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Particle Engulfment and Pushing Micro-Gravity Experiments and Mathematical ModelingThe phenomenon of interaction of particles with solid-liquid interfaces that results in particle engulfment or pushing (PEP) has been Studied since mid 1960's. While the original interest stemmed from geology applications (frost heaving in soil), it was recognized early that understanding particle behavior at solidifying interfaces mi ht yield 9 practical benefits in other fields. In metallurgical applications the issue is the location of particles with respect to grain boundaries at the end of solidification. Considerable amount of experimental and theoretical research was lately focused on applications to metal matrix composites produced by casting; or spray forming techniques. Another application of PEP is in the growing of Y1Ba2CU3O7-delta(123) superconductor crystals from an undercooled liquid. The oxide melt contains Y2Ba1CU1O5 (211) precipitates, which act as flux pinning sites. The paper presents results of PEP micro-gravity research performed by the authors on two shuttle missions using metallic and polymeric materials. In addition. a discussion on the theoretical aspects of the physics of PEP is offered. Analytical and numerical models for planar solidification interfaces developed by the authors are used to explain the experimental results. Shortcomings of steady-state models are emphasized. A numerical model that includes the effect of the solutal field and of natural convection is introduced. A discussion of phenomena associated with dendritic solidification based on experimental observations is also offered. A mechanism of engulfment is proposed.
Document ID
20000043161
Acquisition Source
Marshall Space Flight Center
Document Type
Conference Paper
Authors
Stefanescu, Doru M.
(Alabama Univ. Tuscaloosa, AL United States)
Catalina, A. V.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Juretzko, F.
(Alabama Univ. Tuscaloosa, AL United States)
Mukherjee, S.
(Alabama Univ. Tuscaloosa, AL United States)
Sen, S.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Date Acquired
August 19, 2013
Publication Date
January 1, 2000
Subject Category
Space Processing
Meeting Information
Meeting: First International Symposium on Microgravity Research and Application
Location: Sorrento
Country: Italy
Start Date: September 11, 2000
End Date: September 15, 2000
Funding Number(s)
CONTRACT_GRANT: NCC8-66
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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