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1.
Observations on the structural degradation of silver during simultaneous exposure to oxidizing and reducing environments 总被引:1,自引:0,他引:1
Prabhakar Singh Zhenguo Yang Vish Viswanathan Jeff W. Stevenson 《Journal of Materials Engineering and Performance》2004,13(3):287-294
The structural stability of silver (Ag) in dual atmosphere exposure conditions, which are representative of solid oxide fuel
cell (SOFC) current collector and gas seals, has been examined in the 600–800 °C temperature range. Experiments conducted
on Ag tubular sections exposed to flowing H2-3% H2O (inside the tube) and air (outside the tube) showed extensive porosity formation along the grain boundaries in the bulk
metal. Similar tubular sections, when exposed to air only (both inside and outside the tube), showed no bulk porosity or structural
changes. It is postulated that the porosity formation in the bulk metal is related to the formation of gaseous H2O bubbles due to simultaneous diffusion of hydrogen and oxygen followed by subsequent interaction resulting in the formation
of steam. Thermochemical processes that are responsible for structural degradation are presented and discussed. Based on experimental
observations, it is concluded that Ag metal may not provide adequate long-term structural stability under a dual-environment
condition that is typical of interconnects or gas seals in intermediate temperature SOFCs.
This paper was presented at the Fuel Cells: Materials, Processing, and Manufacturing Technologies Symposium sponsored by the
Energy/Utilities Industrial Sector & Ground Transportation Industrial Sector and the Specialty Materials Critical Technologies
Sector at the ASM International Materials Solutions Conference, October 13–15, 2003, in Pittsburgh, PA. The symposium was
organized by P. Singh, Pacific Northwest National Laboratory, S.C. Deevi, Philip Morris USA, T. Armstrong, Oak Ridge National
Laboratory, and T. Dubois, U.S. Army CECOM. 相似文献
2.
K. Scott Weil 《Journal of Materials Engineering and Performance》2004,13(3):309-315
The development of high-temperature solid-state devices for energy generation and environmental control applications has advanced
remarkably over the past decade. However, there remain a number of technical barriers that still impede widespread commercial
application. One of these, for example, is the development of a robust method of conductively joining the mixed-conducting
oxide electrodes that lie at the heart of the device to the heat resistant metal interconnect used to transmit power to or
from the electrodes and electrochemically active membrane. This study investigated the high-temperature electrical and microstructural
characteristics of a series of conductive glass composite paste junctions between two contact materials representative of
those used in solid-state electrochemical devices, lanthanum calcium manganate, and 430 stainless steel.
This paper was presented at the Fuel Cells: Materials, Processing, and Manufacturing Technologies Symposium sponsored by the
Energy/Utilities Industrial Sector & Ground Transportation Industrial Sector and the Specialty Materials Critical Technologies
Sector at the ASM International Materials Solutions Conference, October 13–15, 2003, in Pittsburgh, PA. The symposium was
organized by P. Singh, Pacific Northwest National Laboratory, S.C. Deevi, Philip Morris USA, T. Armstrong, Oak Ridge National
Laboratory, and T. Dubois, U.S. Army CECOM. 相似文献
3.
Zhenguo Yang Guanguang Xia Kerry D. Meinhardt K. Scott Weil Jeff W. Stevenson 《Journal of Materials Engineering and Performance》2004,13(3):327-334
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.
This paper was presented at the Fuel Cells: Materials, Processing, and Manufacturing Technologies Symposium sponsored by the
Energy/Utilities Industrial Sector & Ground Transportation Industrial Sector and the Specialty Materials Critical Technologies
Sector at the ASM International Materials Solutions Conference, October 13–15, 2003, in Pittsburgh, PA. The symposium was
organized by P. Singh, Pacific Northwest National Laboratory, S.C. Deevi, Philip Morris USA, T. Armstrong, Oak Ridge National
Laboratory, and T. Dubois, U.S. Army CECOM. 相似文献
4.
