Energy Materials 2017: Materials in Clean Power: Session II
Sponsored by: Chinese Society for Metals, TMS: Corrosion and Environmental Effects Committee
Program Organizers: Sebastien Dryepondt, Oak Ridge National Laboratory; Zhengdong Liu, China Iron & Steel Research Institute Group; Jeffrey Fergus, Auburn University; Jeffrey Hawk, U.S. Department of Energy, National Energy Technology Laboratory; Ji Zhang, China Iron and Steel Research Institute Group

Monday 2:00 PM
February 27, 2017
Room: 15A
Location: San Diego Convention Ctr

2:00 PM  Invited
High Temperature Oxidation of Ni-base Alloys and Stainless Steels in Supercritical CO2 for Power Systems Applications: Gordon Holcomb1; mer Doğan1; Joseph Tylczak1; Casey Carney2; Kyle Rozman1; Jeffrey Hawk1; 1National Energy Technology Laboratory; 2National Energy Technology Laboratory, AECOM
    Materials selection for components exposed to emerging supercritical CO2 (sCO2) power cycles is challenging since materials have not been commonly tested under these conditions. It is expected that these systems will use sCO2 as a working fluid at temperatures up to 800C and pressures up to 35 MPa. The high temperature oxidation behavior of chromia-forming alloys was investigated in sCO2 and atmospheric pressure CO2. Environments associated with both indirect and direct sCO2 power cycles were examined. The alloys studied included model alloys based on Ni (5-24)Cr, Ni22Cr(0-1.5)Si, Fe22Cr(0-1.5)Si, and Fe22Ni22Cr(0-1.5)Si, commercial iron-base stainless steels E-Brite, 304H and 600, and Ni-base alloys 230, 263, 282, 617, 625, 740H, and 800. Experimental work included coupon exposures up to 2000 hours, mass change determination, SEM and XRD. Distinctions in the materials response with pressure are discussed, along with the effects of chromium and silicon contents.

2:30 PM  
Corrosion of Energy System Materials in Supercritical Carbon Dioxide (sCO2): Benjamin Adam1; Lucas Teeter1; Sebastien Teysseyre2; Julie Tucker1; 1Oregon State University; 2Idaho National Laboratory
    The corrosion behavior of various high temperature corrosion-resistant alloy systems in sCO2 is being investigated. The alloys are compared and discussed based on the microstructure-mechanical property relationships examined, with consideration of their different metallurgical makeup. An autoclave with a testing capacity of 1 [L] was designed to operate at temperatures and pressures up to 850 [C] and 26.4 [MPa], respectively. Test samples were exposed to for up to 1500 hours. Examined alloys include Haynes Alloys 214, HR 224, 230, 282, 617, 625, 718, 740, 800H; and Stainless Steels 316 and 347. Characterization that has been employed includes incremental weight change and corrosion rate, microbalance measurements; oxide thickness, SEM and microbalance; surface morphology, optical microscopy and SEM; cross-sectional oxide morphology, TEM; chemistry, XPS EDX WDX; and phase identification, XRD and TEM.

2:50 PM  
Manipulating Creep through Modifying Gamma Prime Coarsening Rate in Haynes 282 for A-USC Power Plants: Jeffrey Hawk1; John Sears2; Paul Jablonski1; 1U.S. Department of Energy, National Energy Technology Laboratory; 2AECOM
    Haynes 282 has been proposed for Advanced Ultra Supercritical (A-USC) energy applications. Haynes 282 is a gamma prime strengthened nickel superalloy that also contains various carbide phases. The alloy has good high temperature strength and excellent creep resistance. However, components for use in A-USC conditions must also be microstructurally stable for long times (i.e., 100,000 hours). The research performed at NETL highlights changes in the Ti/Al ratio and its effect on gamma prime coarsening rate and concomitant effect on creep life. The important strengthening features in Haynes 282 have been documented through use of TEM and ThermoCalc modeling, and then speaks to its long-term stability (i.e., gamma prime and carbide coarsening) based on microstructures from various selected creep tests as well as from isothermal exposure experiments through 20,000 hours. The creep behavior of Ti/Al ratio modified Haynes 282 is then compared against creep in preferred chemistry Haynes 282.

