Additional Engine Testing of an Advanced Alloy for Microturbine Primary Surface Recuperators

2006 ◽  
Author(s):  
Wendy J. Matthews
Keyword(s):  
Operating Temperature ◽  
Engine Test ◽  
Test Results ◽  
Preliminary Estimate ◽  
Parabolic Model ◽  
Scale Growth ◽  
Temperature Oxide ◽  
Model Engine ◽  
Engine Testing ◽  
Elemental Depletion

HAYNES ® alloy HR-120 ® is being evaluated as a replacement for type 347 stainless steel for use in Microturbine Primary Surface Recuperators. The material has been characterized after being subjected to both steady-state and cyclic engine exposure in a Capstone C60 MicroTurbine™ operating at 100°F above the normal operating temperature. Oxide scale growth and elemental depletion has been analyzed and documented after 1,800 and 2,500 hours of exposure. A preliminary estimate of the remaining usable oxidation life has been made using a simplified parabolic model. Engine test results indicate that HR-120 has improved oxidation resistance and elemental stability.

Elemental Depletion

2011 ◽  
pp. 484-485
Author(s):  
Steven Charnley
Keyword(s):  
Elemental Depletion

scholarly journals Influence of galactic arm scale dynamics on the molecular composition of the cold and dense ISM III. Elemental depletion and shortcomings of the current physico-chemical models

2020 ◽  
Vol 497 (2) ◽  
pp. 2309-2319
Author(s):  
V Wakelam ◽  
W Iqbal ◽  
J-P Melisse ◽  
P Gratier ◽  
M Ruaud ◽  
...  
Keyword(s):  
Gas Phase ◽  
Molecular Form ◽  
Dense Medium ◽  
Chemical Model ◽  
Physical Conditions ◽  
Dense Cores ◽  
Chemical Models ◽  
Physico Chemical ◽  
Galactic Model ◽  
Elemental Depletion

ABSTRACT We present a study of the elemental depletion in the interstellar medium. We combined the results of a Galactic model describing the gas physical conditions during the formation of dense cores with a full-gas-grain chemical model. During the transition between diffuse and dense medium, the reservoirs of elements, initially atomic in the gas, are gradually depleted on dust grains (with a phase of neutralization for those which are ions). This process becomes efficient when the density is larger than 100 cm−3. If the dense material goes back into diffuse conditions, these elements are brought back in the gas phase because of photo-dissociations of the molecules on the ices, followed by thermal desorption from the grains. Nothing remains on the grains for densities below 10 cm−3 or in the gas phase in a molecular form. One exception is chlorine, which is efficiently converted at low density. Our current gas–grain chemical model is not able to reproduce the depletion of atoms observed in the diffuse medium except for Cl, which gas abundance follows the observed one in medium with densities smaller than 10 cm−3. This is an indication that crucial processes (involving maybe chemisorption and/or ice irradiation profoundly modifying the nature of the ices) are missing.

Micromechanical Modeling of Precipitation Hardened NiTiHf

2018 ◽  
Vol 915 ◽  
pp. 147-156
Author(s):  
Jobin K. Joy ◽  
Alexandros Solomou ◽  
Theocharis Baxevanis ◽  
Ibrahim Karaman ◽  
Dimitris C. Lagoudas
Keyword(s):  
High Temperature ◽  
Precipitation Hardening ◽  
Structural Effect ◽  
Micromechanical Modeling ◽  
Composition Distribution ◽  
Mechanical Responses ◽  
Novel Approach ◽  
Suitable Heat Treatment ◽  
Heat Treated ◽  
Elemental Depletion

Actuation response of NiTiHf high temperature SMAs can be enhanced by means of suitable heat treatment on the material through precipitation hardening. Heat treatments can be chosen carefully to improve the performance of the NiTiHf SMAs in order to meet the requirements of targeted applications to design more robust and efficient high temperature solid-state actuator systems. The present work aims to develop a novel approach to model and predict the behavior of heat-treated NiTiHf SMAs. The predictions of the thermomechanical response of NiTiHf SMAs are based on Representative Volume Elements (RVEs). The precipitated NiTiHf SMA is modeled as a composite consist of of thermo-elastic non-transforming precipitates and a polycrystalline SMA matrix. The structural effect of precipitates and the effect of Hf-concentration gradient resulted from Hf depletion during precipitation are included. The composition distribution resulting from the elemental depletion and the transformation temperature distributions in the SMA matrix are related. In the present work, these relations are developed from experimental measurements on several NiTiHf compositions. Thermo-mechanical responses of Ni50.3Ti29.7Hf20heat-treated at 500°C for 48h at different loading conditions are predicted and the correlations with experimental results demonstrate the validity of the proposed framework.

