Dendritic Growth of Succinonitrile in Terrestrial and Microgravity Conditions as a Test of Theory.

Dendritic Growth tip velocities and radii of curvature in microgravity

“…Inasmuch as the [NC(CH 2 ) 2 CN], an organic plastic, is an excellent experisupercooling, ⌬, is in practice the independent variable, a mental system for studying dendritic growth as it solidifies more useful transport relation is the following: similarly to the cubic metals; i.e., with a molecularly "rough" solid-liquid interface, but also has a convenient melting al. [14] were consistent with a scaling constant of * Ϸ 0.019, provides an incomplete description of steady-state dendritic which was in reasonable agreement with the theoretical value growth insofar as it specifies only the Péclet number. The 0.025.…”

“…The other end of the stinger, the Designated the IDGE, the first flight, manifested on the aperture, where dendrites emerge into the central volume of United States Microgravity Payload-2 (USMP-2) mission, the chamber, is shaped like the tip of a fountain pen. This was launched and operated on the Space Transportation design helps produce, and eventually isolates, a single leadSystem-62 (STS-62) on March 4 through 14,1994. Three ing dendrite, thereby reducing the time needed for the denof the authors of this article have published elsewhere an drite tip to achieve steady-state conditions.…”

“…This joining and sealing method protects the high purity of The experimental techniques for accomplishing simultathe SCN test material from contamination by avoiding the neous kinetic and morphological measurements for SCN introduction of any solder, fluxes, elastomers, or other subdendrites are now well established. [14,15] However, the constances that might, over time, contaminate the SCN during straints of an autonomous, or tele-operated, microgravity the long stowage period preceding the launch. [26] experiment required extensive modification of established…”

“…(⌬h f /c p ), in terms of the Péclet number, P ϭ VR/(2␣), where A great deal of the more recent experimental work con⌬h f is the molar latent heat, c p is the constant pressure molar cerning dendritic growth has been performed using succispecific heat, ␣ is the thermal diffusivity of the melt phase, nonitrile (SCN) since Glicksman et al [14] first grew and and E 1 (P) is the first exponential integral function. This photographed SCN dendrites in the early 1970s.…”

Shape parameter for a non-axisymmetric isothermal dendrite

“…6 of Ref. [9]). For P much below 0.004, the experimental data actually lie above the Ivantsov curve, possibly due to the effects of finite container size and/or convection [18,19].…”