R. J. Smith C. Tripp A. Knospe C. V. Ramana A. Kayani Vladimir Gorokhovsky V. Shutthanandan D. S. Gelles 《Journal of Materials Engineering and Performance》2004,13(3):295-302
The requirements of low-cost and high-temperature corrosion resistance for bipolar interconnect plates in solid oxide fuel
cell stacks has directed attention to the use of metal plates with oxidation resistant coatings. The performance of steel
plates with multilayer coatings, consisting of CrN for electrical conductivity and CrAlN for oxidation resistance, was investigated.
The coatings were deposited using large area filtered arc deposition technology, and subsequently annealed in air for up to
25 hours at 800 °C. The composition, structure, and morphology of the coated plates were characterized using Rutherford backscattering,
nuclear reaction analysis, atomic force microscopy, and transmission electron microscopy techniques. By altering the architecture
of the layers within the coatings, the rate of oxidation was reduced by more than an order of magnitude. Electrical resistance
was measured at room temperature.
This paper was presented at the Fuel Cells: Materials, Processing, and Manufacturing Technologies Symposium sponsored by the
Energy/Utilities Industrial Sector & Ground Transportation Industrial Sector and the Specialty Materials Critical Technologies
Sector at the ASM International Materials Solutions Conference, October 13–15, 2003, in Pittsburgh, PA. The symposium was
organized by P. Singh, Pacific Northwest National Laboratory, S.C. Deevi, Philip Morris USA, T. Armstrong, Oak Ridge National
Laboratory, and T. Dubois, U.S. Army CECOM. 相似文献
5.
S. Elangovan S. Balagopal M. Timper I. Bay D. Larsen J. Hartivgsen 《Journal of Materials Engineering and Performance》2004,13(3):265-273
Interconnect development for planar solid oxide fuel cells is considered a vital technical area requiring focused research
to meet the performance and cost goals. A commercial ferritic stainless steel composition for oxidation resistance properties
was investigated by measuring the weight gain due to air exposure at fuel cell operating temperature. A surface treatment
process was found to produce a dense, adherent scale and to reduce the oxide scale growth rate significantly. A process was
also identified for coating the surface of the alloy to reduce the in-plane resistance and potentially to inhibit chromium
oxide evaporation. The combination of treatments provided a very low resistance through the scale. The resistance measured
was as low as 10 mΩ-cm2 air. The resistance value was stable over several thermal cycles. The treated samples were exposed to a variety of atmospheres
that were relevant in fuel cell operation to evaluate changes in scale morphology. Analysis of the scale after such exposure
showed the presence of a stable composition. When exposed to a dual atmosphere (air and hydrogen on opposite sides of the
metal sheet), however, the scale composition contained a mixture of phases. Additional process modifications are planned to
reduce the effect of dual-atmosphere exposure.
This paper was presented at the Fuel Cells: Materials, Processing, and Manufacturing Technologies Symposium sponsored by the
Energy/Utilities Industrial Sector & Ground Transportation Industrial Sector and the Specialty Materials Critical Technologies
Sector at the ASM International Materials Solutions Conference, October 13–15, 2003, in Pittsburgh, PA. The symposium was
organized by P. Singh, Pacific Northwest National Laboratory. S.C. Deevi, Philip Morris USA, T. Armstrong, Oak Ridge National
Laboratory, and T. Dubois, U.S. Army CECOM. 相似文献
6.
N. P. Brandon D. Corcoran D. Cummins A. Duckett K. El-Khoury D. Haigh R. Leah G. Lewis N. Maynard T. McColm R. Trezona A. Selcuk M. Schmidt 《Journal of Materials Engineering and Performance》2004,13(3):253-256
A novel metal-supported solid oxide fuel cell has been developed that is capable of operating at temperatures of 500–600 °C.
The rationale behind the materials used to construct this fuel cell type is given, and results are presented from cell testing
on hydrogen and reformed natural gas, including durability trials of some 2500 h duration. This new fuel cell variant is shown
to be tolerant of carbon monoxide, durable, robust to thermal and redox cycling, and capable of delivering technologically
relevant power densities.