3:10 PM  
Defect Chemistry of Black Anatase TiO2: An Ab Initio Study: Heechae Choi1; Taeseup Song2; Seungchul Kim3; 1Virtual Lab Inc. ; 2Yeungnam University; 3KIST
    Due to the strong photocatalytic activity and metallicity, black TiO2 is regarded as a promising material in wide ranges of energy and environmental applications. A number of experimental and theoretical works have been devoted to understanding the rich solar-light harvesting and high electrical conductivity of black TiO2. However, the origins of the defect states and metallicity are still in debate. In this study, using ab initio molecular dynamics simulations and electronic structure calculations based on DFT+U method, we investigated defect chemistry for high temperature reduction condition. We found that the positions of defect levels induced by oxygen vacancies are changed by lattice distortions and metallicity is mainly originated from a newly suggested defect complex, (Tii-VO)4+, which is stabilized in low oxygen partial pressure and high temperature.

3:30 PM Break

3:50 PM  Invited
Solid-State, High-Shear Manufacturing to Enable Lower Cost and Higher Performance Materials for Energy Conversion: Glenn Grant1; David Catalini1; Jens Darsell1; Anthony Reynolds1; Suveen Mathaudhu1; 1Pacific Northwest National Laboratory
    Over the last 30 years, research has shown that nanostructured materials, especially Ferritic ODS alloys, have superior performance in the harsh environments required by high temperature, energy conversion processes. However, due to the powder processing methods used to manufacture ODS alloys, their costs have been prohibitively high. For these alloys the barrier to their implementation is a lack of scalable, high-volume manufacturing methods. To realize the advantages available from nanostructured metals, new manufacturing processes need to be developed that can produce useable product forms (rod, tube, plate or sheet) that retain the nano- or high performance microstructures in the bulk materials. Recent research at PNNL and the University of South Carolina, has demonstrated a new Shear-Assisted Extrusion method that can fabricate bulk materials from nanostructured precursors (billet or powder). This presentation will outline the method and performance of extrusions made by the process, and its application to Ferritic ODS alloys.

4:20 PM  
Transient Liquid Phase Bonding of Ni-based-superalloy-H230 for Microchannel Heat Exchanger for Application in Supercritical CO2 Cycles: Monica Kapoor1; Omer Dogan1; Brian Paul2; Rajesh Saranam2; Patrick McNuff2; 1National Energy Technology Lab; 2Oregon State University
    The highly efficient supercritical CO2 (sCO2) cycles for power generation rely heavily on heat recuperation to increase efficiency. To this end, microchannel heat exchangers (HX) are proposed to enhance heat transfer between heat source and sCO2 and also to reduce equipment size. Microchannel-architectures are formed by a lamination process wherein micro-sized-channels are formed in shims, which are then stacked and bonded to form a monolithic structure. Transient-liquid-phase-bonding (TLP) is one such joining techniques for HX and was studied in Ni-based-superalloy-H230 for use in an HX operating at 700C-800C and 20-30 MPa pressure. Tensile testing of the stacks at 760C indicated an yield strength of ~ 86% that of the bulk H230. sCO2 exposures of these stacks in an autoclave at 720C and 25 MPa pressure for 500h – 1500 h were carried out. Microstructure characterization before and after corrosion was performed using x-ray diffraction, optical, scanning-electron and transmission-electron microscopy.

4:40 PM  Invited
Pb-Bi-Sb and Pb-Bi-Ge: Novel Alternative Alloys for Application as Heat-transport Fluids in Concentrated Solar Power Systems: Miroslav Popovic1; Alan Bolind1; Mark Asta1; Peter Hosemann1; Ruijie Shao1; 1UC Berkeley
    Liquid lead-bismuth eutectic (LBE) appears to be the best candidate among the heavy-metal-based alloys for heat transport in concentrated solar power systems, but even LBE has proven to be highly corrosive to steel pipes at the highest operating temperature (8000C) to which CSP developers would like to go (for increasing the efficiency of the power cycle). Here we present the results of corrosion experiments with two novel Pb-Bi-based alloys as potential alternatives to the existing LBE technology: lead-bismuth-antimony and lead-bismuth-germanium. Both alloys have been tested in static corrosion tests with candidate structural materials (Fe-Cr-Al-steels) at high temperatures, under oxygen-controlled conditions. The protective oxide scales that formed on these steels during exposure to these liquid alloys have been analyzed by various methods. Subsequently, the structural and diffusional properties of the scales have been characterized and compared to those formed in exposure to LBE.