converted to K 2 SO 4 . Preoxidation of Kanthal APMT had a strong beneficial effect on the subsequent exposure at 600°C in the presence of KCl and SO 2 , resulting in the formation of K 2 SO 4 and the evaporation of HCl and KCl. In summary, the alumina-forming FeCrAl material Kanthal APMT is not completely inert to KCl in an oxidizing SO 2 -containing atmosphere at 600°C. However, the corrosion rate is significantly lower than that of the commonly used chromia-forming alloy, 304L. Preoxidation decreases the corrosion rate even further, making Kanthal APMT a promising candidate material for combustion plant components, particularly from a corrosion point of view.

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Cyclic Corrosion and Chlorination of an FeCrAl Alloy in the Presence of KCl

Cited by 29 publications

References 37 publications

Pre-oxidation and its effect on reducing high-temperature corrosion of superheater tubes during biomass firing

Pre-oxidation and its effect on reducing high-temperature corrosion of superheater tubes during biomass firing

In-situ investigation of the initial stages of KCl-induced corrosion of a chromia-forming steel at 450ºC using an environmental scanning electron microscope

Mitigation of Fireside Corrosion in Power Plants: The Combined Effect of Sulfur Dioxide and Potassium Chloride on the Corrosion of a FeCrAl Alloy

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