NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Toward Understanding Pore Formation and Mobility during Controlled Directional Solidification in a Microgravity Environment Investigation (PFMI)The generation and inclusion of detrimental porosity, e.g., pipes and rattails can occur during controlled directional solidification processing. The origin of these defects is generally attributed to gas evolution and entrapment during solidification of the melt. On Earth, owing to buoyancy, an initiated bubble can rapidly rise through the liquid melt and pop at the surface; this is obviously not ensured in a low gravity or microgravity environment. Clearly, porosity generation and inclusion is detrimental to conducting any meaningful solidification-science studies in microgravity. Thus it is essential that model experiments be conducted in microgravity, to understand the details of the generation and mobility of porosity, so that methods can be found to eliminate it. In hindsight, this is particularly relevant given the results of the previous directional solidification experiments conducted in Space. The current International Space Station (ISS) Microgravity Science Glovebox (MSG) investigation addresses the central issue of porosity formation and mobility during controlled directional solidification processing in microgravity. The study will be done using a transparent metal-analogue material, succinonitrile (SCN) and succinonitrile-water 'alloys', so that direct observation and recording of pore generation and mobility can be made during the experiments. Succinonitrile is particularly well suited for the proposed investigation because it is transparent, it solidifies in a manner analogous to most metals, it has a convenient melting point, its material properties are well characterized and, it has been successfully used in previous microgravity experiments. The PFMI experiment will be launched on the UF-2, STS-111 flight. Highlighting the porosity development problem in metal alloys during microgravity processing, the poster will describe: (i) the intent of the proposed experiments, (ii) the theoretical rationale behind using SCN as the study material for porosity generation and migration and, (iii) the experimental protocol for the investigation of the effects of the processing parameters. Photographs of the flight experimental hardware, and the novel sample ampoule, will be exhibited. The experimental apparatus will be described in detail and a summary of the scientific objectives will be presented.
Document ID
20030060545
Document Type
Conference Paper
Authors
Grugel, Richard N. (NASA Marshall Space Flight Center Huntsville, AL, United States)
Anilkumar, A. V. (Vanderbilt Univ. Nashville, TN, United States)
Luz, Paul (NASA Marshall Space Flight Center Huntsville, AL, United States)
Jeter, Linda (NASA Marshall Space Flight Center Huntsville, AL, United States)
Volz, Martin P. (NASA Marshall Space Flight Center Huntsville, AL, United States)
Spivey, Reggie (Tec-Masters, Inc. Huntsville, AL, United States)
Smith, G. (Alabama Univ. Huntsville, AL, United States)
Date Acquired
August 21, 2013
Publication Date
February 1, 2003
Publication Information
Publication: 2002 Microgravity Materials Science Conference
Subject Category
Space Processing
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

Related Records

IDRelationTitle20030060494Analytic Primary2002 Microgravity Materials Science Conference