This paper was presented at the Fuel Cells: Materials, Processing, and Manufacturing Technologies Symposium sponsored by the
Energy/Utilities Industrial Sector & Ground Transportation Industrial Sector and the Specialty Materials Critical Technologies
Sector at the ASM International Materials Solutions Conference, October 13–15, 2003, in Pittsburgh, PA. The symposium was
organized by P. Singh, Pacific Northwest National Laboratory, S.C. Deevi, Philip Morris USA, T. Armstrong, Oak Ridge National
Laboratory, and T. Dubois, U.S. Army CECOM. 相似文献
7.
W. Choi P. N. Enjeti J. W. Howze G. Joung 《Journal of Materials Engineering and Performance》2004,13(3):257-264
In this article, an impedance model of the proton exchange membrane fuel cell stack (PEMFCS) is proposed. The proposed study
employs an equivalent circuit of the PEMFCS derived by the frequency response analysis technique. An equivalent circuit for
the PEMFCS is developed to evaluate the effects of ripple currents generated by the power-conditioning unit. The calculated
results are then verified by means of experiments using a commercially available PEMFCS. The relationship between ripple current
and fuel cell performance, such as power loss and fuel consumption, is investigated. Experimental results show that the ripple
current can contribute up to a 6% reduction in the available output power.
This paper was presented at the Fuel Cells: Materials, Processing, and Manufacturing Technologies Symposium sponsored by the
Energy/Utilities Industrial Sector & Ground Transportation Industrial Sector and the Specialty Materials Critical Technologies
Sector at the ASM International Materials Solutions Conference, October 13–15, 2003, in Pittsburgh, PA. The symposium was
organized by P. Singh, Pacific Northwest National Laboratory, S.C. Deevi, Philip Morris USA, T. Armstrong, Oak Ridge National
Laboratory, and T. Dubois, U.S. Army CECOM. 相似文献
8.
Scott A. Speakman Robert D. Carneim E. Andrew Payzant Timothy R. Armstrong 《Journal of Materials Engineering and Performance》2004,13(3):303-308
The pyrochlore-perovskite binary systems La2Zr2O7-SrZrO3 and La2Zr2O7-LaYO3 were studied as potential high-temperature proton conductors. X-ray diffraction and direct current conductivity measurements
were used to develop empirical relationships between structure and conductivity. The solubilities of Sr in La2Zr2O7 and La in SrZrO3 were low, less than 0.1 mol fraction. The solubility of Zr in LaYO3 was at least 0.125 mol fraction, and the solubility of Y in La2Zr2O7 was at least 0.25 mol fraction. Y-doped La2Zr2O7 had the highest electrical conductivity, though no composition exceeded σ=3×10−4 S/cm at the target temperature of 600 °C. The effectiveness of Y as a dopant in La2Zr2O7 was limited because Y substituted for both La on the A-site and Zr on the B-site.
This paper was presented at the Fuel Cells: Materials, Processing, and Manufacturing Technologies Symposium sponsored by the
Energy/Utilities Industrial Sector & Ground Transportation Industrial Sector and the Specialty Materials Critical Technologies
Sector at the ASM International Materials Solutions Conference, October 13–15, 2003, in Pittsburgh, PA. The symposium was
organized by P. Singh, Pacific Northwest National Laboratory, S.C. Deevi, Philip Morris USA, T. Armstrong, Oak Ridge National
Laboratory, and T. Dubois, U.S. Army CECOM. 相似文献
9.
Wenquan Gong Srikanth Gopalan Uday B. Pal 《Journal of Materials Engineering and Performance》2004,13(3):274-281
Alternating current complex impedance spectroscopy studies were conducted on symmetrical cells of the type [gas, electrode/La1−x
Sr
x
Ga1−y
Mg
y
O3 (LSGM) electrolyte/electrode, gas]. The electrode materials were slurry-coated on both sides of the LSGM electrolyte support.
The electrodes selected for this investigation are candidate materials for solid oxide fuel cell (SOFC) electrodes. Cathode
materials include La1−x
Sr
x
MnO3 (LSM), La1−x
Sr
x
Co
y
Fe1−y
O3 (LSCF), a two-phase particulate composite consisting of LSM and doped-lanthanum gallate (LSGM), and LSCF + LSGM. Pt metal
electrodes were also used for the purpose of comparison. Anode material investigated was the Ni + Ce0.85Gd0.15O2 composite. The study revealed important details pertaining to the charge-transfer reactions that occur in such electrodes.
