Powder Preparation under Reduced Gravity

At the peak of the high-temperature superconductor (HTSC) ceramic hype during the late 1980s (see Chapter 9), the quest for YBCO (yttrium barium copper 

In order to obtain information on the general trends of the kinehcs of particle precipitation from aqueous solutions in the absence of gravity, a simple model system was adopted by Heimann in 1989 based on the hydrolyhc polycondensation of titanium tetraisopropoxide, Ti(iPrO)4, dissolved in water-free toluene with 5% isopropanol added, and injected into an aqueous soluhon. A short period of microgravity (20-30 s) was achieved during a parabolic flight trajectory of an aircraft. 

The experiment was statistically designed according to a Box-Behnken response surface methodology with three parameters, and flown by NASA on a KC 135 plane in October 1989 under the direction of the Canadian Space Agency (CSA). 

The reactions occurring during hydrolysis are rather complex, but can be summarized (Yoldas, 1986) as  

1) In fact, the reduced gravity achieved during the flight of the aircraft along a parabolic trajectory was not exactly zero, but about 10 g. 

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