We ran a GaAs solution growth experiment using NASA Get Away Special program. This was a preliminary study for large scale experiments those planned to be done aboard Spacelab D-2 and Japanese free flyer SFU. Diffusion-controlled crystal growth in microgravity were achieved using our sample setup which eliminated free surface from the solution. Type II striations as traces of macrosteps occurred in both space-and ground grown crystals, but, did not occur in center region of space-grown crystal.
Al-Pb-Bi system is a typical system with immiscible two liquid solutions. Above the monotectic reaction temperature, Al-rich liquid solution and (Pb, Bi)-rich liquid solution coexist in the equilibrium. In this molten state, (Pb, Bi)-rich liquid drops can easily segregate gravitationally because of a large deference in density between two liquid solutions. On the other hand, in microgravity, there is no gravitational segregation and uniform dispersion of (Pb, Bi)-rich particles can be expected. In this paper, microstructural study on AI-Pb-Bi alloy molten and solidified in microgravity environment and in the terrestrial one is reported. Microgravity experiment was carried out by utilizing a parabolic flight of airplane (Mitsubishi, MU-300). In this flight experiment, microgravity environment of about 20 seconds was obtained. Furthermore, another objective of this study is to establish a basic technique for high temperature and short durational experiment in microgravity.
The Convection Diffusion Unit (CDU), which is going to be flown in 1994 aboard the planned IML-2 mission, will use electrolysis and a pH indicator to track diffusion and fluid flow within an experimental container. This paper presents results from a set of preliminary low-gravity experiments used to confirm the effectiveness of this method for tracing fluid motions.Pitch of the airplane as well as acceleration along all three axes were measured together with a video of the fluid, in which movement was clearly indicated by the dye. Large rotations of the fluid were observed not only during the parabolic sections of the flight, but before and after as well. Magnitudes of the rotations were clearly seen to differ according to the pitch of the nose, acceleration of the airplane, and density distribution of the liquid.
A fluid physics equipment was developed for in-situ monitoring of fluid phenomena under the microgravity condition dedicated for use at Kamisunagawa Dropshaft. Schlieren optics was designed to observe distribution of temperature and concentration in the fluid. Light scattering device was also available for the diffusion on the interface, nucleation and phase separation phenomena. The restriction of Rayleigh convection in an experimental cell was shown as an example of a free fall.