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Access type: UnknownAuthor: search.filters.author.Muengjai, Angkana

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    Oxidation and Scale Adhesion of a Type 430 Stainless Steel in Ar–CO2 Gas Mixtures at 800 °C
    (2023-04-01)
    Wiman, Panya
    ;
    Muengjai, Angkana
    ;
    Srihathai, Padungaut
    ;
    Thublaor, Thammaporn
    ;
    Siripongsakul, Thamrongsin
    Biogas is an alternative source of fuel potentially used to run solid oxide fuel cells (SOFCs). It mainly consists of CH<inf>4</inf> and CO<inf>2</inf> which can degrade the SOFC interconnect, which is typically made of stainless steel. To investigate the effect of each gas constituent, we focussed here on the effect of CO<inf>2</inf> on high-temperature oxidation behavior of and scale adhesion on the stainless steel interconnect, Type 430 stainless steel. The samples studied were oxidised in CO<inf>2</inf> at contents of 5–100% at 800 °C. The oxidation kinetics were found to be parabolic with the rate constant increasing when the CO<inf>2</inf> content increased. The scale adhesion was assessed using a tensile-test method. The scale formed in the atmosphere containing higher CO<inf>2</inf> content exhibited poorer scale adhesion, as indicated by a lower strain initiating the first spallation and a larger spallation percentage after the first spallation took place. The worsened scale adhesion relates to pores formed at the scale/steel interface. The adhesion energies were further quantified giving the values of about 40–100 J m<sup>–2</sup>. Oxidation mechanisms were suggested based on the dependence of the parabolic rate constant on the oxygen partial pressure and the inward diffusion of carbon-bearing species.
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    Fabrication of Mn–Co Alloys Electrodeposited on AISI 430 Ferritic Stainless Steel for SOFC Interconnect Applications
    (2023-03-01)
    Thanedburapasup, Saravut
    ;
    Wetchirarat, Nattapol
    ;
    Muengjai, Angkana
    ;
    Tengprasert, Watcharapon
    ;
    Wiman, Panya
    Mn–Co alloys were electroplated on AISI 430 stainless steel using an electrodeposition technique with the aim to reduce oxidation and chromium volatilization. The electroplating parameters were designed to improve the coating quality. The increased current density with decreased MnSO<inf>4</inf> content resulted in a denser coating layer. A sample coated with 0.10 M CoSO<inf>4</inf> and 0.50 MnSO<inf>4</inf> at 350 mA cm<sup>−2</sup> showed the best oxidation resistance after being oxidized at 800 °C for 90 h. The X-ray diffraction (XRD) result revealed that the oxide growth on the surface of the coated samples mainly formed oxides of MnCo<inf>2</inf>O<inf>4</inf>, MnCr<inf>2</inf>O<inf>4</inf>, and Cr<inf>2</inf>O<inf>3</inf>. The chromium volatilization was evaluated by exposing the coated samples to humidified synthetic air at 800 °C for 96 h. The mass flux of Cr volatilization was on the order of 10<sup>−11</sup> g cm<sup>−2</sup> s<sup>−1</sup>. Furthermore, different heat treatments in O<inf>2</inf> and CO<inf>2</inf> atmospheres were compared. Annealing in CO<inf>2</inf> at 800 °C for 4 h helped increase the Mn–Co coating density. The relationship between the porosity and its failure behavior was also discussed.