CORROSION OF MATERIALS BY LITHIUM AT ELEVATED TEMPERATURES

Thesis/Dissertation · Mon Mar 23 00:00:00 EST 1959

OSTI ID:4750888

Hoffman, E E

Thesis submitted to Univ. of Tennessee. An investigation was made to determine the corrosion resistance of various materials to lithium in the temperature range 1000 to 1832 deg F (538 to 1000 deg C) in both static and dynamic systems. Evaluation of test results was based primarily on metallographic examination, weight-change data, dimensional changes, and chemical analyses. The static tests were conducted in constant-temperature systems in the range 1500 to 1900 deg F (816 to 1038 deg C) for time periods of 100 to 400 hours. Pure metals, alloys, cermets, and ceramics were included in the studies. The following materials exhibited good corrosion resistance in static systems: beryllium, chromium, cobalt, niobium, iron, molybdenum, rhenium, tantalum, titanium, tungsten, vanadium, zirconium; cobalt-, iron-, and zirconium-base alloys; cobalt-bonded tungsten carbide cermets, and the ceramic carbides of chromium, titanium, and zirconium. Materials which showed promise in static tests and which were available in the form of tubing or pipe were tested in dynamic systems containing temperature gradients. Lithium flow velocities of one- to-eight feet per minute and temperature differences of 100 to 600 deg F (56 to 333 deg C) between hot and cold sections were used. Hot-zone temperatures ranged from 1000 to 1900 deg F (538 ot 1038 deg C), and test periods varied between 100 and 3000 hours. Inconel, stainless steels, niobium, molybdenum, vanadium, and zirconium were the materials studied. All but Inconel and the stainless steels were found to be satisfactory at hotzone temperatures of at least 1500 deg F (816 deg C). Niobium and the stainless steels were investigated extensively. Niobium was observed to undergo a type of intergranular corrosion attack in preliminary static and dynamic tests. This type of attack was found to be particularly severe in and near weld zones. A systematic investigation reveaied that the attack was due primarily to contamination of the metal by oxygen. Subsequent tests showed that niobium containing less than 100 ppm oxygen was completely resistant to attack in static systems at temperatures as high as 1800 deg F (982 deg C) and in dynamic systems at temperatures as high as 1600 deg F (871 deg C) and for time periods up to 300 hours. The austenitic and ferritic stainless steels containing less than 0.12 wt % carbon normally exhibited good corrosion resistance in static systems. Occasionally, intergranular penetration was observed in both static and dynamic tests with austenitic stainless steels. This type of attack was found to be particularly severe under the combined circumstances of high-nitrogen-content lithium and precipitated grain-boundary carbides. The highcarton ferritic stainless steels, such as type 446, always exhibited excessive grain-boundary attack. Both the ferritic and austenitic stainless steels exhibited temperature-gradient mass transfer in flowing, nonisothermal systems at hot-leg temperatures of 1300 F (704 deg C) and above. In thermal convection loops, lithium flow velocity was found to have a major influence on the rate of mass transfer in the range of velocities studied in this investigation. An analysis of the data indicated that this effect was primarily attributable to the velocity dependence of liquid diffusion in the hot leg. In order to determine the effects of nitrogen and oxygen contamination of lithium on its corrosiveness, sampling techniques and methods of purifying lithium were developed. The solubilities of lithium oxide and lithium nitride in molten lithium were also determined. (auth)

• Research Organization: Oak Ridge National Lab., Tenn.
• DOE Contract Number: W-7405-ENG-26
• NSA Number: NSA-17-006570
• OSTI ID: 4750888
• Report Number(s): ORNL-2674
• Resource Relation: Other Information: Thesis submitted to Univ. of Tennessee. Orig. Receipt Date: 31-DEC-63
• Country of Publication: United States
• Language: English

Related Subjects

METALS, CERAMICS, AND OTHER MATERIALS
ALLOYS
ALUMINUM ALLOYS
CERAMICS
CERMETS
CHROMIUM ALLOYS
CORROSION
FLUID FLOW
HIGH TEMPERATURE
IMPURITIES
INCONEL ALLOYS
LIQUID METALS
LITHIUM
LITHIUM NITRIDES
LITHIUM OXIDES
METALLOGRAPHY
METALS
NICKEL ALLOYS
NIOBIUM ALLOYS
NITROGEN
OXYGEN
QUALITATIVE ANALYSIS
SOLUBILITY
STAINLESS STEELS
TEMPERATURE
TITANIUM ALLOYS
VELOCITY
WEIGHT