CORROSION ANALYSIS: LOW-CAPACITY PUMP. Large Sodium Pump Study, Phase II. Page: 24 of 30

CORROSION AND WEAR DATA FOR BEARING MATERIALS

Bearing materials suitable for operation in liquid sodium between 900 and
1200*F, were identified in the Large Pump Study Phase I[4-14 as Haynes
Stellites 1, 3, and Star J. Selection was based on adequacy of properties
and past experience. Corrosion and wear data for these materials in liquid
sodium are limited and consist mainly of screening test data and short-term,
low-temperature, pump operating experience.
Friction and Wear
An extensive evaluation of the friction and wear characteristics of numerous
material combinations is currently under way at the Liquid Metals Engineering
Center[151. Discs of one material are rotated against flat-faced pins of a
second material, at wear path velocities of about 2.5 to 4 cm/sec, while
the pressure between the disc and the pins is maintained at 8.65 Kg/cm
(123 psi). Tests are performed in flowing sodium at 1200*F (650*C) with an
oxygen level of 20 to 30 ppm. Preliminary information from this work is
given in Table 4. The recommended materials are shown in various combina-
tions with themselves and other Stellites, and some data for the Colmonoy
alloys are also included for comparison. The specific wear rate values,
reported as the volume of material removed per unit length of wear path per
unit load, cm3/cmkg, show that Stellite combinations are an order of magni-
tude better than Colmonoy combinations.
A similar program at UKAEA , using a radiused pin held against a rotating
cylinder, showed that the amount of wear experienced by Stellite 1 -
Stellite 1, Stellite 3 -Stellite 1, and Stellite 6 - Stellite 1 combinations
increased with increasing temperature (Figure 8). Between 392*F (200*C)
and 1112*F (600*C), the specific wear rate increased from 8 X 10-13 cm3/cmKg.
Bearing loads of 2 and 4.5 Kg were used; but, actual stresses were not
reported. Tests were again run at low speeds (3 to 5 cm/sec).
Corrosion Data
Sodium corrosion data for Stellites, or indeed any other bearing materials,
are extremely limited, since unlike structural materials, Stellites have
not been the subject of extensive corrosion studies. The data available have
been generated in screening tests of short duration, such as tilting furnace
experiments.
Baumgartner reported data for Stellites 1, 6, 12, and 21 in 20 to 40 ppm
oxygen sodium up to 1400*F. Stellites 6 and 93 (iron base) hard facings
were tested in NaK at 1200*F[18]. Stellite 6 performed well with no metallo-
graphically observable attack in 100 hours and a recorded weight loss of
about 0.6 mg/cm2 under the same conditions.

18

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Thomas, K.C. & Shiels, S. CORROSION ANALYSIS: LOW-CAPACITY PUMP. Large Sodium Pump Study, Phase II., report, October 31, 1970; Madison, Pennsylvania. (https://digital.library.unt.edu/ark:/67531/metadc1034653/m1/24/ocr/: accessed April 24, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.

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