Thin Sol–Gel Alumina Coating as Protection of a 9% Cr Steel Against Flue Gas Corrosion at 650 °C

Nofz, Marianne; Dörfel, I.; Sojref, Regine; Wollschläger, Nicole; Mosquera-Feijoo, Maria; Schulz, Wencke; Kranzmann, Axel

doi:10.1007/s11085-017-9799-0

Cited by 7 publications

(6 citation statements)

References 37 publications

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“…The excellent adhesive character of the layer can be attributed to a strong connection between steel, chromia, and alumina. Details on that issue can be found in our earlier study …”

Section: Resultsmentioning

confidence: 99%

Exposition of sol‐gel alumina‐coated P92 steel to flue gas: Time‐resolved microstructure evolution, defect tolerance, and repairing of the coating

Wollschläger

Nofz

Dörfel

et al. 2017

Materials & Corrosion

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Technically relevant P92 steel (9% Cr) was coated with a micron‐thick porous alumina layer prepared by sol‐gel technique and treated with flue gas (60 CO2‐30 H2O‐2 O2‐1 SO2‐7 N2 (mole fraction in %)) at 650 °C to mimic an oxyfuel‐combustion process. Local defects in the coating were marked using focused ion beam (FIB) technique and were inspected after exposition to hot flue gas atmosphere at 300, 800, and 1300 h, respectively. Local defects like agglomerated alumina sol particles tend to spall off from the coating uncovering the underlying dense chromia scale. Re‐coating was found to restore the protection ability from oxidation when repeatedly treated with hot flue gas. Cracks and voids did not promote the local oxidation due to the formation of crystalline Mn/S/O species within and on top of the coating. The protective character of the steel‐coating system is a result of (i) the fast formation of a dense chromia scale at the surface of sol‐gel alumina‐coated P92 steel bars in combination with (ii) the porous alumina coating acting as diffusion barrier, but also as diffusion partner in addition with (iii) fast Mn outward diffusion capturing the S species from flue gas.

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“…The excellent adhesive character of the layer can be attributed to a strong connection between steel, chromia, and alumina. Details on that issue can be found in our earlier study …”

Section: Resultsmentioning

confidence: 99%

Exposition of sol‐gel alumina‐coated P92 steel to flue gas: Time‐resolved microstructure evolution, defect tolerance, and repairing of the coating

Wollschläger

Nofz

Dörfel

et al. 2017

Materials & Corrosion

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“…The concentration of precursor vapour on the substrate surface is obtained by the assumption of zero gas-solid interfacial accumulation on the substrate surface. With this assumption, the rate of mass transport of precursor vapour from the gas phase of emulsion to substrate surfaces equals the rate of consumption of precursor vapour on the substrate surface due to thermal decomposition as shown in Equation (36). Here, the interfacial area of the substrate equals a Isub for the inner substrate surface and a Osub for the outer substrate surface.…”

Section: Specie Mass Balance Solvermentioning

confidence: 99%

“…Rearrangement of Equation (36) gives Equation ( 37) to obtain C AA surf in terms of concentration of precursor vapour in gas phase of local emulsion C AA emul . Substituting this value of C AA surf in Equation (34) gives Equation (38).…”

Section: Specie Mass Balance Solvermentioning

confidence: 99%

“…[27] The general techniques used for alumina coating on carbon steels are physical vapour deposition, chemical vapour deposition (CVD), sol-gel, plasma electrolytic oxidation, thermal spray, and pack cementation. [27][28][29][30][31][32][33][34][35][36][37][38] In the present work, a fluidizationbased CVD process is employed owing to its ability to achieve simultaneous deposition of alumina on inner and outer surfaces of a tubular carbon steel substrate. Fluidized bed sublimation and induction heating are employed to optimize precursor inventory.…”

Section: Introductionmentioning

confidence: 99%

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Fluidization‐based chemical vapour deposition for alumina coating on tubular carbon steel substrates—Modelling and validation

et al. 2022

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The degradation of carbon steels due to corrosion and gaseous permeation phenomena can be significantly reduced by a thin alumina coating. Tubular carbon steel structures, commonly employed in nuclear establishments are particularly vulnerable to chemical degradation on the inner surface due to the flow of corrosive fluids. In the present work, a fluidization-based chemical vapour deposition process is applied as a one-step solution for simultaneous chemical passivation of both inner and outer substrate surfaces meanwhile optimizing precursor inventory by utilizing fluidized bed sublimation and induction heating techniques. The process is studied by using a 2D-1D mathematical model, which has been validated with experimental results for different carbon steel grades. It was observed that there exists an optimum fluidization velocity for a specified initial mass fraction of precursor powder at which mass of alumina deposited per unit mass of precursor sublimated is maximized.

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“…However, early studies [10,11] have found that simple aluminide coatings cannot preserve the protection ability in harsh serving environment for a long period. Recently, Wollschläger et al [12,13] prepared a micron-thick porous alumina layer by sol-gel technique on P92 steel against flue gas corrosion. Results have shown that deposition of a thin and porous alumina coating enabled the formation of a dense and protective chromium oxide scale at the interface between coating and steel, which significantly improved the flue gas corrosion resistance.…”

Section: Introductionmentioning

confidence: 99%

Microstructure and Improved Thermal Shock Behaviour of an In Situ Formed Metal-Enamel Interlocking Coating

Wang

Zhang

Jiang

et al. 2021

Acta Metall. Sin. (Engl. Lett.)

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A novel metal-enamel interlocking coating was designed and prepared in situ by co-deposition of Ni-enamel composite layer and subsequent air spray of enamel with 10 wt% nanoscale Ni. During the firing process, the external enamel layer was melted and jointed with the enamel particles at the upper part of the Ni-plating layer to form the enamel pegs. Thermal shock tests of pure enamel, enamel with 10 wt% Ni composite and metal-enamel interlocking coatings were conducted at 600 °C in water and static air. The results indicated that the metal-enamel interlocking showed superior thermal shock resistance to both pure enamel and enamel with 10 wt% Ni composite coatings. The enhanced performance was mainly attributed to the advantageous effects of mechanical interlocking of the enamel pegs formed at the enamel/Ni-plating interface. Meanwhile, during thermal shock test, big clusters formed by nanoscale Ni agglomerations were oxidised to be a Ni/NiO core-shell structure while small single nanoscale Ni grains were oxidised completely, which both improved the thermal shock resistance of enamel coating significantly.

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Thin Sol–Gel Alumina Coating as Protection of a 9% Cr Steel Against Flue Gas Corrosion at 650 °C

Cited by 7 publications

References 37 publications

Exposition of sol‐gel alumina‐coated P92 steel to flue gas: Time‐resolved microstructure evolution, defect tolerance, and repairing of the coating

Exposition of sol‐gel alumina‐coated P92 steel to flue gas: Time‐resolved microstructure evolution, defect tolerance, and repairing of the coating

Fluidization‐based chemical vapour deposition for alumina coating on tubular carbon steel substrates—Modelling and validation

Microstructure and Improved Thermal Shock Behaviour of an In Situ Formed Metal-Enamel Interlocking Coating

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