The information obtained can be used to design electrodes for intermediate temperature SOFCs based on LSGM electrolytes.
This paper was presented at the Fuel Cells: Materials, Processing, and Manufacturing Technologies Symposium sponsored by the
Energy/Utilities Industrial Sector & Ground Transportation Industrial Sector and the Specialty Materials Critical Technologies
Sector at the ASM International Materials Solutions Conference, October 13–15, 2003, in Pittsburgh, PA. The symposium was
organized by P. Singh, Pacific Northwest National Laboratory, S.C. Deevi, Philip Morris USA, T. Armstrong, Oak Ridge National
Laboratory, and T. Dubois, U.S. Army CECOM. 相似文献
10.
Gordon Israelson 《Journal of Materials Engineering and Performance》2004,13(3):282-286
This article presents the results of testing many commercially available and some experimental sulfur adsorbents. The desired
result of our testing was to find an effective method to reduce the quantity of sulfur in natural gas to less than 100 ppb
volume (0.1 ppm volume). An amount of 100 ppb sulfur is the maximum limit permitted for Siemens Westinghouse solid oxide fuel
cells (SOFCs). The tested adsorbents include some that rely only on physical adsorption such as activated carbon, some that
rely on chemisorption such as heated zinc oxide, and some that may use both processes. The testing was performed on an engineering
scale with beds larger than those used for typical laboratory tests. All tests were done at about 3.45 barg (50 psig). The
natural gas used for testing was from the local pipeline in Pittsburgh and averaged 6 ppm volume total sulfur. The primary
sulfur species were dimethyl sulfide (DMS), isopropyl mercaptan, tertiary butyl mercaptan, and tetrahydrothiophene. Some tests
required several months to achieve a sulfur breakthrough of the bed. It was found that DMS always came through a desulfurizer
bed first, independent of adsorption process. Since the breakthrough of DMS always exceeds the 100 ppb SOFC sulfur limit before
other sulfurs were detected, an index was created to rate the adsorbents in units of ppm DMS × absorbent bed volume. This
index is useful for calculating the expected adsorbent bed lifetime before sulfur breakthrough when the inlet natural gas
DMS content is known. The adsorbents that are included in these reports were obtained from suppliers in the United States,
the Netherlands, Japan, and England. Three activated carbons from different suppliers were found to have identical performance
in removing DMS. One of these activated carbons was operated at four different space velocities and again showed the same
performance. When using activated carbon as the basis of comparison for other adsorbents, three high-performance adsorbents
were found that removed about 100 to 150 times as much DMS as activated carbon before breakthrough.
This paper was presented at the Fuel Cells: Materials, Processing, and Manufacturing Technologies Symposium sponsored by the
Energy/Utilities Industrial Sector & Ground Transportation Industrial Sector and the Specialty Materials Critical Technologies
Sector at the ASM International Materials Solutions Conference, October 13–15, 2003, in Pittsburgh, PA. The symposium was
organized by P. Singh, Pacific Northwest National Laboratory, S.C. Deevi, Philip Morris USA, T. Armstrong, Oak Ridge National
Laboratory, and T. Dubois, U.S. Army CECOM. 相似文献
11.
High-temperature seals for solid oxide fuel cells (SOFC) 总被引:1,自引:0,他引:1
Raj N. Singh 《Journal of Materials Engineering and Performance》2006,15(4):422-426
A functioning solid oxide fuel-cell (SOFC) may require all types of seals, such as metal-metal, metal-ceramic, and ceramic-ceramic.
These seals must function at high temperatures between 600 and 900 °C and in the oxidizing and reducing environments of fuels
and air. Among the different types of seals, the metal-metal seals can be readily fabricated using metal joining, soldering,
and brazing techniques. However, metal-ceramic and ceramic-ceramic seals require significant research and development because
the brittle nature of ceramics/glasses can lead to fracture and loss of seal integrity and functionality. Consequently, any
seals involving ceramics/glasses also require significant attention and technology development for reliable SOFC operation.
