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Particle Engulfment and Pushing by Solidifying InterfacesResults of the directional solidification experiments on Particle Engulfment and Pushing by Solidifying Interfaces (PEP) conducted on the space shuttle Columbia during the Life and Microgravity Science Mission are reported. Two pure aluminum (99.999%) 9 mm cylindrical rods, loaded with about 2 vol.% 500 micrometers diameter zirconia particles were melted and resolidified in the microgravity (microg) environment of the shuttle. One sample was processed at step-wise increased solidification velocity, while the other at step-wise decreased velocity. It was found that a pushing-to-engulfment transition (PET) occurred in the velocity range of 0.5 to 1 micrometers. This is smaller than the ground PET velocity of 1.9 to 2.4 micrometers. This demonstrates that natural convection increases the critical velocity. A previously proposed analytical model for PEP was further developed. A major effort to identify and produce data for the surface energy of various interfaces required for calculation was undertaken. The predicted critical velocity for PET was of 0.775 micrometers/s.
Document ID
19990099263
Document Type
Preprint (Draft being sent to journal)
Authors
Stefanescu, Doru M. (Alabama Univ. Tuscaloosa, AL United States)
Juretzko, Frank R. (Alabama Univ. Tuscaloosa, AL United States)
Dhindaw, Brij K. (Alabama Univ. Tuscaloosa, AL United States)
Catalina, Adrian (Alabama Univ. Tuscaloosa, AL United States)
Sen, Subhayu (Universities Space Research Association Huntsville, AL United States)
Curreri, Peter A. (NASA Marshall Space Flight Center Huntsville, AL United States)
Date Acquired
August 19, 2013
Publication Date
January 1, 1998
Subject Category
Materials Processing
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.