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BRAZING ALLOYS IN LIQUID METALS AND
IN FLUORIDE FUEL MIXTURES
D. H. Jansen
Two lnconel thermal-convection loops with in-
serts brazed with 70% Ni-13% Ge-11% Cr-6% Si
brazing alloy in the hot-leg section were operated
for 500 hr. In one loop NaK (56-44 wt %) was
circulated, and in the other the fuel mixture (No.
44) NaF-ZrF4-UF, (53.5-406.5 mole %) was cir-
culated. The hot-leg sections of these loops
consisted of seven lnconel segments brazed with
the alloy being tested, This type of thermal-
convection loop test assembly was illustrated
previously.' The hot legs of both loops were
3.2. GENERAL CORROSION STUDIES
E. E. Hoffman
PERIOD ENDING JUNE 70, 1956
maintained at a temperature of 1500OF for the
duration of the tests. The cold-leg temperature
of the loop that circulated NaK was maintained
at 1165OF, and the cold-leg temperature of the
loop that circulated the fuel mixture was held
at 115OOF.
The inner walls of the lnconel segments and two
samples from each brazed joint were examined
after the tests for evidence of attack. The results
of the examinations are summarized in Table 3.2.1.
The attack of the fuel mixture on the brazed
joints averaged about 5 mils. Typical samples
are shown in Fig. 3.2.1. The attack of the fuel
mixture on the lnconel tubing adjacent to the
joint ranged from 4.5 mils in the coolest (1450OF)
portion of the hot leg to 9 mils in the hottest
(1500OF) portion of the hot leg, as shown in
'0. H. Jansen, ANP Qua?. Prog. Rep. Dec. 10. 1955,
ORNL-2012, p 113, Fig. 5.9. Fig. 3.2.1. A slight trace of metallic crystals
TABLE 3.2.1. RESULTS OF THERMAL-CONVECTION LOOP TESTS OF INCONEL SEGMENTS BRAZED
WITH 70% Ni-13% Ge-11% Cr-6% Si BRAZING ALLOY
Operating time: 500 hr
Brazed Joint Metallographic Notes
No.
Effect of Fuel Mixture Effect of NaK
12 Brazing alloy attacked to a depth of 4.5 mils;
adjacent Inconel tube attacked to a maxi-
mum depth of 9 mils
2 Brazing alloy attacked to a depth of 4.5 mils;
spotty, nonuniform attack on tube wall to a
3 Brazing alloy attacked to a d
spotty attack on tube wall t
7.5 mils
Is;
No attack apparent; large crack through brazing
alloy to center of tube wall
Attack to a depth of 0.5 mil
No attack; large crack, as in joint 1 above
lloy attacked to a depth of 3 mils; Attack to a depth of 0.5 mil; large crack in
tube wall attacked to a depth of 4.5 mils
Brazing alloy attacked to a depth of 5 mils;
tube wall attacked to a depth of 4.5 mils
brazing alloy
Large crack In brazing allay
6** Brazing alloy attacked to a depth of 5 mils; Attack to o depth of 1.5 mils; some porosity in
tube wall attacked to o depth of 4.5 mils brazing alloy; no large cracks
*Brazed joint No. 1 was locoted at the hottest (1500°F) portion of the hot leg.
**Joint No. 6 was located at the coolest (145OOF) portion of the hot leg.
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