Effect of oxide films on hydrogen permeability of candidate Stirling heater head tube alloys
High pressure hydrogen has been selected as the working fluid for the developmental automotive Stirling engine. Containment of the working fluid during operation of the engine at high temperatures and at high hydrogen gas pressures is essential for the acceptance of the Stirling engine as an alternative to the internal combustion engine. Most commercial alloys are extremely permeable to pure hydrogen at high temperatures. A program was undertaken at NASA Lewis Research Center (LeRC) to reduce hydrogen permeability in the Stirling engine heater head tubes by doping the hydrogen working fluid with CO or CO/sub 2/. Small additions of these gases were shown to form an oxide on the inside tube wall and thus reduce hydrogen permeability. A study of the effects of dopant concentration, alloy composition, and effects of surface oxides on hydrogen permeability in candidate heater head tube alloys is summarized. Results showed that hydrogen permeability was similar for iron-base alloys (N-155, A286, IN800, 19-9DL, and Nitronic 40), cobalt-base alloys (HS-188) and nickel-base alloys (IN718). In general, the permeability of the alloys decreased with increasing concentration of CO or CO/sub 2/ dopant, with increasing oxide thickness, and decreasing oxide porosity. At high levels of dopants, highly permeable liquid oxides formed on those alloys with greater than 50% Fe content. Furthermore, highly reactive minor alloying elements (Ti, Al, Nb, and La) had a strong influence on reducing hydrogen permeability.
- Research Organization:
- National Aeronautics and Space Administration, Cleveland, OH (USA). Lewis Research Center
- DOE Contract Number:
- AI01-77CS51040
- OSTI ID:
- 5199321
- Report Number(s):
- DOE/NASA/51040-38; NASA-TM-82824; CONF-810203-17; ON: DE82014953
- Resource Relation:
- Conference: 110. AIME annual meeting, Chicago, IL, USA, 22 Feb 1981
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
33 ADVANCED PROPULSION SYSTEMS
COBALT BASE ALLOYS
PERMEABILITY
HYDROGEN
ADDITIVES
DIFFUSION
IRON BASE ALLOYS
NICKEL BASE ALLOYS
STIRLING ENGINES
AUTOMOBILES
CARBON DIOXIDE
CARBON MONOXIDE
EXPERIMENTAL DATA
HEAT EXCHANGERS
WORKING FLUIDS
ALLOYS
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
COBALT ALLOYS
DATA
ELEMENTS
ENGINES
FLUIDS
HEAT ENGINES
INFORMATION
IRON ALLOYS
NICKEL ALLOYS
NONMETALS
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
VEHICLES
360104* - Metals & Alloys- Physical Properties
330201 - External Combustion Engines- Stirling Cycle