AN EVALUATION OF THE CORROSION AND OXIDATION RESISTANCE OF HIGH-TEMPERATURE BRAZING ALLOYS. Period covered: July 1954-September 1955
Many of the brazing alloys which were investigated were highly promising for sodium-to-air radiator service. Alloy systems of Ni-- Si-- B, Ni-- Cr-- Si-- B, and Ni-- Cr-- Si were especially favorable. Precious-metal alloys were, in general, severely attacked by sodium, as were many of the silicon-free, chromium- free, phosphorus-bearing alloys. Alloys containing manganese, tin, or copper exhibited poor resistance to oxidation at 1500 deg F. In most cases, oxidation was more pronounced at 1700 deg F. For fused-fluoride-tosodium heat exchanger service, the alloy systems Ni-- Cr-P, Ni-- Cr-- Si-- B, Ni-- Si-- B, and Ni-- Ge-- Cr-- Si show promising corrosion resistance. Although the Ni-- Cr-- Si alloy was compatible with sodium, it was severely attacked by the fluoride bath. The binary alloy 88 Ni-- 12 P (alloy A-10) was incompatible with sodium but possessed good resistance to fluoride attack. Tests seem to indicate that complex alloy systems containing varying percentages of silicon and phosphorus as minor constituents may be compatible with both sodium and the fused salts, whereas the binary alloys exhibited compatibility with only one of these testing media. The only brazing alloys found to be compatible with fused sodium hydroxide were precious-metal alloys such as 82 Au-- 18 Ni. In evaluating the corrosion and the oxidation resistances of a brazing alloy for a specific application, emphasis was placed on the seesawcorrosion and cyclic-oxidation studies, since these tests more nearly simulate the expected operating conditions than do the static tests. It must be remembered, however, that before a brazing alloy is selected for a given operation it should be tested further under the conditions which would closely simulate service conditions. (auth)
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- DOE Contract Number:
- W-7405-ENG-26
- NSA Number:
- NSA-14-001804
- OSTI ID:
- 4227334
- Report Number(s):
- ORNL-1934
- Resource Relation:
- Other Information: Decl. Oct. 9, 1959. Orig. Receipt Date: 31-DEC-60
- Country of Publication:
- United States
- Language:
- English
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