Advanced Materials for Energy Conversion and Storage: Micro & Macro Reliability
Sponsored by: TMS Functional Materials Division, TMS: Energy Conversion and Storage Committee
Program Organizers: Amit Pandey, LG Fuel Cell Systems Inc.

Tuesday 8:30 AM
February 28, 2017
Room: 15A
Location: San Diego Convention Ctr

Session Chair: Amit Pandey, LGFCS; Dwayne Arola, University of Washington

8:30 AM Introductory Comments

8:35 AM  Keynote
Quantifying Alloy and Coating Degradation Mechanisms for Energy-Related Applications: Bruce Pint1; 1Oak Ridge National Laboratory
    To increase efficiency, a wide range of energy-related applications are pushing components to higher temperatures where environmental degradation can be life limiting. Unlike mechanical properties such as creep, there is no simple degradation parameter to capture the time-temperature-thickness limitations of candidate alloys. For simple high temperature oxidation, an issue is how to quantify the degradation rate in a manner useful to component designers. The Quadakkers reservoir model has been widely applied to alumina-forming and ferritic chromia-forming alloys and interdiffusion models such as NASA’s COSIM have been useful to study coatings. Case studies from a range of uncoated and coated alloys will be highlighted such as predicting 25-100 kh lifetimes of thin-walled heat exchangers and coatings on ferritic steels and superalloys. Research sponsored by the U. S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office & SunShot Initiative.

9:05 AM  Invited
Young's Modulus and Poisson's Ratio Changes in Machined Porous Microcracked Cordierite: Ryan Cooper1; Giovanni Bruno2; Yener Onel2; Axel Lange2; Thomas Watkins3; Amit Shyam3; 1University of Connecticut; 2BAM Federal Institute for Materials Research and Testing; 3Oak Ridge National Laboratory
    Porous microcracked ceramics represent a unique material class widely used in thermal management, power generation, and filtration applications. The bulk processing affects the grain orientation and porosity. Microstructural changes in porous cordierite caused by machining were characterized using microtensile testing, X-ray computed tomography and scanning electron microscopy. Young’s moduli and Poisson’s ratios were determined on ~215-380 um thick machined samples by combining digital image correlation and microtensile loading. The results provide evidence for an increase in microcrack density due to machining of the thin samples extracted from diesel particulate filter honeycombs.

9:30 AM  Invited
Precision High Temperature Elasticity Studies of Novel Ceramics: Joseph Gladden1; Sumudu Tennakoon1; Ashoka Karunarathne1; Amit Pandey2; Richard Goettler2; 1University of Mississippi; 2LG Fuel Cell Systems Inc.
    Elastic constant measurements, along with temperature and pressure derivatives, are of interest to both the physics and engineering communities. One of the most precise and efficient methods for such measurements is resonant ultrasound spectroscopy (RUS) in which the vibrational resonance spectrum of a sample is used to determine the full elastic tensor of the material. We will discuss several methodologies our lab has developed to make RUS measurements at temperatures up to 1300K and pressures up to 140 atm, with options to vary the environment of the sample. We report here a series of measurements of novel glass ceramics with applications in high temperature fuel cells between room temperature and 800 C at 1 atm pressure. Hysteresis and thermal cycling effects were observed depending on the synthesis history of the material. Attempts to perform similar measurements on porous ceramic samples will also be discussed.

9:55 AM Break

10:15 AM  Invited
Durability and Reliability of Materials and Components for Solid-Oxide Fuel Cells: Edgar Lara-Curzio1; 1Oak Ridge National Laboratory
    The reliability of solid-oxide fuel cells (SOFC) is dictated by their state of stress, which is the superposition of residual stresses, assembly stresses and operational stresses. Test techniques to measure residual stresses in SOFC materials and components and models to estimate operational stresses will enable the design and fabrication of SOFC stacks with enhanced reliability, robustness, and endurance to commercially-viable levels. In this presentation the applicability of different techniques to measure residual stresses in SOFC materials and components will be reviewed using a model system and potential strategies for reducing the magnitude of operational stresses will be discussed, including the use of non-conventional SOFC geometries that could be enabled by the advent of advanced manufacturing technologies.

10:40 AM  
Elastic-Anelastic-Inelastic Boundaries in Materials for High Temperature Applications: Amit Pandey1; Robert Wheeler2; Amit Shyam3; Thomas Stoughton4; 1LG Fuel Cell Systems Inc.; 2MicroTesting Solutions LLC; 3Oak Ridge National Laboratory; 4General Motors Research and Development Center
    The concept of a yield point in alloys is sometimes difficult to define because plastic deformation due to dislocation generation and movement is often a diffuse process rather than a singular event. Likewise, in the case of ceramics the non-linear stress- strain response is either due to extension of existing microcracks or formation of new microcracks. For most engineering design applications the 0.2% offset definition or other definitions of yield is favored and are subjective in nature. In this presentation we will introduce a new methodology and results on few high temperatures ceramics and alloys. We have already proved that at room temperature this new definition of yield is self-consistent in nature and, as such, provides an objective observation of the very onset of inelastic flow. The application of use of such a definition has proven to be very critical for in structural and functional alloys and ceramics used in automotive and fuel cell industries.

11:00 AM  Invited
Importance of Flaws to the Reliability of MMA Substrates: Alex Stark1; Sandra Murcia1; Amit Pandey2; Richard Goettler2; Dwayne Arola1; 1University of Washington; 2LG Fuel Cell Systems Inc.
    Discussions concerning the reliability of Solid Oxide Fuel Cells (SOFCs) are generally focused on the stability of the power output. However, the structural reliability of SOFCs is equally important. The structural behavior of these systems depends on the mechanical integrity of its ceramic components at room temperature, as well as across the range of the operating conditions. Manufacturing of these components can introduce flaws that are detrimental to their strength. In addition, residual stresses that result from processing can contribute to the effective stress state. There is limited detailed information regarding the flaws within these components and their relative contribution to the thermo-mechanical reliability over the desired lifetime of the SOFC stack. This talk will present results of experimental evaluations on the strength distributions of dense Magnesia Magnesium Aluminate (MMA) substrates. The flaw distribution and its importance to the reliability of the MMA components in SOFCs will also be discussed.