The Experts below are selected from a list of 219 Experts worldwide ranked by ideXlab platform

Lorenz Singheiser - One of the best experts on this subject based on the ideXlab platform.

  • chromium vaporization from High Temperature Alloys i chromia forming steels and the influence of outer oxide layers
    Journal of The Electrochemical Society, 2007
    Co-Authors: Michael Stanislowski, Klaus Hilpert, Torsten Markus, E Wessel, Lorenz Singheiser
    Abstract:

    The vaporization of chromium species from chromia scales limits the applicability of chromia-forming steels at High Temperatures and is one of the major reasons for degradation in the development of planar solid oxide fuel cells (SOFCs). Cr(VI) vaporized from the interconnector is reduced at the cathode and deposits in the form of solid Cr(III)-oxide, thereby inhibiting the electrochemical processes. This work presents the first systematic study on the Cr vaporization of Cr-, Fe-, Ni-, and Co-based Alloys in air and in H 2 atmospheres at High Temperatures. The influence of outer oxide layers of (Cr,Mn) 3 O 4 , (Fe, Cr) 3 O 4 , Co 3 O 4 , TiO 2 , and Al 2 O 3 on the Cr vaporization is investigated. It is shown that the Cr vaporization of chromia-forming steels can be reduced by more than 90% by alloying. An estimate of the expected degradation effects on planar SOFC designs for the use of uncoated interconnector materials is used to show that in order to achieve the desired lifetimes for SOFC systems, additional Cr-retention coatings are necessary. Additionally, equilibrium vaporization measurements are carried out for pure Cr 2 O 3 (s) in humid air in order to elucidate controversies in the literature concerning the thermodynamic data of CrO 2 (OH) 2 (g).

Jeff W Stevenson - One of the best experts on this subject based on the ideXlab platform.

  • chemical stability of glass seal interfaces in intermediate Temperature solid oxide fuel cells
    Journal of Materials Engineering and Performance, 2004
    Co-Authors: Zhenguo Yang, Kerry D Meinhardt, Scott K Weil, Jeff W Stevenson
    Abstract:

    In intermediate Temperature planar solid oxide fuel cell (SOFC) stacks, the interconnect, which is typically made from cost-effective, oxidation-resistant, High-Temperature Alloys, is typically sealed to the ceramic positive electrode-electrolyte-negative electrode (PEN) by a sealing glass. To maintain the structural stability and minimize the degradation of stack performance, the sealing glass has to be chemically compatible with the PEN and alloy interconnects. In the present study, the chemical compatibility of a barium-calcium-aluminosilicate (BCAS) based glass-ceramic (specifically developed as a sealant in SOFC stacks) with a number of selected oxidation resistant High Temperature Alloys (and the yttria-stabilized zirconia electrolyte) was evaluated. This paper reports the results of that study, with a particular focus on Crofer22 APU, a new ferritic stainless steel that was developed specifically for SOFC interconnect applications.

Michael Stanislowski - One of the best experts on this subject based on the ideXlab platform.

  • chromium vaporization from High Temperature Alloys i chromia forming steels and the influence of outer oxide layers
    Journal of The Electrochemical Society, 2007
    Co-Authors: Michael Stanislowski, Klaus Hilpert, Torsten Markus, E Wessel, Lorenz Singheiser
    Abstract:

    The vaporization of chromium species from chromia scales limits the applicability of chromia-forming steels at High Temperatures and is one of the major reasons for degradation in the development of planar solid oxide fuel cells (SOFCs). Cr(VI) vaporized from the interconnector is reduced at the cathode and deposits in the form of solid Cr(III)-oxide, thereby inhibiting the electrochemical processes. This work presents the first systematic study on the Cr vaporization of Cr-, Fe-, Ni-, and Co-based Alloys in air and in H 2 atmospheres at High Temperatures. The influence of outer oxide layers of (Cr,Mn) 3 O 4 , (Fe, Cr) 3 O 4 , Co 3 O 4 , TiO 2 , and Al 2 O 3 on the Cr vaporization is investigated. It is shown that the Cr vaporization of chromia-forming steels can be reduced by more than 90% by alloying. An estimate of the expected degradation effects on planar SOFC designs for the use of uncoated interconnector materials is used to show that in order to achieve the desired lifetimes for SOFC systems, additional Cr-retention coatings are necessary. Additionally, equilibrium vaporization measurements are carried out for pure Cr 2 O 3 (s) in humid air in order to elucidate controversies in the literature concerning the thermodynamic data of CrO 2 (OH) 2 (g).

Rajiv Sharan Mishra - One of the best experts on this subject based on the ideXlab platform.

  • Friction Stir Welding of High Temperature Alloys
    Friction Stir Welding and Processing, 2014
    Co-Authors: Rajiv Sharan Mishra, Partha Sarathi De, Nilesh Kumar
    Abstract:

    High Temperature Alloys pose an interesting challenge to friction stir welding. In the previous chapters on aluminum and magnesium Alloys, we dealt with matrix elements that do not undergo allotropic transitions. This implies that the microstructural changes were limited to grain size and precipitates. Among High Temperature Alloys of industrial significance, the present chapter is limited to titanium Alloys and steels. Both alloy systems involve complexity of phase transformation, and therefore peak Temperature as well as cooling rate during friction stir welding makes a significant difference. Nickel base Alloys and copper Alloys are not covered in this book, but much of what is discussed applies to those. Students and readers can apply the treatment of Alloys covered in this book to nickel and copper Alloys by selecting the right type of physical metallurgy.

  • friction stir welding and processing science and engineering
    2014
    Co-Authors: Rajiv Sharan Mishra, Nilesh Kuma
    Abstract:

    Overview of friction stir welding and examples of adoptions Highlights and issues.- Fundamentals of the friction stir process process parameters, material flow and microstructural evolution, tool features and role.- Modeling and simulation of microstructural evolution during FSW/P.- Friction stir welding configurations and tool selection gaps and mismatches.- FSW of aluminum Alloys low strength Alloys, tailor welded blanks and tool/process design to maximize productivity, High strength Alloys and strategies to maximize joint efficiency.- FSW of magnesium Alloys.- FSW of High Temperature Alloys issues with tool materials and examples of titanium Alloys and steels.- Friction stir processing overview of derivative processes and potential.- Residual stresses and mitigation strategies.

Xiaobin Yang - One of the best experts on this subject based on the ideXlab platform.

  • j integral for spallation of protective layer subjected to metal dusting corrosion
    Materials & Design, 2017
    Co-Authors: Xiaobin Yang
    Abstract:

    Abstract The failure of High Temperature Alloys exposed to a carburizing gas atmosphere due to metal dusting corrosion was studied. A coupled model of the solid subjected to mechano-diffusional stresses was developed. For an interface crack between the protective film and the alloy substrate under an applied diffusion stress, the J -integral for film spallation was determined. The effects of interface crack length, film thickness and film mechanical properties on the J -integral (that is, the energy release rate) for spallation were investigated. Finally, comparisons of calculated J -integral values and experimental results are given and discussed.