Succinonitrile (sn) was purified to a superior level using a fractional recrystallization method. The melting point of the best twice recrystallized sn was not raised by following with double distillation. This was tested using differential scanning calorimetry. The peak shape on melting also proved that double distillation after double recrystallization did not improve the quality. Stability and phase diagrams for succinonitrile and glycerol are presented

Kaukler, William F.

English

NASA Technical Reports Server

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CELLULAR MONOTECTIC MODEL SOLIDIFICATION 
79006 --c& 
(hASA-CB- 16 1C27) CLLLDLAB FlCbC'LECTIC HODEL 187-2Z7 17 
: L L l C I F I C A T X  h lSf i iannual  b o f c r t  (Alabama 
cniv.) 10 F A v a i l :  P'IIS EC E O i / M P  A01 
C S C L  070 O n c l a s  
G3/25 G G 7 9 O C 6  
Grant No. NAG8-069 
Semi-annual Report 
William F. Kaukler, Ph.D. 
Principal Investigator 
School of Science 
Chemistry Department 
The University of Alabama in Huntsville 
For 
National Aeronautics and Space Administration 
George C. Marshall Space Flight Center 
35812 Marshall Space Flight Center, Alabama 
June, 1987 
. .  
https://ntrs.nasa.gov/search.jsp?R=19870014284 2020-03-20T10:27:33+00:00Z
I 
Cellular Monotectic Model Solidification Report by William F. Kaukler - UAH 
Cellular Monotectic Model Solidification 
Semiannual Report June 1987 
by Dr. William F. Kaukler UAH 
Introduction: 
This report summarizes the most recent experiments and 
results from this project. A s  the work is near completion, a 
brief compilation of points will be made as a more detailed 
report will soon be made that spells out everything. 
Since the last report, more experiments were run, suc- 
cinonitrile was purified to a superior level of purity, the 
phase diagram for succinonitrile and glycerol was filled out 
(figure 1) and considerable data was analysed on the growth mor- 
phologies that allowed a stability diagram (figure 2) to be 
prepared. 
Experiments: 
Great success was obtained for the fractional recrystal- 
lization purification of sn method I developed. 
point of the best twice recrystallized sn was not raised by fol- 
lowing with double distillation. This was tested using the Dif- 
ferential Scanning Calorimeter in Frazier's lab. The peak shape 
The melting 
on melting was also proving that double distillation after 
double recrystallization did not improve the quality. 
From the first series of runs made with hyperrnonotectic sn- 
glycerol, it was found that thinner cells were needed for the 
1 
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Cellular Monotectic Model Solidification Report by William F. Kaukler - UAH 
satisfactory suppression of the worm morphology so that coupled- 
growth of the two phase interface could proceed and to do so 
even under constitutional breakdown conditions. Special care 
was taken to manufacture as thin a cell as possible. The cells 
were dissected and measurements of the cell gap thickness were 
made. Now with very thin cells, although the micrographs have 
low contrast as a result, the desired cellular structures are 
readily formed. Originally, it was thought necessary to pur- 
posely inoculate the alloy in order to induce cell formation. 
This was to be done to otherwise pure original constituents. 
it appeared that self-degredation of the solution with time and 
heat occurred, unknown impurities may have developed. The con- 
stitutional undercooling of these hypermonotectic alloys will 
still occur because of the excess solute in the solution. 
Monotectic freezing will occur, but rejection of excess glycerol 
into the L1 phase will lead to constitutional undercooling, in 
theory. The attempt to grow the alloy inoculated with the 
orange-colored azobenzene, was a failure. The azobenzene did 
not significantly segregate to make the interface colored into 
clear solid and orange liquid as expected. I could expect this 
because experiments showed the azobenzene has a higher affinity 
for the glycerol than the sn. The inclusion of the azobenzene 
did not significantly alter the growth morphology, although 
measurements were not made to test this. 
As 
It seemed that the approach to cellular breakdown solely 
from excess solute was the best one. The stability diagram will 
2 
Cellular Monotectic Model Solidification Report 
7 
by William F. Kaukler - UAH 
bear this out ( probably ). To fine tune this approach some 
measurements are needed to determine more accurately the planar 
to cellular transition for two hypermonotectic compositions. 
This will allow the appropriate equations to be used and see 
which mechanism is expected ( Hellawell or Parr ). The two com- 
positions are needed to determine if the cellular to planar 
transition is indeed composition dependent. This should lead to 
a sloped line delineating the planar-cellular transition points 
at various compositions. The best compositions to try will be 8 
and 16 weight per cent glycerol. The reasons more detailed 
measurements of this transition have not been made is simply 