This paper is prepared to primarily address the needs and possible approaches for high-temperature seals for SOFC and seals
fabricated using some of these approaches. A new concept of self-healing glass seals is proposed for making seals among material
combinations with a significant expansion mismatches.
This paper was presented at the ASM Materials Solutions Conference & Show held October 18–21, 2004 in Columbus, OH. 相似文献
12.
K. Scott Weil John S. Hardy Brian J. Koeppel 《Journal of Materials Engineering and Performance》2006,15(4):427-432
A key element in developing high-performance planar solid oxide fuel-cell stacks is the hermetic seal between the metal and
ceramic components. Two methods of sealing are commonly used: (a) rigid joining and (b) compressive sealing. Each method has
its own set of advantages and design constraints. An alternative approach is currently under development that appears to combine
some of the advantages of the other two techniques, including hermeticity, mechanical integrity, and minimization of interfacial
stresses in the joint substrate materials, particularly the ceramic cell. The new sealing concept relies on a plastically
deformable metal seal; one that offers a quasi-dynamic mechanical response in that it is adherent to both sealing surfaces,
i.e., non-sliding, but readily yields or deforms under thermally generated stresses. In this way, it mitigates the development
of stresses in the adjacent ceramic and metal components even when a significant difference in thermal expansion exists between
the two materials. The pre-experimental design of the seal, initial proof-of-principle results on small test specimens, and
finite-element analyses aimed at scaling the seal to prototypical sizes and geometries are described herein.
This paper was presented at the ASM Materials Solutions Conference & Show held October 18–21, 2004 in Columbus, OH. 相似文献
13.
总结了近年来本课题组在外加强化相非晶复合材料制备方面取得的主要研究结果。通过制备过程凝固控制获得了性能优异的非晶复合材料,其中金属W/Zr基非晶合金双连续相复合材料压缩强度达到3450MPa,压缩应变为48%;金属Ti/Mg基非晶合金双连续相复合材料压缩强度达到1750MPa,塑性应变为30%;8%Nb颗粒/Mg基非晶复合材料压缩强度达到900MPa,塑性应变为12.1%;6%SiC颗粒/Zr基非晶复合材料压缩强度达到2230MPa,塑性应变为3%。 相似文献
14.
The Effects of Pre-Oxidation and Alloy Chemistry of Austenitic Stainless Steels on Glass/Metal Sealing 总被引:1,自引:0,他引:1
D. F. Susan J. A. Van Den Avyle S. L. Monroe N. R. Sorensen B. B. McKenzie J. E. Christensen J. R. Michael C. A. Walker 《Oxidation of Metals》2010,73(1-2):311-335
An oxidation treatment is often performed on austenitic stainless steel prior to joining to alkali barium silicate glass to produce hermetic seals. The thin oxide formed during this pre-oxidation step acts as a transitional layer and a source of Cr and other elements that diffuse into the glass during the subsequent bonding process. Pre-oxidation is performed in a low pO2 atmosphere to avoid iron oxide formation; the final oxide is composed of Cr2O3, MnCr2O4 spinel, and SiO2. Significant heat-to-heat variations in the oxidation behavior of austenitic stainless steel were observed in this work, resulting in inconsistent glass/metal seal behavior. Twenty-five (25) stainless steel heats were examined including 304L, 316L, and experimental high sulfur alloys similar to 303SS. The objectives were to characterize the oxidation kinetics, the oxide morphologies, and compositions that affect glass/metal adhesion. It was found that poor glass sealing is associated with a more continuous layer of SiO2 at the metal/oxide interface. The effects of alloy chemistry, in particular Mn and Si concentrations, on glass/metal sealing behavior were empirically determined. A criterion based on the Mn/Si ratio was developed for use in selecting heats with good glass/metal bonding characteristics. To test this criterion, four other austenitic stainless steels were evaluated: 21-6-9 (also known by original Armco Steel Co. trade name Nitronic® 40), 22-13-5 (Nitronic® 50), Nitronic® 60, and Gall-Tough® (Carpenter Technology Corp.). These alloys have compositions significantly different from 300-series alloys, but they were still found to comply with the compositional guidelines developed for predicting glass/metal adhesion. 相似文献
15.
