Christopher J. Cowen
United States Department of Energy
ParticlePorous mediumRayleigh numberAnalytical chemistryOpticsCeramicNimonicTransmission electron microscopySteam turbineCreepBoiler (power generation)Composite materialFlow velocityGrain boundary diffusion coefficientChemistryMetallurgyMaterials scienceSuperalloyScanning electron microscopeLaves phaseMischmetalTurbineSolid oxide fuel cellIngotInconelOxideAlloyCharacterization (materials science)Stress concentrationRidgeHomogenization (chemistry)Pulverized coal-fired boilerGrain boundaryNickelIon beamElectrochemistryCarbide5005 aluminium alloyNucleationParis' lawPrecipitation (chemistry)MicrostructureWeldabilityElectron microscope
8Publications
5H-index
163Citations
Publications 7
Newest
#1Paul D. JablonskiH-Index: 15
Last. Philip J. Maziasz (ORNL: Oak Ridge National Laboratory)H-Index: 42
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The high-temperature components within conventional supercritical coal-fired power plants are manufactured from ferritic/martensitic steels. To reduce greenhouse-gas emissions, the efficiency of pulverized coal steam power plants must be increased to as high a temperature and pressure as feasible. The proposed steam temperature in the DOE/NETL Advanced Ultra Supercritical power plant is high enough (760°C) that ferritic/martensitic steels will not work for the majority of high-temperature compon...
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#1Christopher J. Cowen (DOE: United States Department of Energy)H-Index: 5
#2Paul E. Danielson (DOE: United States Department of Energy)H-Index: 1
Last. Paul D. JablonskiH-Index: 15
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In this study, the microstructural evolution of Inconel alloy 740 during solution treatment and aging was characterized using optical and scanning electron microscopy. During double solution heat treatment, carbon is liberated from the dissolution of MC carbides during the first solution treatment at 1150 °C, and fine MC carbides are precipitated on gamma grain boundaries during the second solution treatment at 1120 °C. Due to the concurrent decrease in carbon solubility and the increase in the ...
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#1Jingxi Zhu (CMU: Carnegie Mellon University)H-Index: 8
#2Laura M. Fernandez Diaz (UNAM: National Autonomous University of Mexico)H-Index: 3
Last. Seetharaman Sridhar (CMU: Carnegie Mellon University)H-Index: 32
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In this study, the effects of Ce (270 ppm) and La (120 ppm) mischmetal additions on the transient oxidation of an Fe-22Cr alloy were investigated. The oxidation process was imaged in situ using a confocal scanning laser microscope. The oxidation microstructures were studied by scanning electron microscopy, energy dispersive X-ray analysis, and transmission electron microscopy with the help of focused ion beam in situ lift-out specimen preparation. The Ce and La, referred to as reactive elements,...
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#1Jingxi Zhu (CMU: Carnegie Mellon University)H-Index: 8
#2Laura M. Fernandez Diaz (CMU: Carnegie Mellon University)H-Index: 3
Last. Seetharaman Sridhar (CMU: Carnegie Mellon University)H-Index: 32
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cNational Energy Technology Laboratory, Albany, Oregon 97321-2198, USA Oxide ridges formed during the transient stage oxidation of the scale evolution in iron alloys containing 22 wt % Cr that were held at 800°C in dry air. The surface oxidation process was imaged in situ through a confocal scanning laser microscope, and the results were correlated with postexperiment characterization through scanning electron microscopy and the DualBeam system focus ion beam and electron beam analysis combined ...
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#1Paul D. Jablonski (DOE: United States Department of Energy)H-Index: 15
#2Christopher J. Cowen (DOE: United States Department of Energy)H-Index: 5
Last. John S. Sears (The New School)H-Index: 2
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Abstract Alloy 441 stainless steel (UNS S 44100) is being considered for application as an SOFC interconnect material. There are several advantages to the selection of this alloy over other iron-based or nickel-based alloys: first and foremost alloy 441ss is a production alloy which is both low in cost and readily available. Second, the coefficient of thermal expansion (CTE) more closely matches the CTE of the adjoining ceramic components of the fuel cell. Third, this alloy forms the Laves phase...
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#1Jairo Valdes (WVU: West Virginia University)H-Index: 2
#2Xingbo Liu (WVU: West Virginia University)H-Index: 34
Last. Paul D. JablonskiH-Index: 15
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By considering the mushy layer as a porous media with variable permeability, a Rayleigh number based freckling criterion was developed from the Flemings ratio between the magnitude of the interdendritic flow velocity and the solidification rate. The proposed form includes the effect of the tilt angle by preserving the anisotropic nature of the permeability tensor throughout the derivation and uses Poirier’s experimentally determined functional forms for the parallel and perpendicular components....
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