that the study was one or cellular growth and not planar. 
The collection of micrographs, when laid out by G / R ,  show 
that the cell size relationship can also be obtained. This 
series of measurements will be done to round out the study and 
make the final paper more of a study of cellular monotectic in- 
terfaces rather than of mechanism determination for alignment. 
The graphic tablet and computer will serve this measurement 
well. 
Arrangements have been made with Frank Szofran to perform 
FTIR analysis on grown cells in order to see if segregation oc- 
curs and is so, by how much. This work will need scheduling 
with other users. It will help in the analysis of planar- 
cellular transitions and the theories for cell formation in 
monotectic systems. I have the absorption curve for sn and 
should easily find the one for glycerol. The instrument may be 
3 
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Cellular Monotectic Model Solidification Report by William F. Kaukler - UAH 
sensltive enough to show the decomposition products in the cell. 
Theory: 
Diagrams to differentiate the two mechanisms for particle 
alignment were prepared. These are shown in figures 3 and 4 .  
They do not illustrate the results obtained experimentally. En- 
hanced photographs and another diagram will be used to show our 
results. The results are not definitive for the case where 
large liquid particles could be pushed and subsequently undergo 
Rayleigh breakdown into aligned spheres. In order to see if 
this could happen, the particle pushing theories have been 
developed. The results, although not reproducible with the 
literature values will help when properly refined. The tests of 
the theories do not match the literature because the data used 
in the literature only fits the model they propose. A general 
model does not exist as yet. Also, and more importantly, the 
data in the models were for dense, solid particles generally of 
a metal type. In our case, the viscosities and thermal conduc- 
tivities are not metal-like at all. The best models work with 
metallic spheres pushed by an organic solid. This way, specific 
thermal and interfacial conditions are set. These models do not 
have applicability to our systems either the organic or the me- 
tal monotectic. The Kaukler model may be the easiest to prove 
useful, but to extend the model to include gravity effects may 
take more time. 
In an effort to develop the models for our organic system, 
4 
Cellular Monotectic Model Solidification Report by William F. Kaukler - UAH 
considerable time was spent collecting the raw data for the sys- 
tem and developing the solution parameters from the pure com- 
ponent parameters. This is not easily done for viscosities or 
diffusion coefficients for organics. It may be easier to 
measure the solution viscosity for a couple of points and fit 
the solution models to those points. 
time and is important to the study. 
This may not take much 
Calculations were made to calibrate the gradient stage 
thermal gradients that develop in the cell for different growth 
rates and thermal inputs to the hot and cold blocks. This 
analysis was needed to obtain the proper G for the G/R analysis 
that is crucial to this study. 
could be performed and would consume more time than is ap- 
propriate for this short project. The thermal characterization 
will also permit prediction of operating conditions other than 
those that have been used to date. 
rates would be desired, for example, a steeper gradient could be 
employed to stabilize the interface. 
determination of the planar to cellular transition since the 
long times of growing at l o w  speeds needed for planar growth can 
accelerate solution decomposition. Higher rates should make 
decomposition a smaller problem. Note however that higher rates 
also mean that diffusion rate sensitivity could also play a part 
in the analysis. 
Little mathematical analysis 
Thus, if growth at higher 
This is important in the 
This opens up a new question about what rate 
of growth can sustain 
be a need to try very 
cell growth at low gradients. There may 
low G and high R but still have the same 
5 
Cellular Honotectjc Model Solidification Report by William F. Kaukler - UAH 
G/R in further experiments. 
Dr. William Kaukler - UAH 
6 
? 
by W i l l i a m  F .  Kaukler - UAH Collular Monotactic Modal So l id i f i ca t ion  Report 
STABILITY DLAGRAM 
SUCCINONITRILE-GLYCEROL SYSTEM 
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16 
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14 
13 
12 
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8 
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5 
4 
3 
2 
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Cellular Monotectic Model Solidification Report by W i l l i a m  F. Kaukler - UAH 
SUCCINONITRILE-GLYCEROL PHASE DIAGRAM 
COMBINED DATA 
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Cellular monotectic model solidification

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