Laboratory experiments on cosmic dust and ices

2019 ◽  
Vol 15 (S350) ◽  
pp. 27-34
Author(s):  
Cornelia Jäger ◽  
Alexey Potapov ◽  
Gaël Rouillé ◽  
Thomas Henning
Keyword(s):  
Molecular Clouds ◽  
Laboratory Experiments ◽  
Recent Progress ◽  
Protoplanetary Disks ◽  
Interstellar Extinction ◽  
Cosmic Dust ◽  
Dust Grains ◽  
Emission And Absorption Spectra ◽  
Ir Emission ◽  
Elemental Depletion

AbstractThe existence of cosmic dust is attested by the interstellar extinction and polarization, IR emission and absorption spectra, and elemental depletion patterns. Dust grains are efficiently processed or even destroyed in shocks, molecular clouds, or protoplanetary disks. A considerable amount of dust has to be re-formed in the ISM. In various astrophysical environments, dust grains are covered by molecular ices and therefore contribute or catalytically influence the chemical reactions in these layers. Laboratory experiments are desperately required to understand the evolution of grains and grain/ice mixtures in molecular clouds and early planetary disks. This review considers recent progress in laboratory approaches to dust/ice experiments.

scholarly journals Chemical and physical properties of interstellar dust

2011 ◽  
Vol 7 (S284) ◽  
pp. 72-81 ◽  
Author(s):  
A. G. G. M. Tielens
Keyword(s):  
Interstellar Dust ◽  
Amorphous Materials ◽  
Dust Formation ◽  
Complex Interplay ◽  
Astronomical Observations ◽  
Accretion Process ◽  
Supernova Explosions ◽  
Stellar Sources ◽  
Elemental Depletion ◽  
Intercloud Medium

AbstractThe characteristics of interstellar dust reflect a complex interplay between stellar injection of stardust, destruction in the ISM, and regrowth in clouds. Astronomical observations and analysis of stardust isolated from meteorites have revealed a highly diverse interstellar and circumstellar grain inventory, including both amorphous materials and highly crystalline compounds (silicates and carbon). This review summarizes this dust budget and inventory. Interstellar dust is highly processed during its sojourn from its birthsite (stellar ejecta) to its incorporation into protoplanetary systems. Processing by strong shocks due to supernova explosions is particularly important. Sputtering by impacting gas ions in shocks in the intercloud medium of the ISM is counteracted by accretion in cloud phases and their balance sets the observed, interstellar, elemental depletion patterns. Astronomical and meteoritical-stardust evidence for these processes is reviewed and it is concluded that dust formation in the ISM is very rapid. Not surprisingly, the characteristics of interstellar dust are expected to vary widely reflecting local stellar sources, the effects of SNe processing, and the interstellar accretion process.

Experiments on Eurofer Steel Corrosion by Pb-16Li

2008 ◽  
Author(s):  
Alessandro Gessi ◽  
Antonio Aiello ◽  
Gianluca Benamati
Keyword(s):  
Liquid Metal ◽  
Steel Corrosion ◽  
Corrosion Mechanism ◽  
Time Step ◽  
Metallurgical Analysis ◽  
Higher Temperature ◽  
Lower Temperature ◽  
Metal Velocity ◽  
Elemental Depletion ◽  
Eurofer 97

Corrosion samples of the EUROFER 97 steel were exposed to Pb-16Li in the LIFUS II loop at 480°C and 550°C, with a liquid metal velocity of about 0,01 m/s in agreement with the foreseen operative conditions of the HCLL (Helium Cooled Lithium Lead) blanket concept. The specimens were extracted after 1500, 3000 and 4500 hours exposure at the lower temperature, while a further time step of 6000 hours was added at the higher temperature. After extraction, weight change measurements and metallurgical analysis were performed on the corrosion specimens. The experimental results demonstrated a linear corrosion mechanism, together with no preferential elemental depletion of the steel in contact with the liquid alloy. In this paper the results are reported and discussed with reference to previous similar works.

scholarly journals Conditions and extent of volatile loss from the Moon during formation of the Procellarum basin

2021 ◽  
Vol 118 (12) ◽  
pp. e2023023118
Author(s):  
Romain Tartèse ◽  
Paolo A. Sossi ◽  
Frédéric Moynier
Keyword(s):  
Isotopic Fractionation ◽  
The Moon ◽  
Magma Ocean ◽  
Heavy Isotope ◽  
Volatile Elements ◽  
Lunar Interior ◽  
Primitive Atmosphere ◽  
Evaporative Loss ◽  
Volatile Loss ◽  
Elemental Depletion

Rocks from the lunar interior are depleted in moderately volatile elements (MVEs) compared to terrestrial rocks. Most MVEs are also enriched in their heavier isotopes compared to those in terrestrial rocks. Such elemental depletion and heavy isotope enrichments have been attributed to liquid–vapor exchange and vapor loss from the protolunar disk, incomplete accretion of MVEs during condensation of the Moon, and degassing of MVEs during lunar magma ocean crystallization. New Monte Carlo simulation results suggest that the lunar MVE depletion is consistent with evaporative loss at 1,670 ± 129 K and an oxygen fugacity +2.3 ± 2.1 log units above the fayalite-magnetite-quartz buffer. Here, we propose that these chemical and isotopic features could have resulted from the formation of the putative Procellarum basin early in the Moon’s history, during which nearside magma ocean melts would have been exposed at the surface, allowing equilibration with any primitive atmosphere together with MVE loss and isotopic fractionation.

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