Scientific and Technical Aerospace Reports Volume 39 April 6, 2001

20010026184 Oak Ridge National Lab., TN USA
Equilibrium-Based Model of Gas Reaction and Detonation
Trowbridge, L. D.; Apr. 01, 2000; 74p; In English
Report No.(s): DE00-763241; ORNL/TM-2000/123; No Copyright; Avail: Department of Energy Information Bridge
During gaseous diffusion plant operations, conditions leading to the formation of flammable gas mixtures may ocCASIonally
arise. Currently, these could consist of the evaporative coolant CFC-114 and fluorinating agents such as F2 and ClF3. Replacement
of CFC-114 with a non-ozone-depleting substitute is planned. Consequently, in the future, the substitute coolant must also be considered
as a potential fuel in flammable gas mixtures. Two questions of practical interest arise: (1) can a particular mixture sustain
and propagate a flame if ignited, and (2) what is the maximum pressure that can be generated by the burning (and possibly exploding)
gas mixture, should it ignite. Experimental data on these systems, particularly for the newer coolant candidates, are limited.
to assist in answering these questions, a mathematical model was developed to serve as a tool for predicting the potential detonation
pressures and for estimating the composition limits of flammability for these systems based on empirical correlations between
gas mixture thermodynamics and flammability for known systems. The present model uses the thermodynamic equilibrium to
determine the reaction endpoint of a reactive gas mixture and uses detonation theory to estimate an upper bound to the pressure
that could be generated upon ignition. The model described and documented in this report is an extended version of related models
developed in 1992 and 1999.
NTIS
Thermodynamic Equilibrium; Detonation; Flammable Gases; Gas Mixtures; Chemical Reactions
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METALS AND METALLIC MATERIALS
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20010021858 NASA Marshall Space Flight Center, Huntsville, AL USA
High Undercooling of Ni59Nb41 Alloy in a Containerless Electrostatic Levitation Facility
Robinson, M. B., NASA Marshall Space Flight Center, USA; Li, D., NASA Marshall Space Flight Center, USA; Rogers, J. R.,
NASA Marshall Space Flight Center, USA; Hyers, R. W., NASA Marshall Space Flight Center, USA; Savage, L., NASA Marshall
Space Flight Center, USA; Rathz, T. J., Alabama Univ., USA; [2000]; 1p; In English; No Copyright; Avail: Issuing Activity; Abstract
Only
Utilizing the containerless electrostatic levitation facility at NASA/MSFC, we were able to undercool the Ni59Nb41 (atomic)
alloy by 210 K which was 160 degrees farther than the results of previous flight experiments. Undercoolings were clustered around
200 K during the repeated melting-freezing cycles on a single sample. Prior to this work, a metastable liquid separation had been
presumed to limit the undercooling of this alloy. However, microstructural observations have revealed that undercooling was limited
by crystal nucleation.
Author
Supercooling; Nickel Alloys; Niobium Alloys; Containerless Melts; Electrostatics; Levitation
20010023429 Lehigh Univ., Engineering Research Center, Bethlehem, PA USA
Innovative HPS-70W Ford City Bridge Demonstration Project: Improved Weldability Using Optimized Weld Metal
Strength Final Report
Kaufmann, E. J., Lehigh Univ., USA; Pense, A. W., Lehigh Univ., USA; Oct. 2000; 100p; In English; Original contains color
illustrations
Report No.(s): PB2001-102216; ATLSS-00-08; No Copyright; Avail: CASI; A02, Microfiche; A05, Hardcopy
In 1997, the Pennsylvania Department of Transportation proposed to the Federal Highway Administration the use of High
Performance Steels (HPS)-70W for a Demonstration Bridge Project that had two components. The first component focused on
the design of an HPS-70W bridge for a specific site, Ford City, PA. The second component was to explore using nontraditional
welding procedures to weld the butt joints in HPS-70W girders in the bridge. It is the second aspect of the demonstration project,
the use of non-traditional welding procedures for HPS-70W girders in the Ford City Bridge, that is the focus of the report. The
proposed innovation in welding procedures was to weld the HPS-70W flange splices in the bridge with traditional A588 steel
welding consumables. This produces weldments in which the weld metal undermatches the strength of the base plates to a modest
degree but the cost and reliability of the production process is optimized. This research was to demonstrate that the strength and
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