ORNL-1816 - the Molten Salt Energy Technologies Web Site

spectrographic examination was conducted from
the braze alloy-lnconel tube interface inward to
the internal surface of the tube. Solid state dif-
fusion of gold was found to be
it was not possible to detect any trace of gold at
the internal surface, and an abrupt change in the
gold concentration still existed at the braze
al I oy- I nconel interface.
It would appear that this braze alloy is satis-
factory for fused fluoride salt-tosir heat ex-
changer fabrication within the limits of this study.
The use of this alloy in direct contact with fused
salts has also been considered, since the ease of
fabrication of comp nts with moving parts, such
as pumps, would be improved. Although it is
expected that dissimilar metal mass transfer will
prevent this application, a thermal-convection
loop with several 82% Au-18% Ni braze joint
inserts will be operated to experimentally determine
the effect.
BERYLLIUM OXIDE FUEL ELEMENTS
C. E. Curtis L. M. Doney
J. R. Johnson
Metallurgy Division
Beryl1 ium oxide ceramics are being produced,
probably for the first time, by casting from a slip
which is basic. For successful slip casting, a
well-deflocculated slip is necessary, and hitherto
this has been accomplished through the use of an
acid, usually HCI. In comparison, a basically
deflocculated slip is more easily and rapidly
PERIOD ENDING DECEMBER 10,1954
prepared, does not attack the plaster of paris
molds, is not unpleasant to the operaior, and
requires very small amounts of deflocculants.
AS an example, tubes 4 in. long, 0.25 in. in outside
diameter, with a 0.04-in. wall, have been slip cast
recently from beryllium oxide and also from be-
ryllium oxide containing 16.2 wt % of natural
uranium oxide. These tubes are to be used for
tests by the Advanced Design Section of GE-ANP.
To 83.8 g of Be0 (previously milled to about 2p
average particle size) plus 16.2 wt % of UO, were
added about 26 ml of distilled water and 4 ml of a
2% solution of sodium pyrophosphate. After 5 min
of stirring, a creamy slip with a pH of 8 to 9 was
obtained which spread evenly over a glass stirring
rod and flowed off the rod in a smooth stream.
Casting of the tubes required a two-piece plaster
mold with an opening 5 in. long to allow For
shrinkage and trimming to 4 in. and a diameter of
0.29 in. to allow for shrinkage on the diameter.
The deflocculated slip required about 10 to 15 sec
to form a tube of the proper wall thicknesaj in this
mold. The excess slip was drained off, and, after
an additional 3 to 5 min in the mold, the tubes
released readily from the mold and had sufficient
green and dry strength to permit handling.
A firing operation of 1 hr at 170OOC in a hydrogen
or argon atmosphere is necessary to produce the
density of 3.0to 3.4 required. In order to determine
how warpage in firing may be avoided, sotne tubes
are being fired suspended in a furnace, while
others will be fired lying on their sides.
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