重金属污染土防渗注浆材料的力学性能 总被引:1,自引:0,他引:1
采用水泥基复合注浆材料对有色金属矿区重金属污染土进行防渗隔离处理。水泥、粉煤灰和矿渣等主要材料分别以不同组分与水玻璃混合形成3种复合注浆材料。采用倒杯法试验、无侧限抗压强度试验等方法研究不同水玻璃掺量、波美度以及粉煤灰和矿渣掺量对复合注浆材料凝胶时间和抗压强度等力学性能的影响规律。此外,采用XRD和SEM等测试方法,从材料的物相组成及微观结构方面进一步分析了复合注浆材料的力学特性。研究结果表明:凝胶时间随着水玻璃掺量和波美度的增大而延长;粉煤灰可以显著延长凝胶时间,但使用矿渣代替部分粉煤灰会使凝胶时间略有减少。当水玻璃掺量在20%以下时,复合注浆材料抗压强度随着水玻璃掺量的增加而增加,当水玻璃掺量超过20%,抗压强度显著降低;抗压强度随波美度的增加而增大;粉煤灰和矿渣可提高复合注浆材料的抗压强度。 相似文献
16.
R. Scott Lillard Darryl P. Butt 《JOM Journal of the Minerals, Metals and Materials Society》1998,50(12):56-59
Efforts to measure the real-time corrosion rates of alloy 718 during 800 MeV proton radiation at currents up to 1 mA are reported.
Specially designed corrosion probes, which incorporate ceramic seals, were mounted in a water manifold that allowed samples
to be directly exposed to the proton beam at the Los Alamos Neutron Science Center. The water system that supplied the manifold
provided a means for controlling water chemistry, measuring dissolved hydrogen concentration, and measuring the effects of
water radiolysis and water quality on corrosion rate. Real-time corrosion rate measurements during proton irradiation showed
an exponential increase in corrosion rate with proton-beam current. These results are discussed within the context of water
radiolysis at the diffusion boundary layer/beam-spot interface. However, additional factors that may influence these parameters,
such as oxide spallation and charge build-up in the passive film, are not ruled out.
Scott Lillard earned his Ph.D. in materials science and engineering from Johns Hopkins University in 1992. He is currently a technical
staff member at the Materials Corrosion and Environmental Effects Laboratory, Los Alamos National Laboratory.
Darryl P. Butt earned his Ph.D. in ceramic science from Pennsylvania State University in 1991. He is currently a technical staff member
at the Non-Proliferation and International Security Division, Los Alamos National Laboratory. 相似文献
17.
The development of abradeable gas turbine seals for higher temperature duties has been the target of an EU‐funded R&D project, ADSEALS, with the aim of moving towards seals that can withstand surface temperatures as high as ~ 1100°C for periods of at least 24,000 h. The ADSEALS project has investigated the manufacturing and performance of a number of alternative materials for the traditional honeycomb seal design and novel alternative designs. This paper reports results from two series of exposure tests carried out to evaluate the oxidation performance of the seal structures in combustion gases and under thermal cycling conditions. These investigations formed one part of the evaluation of seal materials that has been carried out within the ADSEALS project. The first series of three tests, carried out for screening purposes, exposed candidate abradeable seal materials to a simulated natural gas combustion environment at temperatures within the range 1050–1150°C in controlled atmosphere furnaces for periods of up to ~ 2,500 h with fifteen thermal cycles. The samples were thermally cycled to room temperature on a weekly basis to enable the progress of the degradation to be monitored by mass change and visual observation, as well as allowing samples to be exchanged at planned intervals. The honeycombs were manufactured from PM2000 and Haynes 214. The backing plates for the seal constructions were manufactured from Haynes 214. Some seals contained fillers or had been surface treated (e.g. aluminised). The second series of three tests were carried out in a natural gas fired ribbon furnace facility that allowed up to sixty samples of candidate seal structures (including honeycombs, hollow sphere structures and porous ceramics manufactured from an extended range of materials including Aluchrom YHf, PM2Hf, Haynes 230, IN738LC and MarM247) to be exposed simultaneously to a stream of hot combustion gas. In this case the samples were cooled on their rear faces to produce a temperature gradient through the seals and the samples were thermally cycled by switching the natural gas off every three hours. The total exposure period for each test was ~ 1,000 h, with seal face temperatures of 1000–1180°C. The performance of the materials in these tests was evaluated using visual observations and cross‐sectional examinations using optical and SEM/EDX techniques. The data gathered have included measurements of oxide thickness and metal‐loss on the exposed samples. A wide range of materials performances has been observed in these studies from minimal damage through to total destruction of samples. Overall, this study has shown that there is still a lot of development work required in order to move to higher temperature sealing systems structures in gas turbine applications. 相似文献
18.
