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Record Details

Record 28 of 784
Suppression of Marangoni Convection in Float Zones
Offline Availability: Go to Request Form
Author and Affiliation:
Dressler, R. F.(George, Washington Univ., Washington, DC, United States)
Abstract: The basic purpose of this program is to demonstrate by means of an Earth-based 1-g experiment that the undesirable Marangoni (surface tension) convection can be suppressed or significantly reduced by means of gas jets directed tangentially to the free surface of the liquid in a float zone. These jets will establish the tangential shear stress field over the surface which must be adjusted to equal the counter-stress resultant of the Marangoni shear stress which causes the convection. For proposed materials processing in space (o-g), particularly of important, highly reactive semiconductor materials, e.g., silicon, microgravity will virtually eliminate the unwanted thermal-buoyancy convection in the liquid silicon, but will have no effect in reducing the Marangoni convection. Unless this can be sufficiently suppressed by other means, there may be no significant advantages to the proposed space processing of reactive semiconductors. Although some inert gas such as argon must be used for the corrosive liquid silicon, the Earth-based experiment uses air jets and various transparent oils, since the basic principle involved is the same. The first float zone is enclosed in a very small rectangular box with a quasi-planar free surface. Stable Marangoni convection has been achieved and velocities measured photographically. The air jet system with variable velocity and temperature is under construction. Three independent parameters must be optimized to attain maximum suppression: the gas velocity, angle of attack, and gas temperature.
Publication Date: May 01, 1985
Document ID:
19860000644
(Acquired Nov 04, 1995)
Accession Number: 86N10111
Subject Category: ASTRONAUTICS (GENERAL)
Document Type: Technical Report
Publication Information: NASA, Washington Microgravity Sci. and Appl. Program Tasks; p 102-103
Publisher Information: United States
Financial Sponsor: NASA; United States
Organization Source: George; Washington Univ., Washington, DC, United States
Description: 2p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: No Copyright
NASA Terms: CONVECTION; FLOAT ZONES; FREE BOUNDARIES; GAS JETS; INTERFACIAL TENSION; LIQUID SURFACES; LOW GRAVITY MANUFACTURING; MICROGRAVITY; RETARDING; ARGON; BUOYANCY; COMPUTERIZED SIMULATION; MICROGRAVITY APPLICATIONS; PAYLOADS; SEMICONDUCTORS (MATERIALS); SHEAR STRESS; SPACE COMMERCIALIZATION; STRESS DISTRIBUTION
Imprint And Other Notes: In NASA, Washington Microgravity Sci. and Appl. Program Tasks p 102-103 (SEE N86-10053 01-12)
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