Search for: cyclic-oxidation
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    Comparison of isothermal with cyclic oxidation behavior of “Cr-Aluminide” coating on inconel 738LC at 900 °C

    , Article Oxidation of Metals ; Volume 87, Issue 1-2 , 2017 , Pages 57-74 ; 0030770X (ISSN) Salehi Doolabi, M ; Ghasemi, B ; Sadrnezhaad, S. K ; Feizabadi, A ; HabibollahZadeh, A ; Salehi Doolabi, D ; AsadiZarch, M ; Sharif University of Technology
    Springer New York LLC  2017
    A two-step pack cementation technique was used to cover nickel-based IN-738LC superalloy with a Cr-aluminide coating layer. The IN-738LC/Cr-aluminide samples were oxidized at 900 °C for 350 and 700 h, isothermally, and 175 and 350 h, cyclically. Each cycle lasted for 25 h. Effects of the isothermal and the cyclic oxidation on (a) morphology, (b) new-phase formation, (c) weight gain, and (d) oxidation reactions were investigated by scanning electron microscopy, electron dispersive spectroscopy, X-ray diffraction, and weight gain measurements. From results, it was concluded that the oxygen attack was more severe during the cyclic oxidation than the isothermal procedure. Kinetics of the... 

    Cyclic oxidation characteristics of HVOF thermal-sprayed NiCoCrAlY and CoNiCrAlY coatings at 1000 °C

    , Article Journal of Alloys and Compounds ; Volume 746 , 25 May , 2018 , Pages 509-519 ; 09258388 (ISSN) Feizabadi, A ; Salehi Doolabi, M ; Sadrnezhaad, S. K ; Rezaei, M ; Sharif University of Technology
    Elsevier Ltd  2018
    Thermal-sprayed MCrAlY coatings have become widespread in various industries such as power plants, aeronautics, and oil and gas firms. High-temperature oxidation behavior of these coatings is therefore of significance. Spraying of two prevalent MCrAlY powders (NiCoCrAlY and CoNiCrAlY) on Hastelloy substrate by high velocity oxygen and fuel method and exposing them to 1000 °C air for resolving of their cyclic oxidation behavior are presented in this paper. The coatings were characterized by x-ray diffraction, scanning electron microscopy and energy-dispersive x-ray spectroscopy. The obtained oxidation kinetic indicated that at 1000 °C, the thermally sprayed NiCoCrAlY coating has greater... 

    Effect of Sr and Ca dopants on oxidation and electrical properties of lanthanum chromite-coated AISI 430 stainless steel for solid oxide fuel cell interconnect application

    , Article Ceramics International ; Volume 39, Issue 7 , September , 2013 , Pages 8123-8131 ; 02728842 (ISSN) Rashtchi, H ; Sani, M. A. F ; Dayaghi, A. M ; Sharif University of Technology
    Lanthanum chromite coating occupies a noticeable position as a ceramic coating on metallic interconnects in solid oxide fuel cells because of its excellent electrical conductivity, high oxidation resistance and desirable chemical stability in both oxidizing and reducing atmospheres. In the present work, a sol-gel process based on the dip-coating technique was used to prepare dense and uniform coatings on metallic alloy for interconnect application (AISI 430 type). The effect of strontium and calcium doping into lanthanum chromite structure on electrical conductivity and oxidation behavior of the coated sample has been investigated. The oxidation behavior was evaluated by cyclic oxidation... 

    Pre-treatment and oxidation behavior of sol-gel Co coating on 430 steel in 750°C air with thermal cycling

    , Article Surface and Coatings Technology ; Volume 206, Issue 16 , 2012 , Pages 3495-3500 ; 02578972 (ISSN) Dayaghi, A. M ; Askari, M ; Gannon, P ; Sharif University of Technology
    Research and development efforts continue to improve oxidation resistance and electrical conductivity of solid oxide fuel cell (SOFC) interconnects. This research evaluates the performance of a ferritic stainless steel (AISI 430 - a candidate SOFC interconnect material) with and without a Co coating (via sol-gel dip coating technique) with various pre-treatments, during cyclic oxidation exposures up to 750°C in laboratory air. A pre-treatment exposure of Co coated samples to a 750°C reducing atmosphere (prior to oxidation exposures) led to the formation of an effective Co-based spinel oxide coating that lowers oxidation rates by more than 40 times, and substantially lowers area specific...