The fundamentals of nanostructured materials processed by severe plastic deformation 总被引:3,自引:0,他引:3
Yuntian T. Zhu Terence G. Langdon 《JOM Journal of the Minerals, Metals and Materials Society》2004,56(10):58-63
Nanostructured materials produced by severe plastic deformation (SPD) are 100% dense, contamination-free, and sufficiently
large for use in real commercial structural applications. These materials are found to have high strength, good ductility,
superior superplasticity, a low friction coefficient, high wear resistance, enhanced high-cycle fatigue life, and good corrosion
resistance. This article reviews the structures and properties of nanostructured materials produced by SPD and reports recent
progress in determining the deformation mechanisms that lead to these superior mechanical properties.
For more information, contact Yuntian T. Zhu, Los Alamos National Laboratory, Materials Science and Technology Division, Los
Alamos, NM 87545; (505) 667-4029; fax (505) 667-2264; e-mail yzhu@lanl.gov. 相似文献
19.
J. L. Pierce L. P. Zawada R. Srinivasan 《Journal of Materials Engineering and Performance》2003,12(3):354-362
The durability of coated Nicalon silicon carbide fiber-reinforced carbon (SiC/C) as the flap and seal exhaust nozzle components
in a military aerospace turbine engine was studied. Test specimens machined from both a flap and a seal component were tested
for residual strength following extended ground engine testing on a General Electric F414 afterburning turbofan engine. Although
small amounts of damage to the protective exterior coating were identified on each component following engine testing, the
tensile strengths were equal to the as-fabricated tensile strength of the material. Differences in strength between the two
components and variability within the data sets could be traced back to the fabrication process using witness coupon test
data from the manufacturer. It was also observed that test specimens machined transversely across the flap and seal components
were stronger than those machined along the length. The excellent retained strength of the coated SiC/C material after extended
exposure to the severe environment in the afterburner exhaust section of an aerospace turbofan engine has resulted in this
material being selected as the baseline material for the F414 exhaust nozzle system. 相似文献
20.
Metal forming at the center of excellence for the synthesis and processing of advanced materials 总被引:2,自引:0,他引:2
D. A. Hughes M. E. Kassner M. G. Stout J. S. Vetrano 《JOM Journal of the Minerals, Metals and Materials Society》1998,50(6):16-21
The U.S. Department of Energy’s Office of Basic Energy Sciences recently established the Center for Excellence in the Synthesis
and Processing of Advanced Materials. Projects at the center typically include several national laboratories, industrial partners,
and universities; metal forming is one of eight projects within the center. This article describes the center’s metal forming
project, which emphasizes aluminum alloy forming, particularly as applicable to the automotive industry.
D.A. Hughes earned her Ph.D. in materials science at Stanford University in 1986. She is a principal member of the technical staff at
Sandia National Laboratories.
M.E. Kassner earned his Ph.D. in materials science at Stanford University in 1981. He is Northwest Aluminum Professor at Oregon State
University.
M.G. Stout earned his Ph.D. in materials science at the University of Minnesota in 1976. He is a staff member at Los Alamos National
Laboratory.
J. Vetrano earned his Ph.D. in metallurgy at the University of Illinois in 1990. He is a senior research scientist at Pacific Northwest
National Laboratory.
Editor’s Note: A hypertext-enhanced version of this article can be found on the TMS web site at www.tms.org/pubs/joumals/JOM/9806/Hughes-9806.html. 相似文献