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The Interaction Between an Insoluble Particle and an Advancing Solid/Liquid Interface: Micro-Gravity Experiments and Theoretical DevelopmentsThe interaction of an insoluble particle with an advancing solid/liquid interface (SLI) has been a subject of investigation for the past four decades. While the original interest stemmed from geology applications (e.g., frost heaving in soil), researchers soon realized that the complex science associated with such an interaction is relevant to many other scientific fields encompassing metal matrix composites (MMCs), high temperature superconductors, inclusion management in steel, growth of monotectics, and preservation of biological cells. During solidification of a liquid containing an insoluble particle, three distinct interaction phenomena have been experimentally observed: instantaneous engulfment of the particle, continuous pushing, and particle pushing followed by engulfment. It was also observed that for given experimental conditions and particle size there is a critical solidification velocity, V(sub cr), above which a particle is engulfed. During solidification of MMCs pushing leads to particle agglomeration at the grain boundaries and this has detrimental effects on mechanical properties of the casting. Consequently, the process must be designed for instantaneous engulfment to occur. This implies the development of accurate theoretical models to predict V(sub cr), and perform benchmark experiments to test the validity of such models. Although considerable progress has been made in understanding the pushing/engulfment phenomenon (PEP), its quantification in terms of the material and processing parameters remains a focus of research. Since natural convection currents occurring during terrestrial solidification experiments complicate the study of PEP, execution of experiments on the International Space Station (ISS) has been approved and funded by NASA. Extensive terrestrial (1g) experiments and preliminary micro-gravity (mu g) experiments on two space shuttle missions have been conducted in preparation for future experiments on the ISS. The investigated systems included metal-ceramic particles (pure aluminum - zirconia particles) and transparent organic - non-reactive particles (succinonitrile - polystyrene and biphenyl - glass). This paper will discuss the experimental results obtained in both lg and pg conditions and the influence of the natural convection on V(sub cr). A summary of past mathematical models and our recent theoretical developments will also be presented to explain the experimentally observed particle/SLI interaction.
Document ID
20030106624
Acquisition Source
Marshall Space Flight Center
Document Type
Conference Paper
Authors
Catalina, Adrian V.
(Universities Space Research Association Huntsville, AL, United States)
Ssen, Subhayu
(Universities Space Research Association Huntsville, AL, United States)
Stefanescu, Doru M.
(Alabama Univ. Tuscaloosa, AL, United States)
Date Acquired
August 21, 2013
Publication Date
January 1, 2003
Subject Category
Solid-State Physics
Meeting Information
Meeting: Microgravity Transport Processes in Fluid, Thermal, Biological, and Materials Sciences Conference III
Location: Davos
Country: Switzerland
Start Date: September 14, 2003
End Date: September 19, 2003
Funding Number(s)
CONTRACT_GRANT: NAS8-02096
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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